application of low frequency electrotherapy in rehabilitatio
low frequency current: the pulse current below 1000hz is called low frequency current or low frequency pulse current in medicine. our clinical frequency is usually 1-150hz.
characteristics of low frequency current:
1, low frequency current, electrolytic action is weaker than dc, and some of the current has no obvious electrolytic action.
2, the sensory nerve and motor nerve have a strong stimulus.
3, no obvious heat effect (usually not burn patients)
classification of low frequency currents:
1, according to the waveform is divided into: triangle wave (to stimulate the most nerve), fang bo (tens waveform), trapezoidal wave, sine wave (most soft), ladder wave.
2, according to whether modulation: modulation type and non modulation type
3, according to the current direction: divided into single phase and dual phase
1, stimulate the nerves, muscle tissue
the mammalian animal nerve of the absolute refractory period of about 1ms, 1ms stimulation can cause more than 1 excited apart, so every time the low frequency pulse current stimulation can cause motor nerve and sensory nerve excitement 1. the current frequency is best to be below 100hz.
pathophysiological characteristics of pain:
1. the complex, partial or systemic pathophysiological changes produced by the stimulation of strong physical and chemical factors in pain.
2, the degree of sensation and reaction of pain to the body is closely related to the nature, intensity, range and duration of pain.
3 、 pain is related to mental state.
4 can be accompanied by other sensory disorders, movement disorders and other symptoms
there are several theories of pain analgesia mechanism: gate control theory, cortical interference hypothesis and masked effect hypothesis
the effect of low frequency analgesia is divided into:
immediate analgesic action and analgesic effects after repeated treatment. the so-called "immediate analgesia" is the electrotherapy and electrotherapy after several minutes to several hours of the analgesic effect. the analgesic effect after many times of treatment is closely related to the factors such as immediate analgesia and promoting blood circulation. most of the physical factors stay in the body for some time or a few days, so the superposition effect of many treatments is also very good.
the choice of low frequency analgesia requires attention:
2 、 superficial layer of human body
3, promote local blood circulation
low frequency currents improve local blood circulation and may be produced by the following pathways:
(1) axon reflex
(2) the low frequency current stimulates the nerves (especially the sensory nerves) to release a small amount of substance p and acetylcholine, causing the expansion of the blood vessels
(3) the skin is stimulated to release histamine, which causes telangiectasia (which is also the cause of a prolonged congestion response below the electrode plate after low-frequency treatment)
(4) electrical stimulation produces rhythmic contractions of muscles, and metabolites such as lactic acid and adp have strong vasodilator action, which can improve the blood supply of muscle tissues.
(5) inhibiting sympathetic nerve and causing vasodilatation
in addition to the above three functions, the low-frequency also promote wound healing, fracture healing, anti-inflammatory, sedative and hypnotic effect. it doesn't go into detail here.