2016 Volume 36 Issue 3 Pages 271-279
[Background] Laparoscopic surgery, which aims to minimize surgical invasiveness, achieves satisfactory therapeutic results. Surgical and anesthesiological methods have been improved, but many laparoscopic surgeries have been associated with cardiorespiratory complications.
[Objective] We hypothesized that severe bradycardia during surgery is caused by increased baroreflex sensitivity (BRS) when the pneumoperitoneum is created. We conducted BRS analysis and heart rate variability (HRV) analyses in order to concurrently assess arterial baroreceptor sensitivity and autonomic nerve balance.
[Methods] Twenty-three ASA 1-2 patients undergoing laparoscopic gynecological surgeries were enrolled in the study. After anesthesia was induced with propofol, remifentanyl, sevoflurane, and rocuronium, tracheal intubation was performed. The depth of hypnosis was monitored with a bispectral index sensor. Spectral analysis of HRV that was conducted with a logistic regression analysis resulted in a characteristic power spectrum with two main regions : high frequency (HF) and low frequency (LF). BRS-up and -down sensitivities were obtained in linear regression if three-beat intervals occurred with successive increases or decreases in blood pressure and in the RR interval. Mean blood pressure (MBP), heart rate (HR), LF region, HF region, LF/HF, and BRS were recorded at 1 min at each time point (baseline, equilibration period, pneumoperitoneum period, and head-down tilting period).
[Result] LF/HF was 1.1, 0.5, 1.2, and 0.6 at each respective time interval. LF/HF significantly increased after the pneumoperitoneum. The BRS-up value was 12.2, 8.2, 9.0, and 34.7 ms/mmHg, respectively.
[Consideration and conclusion] During the head-down tilting period, the combined effects of anesthesia, the pneumoperitoneum, and posture resulted in a significant increase in BRS with an LF/HF decrease. Contrary to expectations, the effect of the pneumoperitoneum on BRS was restrictive. This study demonstrated that the effect of pneumoperitoneum, anesthesia and head-down posture in cardiac autonomic function should seriously be taken into account, and strict BRS monitoring should be done in all patients, especially in those with cardiac risk.
