Treatment - Clinical Application

Approximately 6 minutes

When selecting electrical stimulation, a therapist must select a device and an application that will support achieving the desired effect. Common goals that may be achieved with including electrical stimulation into the treatment include:

• improving muscle performance and strength
• decreasing or alleviating pain
• improving blood flow
• decreasing or controlling edema
• facilitating tissue healing

Application Decision-Making 

The physical therapist will screen each patient for contraindications. Precautions are conditions to consider when selecting and applying electrical stimulation

Contraindications

• Pregnancy - except during labor for pain control
• Pacemaker or other cardiac implants for interference
• Cancer - risk metastasis
• Location of thrombophlebitis or phlebothrombosis for risk of embolism
• Active Tuberculosis
• Over carotid sinus
• Area of active hemorrhage
• Cognitive Impairments - unable to follow directions or provide feedback

Precautions

• Obesity - insulator
• Absent or diminished sensation
• Skin conditions - eczema, psoriasis, acne, dermatitis, infection, allergies to gel or tape
• Diabetes - fragile thin skin
• Peripheral neuropathies or areas of denervation
• Metal - internal or external
• Range of Motion or exercise limitations
• Spinal Cord Injury - dysreflexia

 

There are times when a Physical Therapist may decide to use a modality that is normally contraindicated after discussion with the patient's physician. For example, a patient with a history of cancer in the distant past or application of the modality at an extremity away from the cancer site may not pose more risk than benefit.

 Estim Parameters

Electrical stimulation parameters are intentionally selected to produce the desired effect. Electrical stimulation parameters are frequency, duty cycle, ramp time, and duration. For direct current and monophasic pulsed current, the active electrode is set for a positive or negative tissue charge.

Frequency - number of electrical pulses delivered to the body in one second

• Also called pulses per second (pps), Hertz (Hz) with AC
• Higher frequencies cause higher levels of muscle fatigue due to less time between bursts/pulses
• Impedance decreases when frequency increases
• Frequencies of 1-120pps meets most therapeutic goals
• Stimulation at 50pps tends to be more comfortable than 35pps
• Classified as low, medium, and high in clinical units:

low	medium	high
<= 1 kHz "microcurrent"	1-100kHz IFC, Russian, LIDC	>100kHz TENS, HVPS

 

Duty Cycle - percentage of on time to total time between pulses

• Current flows during 'on time' and ceases during 'off time'
• Percentage of on time divided by the sum of the on and off time
• Example, on time is 5 seconds, off time is 20 seconds = 1:4 ratio or 5 sec/(5+20sec) = 20%
• Clinically speaking, muscle contractions elicited through electrical stimulation are more fatiguing, so longer off time allows for recovery/rest and fends off fatigue.

 

Ramp Time - the time it takes to increase wave amplitude to its peak amplitude

• Fixed on some commercial machines, ranging from 1 - 8 seconds
• 2 second ramp up is often adequate for comfort
• Slow rise times can allow a tissue to accommodate to a stimulus
• Ramp down or off can increase patient comfort and provides opportunity to actively hold a contraction after the stimuli has ended.

 

 

 

 

 

 

 

 

 

 

 

Duration - the total time providing electrical stimulation. Treatment times can range from 10 to 45+ minutes

 

This table provides a summary of conditions that may be treated effectively with electrical stimulation.

Key point: You will find variations in the literature about parameters with respect to pulse frequency, pulse duration, and duration. For this reason, you will not be teste on pulse frequency or pulse duration or duration. In clinical practice, you will consult the literature and use observation, patient feedback, and measures to inform your effectiveness.

Indication	Type	Waveform	Pulse Frequency (pps)	Pulse Duration (µS)	Intensity	Duration
Muscle strengthening	NMES	AC, Russian	50-80	200-800	to 60&-70& max voluntary contraction	10-20 strong contractions
Contraction for function	FES	AC, Russian	20-60	200-800	to the desired effect	task specific
Pain Modulation	High frequency TENS	pulsed AC or DC	>50; generally 80-110	50-100	to perception of stimulus; no motor response	20-30+ minutes
	Low frequency TENS	pulsed AC or DC	<10	> 150	to point of visible muscle twitch	20-45 minutes
	Hyperstimulation	DC or pulsed DC	(High) 100 (Low) 1-5	250. up to 1 second	to highest tolerated painful stimulus	30-60 seconds each area
Edema Management (acute)	Sensory stim	pulsed DC	100-125	2-100	to comfortable sensory threshold; just below motor response	20-45+ minutes
Edema Management (subacute/chronic)	NMES	AC, Russian	20-80	100-600	to tetanic muscle contraction	3 seconds on: 3 seconds off x 10-20 minutes

 

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