[Experimental study on mechanism of recompression therapy of decompression sickness].

OBJECTIVE: To elucidate that recompression is the most efficient measure in removing the pathogenic factors. METHOD: When rabbits were suffering from severe DCS, their pressure were immediately compressed to 0.5 Mpa. Precordial region was monitored continuously with a Doppler flow meter, micrography of the bulbar conjunctiva was done intermittently and the behaviors of the animals were recorded. RESULT: Effects of therapeutic recompression and elimination of circulating bubbles were correlated to rate and extent of recovery of microvascular function. The animals' DCS with severe dysfunction or failure of blood vessels, DCS became worse owing to progressive impairment of microvascular function during recompression and decompression. CONCLUSION: The pressure could only cancel the tension provoked by supersaturated gas in the blood so as to relieve the spasm of the compensatory blood vessels, which can restore the blood circulation and reverse the developing course of the DCS. The pressure, however, couldn't recover the function of the blood vessels with severe dysfunction or failure, or repair the injured tissues, or eliminate the circulating bubbles directly.

[A study on etiology and pathogenic mechanism of decompression sickness].

OBJECTIVE: To explain the etiology of decompression sickness (DCS) and to elucidate its pathogenic mechanism. METHOD: Tunica conjunctiva was examined by microscopy and blood pressure was measured at the exposed femoral arteries in inadequately decompressed animals after hyperbaric exposure. Then pathological examinations were done. RESULT: Animals with vascular spasm and dysfunction after decompression showed DCS symptoms. Severe DCS was found in the period of increasing of blood pressure swelling. Appeared in endothelial cells, fracted, hemorrhages were also formed in the body of DCS animals. CONCLUSION: DCS is a disease with vascular spasm and dysfunction caused by decompression. It's resulted from anoxia or pathological change caused by vascular spasm, dysfunction or even failure of blood vessels due to the gas tension (etiology) provoked by supersaturated gas in the blood during descending of ambient pressure. Vascular spasm and dysfunction impede the elimination of gas from the blood, and once the gas amount is sufficient to cause severe ischemia of the circulation system, the state of disease would be severe.