The Effects Of The Operative Sedation On Heart Rate Variability In The Elderly Patients Under The Peripheral Nerve Block

ObjectiveTo assess the changes in heart rate variability(HRV) during midazolam and propofol sedation with target-controlled infusion(TCI) in the elderly patients.MethodThirty ASA I ~ II elderly patients scheduled for elective surgery on limbs under peripheral nerve block,who were over 65, were randomly divided into two groups of 15 patients each: the midazolam group(M) and the propofol group(P).TCI was used to a rapid induction and maintenance of a stable target blood concentration. HRV parameters were recorded at different OAA/S scores during both the induction of and recovery from sedation.ResultsWith increasing depth of sedation, most of the HRV parameters(LF ,nuLF, LF/HF and TP) in the midazolam group decreased progressively, while nuHF increased and HF remained unchanged. All frequency components of HRV were significantly reduced as patients' OAA/S scores decreased, especially in HF. LF/HF ratio increased. The recovery time was significantly different in the two groups.ConclusionsWith increasing depth of sedation, midazolam and propofol both affect HRV in elderly patients. Midazolam has more potent inhibitory effect on sympathetic component than that on parasympathetic component of the autonomic nerve system. While propofol reduces par- asympathetic activity more significantly than...