Canadian/US Expert Consensus

Eight physical therapists who instruct students on the use of EPAs within physical therapy programs in Canada and the United States and who are experienced in EPA practice were surveyed for their recommendations on commonly cited EPA contraindications. Many of these individuals are independent investigators with active research programmes in the field of EPA use, and their work is published in peer-reviewed journals. These eight individuals were invited to respond to a given list of conditions for the selected EPAs (see Appendix 1). For some conditions or specific body areas, fewer than eight responses were received. For the purposes of the present discussion, consensus among these experts is expressed as percent (raw) agreement that the particular EPA should not be used on patients with a given condition (i.e., that it is contraindicated). Raw percent agreement was determined by dividing the number of experts who stated that a condition was contraindicated by the total number of experts who provided a response. Experts were encouraged to give no response when they were unsure, rather than making an uninformed decision. When an expert did not register a response, the denominator and raw percent agreement were adjusted accordingly. Thus, higher percent agreement in this consensus process was considered stronger support for a recommendation that the EPA should be contraindicated for the given condition.

Resources

A total of 17 textbooks that included contraindications and precautions for one or more of the six EPAs addressed in this document were identified by reviewing the reference lists of English-language journal articles and by contacting academic and clinical colleagues. The most recent edition of each text was obtained by contacting publishers (see Appendix 2). Using these resources, a list was compiled of all medical conditions, scenarios, and body areas mentioned as contraindications. Percent (raw) agreement of contraindications for text resources was calculated as the number of resources listing the condition as a contraindication divided by the total number of resources that included a section on contraindications and precautions for the particular EPA. Where a textbook did not mention a particular condition or recommend treating the condition with caution (a precaution), it was assumed that the authors considered the condition safe to be treated (i.e., not contraindicated). Higher raw percentage values were considered to indicate stronger agreement among textbook resources that the EPA is contraindicated for a given condition. Overall, the consensus among authors of textbooks was quite low for most EPAs.

Rationale

A key feature of these guidelines is a discussion of the underlying biophysical mechanisms and concerns related to each recommendation. When adverse reactions are theorized but no evidence of such an adverse effect could be found in the literature, the rationale is hypothesized based on known physical principles and biological effects of the relevant EPA. In cases of controversy as to the relative risks and benefits of using an EPA, alternative viewpoints are presented. It is hoped that this information will assist clinicians in making their own decisions about EPA use in particular circumstances.

Research Evidence

Original articles addressing contraindications, precautions, and adverse reactions related to use of EPAs were identified by searching several electronic databases (CINAHL, Medline, and PubMed) for papers published between 1966 and January 2007. A secondary search of all references in book chapters, review articles, and articles located via the database search was also performed. An updated search was performed in March 2008 using the CINAHL, EMBASE, EBM Reviews, and PubMed databases and the following search terms: contraindication, adverse reaction, side effect, complication, safety, rehabilitation, physical therapy, physiotherapeutic, ultrasound, therapy, laser, LLLT, LILT, light, heat, cold, cryotherapy, electrical stimulation, TENS, EMS, high voltage pulsed current, HVPC, interferential current, IFC, and electrotherapy. The studies included in the literature review were original research articles, experimental research (animal models, cell culture studies, and trials using healthy human subjects), and clinical reports (case reports, Phase I clinical trials that reported adverse reactions as a primary outcome) published in English. Primary sources are referred to whenever possible in these guidelines to support or refute the suggested contraindication, precaution, or recommendation for safe practice.

Recommendations

The authors have made a clear recommendation for each condition considered here. These recommendations are based on specific criteria that have been applied consistently across all EPAs and all conditions considered (see chart below). Criteria include the seriousness of the potential adverse reaction, the level of research evidence supporting the recommendation, and the degree of consensus among North American and international experts. Because consensus among experts and resources was generally poor, however, the consensus data seldom informed the authors' recommendation for practice. Note that the authors have chosen to consider any condition that has the potential for a serious adverse reaction as a contraindication, regardless of the research evidence.

3-2 Malignancy

Recommendation	Pulsed and continuous ultrasound should not be used over suspected or confirmed malignancy. Abnormal growth should be regarded as malignant until diagnosis has been confirmed. Use caution when a patient with a history of cancer within the last 5 years has pain of undiagnosed origin.
Rationale	Sound waves applied to tumour cells can stimulate growth and induce new blood-vessel growth, which helps provide fuel for further tumour growth and potentially promotes metastases.
Research Evidence MODERATE	Ultrasound increased tumour growth and the incidence of metastases in animal models; effects were thought to be due to ultrasound-enhanced angiogenesis.9–16 The literature is not consistent in these findings. Therapeutic ultrasound equipment should not be used to induce hyperthermia for the purpose of tumour ablation.17–18

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3-3 Active Epiphysis, Myositis Ossificans

Recommendation Active EpiphysisMyositis Ossificans	Continuous and pulsed ultrasound can be used over bone-growth plates in adolescents using low intensities. There should be no discomfort during or after treatment. Continuous and pulsed ultrasound should not be applied in the vicinity of myositis ossificans.
Rationale	Ultrasound over unfused epiphyseal growth plates may alter bone growth. About 75% of ultrasound energy is reflected at tissue/bone interfaces, and the transmitted portion is largely absorbed by periosteum. Intensities that could produce unwanted bone growth are likely to cause pain as a result of the periosteal absorption. Therefore, ultrasound over bone using parameters and techniques that avoid painful stimulation is unlikely to produce adverse effects. Ultrasound over ectopic bone (myositis ossificans, hypertropic ossification) could stimulate further bone growth and exacerbate impairments.
Research Evidence MODERATE	Early studies in animal models that demonstrated abnormal bone growth following ultrasound used extraordinarily high ultrasound intensity and a stationary sound head.19–26 The pre-clinical research is therefore not relevant to normal clinical practice. Ultrasound stimulates osteoblast function and has been shown to promote repair of bone fractures. However, the effective parameters (1.5 MHz, 0.15 W/cm2, SATP, and a mark:space ratio of 1:4) are different from those typically used with therapeutic ultrasound.27

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3-4 Plastic and Cement Implants

Recommendation US Cont US Pulsed	Continuous ultrasound should be avoided directly over joint replacements or prostheses constructed of cement or plastic. Low-intensity pulsed ultrasound may be used with caution over areas containing plastic/cement implants.
Rationale	Most plastic materials have a high coefficient of ultrasound absorption. Methyl methacrylate cement and plastic are rapidly heated by ultrasound. Water-saturated acrylic bone cement used to fixate endoprostheses becomes rubbery and soft if heated to 60–70°C. However, this degree of heating would never occur using typical therapeutic ultrasound.
Research Evidence MODERATE	Therapeutic ultrasound applied to animal models has been shown to alter the mechanical properties of plastic and cement components of surgical implants.28–31

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3-5 Metal Implants

Recommendation	Continuous and pulsed ultrasound are not contraindicated over metal implants. Application requires precautions to avoid standing waves and unstable cavitation.
Rationale	Metal reflects about 90% of incident ultrasound—slightly more than is reflected by bone.
Research Evidence STRONG	Metal is not heated by ultrasound, and sound waves do not loosen screws or plates.31–36

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3-6 Electronic Devices

Recommendation	Continuous and pulsed ultrasound should not be applied directly over the site of implanted pacemakers or other electronic devices (defibrillators, neuromuscular devices). This means that ultrasound should be used only when the exact location of device components is known. This contraindication applies regardless of whether or not the device is in use. Monitor patients closely when applying ultrasound at sites remote from the components of implanted systems.
Rationale	Sound waves reflected at a device–tissue interface could possibly cause tissue heating; the risk of an adverse effect would depend on the location of the implanted components and the intensity and duration of the exposure. The CSP guidelines recommend that only thermal ultrasound (continuous mode) be avoided over electronic implants.
Research Evidence LOW	The effect of therapeutic ultrasound waves on function of pacemakers and electronic stimulators is not known. No adverse effects have been reported in the literature. Various organizations have issued alerts about the definite risk of serious injury or death if patients with implanted electrical leads are exposed to ultrasound diathermy;37–39 however, ultrasound diathermy is not a device used by physiotherapists.

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3-7 Active Deep Vein Thrombosis, Thrombophlebitis

Recommendation	Continuous and pulsed ultrasound should not be applied over the area of an active deep vein thrombus (DVT). The area overlying a previous DVT that has been treated with anticoagulant therapy can be treated with caution.
Rationale	Ultrasound could dislodge or cause partial disintegration of a thrombus, potentially blocking circulation to vital organs. Mechanisms by which this may occur include disintegration of existing blood clots induced by mechanical effects of ultrasound and possible increased local blood flow. There is no risk of ultrasound-induced emboli when anticoagulative therapy has resolved the clot(s).
Research Evidence LOW	Ultrasound caused red blood cell stasis in a chick embryo model and has also been shown to cause partial disintegration of a thrombus.40,41 Studies that examined the effects of continuous and pulsed ultrasound on local blood flow produced inconsistent and inconclusive findings.42–44

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3-8 Infection, Tuberculosis (TB)

Recommendation US Cont US Pulsed TB	Ultrasound heat should not be applied to infected tissue that is under tension (e.g., abscess). However, infection with open drainage can be treated using very low intensity pulsed ultrasound. Ultrasound should be discontinued if an increase in any signs of inflammation (redness, heat, pain, and swelling) occurs. Tuberculous lesions should not be treated with either pulsed or continuous ultrasound.
Rationale	Heating may lead to increased swelling in closed spaces and, therefore, to increased pain. In diffuse infection that has no open drainage, heat may cause further spread of infection via increased circulation. This would be particularly undesirable in cases of TB.
Research Evidence LOW	It is uncertain whether pulsed or continuous ultrasound can increase regional blood flow and thereby spread infection.42–44 The effect of ultrasound on bacterial growth is unknown. Pro-inflammatory effects of ultrasound may assist in the defence against infection.45–49

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3-9 Acute Injury, Inflammation

Recommendation US Cont US Pulsed	Continuous-mode ultrasound that might increase tissue temperature should not be applied to already inflamed tissue. Pulsed ultrasound can be applied to inflamed tissues provided that cardinal signs of inflammation (redness, swelling, heat, pain) are not exacerbated.
Rationale	Metabolic and vascular changes are induced by local heat that may exacerbate inflammation and increase swelling.
Research Evidence LOW	Pulsed ultrasound is purported to activate cellular processes of inflammation, without heating and without increasing swelling, to promote faster resolution of the inflammatory phase of healing and, overall, to speed repair of injury.45–47,50–53 Pulsed ultrasound has been used in several clinical studies to treat acute injuries; no adverse reactions have been reported.50–53

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3-10 Haemorrhagic Conditions

Recommendation	Neither continuous nor pulsed ultrasound should be applied to actively bleeding tissues. Ultrasound can be used to help resolve bruising following haemostasis. Ultrasound can be used on persons with bleeding disorders (haemophilia) after replacement factor has been administered and coagulopathy has resolved.
Rationale	Mechanical vibration produced by ultrasound can disrupt platelet plug formation and cause uncontrolled blood loss or bleeding into surrounding tissues. Heating-induced increase in local blood flow (continuous ultrasound) may also interfere with haemostasis. Some resources suggest that ultrasound applied over the pelvic region of menstruating women may increase blood loss.
Research Evidence MODERATE	Ultrasound is known to alter platelet degranulation and aggregation.42 The literature is inconclusive with respect to the effects of ultrasound on local blood flow.42–44 Ultrasound appears to have resolved haematoma formation.54

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3-11 Recently Radiated Tissue

Recommendation	Continuous and pulsed ultrasound should not be applied to tissues that have received radiation therapy within the previous 6 months.
Rationale	There is a potential risk of stimulating growth of any remaining malignant cells. Recently radiated tissues may respond atypically to ultrasound because of the presence of radiation-induced inflammation or scar tissue or cellular and circulatory effects.
Research Evidence LOW	The ability of ultrasound to stimulate the growth of cancer cells is well established.9–18 There is little information on how previous radiation therapy might affect tissue response to ultrasound.55

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3-12 Impaired Sensation

Recommendation US Cont US Pulsed	Avoid using continuous thermal ultrasound or high-temporal-peak-intensity pulsed ultrasound (≥2.0 W/cm2, SATP, 1:4) on body areas with impaired pain or heat sensation or with patients who cannot provide appropriate and timely feedback due to an altered level of consciousness or impaired cognition. Perform a sensory discrimination test (refer to the section on US safe practice).
Rationale	When adjustment of ultrasound parameters requires feedback from the client, it must be confirmed that the client can perceive heat and pain and is able to communicate appropriately. Communication between therapist and client is most often required when adjusting continuous-mode ultrasound intensity and rate of applicator movement to produce a moderate, comfortable level of tissue heating, or when insonating over superficial bone. Tissue heating depends on a number of factors specific to the individual client (e.g., tissue perfusion, body type, proximity of bone). Therefore, use of standard ultrasound heating protocols without patient feedback is associated with a significant risk of burns or unstable cavitation, both of which can result in significant tissue damage.
Research Evidence ABSENT	No reference found.

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3-13 Impaired Cognition or Communication

For recommendation see Impaired Sensation (above)

3-14 Impaired Circulation

Recommendation US Cont US Pulsed	Avoid tissue heating through use of continuous ultrasound or high-temporal-peak-intensity pulsed ultrasound. Ultrasound should be discontinued if pain increases during or following treatment. Continuous and pulsed ultrasound should not be used when arterial circulation is severely compromised.
Rationale	Adequate circulation is required to dissipate heat produced by both continuous and pulsed ultrasound. Incapacity of the arterial system to dissipate heat produced by ultrasound may lead to further ischemia, pain, and possibly blister formation. There is evidence that pulsed ultrasound is safe when circulation is somewhat compromised.
Research Evidence LOW	Low-intensity pulsed ultrasound has been used without adverse effect on venous ulcers.56–58

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3-15 Skin Disease, Damaged or “At Risk” Skin, Chronic Wounds

Recommendation US Cont US Pulsed	Continuous- and pulsed-mode ultrasound should not be applied using a gel-coupling in-contact method to areas of skin loss or skin at risk of breakdown. Continuous ultrasound producing heat should not be applied over dermatological conditions (eczema, psoriasis, or other heat sensitive skin disorders). Pulsed ultrasound can be used to treat open wounds.
Rationale	Transducer contact may further irritate or traumatize at-risk skin. Ultrasound delivered using a water bath is a safe alternative method of application to avoid physical trauma to skin.
Research Evidence ABSENT	Ultrasound has been applied using a water-immersion method to chronic venous leg ulcers without adverse reactions.57–59

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3-16 Reproductive Organs

Recommendation	Continuous and pulsed ultrasound should not be applied directly over the reproductive organs.
Rationale	Ultrasound may contribute to infertility by affecting gamete production, especially heat-sensitive spermatogenesis in the testes.
Research Evidence ABSENT	No reference found.

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3-17 Eyes

Recommendation	Continuous and pulsed ultrasound should not be applied directly to eyes.
Rationale	Unstable cavitation could occur in ocular fluid as a result of standing wave formation, leading to retinal damage.
Research Evidence ABSENT	No reference found.

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3-18 Anterior Neck, Carotid Sinus

Recommendation	Continuous- and pulsed-mode ultrasound should not be applied to anterior neck region over carotid sinus.
Rationale	The effects of ultrasound on these excitable tissues are unknown.
Research Evidence ABSENT	No reference found.

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3-19 Spinal Cord

Recommendation	Continuous- and pulsed-mode ultrasound should be used with caution following recent laminectomy above L2 level and in individuals with spina bifida, and should be avoided directly over the area where the spinal cord might be exposed to ultrasound waves.
Rationale	Unstable cavitation may occur in cerebrospinal fluid. Normally, however, the central nervous system elements (brain and spinal cord) are protected by bone and are therefore unlikely to be affected by ultrasound waves.
Research Evidence LOW	Ultrasound may alter nerve conduction (see below).60–65

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3-20 Peripheral and Regenerating Nerves

Recommendation	Monitor patients for discomfort when applying ultrasound directly over large superficial peripheral or regenerating nerves. Ultrasound can produce the sensation of “pins and needles” at or distal to the treatment site (sometimes reported by patients when ultrasound is applied over the carpal tunnel area).
Rationale	There appears to be no clear rationale for avoiding ultrasound over large peripheral nerves. Some discomfort may be experienced by patients when superficial nerves are heated. This sensation is likely to be associated with continuous-mode ultrasound and to be due to heating of the nerve.
Research Evidence LOW	There is some evidence that continuous and pulsed ultrasound can alter nerve-conduction velocity in large superficial nerves; however, there are also contradictory findings.60–65 In pre-clinical studies, pulsed ultrasound accelerated recovery after nerve injury, which suggests a potential clinical role for ultrasound after nerve injury. Adverse clinical outcomes have not been reported.66–68

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Inspect Skin Area

Avoid ultrasound on skin areas affected by psoriasis, eczema, and similar skin disorders. Ultrasound to open skin requires judicious use of universal precautions to ensure that infectious agents are not transferred between patients by the therapist or through contaminated ultrasound couplants.

Avoid Transfer of Infectious Agents

Ultrasound gel dispensers can become contaminated when exposed to an infected individual, and the bacterial agent can spread to subsequent patients through exposure to the contaminated gel or equipment. Single-use gel containers can be used when treating open skin areas or infected individuals. Non-sterile gel applications to intact skin should include procedures that prevent contamination of stock solutions of gel (bottles) that are used for multiple patients. Preheating bottled ultrasound gel may increase patient comfort, but it provides no therapeutic benefit and may promote microbial growth.^39,69,70 Ultrasound transducers are a source of contamination and should therefore be cleaned before and after each use with an alcohol wipe or alternative sanitizer.⁶⁹

Avoid Pre-treatment of the Area with Superficial Heating or Cooling Agents

Altering tissue temperature prior to ultrasound application modifies the amount of tissue heating produced by the ultrasound. The cumulative effect of a hot pack followed by thermal ultrasound can lead to skin damage.^71–73

Avoid Unsupervised Self-Treatment by Clients or Treatment by Unqualified Persons

Inappropriate use of ultrasound may lead to severe pain, tissue damage, or bleeding in the treated area. Inappropriate technique may severely compromise delivery of ultrasound to the target tissues and therefore limit clinical effectiveness.⁷⁴

Use Appropriate Ultrasound Couplants

Some couplants do not transmit, or reduce transmission of, ultrasound. For example, gel- or water-filled latex gloves interfere with transmission, as do certain creams, oils, and lotions.^75–77 In addition, inappropriate products may damage the ultrasound transducer. For example, gels used for electrode stimulation (electrode gels) may damage the transducer because of their high salt concentration.

Limit Thermal Ultrasound Treatment to Surface Areas≤10 cm²

Treating areas more than two times the effective radiating area (ERA) of the ultrasound transducer (about 10 cm²) significantly reduces the thermal effectiveness of ultrasound because of continuing heat loss to adjacent cooler tissue.^78–80 Pulsed ultrasound can be applied to areas two to three times the ERA, but treatment time should be increased.

Apply Ultrasound Using Effective Treatment Duration (≥10 minutes)

Clinical trials of pulsed ultrasound have usually not shown benefit when treatment duration was less than 10 minutes. Pulsed ultrasound is delivered intermittently; using an on:off cycle of 1:4 or 1:1 (mark:space ratio) results in an 80% or 50% reduction, respectively, in total energy delivered relative to the same intensity delivered for the same duration in continuous mode. Therefore, it is recommended that pulsed ultrasound treatments be applied for a minimum of 10 minutes.^70,81,82

Adjust Parameters When Applying Ultrasound in Water

Water temperature should be as close as possible to normal skin temperature. Ultrasound intensity should be increased when ultrasound is applied in water to achieve tissue temperatures similar to those produced when ultrasound is applied using a gel couplant.⁷⁶ In addition, ultrasound intensity should be increased whenever treatment is applied under water with the transducer at a distance >1 cm from the treated surface.⁸³ There is some controversy about the type of basin that should be used for ultrasound in water. Historically, a metal basin was considered to be contraindicated; however, a recent study showed that use of a metal basin produces more efficient heating, since metal reflects about 99% of incident ultrasound energy back into the water, where it can be absorbed by the tissues. By contrast, plastic absorbs ultrasound, decreasing the energy available for tissue absorption. Use of a metal basin requires careful monitoring of patient response in order to achieve a sensation of mild skin warmth while avoiding periosteal pain, which would indicate too much heating.³¹

4-2 Pregnancy

Recommendation	Avoid any type of E-stim over the low back, pelvis, or abdomen during pregnancy. Sensory-level TENS is safe during labour to help alleviate mild to moderate pain. Avoid use of E-stim on acupuncture points (A-TENS) or NMES activation of large muscle groups during pregnancy.
Rationale	E-stim applied directly over the lower abdomen may lead to unwanted uterine contractions and, potentially, to miscarriage or premature labour when applied during the first and third trimesters respectively. A majority of resources state that TENS can safely be applied to body sites remote from the uterus. Some suggest that E-stim is safe even when applied to surface areas overlying the uterus, since the current does not penetrate to the depth of uterine muscle. The direct effects of electrical current on fetal development are not clear. However, because any fetal effects could potentially be devastating, extra caution is required.
Research Evidence MODERATE	A-TENS significantly increased frequency and intensity of uterine contractions during labour.17 Endogenous opiates, which can be released with electrically induced muscle contractions, are potent stimulators of myometrial contractions.18–20 E-stim increased uterine contractility and uterine pressures in non-pregnant women.17 TENS has been used successfully to treat LBP during pregnancy, and no adverse effects on the newborn were reported.18–20 A document published by the Chartered Society of Physiotherapy in the UK (2007) states that it is permissible to apply TENS to the low back during pregnancy in certain circumstances.21

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4-3 Malignancy

Recommendation	E-stim should be avoided over a confirmed or suspected malignancy. Abnormal growth should be regarded as malignant until it has been diagnosed. Caution is advisable in the presence of undiagnosed pain in patients with a history of cancer within the last 5 years. TENS may be used for pain management for patients in palliative care. NMES may improve quality of life in end-stage malignant and non-malignant diseases.
Rationale	E-stim may stimulate growth and promote spread of cancer cells. Bone is a common metastatic site for many types of cancer; the analgesic effects of TENS may mask pain and early signs of metastatic disease.
Research Evidence LOW	E-stim can stimulate DNA synthesis and cell replication and, therefore, potentially increase tumour cell growth. Angiogenic effects of E-stim may promote the spread of tumours. However, application of direct current to animal models has also been shown to reduce tumour growth. This inhibition has been attributed to interference with mitotic spindle formation during cell division.22 Thus, E-stim does influence cancer cell growth; however, whether this influence will promote or inhibit tumour growth is not clear. In advanced disease, improvements in quality of life afforded by E-stim may outweigh any possible risks associated with treatment. TENS has been used to help ameliorate pain, and NMES has relieved breathlessness and improved strength for the use of walking aids in persons with advanced malignancy.22–26

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4-4 Active Deep Vein Thrombosis (DVT), Thrombophlebitis

Recommendation	All forms of E-stim are contraindicated, both locally and at remote sites, in cases of active or suspected DVT and thrombophlebitis. E-stim can be applied with caution to persons with a past history of DVT treated with anticoagulant therapy.
Rationale	Muscle contraction induced by NMES applied near a DVT could dislodge a thrombus that could then embolize a vital organ, causing infarction, shortness of breath, stroke, or major organ failure. Reflex vasodilatation and increased blood flow to contralateral limbs and/or peripheral sites induced by E-stim could also embolize a blood clot. The CSP guidelines and many of the resources suggest that E-stim is safe provided that treatment of the DVT affected limb is avoided (C-local). Although the risk of E-stim's dislodging a thrombus is low, the consequences of a thrombus's travelling to a vital organ could be catastrophic.
Research Evidence MODERATE	E-stim applied to remote acupuncture points has been shown to significantly increase blood flow to the feet.27 Research has demonstrated that electrically induced muscle contractions increased blood flow, while sensory-level IFC had no effects on blood flow.28–32 Research has suggested that NMES may be beneficial for preventing DVT when applied prophylactically prior to clot formation.33

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4-5 Haemorrhagic Conditions

Recommendation	E-stim should not be applied to areas of uncontrolled bleeding or after recent injuries or surgeries that resulted in blood loss. E-stim can be used on persons with bleeding disorders (haemophilia) after replacement factor has been administered and coagulopathy has resolved.
Rationale	E-stim applied in haemorrhagic conditions may cause uncontrolled bleeding.
Research Evidence MODERATE	E-stim stimulates regional blood flow, causes release of inflammatory mediators and vasoactive substances, and reduces platelet aggregation34 These effects could exacerbate bleeding when haemostasis has not been established.27 TENS and NMES have been used to decrease pain and improve muscle strength, respectively, without increased bleeding in people with haemophilia.35,36

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4-6 Infection, Osteomyelitis, Tuberculosis

Recommendation	Do not apply E-stim in the presence of localized abscess formations, tuberculosis, or chronic wounds with possible underlying osteomyelitis. E-stim may be applied in conjunction with antimicrobial therapy to superficially infected open wounds; however, in treating infected lesions, care must be taken to reduce the risk of cross-contamination through equipment or therapist contact (see “Safe Practices” below).
Rationale	E-stim may result in the spread of compartmentalized infections (abscess, TB). E-stim should not be used to promote skin closure in wounds with underlying osteomyelitis, because an exit site is required for drainage. CSP guidelines state that E-stim treatment should not be applied in cases of TB.
Research Evidence LOW	In vitro studies show that E-stim may inhibit bacterial growth.37–39 HVPC increases local blood flow, which may improve defence against infection in persons with impaired circulation. Electrically induced improvements in regional blood flow have been documented in people with diabetes, spinal-cord injury, and chronic wounds.27,40–44 Therefore, it is possible that E-stim may be beneficial when applied to infected open wounds. Laboratory study has demonstrated that bacteria are readily transferred from contaminated skin to areas of sterile skin through inadequately cleaned IFC sponges.45

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4-7 Recently Radiated Tissue

Recommendation	Do not apply E-stim to tissues that have received radiation therapy within the previous 6 months.
Rationale	E-stim could possibly stimulate growth of remaining malignant cells. Recently radiated tissue may respond atypically because of the presence of radiation-induced inflammation or scar tissue and/or because of the cellular or circulatory effects of radiation therapy.
Research Evidence MODERATE	E-stim can stimulate DNA synthesis and cell replication and, therefore, could potentially increase tumour-cell growth. However, application of direct current in animals has also resulted in reduced tumour growth. This inhibiting effect has been attributed to interference with mitotic spindle formation during cell division.22 E-stim-induced increases in angiogenesis and local blood flow would promote the spread of tumours.27,40–44

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4-8 Skin Disease, Damaged or At-Risk Skin

Recommendation	E-stim should be applied only over healthy skin; therefore, the intended electrode application area should be examined for lesions, signs of irritation, and/or allergic reactions. Monitor patients with skin diseases for exacerbation of symptoms following E-stim application.
Rationale	Intact skin offers greater resistance to current flow than does broken skin. Uneven current flow under electrodes as a result of skin damage increases the risk of tissue burns. E-stim could stimulate inflammatory processes associated with dermatitis (eczema, contact dermatitis). Using self-adhesive electrodes on compromised skin or grossly edematous tissue could result in skin loss.
Research Evidence STRONG	Skin disorders are the most common adverse effect of E-stim.46–50 See “Safe Practices” below for guidance on reducing the risk of E-stim-induced skin allergy or burn.

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4-9 Impaired Circulation

Recommendation NMES HVPC/TENS	E-stim may be beneficial in the presence of moderate arterial disease. In the presence of severe arterial disease, however, electrical current can induce ischemia, exacerbate pain, and potentially damage fragile tissue. HVPC/TENS can be applied by experienced clinicians to improve wound healing and reduce claudication in people with arterial disease.
Rationale	Increasing cellular activity increases metabolic demand; in cases of severely compromised circulation, the demand may exceed oxygen supply, resulting in increased pain. Continued treatment may lead to tissue ischemia and necrosis. Deficiency in either arterial or venous circulation is associated with skin deterioration and edema. Applying E-stim electrodes over compromised skin may cause skin breakdown, which is difficult to heal and can potentially lead to chronic wounds. Intact skin offers greater resistance to current flow than does broken skin; uneven current flow under electrodes as a result of skin loss or damage increases the risk of tissue burns.
Research Evidence LOW	Electrically induced improvements in regional blood flow and tissue oxygenation have been documented in people with diabetes, spinal-cord injury, and chronic wounds27,40–44 NMES applied to calf muscles improved functional capacity of people with claudication due to advanced arterial disease. HVPC and A-TENS have been used safely to treat patients with arterial insufficiency.41–44

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4-10 Impaired Sensation

Recommendation TENS NMES, HVPC	TENS and IFC should not be applied when impaired sensation (touch or pain) interferes with the patient's ability to appreciate the prescribed and/or maximum safe level of current intensity. Experienced therapists may apply E-stim (HVPC or NMES) to anaesthetic areas to improve healing and/or increase muscle strength in persons with neurological injuries (e.g., spinal-cord injury, stroke). In these instances, stimulus parameters should be tested on an area of the body with intact sensation if possible; stimulus parameters should be carefully selected and patients closely monitored for early signs of adverse reactions. Types of electrical currents that are associated with greater risk of skin burns (direct current) should not be applied to anaesthetic areas.
Rationale	Impaired sensation interferes with E-stim that requires patient feedback to set treatment intensity (TENS, IFC, NMES) and thus increases the risk of an E-stim-induced adverse event.51 Analgesic effects of TENS and IFC require intact afferent nerves.
Research Evidence MODERATE	Peripheral nerve block is known to abolish the analgesic effects of TENS. Ice applied concomitantly with IFC abolishes perception of IFC within 2–8 minutes of ice application.52 Conversely, HVPC and NMES have been used successfully in individuals with neurological conditions that interfere with sensory awareness (e.g., spinal-cord injury).53–55

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4-11 Impaired Cognition or Communication

Recommendation TENS HVPC, NMES	TENS and IFC should not be applied when altered consciousness or other cognitive impairment could interfere with the patient's ability to appreciate the prescribed and/or maximum safe intensity of current. Provided that informed consent is obtained, experienced therapists may elect to apply HVPC or NMES to patients who are unable to provide reliable feedback, using carefully selected stimulus parameters and closely monitoring the person for early signs of adverse reactions.
Rationale	When feedback is required to set stimulus parameters, misunderstood instructions may result in ineffective treatment and increased risk of a skin burn. Application of E-stim for wound healing (HVPC) or muscle re-education (NMES) often involves using preset protocols that do not require patient feedback.
Research Evidence MODERATE	E-stim is commonly used to treat wounds (HVPC) and to stimulate muscle contraction (NMES) in patients who are unable to perceive the stimulation (e.g., in cases of spinal-cord injury).51,52,54,55

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4-12 Metal Implants

Recommendation	Tissues overlying metal implants can be treated with all forms of E-stim. However, E-stim should not be applied over skin staples or to tissues treated with dressings or topical agents containing metal ions (silver, zinc).
Rationale	Some experts suggest that applying E-stim to skin overlying superficial implanted metal creates a risk of burn. However, there is little consensus among experts on how near the skin the metal must be in order to influence current flow. Resources generally agree that the conduction of electrical current is not likely to be affected by most metal components, including surgical implants of the type used in joint-replacement surgery.
Research Evidence LOW	Persons with joint replacements that include metal components have been treated with E-stim with benefit and without adverse reactions.56–58

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4-13 Recent Surgery, Unstable Fracture, Osteoporosis

Recommendation TENS HVPC, TENS	High-intensity NMES should not be used on recent postoperative ligament or tendon repairs, skin flaps, joint replacements, or fracture stabilization. Consult with the surgeon to determine the safety of NMES in the presence of injured or recently repaired tissue.
Rationale	Forceful muscle contraction produced by NMES could cause fracture displacement, tear recent tendon or skin sutures, disrupt staples, or disturb an incision site or graft.
Research Evidence MODERATE	In one study, electrically induced high-force muscle contractions produced an avulsion fracture.59

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4-14 Seizure Disorders, Epilepsy

Recommendation head, trunk neck, limbs	Avoid neck and transcranial placement of electrodes in individuals with epilepsy; apply E-stim cautiously to the trunk and limbs in persons who are known to have seizures.
Rationale	E-stim may induce seizures. CSP guidelines state that electrodes placed on the neck are contraindicated in patients with epilepsy.
Research Evidence MODERATE	Epileptic seizures have occurred following TENS treatment in a person post stroke and in a boy known to have seizures.60,61 In contrast, research using an animal model of epilepsy suggests that A-TENS applied to a limb may help reduce epileptic activity.62

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4-15 Anterior Neck, Carotid Sinus

Recommendation	Direct application of any type of E-stim using surface electrodes over the anterior neck is not advisable.
Rationale	Stimulation in this area may reflexively stimulate the vagus or phrenic nerves, which may induce a rapid fall in blood pressure, causing the patient to faint. Stimulation may also cause laryngeal spasm. Resources generally recommend that this body region should be avoided.
Research Evidence LOW	The FDA advises that E-stim is contraindicated in this region. CSP guidelines state that electrodes placed on the neck are contraindicated in patients with epilepsy.

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4-16 Chest, Heart, Cardiac Failure

Recommendation NMES HVPC, TENS	TENS should be applied cautiously over the anterior chest and heart (using low-intensity and sensory-level stimulation only). This location should be avoided in patients with cardiac disease, arrhythmias, or a cardiac pacemaker. It is not advisable to apply NMES to intercostal muscles of the anterior chest wall. However, lower-extremity E-stim appears to be safe in patients with cardiac failure.
Rationale	Stimulation using relatively high current amplitude over the anterior chest area may cause heart arrhythmias or fibrillation. NMES of intercostal muscles may interfere with breathing. CSP guidelines suggest that electrical current be applied to the anterior chest area with great caution.
Research Evidence MODERATE	Development of respiratory distress has been reported as a result of applying E-stim to intercostal muscles.63 However, TENS applied to the chest wall has been shown to significantly reduce mild to moderate postoperative pain following thoracotomy.64 NMES applied to lower-limb muscles has been shown to benefit persons with advanced chronic obstructive pulmonary disease.65–70

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4-17 Head, Transcranial Application

Recommendation	Only therapists who have attained an advanced skill level should apply E-stim transcranially. Careful monitoring of patients after treatment is recommended.
Rationale	The risks of treating this body region are not fully understood. Transcranial application should be avoided in persons with epilepsy.
Research Evidence MODERATE	Epileptic seizures have occurred following TENS treatments, especially when electrical current was applied using electrodes placed transcranially.60,61 However, TENS has been used transcranially to reduce tension headaches, with 10% of patients experiencing minor adverse reactions.71

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4-18 Reproductive Organs

Recommendation	E-stim near reproductive organs or genitalia requires specialized training and otherwise should be avoided.
Rationale	The risks of E-stim for gametogenesis are not known.
Research Evidence ABSENT	E-stim has been used successfully for electroejaculation in patients with spinal-cord injury with no serious adverse effects.72 NMES is also successfully used to treat urinary incontinence, using conventional electrodes or specialized rectal or vaginal probes to activate pelvic floor muscles.73,74

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4-19 Eyes

Recommendation	Avoid applying E-stim to areas near or over the eyes.
Rationale	The risks of treating this body area are not known. There is no known clinical indication that requires eye stimulation.
Research Evidence ABSENT	No reference found

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Check and Prepare Skin Before Starting

Ensure that skin is intact at the intended electrode site. Wipe the skin surface with an alcohol swab and allow it to dry prior to applying electrodes. Cleaning the skin using warm water is also acceptable. Reduced skin impedance means that lower amplitude is required for effective treatment, which in turn increases patient comfort.

Monitor Skin for Signs of Irritation

Skin irritation is the most frequent complication of electrical stimulation treatment; it may develop gradually, and commonly occurs when self-adhesive electrodes are used, as a result of an allergic reaction to the self-adhesive gel.^47,76–82

Avoid Repeated Use of Self-Adhesive Electrodes

Electrical conductivity is significantly reduced with successive uses of self-adhesive electrodes. This can cause uneven distribution and inadvertent concentration of current over the electrode area. Self-adhesive electrodes also have a limited lifespan and should be discarded when the adhesive surface is dry. Self-adhesive electrodes should not be shared among patients.

Monitor, Regulate, and Document Medication and Caffeine Consumption When Using E-stim for Pain Management

Opioid drugs and caffeine may interfere with the analgesic effects of E-stim. Repeated opioid medication can lead to opioid tolerance. High caffeine intake (200 mg/day, or three cups of coffee) blocks adenosine receptors; adenosine is thought to be a neurotransmitter in the C-fibre pathway.^83–85

Monitor Patients Receiving IFC

A variety of adverse effects have been associated with E-stim, including fainting, nausea, burns, rashes, increased swelling, and pain. These effects occur more frequently with application of IFC than with other types of E-stim, such as TENS. Ice reduces, then abolishes, the sensation of IFC. Therefore, applying IFC in combination with ice increases the likelihood of an adverse effect, and particularly the risk of an electrical burn. Do not use small electrodes combined with high-amplitude current when applying IFC. Using high-intensity (high-concentration) IFC may lead to skin and tissue burns.^{51,52,75,86–88}

Maintain a Regular Protocol for Disinfection of Sponges

Sponges and electrodes used for E-stim are commonly contaminated with microorganisms.⁴⁵ Soaking electrodes and/or sponges in a solution of dimethyl-benzyl ammonium chloride diluted with water for 20 minutes, followed by 5 minutes of tap-water rinsing, removes about 95% of bacteria. Ensure a sufficient sponge supply to permit complete drying between uses.⁸⁹

Use Suction Electrodes with Care

Carefully increase the amount of negative pressure used to hold electrodes in place in order to avoid bruising the skin. Do not use suction electrodes over areas of pain or gross edema or on damaged skin. For patients on anticoagulant therapy, there may be added risk of causing bruising as a result of vigorous mechanical effects on skin capillaries.

Secure Electrodes with Even Pressure Distribution and Full Contact

Patients should be instructed prior to treatment about any need to maintain a particular position during the treatment. Electrodes coupled to the skin using electroconductive gel can be moved during NMES to search for the optimal location of a motor point. To ensure patients' comfort during this procedure, use sufficient gel, move the electrodes slowly, and keep the full surface of the carbon electrode in even contact with the skin.

Adjust Stimulus Parameters and Intensity with Care

At the end of treatment, slowly reduce stimulus intensity and then turn the machine off. E-stim machines that allow stimuli to be turned off without reducing intensity should be used with extreme caution. Check that the intensity dial registers zero current flow before turning the E-stim machine back on. Advise patients not to adjust the intensity or parameters of E-stim treatment without consulting a professional. Excessive duration or intensity of treatment can lead to injury.^75,88

Maintain and Replace Carbon Electrodes

Carbon-impregnated rubber electrodes have a limited lifespan. Discard electrodes when the surface appears dull, because the impedance is likely too high for safety, effectiveness, and patient comfort (impedance should not exceed 300 ohms). When conductivity is low or uneven, there is a greater risk of skin burn. Protect the surface of conductive electrodes by avoiding abrasive materials, alcohol-based cleansers, and rough cleaning. Needles for intramuscular stimulation should be sterilized between uses according to the manufacturer's directions.

Maintain a Safe Distance between Electrical Stimulation Units and Short-Wave Equipment

High-frequency electromagnetic radiation, such as that produced by short-wave and microwave diathermy, can purportedly induce current flow in medium-frequency stimulators such as interferential devices, even when the power control in the medium-frequency device is set at zero. Electrical stimulators and diathermy units should operate at least 3 m from each other. Where space is limited, IFC and SWD devices should not be operated simultaneously.⁹⁰

5-2 Pregnancy

Recommendation	LLLT should be avoided over the low back, abdomen, and pelvic region during the first 35 weeks of pregnancy.
Rationale	Recommendations are based on possible light-induced effects on fetal growth and/or fetal malformations. CSP guidelines also recommend using caution during pregnancy even when the target tissue is not in the pelvic region.
Research Evidence LOW	Adverse effects of LLLT on the fetus have not been shown. It is also not known whether LLLT applied to the pelvic region will reach the fetus. Most resources recommend that LLLT be avoided over the pregnant uterus because any fetal malformation could have long-term and devastating effects.​effects.44 The types of lasers that are used for prenatal tissue coagulation/ablation should not be confused with low-intensity lasers used by physiotherapists.

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5-3 Malignancy

Recommendation	LLLT should not be used over confirmed or suspected malignancy. Abnormal growth should be regarded as malignant until diagnosis has been confirmed. Use caution when a patient with a history of cancer within the last 5 years has pain of undiagnosed origin.
Rationale	Applying LLLT directly to malignant cells may stimulate cancerous cell activity and growth; light-enhanced angiogenesis may play a role in sustaining tumour growth.
Research Evidence MODERATE	In cell-culture studies, LLLT has been shown to alter DNA synthesis and ATP production and to stimulate protein synthesis.5 Dermal angiogenesis has been demonstrated after laser treatment.6 These stimulating effects of light have not been studied in the context of tumour growth. There is no indication that LLLT could transform normal cells into malignant cells; on the contrary, the literature suggests that LLLT may promote repair of DNA.4,7,8

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5-4 Haemorrhagic Conditions

Recommendation	LLLT should not be applied to actively bleeding tissue. It can be used to promote resolution of haematoma once bleeding has ceased. LLLT can be used on persons with bleeding disorders (haemophilia) after replacement factor has been administered and coagulopathy has resolved.
Rationale	Although the risk of LLLT-induced exacerbation and/or prolongation of bleeding is probably minimal, the safe approach is not to irradiate, since the consequences of haemorrhage are potentially life threatening.
Research Evidence LOW	It is uncertain whether therapeutic light has adverse effects on coagulation.9,10

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5-5 Recently Radiated Tissue

Recommendation	LLLT may be used to treat tissues that have been treated with radiation therapy. Careful monitoring for signs of abnormal growth or tissue damage is recommended.
Rationale	Skin ulcers usually develop as an acute complication of ionizing irradiation, but they may persist for months or even years post radiation. LLLT has been used to promote healing of acute and chronic radiation ulcers; however, some authors suggest avoiding LLLT for 6 months following radiation therapy.
Research Evidence LOW	No evidence was found for adverse effects of using light to promote ulcer healing in radiation-damaged skin. In 5 patients 3 to 7 months post radiation therapy, radiogenic mastitis resolved,11 and in one patient, a skin ulcer healed following laser therapy.6,12 LLLT safely reduces duration and symptoms of chemotherapy-induced oral mucositis; however, this particular use of LLLT does not involve applying LLLT to previously radiated tissue.13

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5-6 Infection, Tuberculosis

Recommendation TB Other	LLLT should not be used in persons with tuberculosis; other less virulent soft-tissue infections may be treated with caution. Bacterial growth should be analyzed at baseline and biweekly when treating infected open wounds. Patients who are immunocompromised should be closely monitored for spread of infection.
Rationale	LLLT is known to modulate the growth of some bacterial species; its effects on TB are not known. LLLT produces some effects via systemic mechanisms; thus, the safe approach is not to use LLLT at any location in persons with TB until it becomes clear whether LLLT can increase or spread TB infection. All patients should be monitored for signs of increased bacterial concentration or advancing infection when LLLT is used on infected tissues.
Research Evidence MODERATE	LLLT modulates in vitro growth of bacteria, depending on laser parameters as well as on the bacterial species.14–19 Blue light has been shown to kill methicillin-resistant Staphylococcus aureus (MRSA); however, this wavelength is not commonly available in clinical practice at present.19 Pre-clinical research shows that clearing wounds of all bacteria, including normal flora, does not necessarily produce improved wound healing. 808 nm light increased S. aureus growth in animal wounds.20 Laser irradiation has been used with apparent effectiveness in cases of tissue gangrene and osteomyelitis.21

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5-7 Impaired Cognition or Communication

Recommendation	LLLT should be used cautiously if a patient is unable to understand treatment explanations or to follow instructions and warnings.
Rationale	LLLT is commonly used to treat conditions involving absent or reduced sensation in the treatment area. Although communication is not essential for the purpose of giving immediate sensory feedback, the patient must be able to comply with safety procedures.
Research Evidence ABSENT	LLLT has been used without reports of adverse effects in very elderly institutionalized persons and in individuals with diabetic neuropathy or sensory loss in the treatment area.22–26

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5-8 Active Deep Vein Thrombosis, Thrombophlebitis

Recommendation	LLLT should not be applied directly over an active or suspected DVT. The area overlying a previous DVT treated with anti-coagulant therapy can be treated with caution.
Rationale	The effects of LLLT on a thrombus are not known. LLLT has a modest effect on capillary blood flow, and thus the risk that LLLT will dislodge a thrombus is minimal. However, should a clot embolize, a vital organ could be compromised, with devastating results.
Research Evidence ABSENT	LLLT increased capillary blood flow in persons with diabetic microangiopathy and also in persons with Buerger's disease.26,27 There appear to be no studies on LLLT's effects on the formation or dissolution of blood clots.

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5-9 Impaired Circulation

Recommendation	LLLT may be used to treat areas of impaired circulation (arterial disease or venous insufficiency).
Rationale	There is an extensive literature supporting the safe use of laser therapy in patients with circulatory impairment and no evidence that increasing cellular activity could increase existing ischemia.
Research Evidence LOW	Advantageous cellular effects of LLLT have been established, although there are some conflicting findings.28 LLLT has been used safely to treat skin ulcers in individuals with diabetes and severe arterial insufficiency.6,22,29 There is some evidence that episodic-type ischemia associated with connective tissue diseases or Raynaud's phenomenon improves after laser treatment of the hands.30

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5-10 Acute Injury, Inflammation

Recommendation	LLLT appears safe to use in the management of acute injury. Monitor the patient for exacerbation of symptoms after each treatment.
Rationale	It is prudent to monitor the response following each application, since the literature shows that results on acute injury are variable.
Research Evidence MODERATE	LLLT is known to attenuate the release of inflammatory mediators, including TNF-α, IL-1, and other cytokines, following acute soft-tissue injury.31,32 Reducing such mediators may lead to less inflammation.33,34 LLLT's effects on the development and resolution of inflammation may be wavelength and dose dependent.35–37

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5-11 Photosensitivity, Systemic Lupus Erythematosus

Recommendation	LLLT should be used cautiously in patients with diseases known to be light sensitive, including xeroderma pigmentosum, polymorphic light eruption (PLE), and systemic lupus erythematosus (SLE). It is advisable to use LLLT at low irradiance (power density) and low radiant exposure (energy density), to follow up with patients after the first application, and to allow a 2- to 3-day interval between applications.
Rationale	LLLT does not induce tissue heating or erythema and can therefore be used safely with persons who sunburn easily. For certain diseases of the skin, however, a cautious approach is advisable because of a potential atypical response to LLLT (SLE affects capillary blood flow, and microvasculitis is common).
Research Evidence MODERATE	Exposures to ultraviolet radiation (UV) and visible light sufficient to produce erythema are known to exacerbate skin lesions in individuals with SLE38–40 and PLE.41,42 Conversely, repeated low doses of UV (A1, A, and B wave bands) are used to reduce symptoms of SLE. No reports were found on the use of LLLT in persons with light-sensitivity conditions or SLE.

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5-12 Skin Disease, Damaged or At-Risk Skin

Recommendation	LLLT may be used over open wounds or damaged skin, provided that treatment parameters are appropriately adjusted.
Rationale	Light absorption will be altered based on a number of factors, including absence of skin, skin thickness, skin pigmentation, and skin perfusion (because red light is strongly absorbed by haemoglobin and melanin). Therefore, LLLT should be adjusted based on anticipated changes to light absorption. Monitoring patient response is important.
Research Evidence STRONG	LLLT has been used safely to treat many types of open wounds. Adverse effects have not been documented.23,43 The effects of skin characteristics on light transmission have been established.44

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Restrict Use of Laser Devices to Qualified Personnel

Safety should be assured by providing only approved operators with a key to access Class II and III laser devices.

Clean and Disinfect Laser Applicators Regularly

Dust and skin debris accumulated at the laser tip may interfere with emission. Disinfect the applicator (using 70% alcohol) between patients. Plastic wrap can be applied to the applicator when treating open wounds (note that this produces a light-transmission loss of about 8%).⁴⁵ Other types of semi-transparent dressings can block up to 48% of incident light, and exposure duration should be increased to compensate for such loss.^45,46

Plan Regular Equipment Maintenance and Calibration (every 6 months recommended)

Laser diodes are easily damaged, and their emission should be checked if the applicator is dropped. Laser output decreases over time. Output must be measured using a light metre of the appropriate wavelength. Treatment dosage should be calculated using actual output rather than the estimated output at the time of equipment purchase. Poor performance of laser diodes has been demonstrated: in one study, clinical devices emitted, on average, between 31% and 60% of manufacturers' rated output, and a few devices emitted no light at all.⁴⁷

6-2 Impaired Cognition or Communication

See explanation for Impaired Sensation (above)

6-3 Acute Injury, Inflammation

Recommendation	Avoid heating acutely inflamed tissue.
Rationale	Inflammation occurs soon after injury (within 3 days) and can persist or reappear with exacerbation of chronic conditions. Therefore, the area should be examined regardless of time post injury to look for signs of inflammation: redness, heat, swelling, pain, and loss of function. Heat exacerbates inflammatory processes, which may extend the area of injury and prolong the recovery period.
Research Evidence MODERATE	Metabolic and vascular changes are induced by local heat, which perpetuates many inflammatory processes (increased blood perfusion, release of local inflammatory mediators, formation of tissue edema).5 There is a risk of secondary hypoxic injury when the supply of oxygen is inadequate to meet tissue demands.

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6-4 Haemorrhagic Conditions

Recommendation	Avoid local use of superficial heat until haemorrhage has ceased. Avoid using heat anywhere on the body that is sufficient to cause a systemic response (sweating and general vasodilatation) in an individual who is at risk of haemorrhage. In persons with bleeding disorders (haemophilia), superficial heat can be used after replacement factor has been administered and coagulopathy has resolved.
Rationale	Heat-induced increase in local blood flow may prolong bleeding.
Research Evidence MODERATE	Tissue heating is known to cause vasodilatation and increased local and limb blood flow.6

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6-5 Impaired Circulation

Recommendation	Avoid heating tissues with circulatory insufficiency. Do not apply heating agents at an intensity sufficient to change core body temperature in persons with peripheral vascular disease (PVD). Examine distal extremities for signs of peripheral arterial disease prior to applying heating agents. Reduce dosage of heat to hands and feet.
Rationale	Adequate blood circulation is needed to avoid excessive heat accumulation in areas treated with superficial heating agents. Increasing the core body temperature in persons with PVD may lead to thrombus formation and can potentially compromise vital organs and cause heart attack or stroke. Distal extremities are most affected by arterial disease; therefore, it is important to check hands and feet for signs of arterial disease (thin, shiny, pale skin; cold to touch; thickened, brittle nails). Hands and feet are particularly susceptible to applied heat because their skin surface area is large in relation to the volume of tissue, which results in very efficient heat transfer. The CSP guidelines advise avoiding the use of hot packs over areas of impaired circulation and using wax with caution.
Research Evidence STRONG	There is a risk of burns if local circulation is insufficient to dissipate applied heat3,7,8 Increasing core body temperature to 39°C leads to haemoconcentration, an increase in platelet count, and a reduction in anti-thrombotic processes. This core temperature could be achieved with full-body immersion in 40°C water for about 50–60 min. At this temperature, the risk of a thrombotic event may be elevated in individuals with PVD.9

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6-6 Malignancy

Recommendation	Avoid using superficial heating agents on persons with cancer. Abnormal growth should be regarded as malignant until diagnosis has been confirmed. Use caution when a patient with a history of cancer within the last 5 years has pain of undiagnosed origin.
Rationale	Some sources advise not using superficial heat anywhere on the body for an individual with confirmed or suspected malignancy; the CSP guidelines, however, advise avoidance only over the malignant tissue. Local heat can increase tumour growth and increase incidence of metastases by increasing blood flow and/or by increasing metabolic rate. Applying heat anywhere on the body is a potential risk, according to some experts, because heating large surface areas may produce a systemic response (i.e., sweating and general vasodilatation) and because heating one limb may produce a reflex increase in blood flow in the contralateral limb.
Research Evidence MODERATE	Increasing tissue temperature stimulates metabolic activity of all types of cells. Heat-induced vasodilatation increases tissue perfusion.6,10,11 The effects of superficial heat on tumour growth and metastatic processes have not been examined directly.

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6-7 Infection, Tuberculosis

Recommendation	Avoid applying heat directly over infected tissue (e.g., abscess, septic arthritis, TB, infected open wounds) or to large areas of the trunk or limbs remote from the infected site. When an individual's body temperature is higher than the physiological norm, avoid applying heat to large surface areas, as this may produce a further rise in core temperature.
Rationale	Applying heat to an area of tissue that is hot, red, and swollen as a result of infection can exacerbate swelling and pain. However, when a localized infection such as an abscess has an opening for drainage, mild local heat may help to resolve the infection by increasing blood flow. The CSP guidelines specifically recommend avoiding wax treatment.
Research Evidence MODERATE	There are clinical reports of heat-induced changes in limb blood flow.6 The effects of applying heating agents to infected tissues have not been documented.

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6-8 Active Deep Vein Thrombosis, Thrombophlebitis

Recommendation	Avoid use of superficial heat directly over the site of an active DVT and to large surface areas of the trunk or to the unaffected contralateral limb of individuals with an active DVT. Individuals with a previous DVT that was successfully treated with anti-coagulant therapy can be treated with caution.
Rationale	Application of heat to large surface areas sufficient to produce sweating can produce generalized vasodilatation and increased blood flow at remote sites, which may dislodge a thrombus. The consequences of a thrombus travelling to a vital organ can be catastrophic. The CSP guidelines recommend that use of a hot pack is contraindicated, whereas the use of wax requires precautions. Application of wax to the hand is unlikely to cause general vasodilatation; as a precaution, however, the patient should be monitored during treatment for generalized increased body temperature (general sweating response), particularly when both hands are treated simultaneously.
Research Evidence STRONG	There are clinical reports of heat-induced changes in limb blood flow.6 Experimental studies using healthy human subjects have shown that heating one hand produces reflex changes in blood flow in the contralateral limb.10,11

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6-9 Pregnancy

Recommendation Systemic Local	Avoid applying heat that could elevate core temperature in pregnant women. Application of hot packs to the trunk or other surface areas or full-body immersion in hot water (hydrotherapy tanks) should be avoided. Heat can be safely applied to small areas of the extremities (e.g., wax to the hand). The patient should be monitored, and treatment should be discontinued if there is any sign of body-temperature elevation (central erythema, generalized sweating, etc.).
Rationale	Applying superficial heat to the low back is not likely to heat fetal tissues directly. However, increasing maternal body temperature could have devastating consequences. Although teratogenic effects of heat on the fetus are worst during the first trimester, heating fetal tissues later in pregnancy can also alter fetal growth and development. CSP guidelines recommend avoiding superficial heat until week 35 of pregnancy. Applying wax to hands or feet is unlikely to raise either maternal core temperature or fetal temperature.
Research Evidence MODERATE	Elevation of maternal body temperature (hyperthermia) is known to cause fetal malformations.12,13 Whether or not superficial heating agents can induce changes in maternal and fetal temperature has not been established.

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6-10 Skin Diseases, Damaged or At-Risk Skin, Chronic Wounds

Recommendation Diseases Damaged skin Wounds	Heat (hot packs and wax) should not be applied over heat-sensitive skin diseases (e.g., eczema, psoriasis, vasculitis, dermatitis). Conductive heating agents should not be applied to damaged skin that would alter heat transfer. Tissues surrounding chronic wounds may be treated with mild heat, provided there is adequate local circulation.
Rationale	Heat exacerbates certain inflammatory-type skin diseases (e.g., eczema, psoriasis). The conductive property of skin should be consistent across the surface area that is in contact with the heating agent; heat conduction is uneven over damaged skin, which can potentially result in tissue burns. Heating skin that is poorly perfused (e.g., vasculitis, arterial ulcers) increases the risk of tissue burn. The CSP guidelines recommend not applying wax to diseased skin and using hot packs with caution. Applying heat to early-stage skin grafts before circulation is well established may cause graft failure.
Research Evidence MODERATE	Heat is known to exacerbate certain skin conditions.1 Tissue heating also increases many inflammatory processes.5 Increasing tissue temperature increases cell activity and the demand for oxygen and other nutrients, which may exacerbate tissue hypoxia. It should be noted that controlled warming that raises wound temperature by 1–2°C, but not above physiological temperature (37°C), may be an effective treatment for venous ulcers.14 Wax has been used safely to reduce skin contractures after burn injury and once tissues have healed.15–17

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6-11 Cardiac Failure, Hypertension

Recommendation Systemic Local	Applying superficial heat over the trunk or large surface areas sufficient to cause a systemic response to heat (sweating) is not recommended. Full-body heating (hydrotherapy tanks) should be avoided.
Rationale	Generalized peripheral vasodilatation is produced by heating a large surface area of the body or in response to an increase in core body temperature. This elevation in skin blood flow requires more cardiac output in order to maintain blood pressure. People with impaired heart function may not tolerate the increased cardiac demand.
Research Evidence LOW	No reference found.

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6-12 Metal Implants

Recommendation	Avoid use of heat directly over very superficial metal implants (e.g., staples in skin) or over metal jewellery.
Rationale	Metals have high thermal conductivity; therefore, there is high potential for thermal injury of tissues surrounding heated metal implants. Metal implants underlying thick subcutaneous or muscular layers pose a negligible risk, since superficial thermal agents are unlikely to raise resting temperature at such depths. The CSP advisory applies only to hot packs.
Research Evidence ABSENT	No reference found.

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6-13 Recently Radiated Tissues

Recommendation	Avoid heating tissues that have received radiation therapy during the last 6 months.
Rationale	Heat could stimulate growth of any residual malignant cells. Radiation alters cell metabolism, including that of endothelial cells and fibroblasts. The presence of radiation-induced inflammation, scar tissue, or circulatory effects may adversely affect tissue response, especially the ability to dissipate heat.
Research Evidence LOW	Increasing tissue temperature stimulates metabolic activity in all types of cells. The effects of heat therapy on radiated tissues have not been examined.

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6-14 Reproductive Organs

Recommendation	Heat should not be applied directly to testes.
Rationale	Heat is known to affect spermatogenesis and reduce fertility.
Research Evidence LOW	No references have examined the effect of physiotherapeutic heating agents on male reproductive function.

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Check Skin Integrity

Inspect target area for presence of skin disease and open lesions. Remove jewellery and clothing. Wash skin before applying wax.

Monitor for Systemic Temperature Change

An increase in core temperature is indicated by generalized sweating. Significant changes in core temperature may affect treatment effectiveness and/or compromise patient safety, especially in the frail elderly.

Check Skin Response under Heating Agents

Check skin a few times during the application and as frequently as every 5 minutes if a patient is receiving a particular treatment for the first time.¹⁸ It may be unsafe to apply superficial heat to obese individuals. The risk of a burn increases with the amount of subcutaneous fat, because fat is an insulator, retaining heat rather than transferring (conducting) it to adjacent tissue layers. Patients should not lie on top of hot packs or pads, as pressure sufficient to compress skin capillaries (>32 mmHg) compromises the normal protective reflex vasodilatation response, a mechanism that protects skin from thermal injury.

Monitor Vital Signs and Watch for Sudden Changes in Blood Pressure and Syncope

Persons with orthostatic hypotension, recent traumatic injury, or history of cardiovascular deficiency are particularly susceptible to heat treatments that cause a sudden change in surface temperature (intense heat) and to applications that involve large areas of the body surface (hydrotherapy tanks).

Use a Bell and Timer

Provide enough instruction for the patient to understand the expected thermal sensation and how an unwanted response might manifest or feel. A bell that is sufficiently loud to attract your attention should be left within the patient's reach, with specific instructions as to when the bell should be used. A timer will remind you to return and check on the patient regularly. Take the timer with you if you are not likely to hear it when you leave the patient.

Observe Precautions When Treating Open Wounds

Discharge from open wounds can contaminate heating agents designed for multi-patient use. Opportunistic bacteria such as Pseudomonas aeruginosa inhabit hot tubs and may pose a risk to some individuals.¹⁹ Avoid immersing hands and feet with open skin lesions in paraffin wax baths; instead, wax can be ladled over affected limbs once skin lesions have been covered with protective barriers.

7-2 Raynaud's Disease, Raynaud-Like Phenomenon

Recommendation	Avoid applying cold to hands and feet that show signs of cyanosis and/or pallor or to individuals with a history of vascular hyperactivity to cold (i.e., reversible vasospasm disproportionate to the triggering event in terms of its duration, diffusion, and intensity).
Rationale	In Raynaud's disease, the blood vessels are commonly in a state of vasospasm, which would be exacerbated by applying cold. Prolonged vasoconstriction can lead to thrombus formation, tissue ischemia, and necrosis.
Research Evidence STRONG	Application of cold to distal extremities can trigger vasospasm in digital arteries.10,11

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7-3 Cryoglobulinemia