Therapeutic Heat and Cold
PTA 101 Introduction to Clinical Practice

Instructional Use Statement

The following information is used for instructional purposes for students enrolled in the Physical Therapist Assistant Program at Lane Community College. It is not intended for commercial use or distribution or commercial purposes. It is not intended to serve as medical advice or treatment.

Contact howardc@lanecc.edu for permissions

Introduction

Heat and cold are commonly used at home and in the clinic to treat symptoms of discomfort and injury. In this lesson, we will learn more about the physiological effects of heat and cold in the treatment of soft tissue injuries

Lesson Objectives

1. Describe five physical mechanisms of heat exchange (conduction, convection, radiation, conversion, evaporation)
2. Describe factors which influence the physiological effects of heat
3. Correlate a therapeutic heat intervention to a specific impairment in a case simulation
4. Describe the expected goals and outcomes for applying heat and cold
5. Describe how heat influences exercise performance
6. Describe signs and symptoms that should not be treated with heat/cold and communicate findings to the supervising physical therapist
7. Recognize precautions for applying heat and cold
8. Select the most appropriate superficial heating agent for a given case scenario
9. Select proper procedures for safe and effective application of a superficial heating agent (hydrocollator packs, paraffin, fluidotherapy, short wave diathermy)
10. Identify the role of the PTA during application of physical therapy interventions covered in this course
11. Discuss how the patient's age and medical status may influence selection and outcome of treatments with heat and cold.
12. Describe essential components of documentation (type, method, area, patient position, response to treatment)

Physiologic Effects of Heat

A brief video message from Christina about studying effectively

• mild heating effect: tissue temperature < 40° C (104° F)
• vigorous heating effect in tissue occurs between 40°- 45° C (104-113 ° F)
• tissue damage and thermal pain above 45° C
• heat accumulation in tissue is based on circulation, intensity and duration of heat stimulus, and tissue properties

Heat can produce a multifactorial effects in body tissues and systems:

Five Mechanisms of Heat Exchange

https://upload.wikimedia.org/wikipedia/commons/e/e6/Heat-transmittance-means1.jpg

1. Conduction - two surfaces directly touching each other (e.g. hot and cold packs)
2. Convection - circulation between two mediums of different temperatures (e.g. fluidotherapy, whirlpool)
3. Conversion - nonthermal energy becomes thermal (e.g. ultrasound)
4. Radiation - direct transfer of energy without a medium for transfer (e.g. ultraviolet radiation)
5. Evaporation - transfer of energy that causes a liquid to gas state with resultant cooling (e.g. sweating, vapocoolant sprays)

Key point: superficial thermal agents (like a hot pack) do not increase temperature below a depth of 12 cm.Once the heat source is removed, temperature changes dissipate almost immediately.

The increased circulation rates to muscles results in bringing cooler blood to the treatment area, and homeostasis with muscle temperatures is maintained. Application of heat to reduce pain from a muscle strain is based on increasing the pain-inhibiting nerves and receptors found in the skin and tendons. Decreased muscle guarding decreases pain.

Exercise (isometric, or other) combined with heat produces the greatest increase to circulation and metabolic rates in body tissues

Goals for Using Heat as an Intervention

Clinical Indicators for Heat Application

Chronic musculoskeletal conditions show ability to benefit from heat. Impairments resulting from chronic spinal pain, sprains and strains, and postural dysfunctions are examples where therapeutic heat can be an integral part of promoting functional recovery.

Conditions and impairments associated with loss of soft tissue extensibility (e.g. scar tissue, myofascial syndromes, joint disorders) can also benefit from thermal agents.

Methods of Heat Application

Superficial

• Hydrocollator
• silica packs immersed in hot water (70-75° C, 158-167° F)
• temperature is regulated by the amount of time the pack is immersed
• 6-8 layers of toweling is needed to prevent heat loss (insulate pack), while protecting patient skin
• remove jewelry or any other clothing items that are effective heat conductors (metal snaps, clasps, etc)
• select the pack design that provides optimum skin contact (cervical, low back)
• prepare with appropriate draping, pt education ("this should feel warm, not hot"), and visually check skin within 5 to 10 minutes
• maximum skin temp is reached in 10 minutes, and is sustained for up to 10 minutes
• Paraffin
• Fluidotherapy
• Infrared

Be sure to spend time with the "application of heat" linked slide show in preparation for the unit and for lab

A brief video message from Christina on how to use tables like the one below to develop clinical decision-making skills

Contraindications and Precautions for Superficial Heat

Parameters for Superficial Heat Application

Diathermy

• delivered as short wave (SWD) and microwave (VWD), and continuous or pulsed (intermittent)
• SWD - deep tissue heating without adding heat through reflection off bones
• MWD - deep tissue heating, some potential to add head through reflection off air, soft tissue, and bones
• intervention is contraindicated for anyone with an implanted electronic medical device (e.g. nerve stimulator), implanted metal, or over bone growth plates

A brief video messages about program expectations for learning about diathermy

Physiological Effects of Diathermy

Clinical Indicators for Diathermy

Much like superficial heat, diathermy can be used effectively in conditions resulting from chronic spinal pain, sprains and strains, and postural dysfunctions. Pulsed diathermy can be used much like our non-thermal agents to control pain and edema. Most specifically, pulsed SWD is used to facilitate wound healing (post-surgical, decubitus ulcers, burn-related injury)

Physiological Effects of Cold

Goals for Using Cold as an Intervention

Clinical Indicators for Cold Application

Acute soft tissue injury and post-surgical conditions show ability to benefit from cold, primarily through pain and edema reduction. Neuromuscular conditions that include increase spasticity (e.g. neurologically-mediated resistance to stretch) can be treated with cold to decrease nerve firing and improve available ROM. Pain from chronic spine and joint conditions can also be reduced with cold.

Depth of penetration is up to 5 cm and and application effects can last 1-2 hours

Methods of Cold Application

• Ice massage
• Cold packs
• Ice baths
• Cryostretching
• Vapocoolant
• Cryostretching

Be sure to spend time with the "Cold Application" linked slide show in preparation for the unit and for lab

Contraindications and Precautions

Parameters for Cold Application

Role of the PTA

• Check the POC for inclusion of heat and cold
• Observe and inspect for signs and symptoms of inflammation
• Consider patient age and medical status when selecting a heating agent
• Intentionally select heat or cold based on the expected change in impairment or functional limitation as it relates to the goals
• Inspect equipment to confirm good working order
• Inform the patient about the procedure: what to expect and what is unexpected
• Check skin for sensory response
• Screen for contraindications and precautions
• Leave patient with call bell if unattended
• Document treatment (informed consent, skin check, type, position, parameters, outcome)

 Consider the Evidence

In the literature, particularly in studies whose aim is to systematically review intervention effectiveness, there is weak evidence supporting the use of heat and cold as pain reducers or in impacting function. Parameters for treatments have been derived from research studies and analysis of effectiveness is ongoing. As a PTA, you are responsible for understanding and applying treatment parameters that are consistent with today's literature and in the PT plan of care. Selecting parameters will always include careful analysis of each patient's condition and interests at the time of treatment. You are also equipped, through evidence-based research skills, to engage in discussions and best practices as we work to restore function with our patients.

Exam Success

1. Consider using these additional linked worksheets and resources your Heat Cold Study Guides Consider sharing your guides on the Can You Help Me? forums
2. Write 5 matching, short answer, multiple choice questions based on lesson objectives, readings, the narration, and the Heat Cold Study Guides. Send them to me and you might see them on the exam
3. Rehearse your understanding of application procedures during laboratory practice and seek feedback from classmates on whether or not you are demonstrating understanding of how to safely select and apply heat or cold