4) Electric, Mechanical, and Light Therapy Flashcards
_____ can produce specific physiological events and target specific tissues
- Type of current
- Current’s parameters (intensity, phase duration, and pulse frequency)
- Electrode size and arrangement
Electrical stimulation has little, if any, direct effect on
- Cellular level inflammation response
Direct current
- Uninterrupted, one-directional flow of electrons
Continuous current flow on only one side of the baseline as the electrons travel from (direct current)
- Cathode (negative pole) to the anode (positive pole)
Example of direct current used therapeutically
- Iontophoresis
Alternating current [AC]
- Cyclically changes from positive to negative
Pulsed current
- Flow of electrons are interrupted by discrete periods of noncurrent flow
Excitable tissues
- Nerves, muscle fibers, and cell membranes
- Influenced directly by the electrical current
Electrical current prefers to follow
- The path of least resistance
- Those formed by muscle, nerves, effusion, and blood
Electrodes introduce the current to the body from the stimulator via
- The electrode leads, forming a closed circuit
As the size of the electrode increases
- Current density decreases
Electrodes are close together
- Current flows superficially, forming a relatively small number of parallel paths
Increasing the distance between electrodes
- Current can reach deeper into the tissues
Subsensory level
- Point at which the output intensity rises from zero to the point where the patient first receives a discrete electrical sensation
- This type of stimulation does not appear to cause therapeutic benefits
Sensory level
- Only depolarizes sensory nerves; this level is found by increasing the output to the point at which a slight muscle twitch is seen or felt, and then decreasing the output intensity by approximately 10%
Motor level
- An intensity that produces a visible muscle contraction without causing pain
Noxious level
- Current applied at an intensity that stimulates pain fibers
Muscle fiber level
- Stimulation is applied with a long phase duration and output intensity that directly causes muscle fibers to depolarize
Accommodation
- Nerve’s rate of depolarization decreases while the depolarization stimulus (an electrical current) remains unchanged
- Require increasingly intense stimulus throughout the treatment to reach the depolarization threshold
Habituation
- CNS process of filtering out a continuous, nonmeaningful stimulus
- Tolerance to the stimulus developed across multiple treatments
Neuromuscular re-education
- “Teaching” a muscle how to contract again
- Low-duty cycle = muscle relax and recover between contractions
- Pulse frequency must produce tetanic contraction (60 pps)
Neuromuscular re-education protocols should not be administered when
- Tendinous attachment is not secure
- Muscle cannot tolerate the tension
- Joint motion is contraindicated
When the goal is to increase the muscle’s strength
- Electrically induced muscle contractions can supplement but should not substitute for voluntary contractions
The functional load placed on the muscle must be equal to at least
- 30% to 60% of maximum voluntary isometric contraction [MVIC]
If the duty cycle is too high
- Premature fatigue can occur because of increased use of the phosphocreatine system
The process of increasing muscle strength, power, endurance, and proprioception is used
- To improve functional outcomes following surgery
The use of electrical stimulation to strengthen muscle prior to surgery results in
- Improved post-surgical recovery, especially in the quadriceps
Electrical stimulation simply masks the pain or encourages the body to release
- Pain-controlling endogenous opiates
_____ activate the gate mechanism of pain modulation
- High-pulse frequency, short-phase duration, sensory-level currents
High-pulse frequency (more than 80 pps) motor-level stimulation triggers the release of
- Enkephalins
Low-pulse frequency, moderate-pulse duration, high-intensity stimulation, and noxious-level stimulation also activate
- The spinal gait
- Additive effect of stimulating the release of the body’s natural opiates—β-endorphin
Muscle contractions are needed for electrical stimulation to increase
- Blood flow in muscle
- Electrically induced contractions increase local blood flow approximately the same amount as voluntary contractions
The increased blood flow may be caused by the release of
- Endothelial relaxing factors that cause vasodilation and the associated oxygen demand of muscle contractions
Sensory-level stimulation does not evoke changes in
- Muscle or skin blood flow
Low-intensity DC or high-voltage pulsed stimulation may reduce
- Time needed for superficial wound healing to 1.5 to 2.5 times faster
_____ is recommended for advanced wound care using electrical stimulation
- Specialized/advanced training
Sensory-level stimulation is theorized to
- Inhibit edema formation by preventing the fluids, plasma proteins, and other solids from escaping into surrounding tissues
If edema has already formed
- Motor-level stimulation assists the venous and lymphatic systems in returning the edema back to the torso, where it can be filtered and removed from the body
Muscular contractions encourage venous and lymphatic return by
- Squeezing the vessels, moving the fluids proximally
- “Milking” the fluids out of the area
Current must produce a tetanic contraction that forces the fluids proximally along the extremity and then is followed by
- A relaxation period (e.g., duty cycle)
- A 50% duty cycle is then used to obtain the desired off-and-on contractions
Bone growth generators
- Attempt to produce electromagnetic fields that mimic the normal electrical signals produced by bone or to activate the bone’s piezoelectric properties
- Encourages the deposition of calcium through increased osteoblastic activity
- Prescribed only in extraordinary circumstances such as certain nonunion fractures and require long-term treatments (6 months or more)
E-stim contraindications
- Exposed metal implants
- History of seizures
- Sensory or mental impairment
- Unstable fractures
E-stim precautions
- Menstruation
- Areas of nerve sensitivity
- Communication impairments
- Severe obesity
- Electronic monitoring equipment
_____ can reduce the effectiveness of electrical stimulation pain control techniques
- More than 200 mg of caffeine