Exam 1

What is thermotherapy?

the application of heat sources over skin surface areas for the purposes of heating soft tissues

What are the two types of thermotherapy?

superficial (hot pack, paraffin bath), deep (ultrasound)

What is the physiologic effect of thermotherapy when the tissue temperature rises 1 deg C?

increases metabolic rate

What is the physiologic effect of thermotherapy when the tissue temperature rises 2-3 deg C?

reduces muscle spasm and pain, increases blood flow

What is the physiologic effect of thermotherapy when the tissue temperature rises 4+ deg C?

increases the collagen extensibility

What should a hydrocollator be set to in deg F?

160-165

How long should a hot pack be immersed in a hydrocollator for prior to usage?

at least 30 minutes

How long should a hot pack be applied for?

20 minutes

Can a hot pack be applied directly over the skin?

no

How many layers of toweling should there be between a hot pack and the skin?

6-8

How many layers of towels is a commercial cloth cover for a hot pack equivalent to?

2-3

What are the advantages to hot packs?

inexpensive, readily available, easy to apply

What are the disadvantages to hot packs?

difficult to conform to treatment area

What should a paraffin bath be set to in deg F?

124-130

What should the PT check prior to using a paraffin bath?

the temperature of the bath, skin inspection and preparation (wash hands, take off jewelry)

How many dips should be done in a paraffin bath?

8

What should you do immediately post treatment with a paraffin bath?

use the wax as an exercise tool, then discard

How long should a paraffin bath be applied for?

15-20 minutes

What are the advantages to paraffin bath?

easy to apply to hands and feet, inexpensive, little to no risk of patient burns

What are the disadvantages to paraffin bath?

no movement of the area during treatment application, cannot visualize area during treatment

Can the patient's immersed hand touch the sides and bottom of the paraffin bath?

no

What are the general indications for superficial thermotherapy (hot pack, paraffin bath)?

pain control, to increase ROM and decrease joint stiffness, to accelerate healing

Which sensory test would you use to assess sensation for thermotherapy?

hot and cold discrimination test

How often should you check on your patient after a modality is applied?

every 5 minutes

Does the risk of burns increase or decrease with high levels of subcutaneous fat?

increase

Should patients lie on top of hot packs?

no

Why should you monitor use of liniments (topical medications) before applying superfical thermotherapy?

medications can produce vasodilation, adding heat could lead to a burn

What is the clinical sign of tissue temperature rise?

erythema

What does it look like at the local area when the tissue gets too hot?

blisters, mottling

What does it look like in general when the tissue gets too hot?

pupil dilation, decrease in blood pressure, increase in heart rate

At what blood pressure should you stop thermotherapy?

if it drops 15-20 mmHg

What is ultrasound?

an acoustic or mechanical energy traveling through a medium

What is the frequency of ultrasound used in PT?

1-3 (or 3.3) MHz

What is the intensity of ultrasound used in PT?

0.1-3 W/cm2

What is the usage of ultrasound used in PT?

soft tissue pathology

When would you use a 1 MHz frequency for ultrasound?

deeper tissues, 2-5 cm beneath the skin

When would you use a 3 or (3.3) MHz frequency for ultrasound?

superficial tissues, within 1-2 cm of skin

What are the two types of modes for ultrasound?

continuous, pulsed

What is a duty cycle for ultrasound?

the proportion of time that ultrasound is on during a single pulse period, expressed in a percentage or ration

What is the duty cycle for continuous mode for ultrasound?

100%

What is effective radiating area (ERA) for ultrasound?

the area of the crystal (inner circle), is always smaller than the sound head surface, ~70%

What is the strength of the ultrasound wave?

the acoustic power produced by the crystal in units of Watts (W)

What is the intensity of the ultrasound?

the power per unit area of the crystal in units W/cm2

Is the power generated by the ultrasound uniform?

no

What is spatial peak intensity (W/cm2) in ultrasound?

the peak intensity of the ultrasound output over the ERA, typically within the central 1/3 of ERA

What is spatial average intensity (W/cm2) in ultrasound?

the average intensity of the ultrasound output across the ERA, commonly labeled as "intensity"

What are the clinical implications of ultrasound?

need to move the soundhead, need to know the BNR

What is beam nonuniformity ratio (BNR)?

the ratio of spatial peak intensity to spatial average intensity

What is the usual BNR for most ultrasound units?

5:1 or 6:1

Does a lower ratio make the ultrasound output more or less uniform?

more

Spatial peak intensities of 8 W/cm2 have been shown to do what to tissues when using ultrasound?

damage

If the BNR for ultrasound is 5:1, what will be the safe maximum intensity (spatial average intensity) for treatment?

8/5 = 1.6, less than 1.6 W/cm2

How should we hold the soundhead of the ultrasound in relation to the tissue surface?

perpendicular

What is a standing wave?

when a reflected wave travels back through its original path and is in phase with the incident wave

What happens when energy from both waves are added together, creating a standing wave and an area of more intense energy in the tissue?

burn

How do we minimize the potential of creating standing waves in ultrasound?

move the soundhead throughout the tissue

What is the physiologic effect of ultrasound when the tissue temperature rises 1 deg C?

increases metabolic rate

What is the physiologic effect of ultrasound when the tissue temperature rises 2-3 deg C?

reduces muscle spasm and pain, increases blood flow

What is the physiologic effect of ultrasound when the tissue temperature rises 4+ deg C?

increases the collagen extensibility

What are the nonthermal/mechanical effects of ultrasound?

shown to facilitate tissue healing and modify inflammation

What duty cycle do we tend to use in pulsed ultrasound?

20%

What are the indications for ultrasound as a deep-heating modality?

joint contracture and scar tissue, subacute and chronic soft tissue inflammation (when increase tissue temperature of blood flow is desired)

What are the indications for ultrasound to facilitate healing?

acute injury or inflammation of soft tissue

What are the general guidelines for applying ultrasound?

- patient should feel some warmth within 2-3 minutes of initiating ultrasound when thermal effects are applied

- patient should not feel increased discomfort at any time during the treatment

- area to be treated should be 2-3x ERA

What should the patient feel when using ultrasound for nonthermal effects?

nothing

When is treatment effect of ultrasound usually detectable?

within 1-3 treatments

What is the sequence of treatment when using ultrasound to heat tissue?

should not be applied after an intervention that may impair sensation, should not be applied to patients right after receiving superficial thermotherapy

What is the water immersion method of ultrasound?

sound head is about 0.5-1 cm away from skin, move sound head about 4 cm per second

What is an advantage to the water immersion method of ultrasound?

conforming to irregular areas

What is a disadvantage to the water immersion method of ultrasound?

water bubbles need to be wiped regularly

What are the three types of electrical currents?

direct current (DC), alternating current (AC), pulsed or pulsatile current (PC)

How can pulsed or pulsatile current (PC) be divided in terms of number of polarity?

monophasic, biphasic

How can biphasic pulse current (PC) be divided in terms of waveform?

symmetrical, asymmetrical

How can asymmetrical biphasic pulse current (PC) be divided in terms of net charge?

balanced, unbalanced

What are the time-dependent parameters for pulsed currents (PC)?

frequency (pulses per second), pulse duration (pulse width), on:off time, ramp up/ramp down time

What are other electrical current parameters?

amplitude, modulation, burst mode

What is modulation in electrical currents?

any pattern of variation in one or more of the stimulation parameters

What is modulation in electrical currents used for?

to limit neural adaptation to an electrical current

What is burst mode in electrical currents?

a current composed of serious of pulses delivered in groups

How many bursts per second in a Russian current?

50

What is monopolar electrode setup?

one active electrode only, active electrode and dispersive electrode on same side of the extremity

What is bipolar electrode setup?

two active electrodes

What is quadripolar electrode setup?

usually two bipolar channels, parallel or crisscross

Should you do parallel or crisscross quadripolar setup for muscle contraction?

parallel

What are the effects of electrical currents?

nerve depolarization (NMES), muscle depolarization (EMS), ionic effects

What happens when a motor nerve gets depolarized via electrical current?

innervated muscle contracts

How long should pulses be to depolarize the muscle cell membrane (not through a nerve)

10 ms

What is the strength-duration curve (SDC)?

a graphic representation of the minimum combination of current strength (amplitude) and pulse duration needed to depolarize a particular nerve

What is the order of nerve stimulation as current strength (amplitude) increases)

alpha-beta sensory, motor, alpha-delta, c dull pain, denervated muscle

What does stimulating an alpha-beta sensory nerve feel like?

tingles

What does stimulating a motor nerve feel like?

muscle twitch

What does stimulating an alpha-delta nerve feel like?

sharp pain

What is the advantage to keeping pulse duration under 1 ms?

won't stimulate C dull pain

Pulses greater than what duration are required to produce muscle contraction in denervated muscle?

10 ms

What are the clinical applications of electrical currents?

muscle contraction (innervated/denervated muscle), pain modulation, edema control, tissue healing, iontophoresis

What are the general guidelines for applying electrical stimulation?

- perform a sensory discrimination test (light touch vs. painful stimuli)

- check and prepare skin before starting

- keep electrical stimulators at least 3 m away from any functioning diathermy units

What are the adverse effects of electrical stimulation?

burns, skin reactions to the electrodes, pain

When are burns from electrical stimulation most common?

when a DC or AC is being applied due to high total charge delivery, chemical effects produced under DC electrodes

When can skin reactions from electrical stimulation occur?

patient is allergic to the contact surface of the electrode, a different type of electrode should be tried

How can you combat pain while using electrical stimulation?

increase current amplitude slowly over a longer period of time