ELECTROPHYSICAL AGENTS - Contraindications And Precautions: An Evidence-Based Approach To Clinical Decision Making In Physical Therapy

doi:10.3138/ptc.62.5

. 2011 Jan 5;62(5):1–80. doi: 10.3138/ptc.62.5

ELECTROPHYSICAL AGENTS - Contraindications And Precautions: An Evidence-Based Approach To Clinical Decision Making In Physical Therapy

PMCID: PMC3031347 PMID: 21886384

Physiother Can. 2011 Jan 5;62(5):1–3.

Foreword

Sandy Rennie ^1,^✉

The importance of the guideline “Electrophysical Agents—Contraindications and Precautions: An Evidence-Based Approach to Clinical Decision Making in Physical Therapy” by Houghton, Nussbaum, and Hoens simply cannot be overstated. This excellent work is timely, relevant, and important both clinically and educationally; it could well become a seminal guide to contraindications and precautions in the use of electrophysical agents (EPAs) not only in Canada but internationally.

While Houghton et al. point out that their primary references were not acquired through a rigorous systematic review process, the thoroughness of the literature review is impressive. It provides a sound basis for examining why certain contraindications and precautions are still viable and appropriate in today's clinical practice. In addition to a comprehensive list of scientific articles, the authors consulted 17 textbooks that address contraindications and precautions for the EPAs; they examined and interpreted guidelines produced by the Chartered Society of Physiotherapy (UK) and the Australian Physiotherapy Association; and, perhaps most importantly from an academic perspective, they conducted a consensus exercise among North American (Canadian and US) and international experts through a direct survey, requesting their recommendations on contraindications and precautions for commonly used EPAs.

The authors' purpose in developing this document was to provide a resource that could guide clinical decision making for the safe and effective use of EPAs; evidence-based practice was at the forefront of their approach. Their purpose was not to address indications for the use of EPAs, but rather to describe the evidence and prevailing opinions on the most common contraindications to and precautions for the effective use of EPAs, and specifically six commonly used EPAs: cold (cryotherapy), heat (superficial thermal agents), electrical stimulation (TENS, NMES, HVPC), low-level laser therapy, short-wave diathermy, and therapeutic ultrasound. Unfortunately, not all examples of the agents used in these groupings are discussed; however, there is enough information that the reader can safely draw conclusions for the EPAs not described, with a few exceptions. These exceptions are discussed below.

ULTRASOUND

In the section on effective duration of ultrasound, the authors describe using pulsed ultrasound for a minimum of 10 minutes, based on good evidence. However, they do not mention that continuous ultrasound should also be used for a minimum of 10 minutes (as described by Draper et al.)¹ in order to produce the tissue-temperature rise of 4°C required to achieve a thermal impact on the tissues.

ELECTRICAL STIMULATION

Houghton et al. have included several types of electrical stimulation in this section: transcutaneous electrical nerve stimulation (TENS), high-voltage pulsed current (HVPC), interferential current (IFC), and neuromuscular electrical stimulation (NMES). It might have been prudent to separate these currents according to their primary uses in physiotherapy practice, rather than combining them together. TENS and IFC are used primarily for pain relief; HVPC is used for wound care and sometimes for pain relief; and NMES is used for muscle-fibre recruitment. Therefore, while the majority of contraindications and precautions are similar, there are some exceptions.

Another precaution should be noted for the use of IFC with suction-cup application. Whether the suction is vacuum or positive pressure (Venturi system), the risk of skin damage is increased when this method of application is used. Therefore, it is important to ensure that the patient's skin condition is appropriately safe for IFC suction application.

Houghton et al. indicate that NMES is contraindicated “anywhere” on pregnant women; however, there appears to be no evidence for this. NMES is an effective tool for muscle recruitment, muscle strengthening, and functional activity.^2–4 Although it should not be used on the abdomen or lumbar spine, NMES should be safe and effective for other situations when motor-unit recruitment (particularly peripherally) would be beneficial for pregnant women.

The authors dismiss myths around the use of electrical stimulation on patients with certain medical conditions, acknowledging that NMES can be used safely and effectively in patients with cancer, chronic obstructive pulmonary disease, and heart disease. Recent research^5–8 has shed more light on the use of electrical stimulation in these situations.

SUPERFICIAL HEATING AGENTS

In this section, the primary electrophysical agents discussed by Houghton et al. are those that fall into the category of superficial heating agents—that is, agents that heat tissues within 3 cm of the skin surface. These agents typically include paraffin wax baths, hydrocollator hot packs, and hydrotherapy. In recent years, another superficial heating agent has appeared on the over-the-counter market for consumers: the heat wrap. Commercially available, wearable heat wraps are air activated and can be worn for up to 8 hours at a time; they consist of cloth embedded with multiple discs made of iron powder, activated charcoal, sodium chloride, and water. These discs are spaced throughout the cloth's application surface; when the wrap is removed from its sealed pouch and exposed to air, the discs oxidize, undergoing an exothermic reaction and thus producing heat. These wearable heat wraps maintain a temperature of about 40°C (104°F), elevate tissue temperature, and can be worn during activities of daily living, at work, and during sleep. They are available in different sizes and shapes to accommodate body size and contour and location of application. Several studies have examined the effectiveness of these heat wraps.^9–12

While practising physiotherapists may not use heat wraps in a clinic or department, they should be aware of these products and their risks for skin damage through burns and/or blisters. Since these products are being used more and more by patients, it is imperative that we understand their mechanism of use and the safety concerns around them, as patients will undoubtedly ask for our advice with respect to their use.

Another concern we often have with the use of superficial heating agents is the impact the heat may have on subcutaneous fatty tissue. In two recent articles, Petrofsky et al.^13,14 examined the effects of superficial heat on subjects with a high body mass index (BMI). In their experiments using hydrocollator hot packs on overweight subjects, they found that the change in muscle temperature was reduced, while the change in skin temperature was increased, relative to non-overweight patients. This temperature accumulation in the skin is potentially dangerous, particularly for obese patients who are older, have diabetes, or have impaired circulation and/or reduced skin thickness, as it may result in burns or skin damage.

SUPERFICIAL COOLING AGENTS

A hierarchy of cooling agents is provided by Houghton et al. Missing from their list, however, are combined cold and compression units such as the Cryo/Cuff. These units are designed to provide both cold and compression simultaneously, and they have been shown to be both safe and effective.^15–18 The authors' list of general contraindications and precautions for the use of cryotherapy would certainly also apply to these cold/compression units; however, an additional relevant precaution is that too much combined cold and compression can compromise tissues even more. The use of these devices is common in acute joint injuries, such as ankle sprains, to help control swelling and possible bleeding in the region. However, caution is advised when adding compression to a cryotherapy application to ensure that circulation and nerve(s) are not compromised.

SHORT-WAVE THERAPY

A primary concern raised by Houghton et al. about the use short-wave therapy (SWT) is that there should be no metal furniture within a 2 m distance of the operating SWT unit, nor should any items of furniture being used by the patient have any metal parts. While this safety approach seems plausible, it may not be possible in today's clinics and hospital physiotherapy departments. The majority of treatment plinths in current use are adjustable in height, with moveable parts to accommodate patients in various positions of support. These modern plinths are designed not only for better patient accessibility and comfort but also for the comfort and safety of the physiotherapist: because they can change the height and configuration of the plinth, physiotherapists are less likely to sustain joint, muscle, or back injuries. These plinths, which are adjustable manually (hydraulic) or electrically (footswitch), have metal frames and parts, and this, according to Houghton et al., makes them unusable for SWT. We may need to rethink this application restriction and find ways of applying SWT safely and effectively using adjustable treatment plinths. If precautions are taken to ensure that the patient is not touching any metal and that the SWT leads and electrode(s) are properly attached and not touching the plinth, treatment may be considered safe.

PROCEDURES FOR ALL ELECTROPHYSICAL AGENT TREATMENTS

A systematic and common-sense approach to the use of EPAs is described by Houghton et al.: ensuring patient safety through explanation, informed consent, sensation testing, and patient monitoring during treatment; reassessment using valid outcome measures; and ensuring completion of appropriate documentation.

CONCLUSION

“Electrophysical Agents—Contraindications and Precautions: An Evidence-Based Approach to Clinical Decision Making in Physical Therapy” is a much-needed resource for physiotherapists in Canada and abroad and should be part of the education of future physiotherapists.

References

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Physiother Can. 2011 Jan 5;62(5):4.

Authors and Contributors

About the Authors

Pamela E. Houghton, PhD, BScPT: Associate Professor, School of Physical Therapy, Faculty of Health Sciences, University of Western Ontario, London, Ontario; Chair of Graduate Program in Health and Rehabilitation Sciences, Faculty of Health Sciences, University of Western Ontario, London, Ontario.

Ethne L. Nussbaum, PhD, MEd, BScPT: Associate Professor, Department of Physical Therapy, University of Toronto, Toronto, Ontario; Research Physiotherapist, Mount Sinai Hospital, Toronto, Ontario.

Alison M. Hoens, MSc, BScPT, PG Sports PT: Clinical Associate Professor and Physical Therapy Knowledge Broker, Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia; Research, Education and Practice Coordinator, Physiotherapy, Providence Health Care, Vancouver, British Columbia.

Address correspondence to Pamela E. Houghton, School of Physical Therapy, University of Western Ontario, London, ON N6G 1H1 Canada. Tel.: 519-661-3360; Fax: 519-661-3866; E-mail: phoughto@uwo.ca.

Acknowledgements

The authors wish to thank the following contributors:

Alain-Yvan Bélanger, PhDPT, MSc, BSc: Professor, Programme de Physiothérapie, Département de Réadaptation, Faculté de Médicine, Université Laval, Québec (Québec).

Susan L. Michlovitz, PhDPT, CHT: Professor, Department of Physical Therapy, Temple University, Philadelphia, Pennsylvania, USA.

Sandy Rennie, PhD, MSc, BPT: Director and Associate Professor, School of Physiotherapy, Faculty of Health Professions, Dalhousie University, Halifax, Nova Scotia.

Barbara Shay, PhD: Associate Professor, Department of Physical Therapy, School of Medical Rehabilitation, University of Manitoba, Winnipeg, Manitoba.

Joseph Anthony, PhD, PT: Clinician, Providence Health Care Vancouver, British Columbia; Sessional Instructor, Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia.

Physiother Can. 2011 Jan 5;62(5):5–10.

1. Introduction

This document was developed by three physical therapists dedicated to evidence-based practice in the use of electrophysical agents (EPAs), with the intent to provide a resource to guide safe practice using EPAs.

Impetus

This project began when the authors taught a workshop on EPAs prior to the 2007 World Congress of Physiotherapy in Vancouver, Canada. The workshop revealed considerable discrepancy between instructors and participants in terms of what was considered safe practice with respect to EPA contraindications and precautions. Furthermore, the authors found that they were frequently being contacted for guidance on EPA safety issues, yet their attempts to provide answers were complicated by conflicting or inadequate evidence in the literature. It was clear that there was a need for a resource to guide this important area of physiotherapy practice. The authors therefore sought to capture traditional EPA safe practice by examining the consensus of opinion among selected EPA experts and authors of recent book chapters and monographs, and to review the literature for evidence to support or refute the common view, with the goal of developing evidence-based recommendations for safe practice in the use of EPAs.

Purpose

The authors' intent in developing this resource was to provide the physical therapy community with a resource that could guide clinical decision making for safe practice in the use of EPAs, thereby reducing the incidence of adverse reactions.

This resource was developed with the following objectives:

To provide a compilation and synthesis of information from original research articles, reviews, and textbook resources about contraindications and precautions for EPAs.
To summarize expert opinion (North American and international, as represented by EPA guidelines of the Australian Physiotherapy Association and the UK Chartered Society of Physiotherapy) in order to highlight the degree of consensus with respect to contraindications and precautions for EPAs.
To make clear recommendations on EPA contraindications and precautions based on scientific evidence, physiological rationale, and/or ethical reasoning.
To provide a rationale for each recommendation to enable physiotherapists to make informed clinical decisions.

Scope

It is important to note that our focus here is restricted to the evidence and prevailing opinions for EPA contraindications and precautions; it does not address their indications (i.e., their clinical effectiveness). Accordingly, this guide should be used in conjunction with the three critical components of evidence-based practice: (1) best research evidence (i.e., clinical effectiveness studies), (2) clinical expertise, and (3) patient values.¹

This resource focuses on the following commonly used electrophysical agents (EPAs):

Superficial heat (hot packs, wax, and hydrotherapy)
Cryotherapy (ice, ice baths, and cold packs)
Therapeutic ultrasound (pulsed and continuous mode)
Short-wave therapy (pulsed and continuous mode)
Light therapy (low-level laser therapy and non-coherent light)
Electrical stimulation therapy (E-stim) using surface electrodes: transcutaneous electrical stimulation (TENS), neuromuscular electrical stimulation (NMES), high-voltage pulsed current (HVPC), and interferential current (IFC)

The use of these energies (electrical, light, sound, and thermal) for diagnostic, medical, or surgical applications is not considered. Microwave diathermy, low-frequency pulsed electromagnetic fields (PEMFs), iontophoresis, electromyography (EMG) biofeedback, compression therapy, ultraviolet irradiation, and radiant heat are not included. This guide considers commonly encountered clinical conditions or patient scenarios associated with the use of EPAs, rather than rare conditions and circumstances.

Provisos

The information provided here should be used in conjunction with the standards mandated by professional associations and regulatory bodies (e.g., Health Canada, the US Food and Drug Administration, provincial physiotherapy regulatory organizations). Contraindications and precautions are also listed in the operating manuals provided by equipment manufacturers, as required by Health Canada, although Health Canada does not vet these listings. In the event of a discrepancy between the information provided in this document and that provided by a manufacturer, the clinician is not bound by the manufacturer's recommendation.

Although this resource provides a review of the evidence, an expression of popular views, and informed recommendations for practice, it is ultimately the clinician who is responsible for making decisions about EPA application in a specific clinical situation. Clinical decisions should be based on weighing the evidence supporting use or non-use of a device and on an appreciation of the unique characteristics of the individual patient. In the absence of clear or substantive evidence of efficacy, and in the presence of potential adverse effects, it is recommended that clinicians err on the side of caution and avoid the use of the EPA.

Methodology

Consensus among North American and international experts was established by surveying experts within Canada and the United States, reviewing textbook resources, and interpreting guidelines from the Chartered Society of Physiotherapy in the United Kingdom and the Australian Physiotherapy Association. The findings are summarized in Appendix 1.

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.

Guidelines of the Australian Physiotherapy Association (APA) and the Chartered Society of Physiotherapy (CSP)

Similar documents addressing this topic have been produced by Robertson et al. in Australia² and by the Chartered Society of Physiotherapy (CSP) in the United Kingdom.³ These guidelines were reviewed by the present authors, and an interpretation of their recommendations is included here in order to give the reader an appreciation of the degree of international agreement on contraindications and precautions for the various EPA modalities. However, caution is advised when comparing recommendations, as the differences in Australian, UK, and Canadian approaches to the topic required a degree of subjective interpretation. For example, the CSP guidelines do not consider TENS, NMES, IFC, and HVPC separately; therefore, the present authors have necessarily assumed that the list of contraindications and precautions pertains to all types of low-frequency E-stim. The APA guidelines group various conditions together (e.g., acute infection, malignancy, tuberculosis, and osteomyelitis are grouped in the category “risk of dissemination”), which likewise requires an assumption that each of these conditions is a contraindication. In addition, terminology varies between the documents. For example, the CSP guidelines include a category termed “local circulatory insufficiency,” which was assumed to denote arterial insufficiency and to be similar to the category here termed “impaired circulation”—and, moreover, to exclude other circulatory disturbances such as deep vein thrombus, venous congestion, and edema.

Recommendations

Within this document, clear recommendations are provided for the safe use of EPAs in specific conditions, together with a rationale and supporting literature for each condition. Tables at the beginning of each section summarize these recommendations. These tables are not meant to stand alone; rather, users of this resource are strongly encouraged to refer to the text, where recommendations are clarified, the rationale underlying the recommendation is provided, and the level of evidence supporting the recommendation is evaluated.

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.

Summaries

Table 1 summarizes the authors' recommendations for the six EPAs discussed here. Thereafter, each EPA-specific section begins with a list that summarizes all recommendations specific to that EPA. This is followed by a table providing the percent (raw) agreement on contraindications among the North American experts and the authors of the textbook chapters consulted, an interpretation of the recommendations found in the APA and CSP guidelines, the seriousness of potential adverse reactions, the level of research evidence, and the authors' recommendations. For the rationale and supporting evidence for these recommendations, the reader is strongly urged to consult the detailed condition-specific discussions presented under the heading “Recommendation, Rationale, and References” in each section. These detailed discussions may include a few conditions not covered in the summary of recommendations or in the tables. Each section concludes with recommendations for safe practice (under the heading “Safe Practice”), followed by a list of references cited in the text and tables.

Symbol	Definition	Criteria
	CONTRAINDICATION DO NOT use the EPA with this condition or in this body location.	Potential for serious adverse reaction Moderate to strong research evidence Consensus among experts and resources
	PRECAUTION Experienced clinicians may elect to treat this condition/location with extra caution (e.g., using lower intensities and/or more frequent monitoring).	Potential for moderate to minor adverse reaction Low to moderate research evidence
	SAFE This condition or body location is NOT contraindicated.	Potential for minor adverse reaction Absent to low research evidence (no adverse reactions have been reported with clinical use)

	Ultrasound		Electrical Stimulation			LLLT Light	Heat	Cold	SWT Therm	SWT Non
Cont	Pulsed	TENS	NMES	HVPC
*Conditions*
Active deep vein thrombosis or thrombophlebitis	C-local	C-local	C	C	C	C-local	C	C	C	C
Active epiphysis	P	P	P	P	P	S	P	S	P	P
Acute injury / inflammation	C-local	P	S	S	S	S	C-local	S	C-local	S
Cardiac failure	S	S	C-local	C-local	C-local	S	P	P	P	S
Chronic wound	P	S	S	S	S	S	S	C	P	S
Cold hypersensitivity (e.g. Raynaud's, cryoglobulinemia, hemoglobulinemia)	S	S	S	S	S	S	S	C	S	S
Cold urticaria	S	S	S	S	S	S	S	C	S	S
Damaged or at-risk skin	P	P	C-local	C-local	C-local	S	C-local	P	P	S
Haemorrhagic conditions	C	C	C	C	C	C	C	C	C	C
Hypertension	S	S	S	S	S	S	S	P	S	S
Impaired circulation	C-local	P	P	C-local	P	S	C-local	C-local	C-local	P
Impaired sensation	C-local	P	C-local	P	P	S	C-local	P	C-local	S
Impaired cognition or communication	C	P	C	P	P	P	C	C	C	P
Infection	C-local	P	C-local	C-local	C-local	P	C-local	P	C-local	P
Malignancy	C-local	C-local	C-local	C-local	C-local	C-local	C-local	S	C-local	C-local
Photosensitivity or systemic lupus erythematosis	S	S	S	S	S	P	S	S	S	S
Pregnancy	C-local	C-local	C-local	C	C-local	C-local	P	S	C	C
Recently radiated tissue	C-local	C-local	C-local	C-local	C-local	P	C-local	S	C-local	C-local
Skin disease (e.g., eczema)	C-local	P	P	P	P	S	C-local	S	C-local	P
Tuberculosis	C-local	C-local	C-local	C-local	C-local	C-local	C-local	C-local	C-local	C-local
*Implants*
Electronic device	C-local	C-local	C-local	C-local	C-local	S	S	S	C	C
Metal implant	S	S	S	S	S	S	S	S	C	S
Plastic, cement implant	C-local	P	S	S	S	S	S	S	C	S
*Local Areas*
Eyes	C	C	C	C	C	C	P	P	C	P
Anterior neck, carotid sinus	C	C	C	C	C	P	P	C	C	C
Chest, heart	S	S	P	C	P	S	S	S	C	C
Head	S	S	C	C	C	S	S	S	S	S
Regenerating nerves	P	P	C	P	P	S	S	C	C	P
Reproductive organs	C	C	C	C	C	C	C	S	C	S

	Resources % (n=12)	Can/US %	APA	CSP	Adverse Reaction^**	Research Evidence^**	For Details See
*Conditions*
Pregnancy	100	100 (n=8)	C	C- local	Serious	Moderate	3-1
Malignancy	83	100 (n=8)	C	C-local	Serious	Strong	3-2
Active epiphysis	50	N/A	N/A	C- local	Moderate	Moderate	3-3
Myositis ossificans	S	N/A	N/A	N/A	Moderate	Absent	3-3
Deep vein thrombosis Thrombophlebitis	75	100 (n=8)	N/A	P	Serious	Low	3-7
Infection Tuberculosis	75	100 (n=8)	C	C	Moderate	Moderate	3-8
Acute injury Inflammation	25	100 (n=8)	C	N/A	Minor	Low	3-9
Haemorrhagic conditions	58	75 (n=8)	C	C	Serious	Moderate	3-10
Recently radiated tissue	42	88 (n=8)	C	P	Serious	Low	3-11
Impaired sensation	58	63 (n=8)	S	P	Moderate	Absent	3-12
Impaired cognition or communication	S	63 (n=8)	C	C	Moderate	Absent	3-13
Impaired circulation	50	88 (n=8)	C	P	Moderate	Moderate	3-14
Skin disease Damaged or at-risk skin	8	86 (n=7)	C	P	Minor	Absent	3-15
*Implants*
Plastic/cement implant	42	50 (n=8)	N/A	N/A	Moderate	Moderate	3-4
Metal implant	S	P (n=8)	N/A	C	Minor	Strong	3-5
Electronic implant Cardiac pacemaker	83	88 (n=8)	C-local	C-local	Serious	Low	3-6
*Local Areas*
Reproductive organs	92	75 (n=8)	C	C-local	Serious	Absent	3-16
Eyes	100	100 (n=8)	C	C-local	Serious	Absent	3-17
Neck	S	N/A	N/A	N/A	Serious	Strong	3-18
Spinal cord Superficial/regenerating nerves	75	N/A	N/A	N/A	Minor	Low	3-19 3-20
Chest, heart Head	58	N/A	N/A	N/A	Moderate	Low	3-21

Recommendation	Continuous and pulsed ultrasound should not be used over the low back, abdomen, or uterus. High-intensity, lower-frequency waves administered in continuous mode are potentially the most dangerous because they produce the greatest penetration and tissue heating.
Rationale	Sound waves transmit through amniotic fluid and could cause fetal malformations, including growth retardation, micropthalmia, exencephaly, microencephaly, neural tube defects, and myelodyplasia. Teratogenic effects of ultrasound are greater if tissue heating occurs or if maternal core temperature is elevated.
Research Evidence MODERATE	Diagnostic ultrasound is thought to be safe for human fetal development at levels below 0.1 W/cm² spatial average temporal peak (SATP) and at increases in temperature of embryonic and fetal tissue of no more than 1.5°C above normal physiological levels (37°C).^1–5 However, therapeutic ultrasound has produced malformations in fetal tissue models.^6–8

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

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

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

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

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

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

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

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

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.

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

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

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

Recommendation	Pulsed or continuous ultrasound applied to the chest wall is safe provided that the transducer head is not stationary and the rib cage is intact. Ultrasound used below the ribcage should not be directed toward the heart and/or lungs.
Rationale	Ultrasound could potentially alter cardiac conduction and cause arrhythmias.
Research Evidence LOW	Ultrasound at 0.1 W/cm² spatial peak temporal average (SPTA) applied to the exposed thoracic cavity in small animals caused bleeding of the lungs and gut.^1,42 The clinical relevance of this research in small animals is questionable.

Recommendation	E-stim should not be applied in a location where it may cause malfunction of implanted electronic devices (e.g., pacemakers, cardioverter defibrillator, neurostimulators implanted in spinal cord or brain, bone-growth stimulators). Malfunction of these devices could be life threatening or require surgical replacement of the device. An ECG should be obtained during E-stim to determine whether there is interference with the cardiac pacemaker function and whether E-stim affects the patient's heart rate or other vital signs. Whenever an ECG is recorded during E-stim treatment, the relevant physicians should be advised so that stimulus artefacts produced by TENS do not result in misinterpretation of the ECG findings, leading to the patient undergoing unnecessary assessments or treatments.
Rationale	E-stim applied over the chest wall or near leads connected to electronic devices could cause fibrillation; changes in heart rate, cardiac output, and blood pressure; and perfusion of vital organs, including the brain. Demand-type pacemakers, the type most commonly implanted, pace heart rate based on feedback from the patient's own heart and are therefore more susceptible to external stimuli produced by E-stim. Less commonly used fixed-rate cardiac pacemakers pace heart rate continuously and are less likely to be influenced by external E-stim such as TENS. Some cardiac pacemakers can be filtered to block interference by external electronic devices such as TENS.
Research Evidence MODERATE	There are documented cases in which E-stim application caused atrial fibrillation and alterations in heart function.^1–11 Some authors recommend that E-stim not be applied directly over implanted devices (C-local), whereas others suggest that E-stim is contraindicated in any body location for people with implanted electronic devices. The literature is not clear on whether these advisories pertain to TENS treatments only or to all types of electrical currents. E-stim has produced ECG artefacts in persons with cardiac pacemakers, and in one case this resulted in unnecessary treatment.^12–15 However, when 20 different TENS models, representing five different manufacturers, were evaluated on 51 patients using demand-type pacemakers, with four or more body sites tested on each patient, the TENS produced no episodes of pacemaker interference, inhibition, or reprogramming.¹⁶

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

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

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

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

PERMALINK

ELECTROPHYSICAL AGENTS - Contraindications And Precautions: An Evidence-Based Approach To Clinical Decision Making In Physical Therapy

Foreword

Sandy Rennie

ULTRASOUND

ELECTRICAL STIMULATION

SUPERFICIAL HEATING AGENTS

SUPERFICIAL COOLING AGENTS

SHORT-WAVE THERAPY

PROCEDURES FOR ALL ELECTROPHYSICAL AGENT TREATMENTS

CONCLUSION

References

Authors and Contributors

About the Authors

Acknowledgements

1. Introduction

Impetus

Purpose

Scope

Provisos

Methodology

Canadian/US Expert Consensus

Resources

Guidelines of the Australian Physiotherapy Association (APA) and the Chartered Society of Physiotherapy (CSP)

Recommendations

Rationale

Research Evidence

Recommendations

Summaries

Criteria for Assigning the Seriousness of Adverse Reaction and Level of Research Evidence

Seriousness of Adverse Reaction

Serious

Moderate

Minor

Level of Research Evidence

Strong

Moderate

Low

Absent

Limitations

Definition of Terms

Abbreviations

References

2. Summary of Recommendations

Table 1.

3. Continuous and Pulsed Ultrasound

Summary of Recommendations

Table 2a.

Table 2b.

ULTRASOUND: RECOMMENDATIONS, RATIONALE, AND REFERENCES

3-1 Pregnancy

3-2 Malignancy

3-3 Active Epiphysis, Myositis Ossificans

3-4 Plastic and Cement Implants

3-5 Metal Implants

3-6 Electronic Devices

3-7 Active Deep Vein Thrombosis, Thrombophlebitis

3-8 Infection, Tuberculosis (TB)

3-9 Acute Injury, Inflammation

3-10 Haemorrhagic Conditions

3-11 Recently Radiated Tissue

3-12 Impaired Sensation

3-13 Impaired Cognition or Communication

3-14 Impaired Circulation

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

3-16 Reproductive Organs

3-17 Eyes

3-18 Anterior Neck, Carotid Sinus

3-19 Spinal Cord

3-20 Peripheral and Regenerating Nerves

3-21 Chest, Heart

Safe Practice

Perform a Sensory Discrimination Test

Inspect Skin Area

Avoid Transfer of Infectious Agents

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

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

Use Appropriate Ultrasound Couplants

Limit Thermal Ultrasound Treatment to Surface Areas≤10 cm2

Apply Ultrasound Using Effective Treatment Duration (≥10 minutes)

Limit Thermal Ultrasound Treatment to Surface Areas≤10 cm²

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

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

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.

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 wounds^27,40–44 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

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

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

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

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

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.

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