Effects Of Low Temperature On Hand Arm Vibration Syndrome And The Significance

ObjectiveDue to the high prevalence of hand arm vibration syndrome in cold climate, it was very significant of low temperature and vibration protection for preventing hand arm vibration syndrome in vibration contacted workers exposed in cold climate. In the present study, the sensitivity indices were investigated preliminarily using experimental methods. Then based on the previous results, the correlation between low temperature and vibration induced vascular and nervous injuries, and the effects of low temperature combined with vibration on peripheral circular and nervousfunction were discussed.MethodsThis study comprised 3 parts.Part I: low temperature experiment was performed with New Zealand rabbits by constant temperature refrigeratory, and concentrations of ET, Ang II, and NO in plasma and the SCV, amplitude of sensory nerve action potential, latency of sensory nerve action potential, MCV, distal amplitude of motor nerve, and distal latency of motor nerve were measured before and after experiment to select the sensitivity index.Part II: rabbits were divided into high sensitivity, middle sensitivity, and low sensitivity groups. Then vibration experiment was carried out. The concentrations of ET, Ang II, and NO in plasma and the SCV, amplitude of sensory nerve action potential, latency of sensory nerve action potential, MCV, distal amplitude of motor nerve, and distal latency of motor nerve were measured after experiment to determine the correlation between low temperature sensitivity and vibration induced vascular and nervous injury. Part III: rabbits were divided into 4 groups randomly to perform control experiment, vibration experiment, low temperature experiment, and vibration + low temperature experiment to determine the injuries induced by low temperaturecombined with vibration.Results1. Compared with pre-experiment, the concentration of ET increased, SCV decreased and latency of sensory nerve action potential delayed at 7-day after experiment (P<0.01). After 5 days of recovery, the above three indices were all returned to baseline level.2. Compared with pre-experiment, the SCV, MCV, amplitude of sensory nerve action potential, and distal amplitude of motor nerve were decreased, and the latency of sensory nerve action potential and distal latency of motor nerve were delayed; the concentrations of ET and Ang II were increased and the NO was decreased after experiment (P<0.05). After experiment, the SCV, MCV, amplitude of sensory nerve action potential and distal amplitude of motor nerve in high-sensitivity group were less than middle-sensitivity and low-sensitivity group (P<0.01), and the middle-sensitivity group were less than low-sensitivity group (P<0.01); the latency of sensory nerve action potential and distal latency of motor nerve in high-sensitivity were longer than middle-sensitivity and low-sensitivity group (P<0.01), and the middle-sensitivity group were longer than low-sensitivity group; the concentrations of ET and Ang II in high-susceptibility group were higher than in middle-susceptibility and low-susceptibility group (P<0.01), and in middle-susceptibility group were higher than in low-susceptibility group (P<0.01); the concentration of NO in high-susceptibility were lower than in middle-susceptibility and low-susceptibility group (P<0.01), and in middle-susceptibility group were lower than in low-susceptibility group (P<0.01) (P<0.01). The measured values of ET and SCV after low temperature experiment and the measured values of SCV, amplitude of sensory nerve action potential, latency of sensory nerve action potential, MCV, distal amplitude of motor nerve, and distal latency of motor nerve, and the ET, Ang II and NO after vibration experiment were analyzed by simple correlation and the results showed that the correlation coefficient was significant (P<0.01).3. Compared with pre-experiment, the concentrations of ET and Ang II in low temperature group, vibration group and combined effect group were increased and NO were decreased after experiment(.P<0.05); the nerve conduct velocity and amplitude were decreased and latency were delayed after experiment (P<0.05). After experiment, the concentrations of ET, and Ang II in combined effect group were higher and the NO were lower than in low temperature group and vibration group; the SNCV, MNCV, amplitude of sensory nerve action potential and distal amplitude of motor nerve in combined effect group were less and the latency of sensory nerve action potential and distal latency of motor nerve were greater than in low temperature group and vibration group. The factorial analysis results indicated the synergistic effect between low temperature and vibration (P<0.05).Conclusions1. The dysfunction in peripheral circulation and peripheral nerve would be caused by low temperature; The changes of ET concentration, SCV and latency of sensory nerve action potential after low temperature experiment were significantly (P<0.01). and all three values were returned to the pre-experiment level after convalescence. So ET concentration, SCV and latency of sensory nerve action potential were selected as sensitivity index to low temperature.2. There was a correlation between low temperature sensitivity and vibration-induced vascular and nervous injuries; the injuries were intensified when the sensitivity increased.3. Vibration-induced peripheral vascular impairment and nerve impairment would be intensified by low temperature.