Physical Agent Modalities Reading

Vocabulary flashcards summarizing key terms, modalities, physiological principles, safety considerations, and therapeutic applications found throughout the lecture on PAMS, cryotherapy, heat agents, ultrasound, laser, diathermy, and electrotherapeutic techniques. Designed for rapid recall of definitions relevant to occupational therapy practice and exam preparation.

Physical Agent Modalities (PAMS)

Systematically applied interventions (heat, cold, electricity, etc.) used to modify client factors limiting occupational performance.

Electrotherapeutic Agent

Any PAMS that uses electrical or electromagnetic energy to promote tissue healing, modulate pain, or improve muscle performance.

Paraffin Bath

A molten wax-and-oil modality delivering moist heat to small joints; commonly used for arthritis or scar management.

Cryotherapy

Therapeutic application of cold to withdraw heat from tissues, reducing pain, edema, spasm, and metabolic rate.

Conduction (cold/heat)

Heat transfer through direct contact between two materials of different temperatures (e.g., ice pack, hot pack).

Convection (cold/heat)

Heat transfer via movement of a fluid or gas over tissue (e.g., whirlpool, fluidotherapy).

Evaporation

Cooling produced as a liquid converts to gas, as with vapocoolant sprays or perspiration.

Hunting Response

Cycles of vasoconstriction and vasodilation occurring after prolonged cold exposure (>15 min).

Spasticity

Velocity-dependent increase in muscle tone due to upper motor neuron lesions; may be temporarily reduced with prolonged cooling.

Edema

Excess interstitial fluid; managed acutely with RICE (rest, ice, compression, elevation).

Inflammatory Phase

First stage of wound healing (0-7 days) marked by hemostasis, vasoconstriction, and leukocyte migration.

Proliferative Phase

Healing stage characterized by granulation, epithelialization, fibroplasia, and wound contraction (day 3-21).

Remodeling Phase

Final healing stage (begins ~2 weeks, lasts months) where collagen reorganizes, increasing tensile strength.

Partial-Thickness Wound

Involves epidermis ± superficial dermis; heals by epithelialization and is usually painful, moist, pink-red.

Full-Thickness Wound

Extends through dermis into subcutaneous tissue; heals by secondary intention (inflammation, proliferation, remodeling).

Red-Yellow-Black Classification

Color-based wound system: red = healthy granulation; yellow = slough/exudate; black = necrotic tissue.

Primary Intention (Closure)

Wound edges approximated and sutured; minimal tissue loss, rapid healing.

Secondary Intention

Open, large wounds left to heal by granulation, contraction, and scar formation.

Delayed Primary Closure

Initially open wound later closed surgically after contamination risk passes.

Scar Tissue

Dense, disorganized collagen replacing normal tissue during healing; matures during remodeling.

Induction Theory

Concept that healing tissue attempts to mimic characteristics of the tissue it replaces.

Tension Theory

External/internal stresses influence collagen alignment; basis for splinting, stretching, CPM.

Pressure Ulcer

Localized tissue necrosis over bony prominences due to prolonged pressure and ischemia.

Epidermis

Avascular outer skin layer providing protective barrier and preventing dehydration.

Dermis

Vascular connective-tissue layer housing hair follicles, glands, receptors; supplies nutrition and thermoregulation.

Subcutaneous Layer

Fat and connective tissue beneath dermis providing insulation, cushioning, and support.

Wound Documentation

Record location, size, shape, tissue type, exudate, granulation, surrounding skin, and pain.

Acute Pain

Short-duration protective pain (seconds-days) signaling potential or actual tissue damage.

Chronic Pain

Persistent or recurrent pain lacking protective function; often linked with emotional distress.

Nociceptive Pain

Pain from activation of peripheral nociceptors by noxious stimuli (sharp, aching, throbbing).

Neuropathic Pain

Pain due to lesion or disease of somatosensory system; burning, electric, lancinating quality.

A-delta Fibers

Small myelinated fibers transmitting fast, sharp pain sensations.

C Fibers

Unmyelinated fibers conveying dull, diffuse, burning pain.

Lateral Spinothalamic Tract

Ascending spinal pathway carrying pain and temperature signals to thalamus and cortex.

Persistent Pain

Long-lasting or frequently recurring pain impacting all areas of occupation.

Trigger Point

Hyperirritable spot in taut muscle band; palpation or cold/heat can refer pain distally.

McGill Pain Questionnaire

Multidimensional tool using descriptors, diagrams, and rating index to assess pain.

Visual Analog Scale (VAS)

10-cm line for patients to mark current pain intensity; quick monitoring tool.

Cold Spray (Vapocoolant)

Topical evaporative agent producing rapid cutaneous cooling for trigger-point or spasm relief.

Ice Massage

Direct circular application of ice to small area (3-10 min) until numbness achieved.

Cold Compression Unit

Device circulating chilled water/air through a sleeve to provide combined cold and compression.

Contrast Bath

Alternating immersion in warm and cold water to induce vasoconstriction/vasodilation cycles and reduce edema.

Fluidotherapy

Dry-heat modality using suspended cellulose particles; allows AROM during treatment, good for desensitization.

Wrap/Gloving Technique

Common paraffin method: 8-10 rapid dips, then plastic and towel wrap for 20 min heat retention.

Therapeutic Heat

Superficial agents (hot packs, paraffin) raising tissue to 104-113 °F to increase extensibility and circulation.

Radiation (heat)

Transfer of thermal energy through air from warmer to cooler source (e.g., infrared lamp).

Hot Pack

Silica-gel pack heated 158-167 °F in hydrocollator; requires 6 towel layers, 20 min application.

Therapeutic Ultrasound

Sound energy (1 MHz or 3 MHz) creating thermal or non-thermal effects for deep tissue treatment.

1 MHz Ultrasound

Low frequency penetrating 3-5 cm for deep structures (muscle, fascia).

3 MHz Ultrasound

Higher frequency treating superficial tissues (1-2 cm) with faster heating rate.

Attenuation

Decrease in ultrasound intensity due to absorption, reflection, or refraction within tissues.

Cavitation

Formation of gas bubbles in fluids during ultrasound; stable (therapeutic) vs. unstable (damaging).

Beam Non-uniformity Ratio (BNR)

Ratio of peak to average ultrasound intensity; lower BNR means more uniform output and safety.

Duty Cycle

Percent of time ultrasound is on during a pulse period; continuous = 100 %, pulsed = ≤50 %.

Phonophoresis

Use of ultrasound to drive topical medications (e.g., dexamethasone) through skin for local effect.

Low-Level Laser Therapy (LLLT)

Monochromatic, coherent light (≈600-1000 nm) delivering non-thermal photobiomodulation for pain and tissue repair.

Helium-Neon Laser

Red-light LLLT source (633 nm) used for superficial wound healing.

Gallium Arsenide Laser

Infrared LLLT source (904 nm) penetrating deeper for musculoskeletal conditions.

Shortwave Diathermy (SWD)

Deep-heating modality using 27.12 MHz radiofrequency to warm large tissue volumes.

Capacitor Electrodes

SWD setup creating strong electric field between two plates, heating more superficially.

Microwave Diathermy

Electromagnetic modality (2450 MHz) focusing heat superficially; higher burn risk than SWD.

Direct Current (DC)

Unidirectional electrical flow; used for iontophoresis and denervated muscle stimulation.

Alternating Current (AC)

Continuous bidirectional flow changing polarity; household electricity and interferential base wave.

Pulsatile Current

Intermittent flow delivered in pulses; can be monophasic, biphasic, or polyphasic.

Monophasic Waveform

Single-phase pulsed current with net positive or negative charge (e.g., high-volt).

Biphasic Waveform

Two opposing phases in each pulse; symmetrical for large muscles, asymmetrical for small.

Polyphasic Waveform

Burst of three or more phases per pulse (e.g., Russian stimulation).

Interferential Current (IFC)

Two medium-frequency ACs intersect to produce low-frequency therapeutic beat for pain/edema.

Russian Stimulation

2500 Hz AC delivered in 50 bps bursts to strengthen large muscles (10 s on / 50 s off).

Pulse Duration

Length of time each electrical pulse lasts; affects depth & comfort of stimulation.

Rate/Frequency (pps)

Number of pulses per second; influences quality of contraction and fatigue.

Electrode Size

Smaller electrodes ↑ current density; larger electrodes disperse current over bigger area.

Monopolar Placement

Small active electrode over target; larger dispersive electrode placed proximally.

Bipolar Placement

Two equal electrodes on same muscle group; common for NMES muscle re-education.

Quadripolar Placement

Four electrodes (two channels) crossing currents—typical for IFC pain management.

Neuromuscular Electrical Stimulation (NMES)

Electrical stimulation of innervated muscle for strengthening, re-education, ROM, edema control.

Functional Electrical Stimulation (FES)

NMES applied during functional tasks to substitute or augment movement (e.g., grasp, dorsiflexion).

Gate Control Theory

Pain modulation concept: A-beta sensory input from TENS closes spinal “gate,” reducing nociceptive transmission.

Endorphin (Opiate) Theory

TENS at low frequency induces endogenous opioid release, providing longer-lasting analgesia.

Sensory-Level TENS

High-frequency (80-100 pps), short pulse (<100 µs) producing tingling without contraction for acute pain.

Motor-Level TENS

Low-frequency (2-10 pps), long pulse (150-200 µs) producing muscle twitch to release endorphins for chronic pain.

Noxious-Level TENS

High-intensity brief pulses causing uncomfortable sensation to trigger opiate release before painful procedures.

Subsensory (Microcurrent) TENS

Very low-amplitude current below sensory threshold aimed at cellular healing and ATP production.

Beam Collimation

Parallel alignment of laser photons allowing focused, deeper tissue penetration.

LED / SLD Light Therapy

Non-laser monochromatic light sources that can produce similar photobiomodulation at lower power.

Capillary Permeability

Ability of heat to increase fluid exchange across vessel walls, aiding inflammation resolution.

Thermal Conductivity

Rate tissues transfer heat; muscle (high water) conducts more than adipose (insulator).

Huntington’s Response (vascular)

(Duplicate concept—see Hunting Response earlier) Repeated cold-induced vasoconstriction/dilation cycles.

Cavitation—Stable

Non-destructive bubble oscillation during pulsed US producing microstreaming and cellular effects.

Cavitation—Unstable

Violent bubble collapse at high intensity causing tissue damage; avoided by moving sound head.

Duty Cycle 20 %

Typical pulsed ultrasound setting (1 ms on / 4 ms off) for non-thermal healing effects.

BNR ≤ 6:1

Recommended safety limit for ultrasound transducers to minimize risk of hot spots.

LASER Precaution—Eye Protection

Both therapist and patient must wear wavelength-specific goggles to prevent retinal damage.

Shortwave Diathermy Contraindication—Metal

SWD should not be applied over implants, pacemakers, or jewelry due to induced heating.

NMES Ramp Time

Gradual rise of current (0-3 s) improving comfort and reducing stretch reflex activation.

Duty Cycle 1:3

Common NMES on:off ratio allowing muscle recovery and reducing fatigue during strengthening.

RICE

Rest, Ice, Compression, Elevation—standard acute injury management protocol.

Hyaline Cartilage Nutrition

Enhanced by joint movement and heat-induced blood flow during rehabilitation.

Vasodilation

Enlargement of blood vessels; promoted by heat, capsaicin, or post-cooling rebound.

Thermal Pain Threshold

Critical tissue temperature (~113 °F / 45 °C) above which protein damage and burns occur.