| Effects of Respiratory Rate on Cardiovascular Variability under General Anesthesia with Mechanical Ventilation. |
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In Young Huh, Sung Kang Cho, Sang Ho Shin, Su Jin Kang, Mee Ok Youn, Jeong Lak Lee, Gyu Sam Hwang |
1Department of Anesthesiology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea. skcho@amc.seoul.kr
2Department of Anesthesiology, Ilsan Baik Hospital, College of Medicine, University of Inje, Ilsan, Korea. |
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| Abstract |
BACKGROUND
Although heart rate variability (HRV) and blood pressure variability (BPV) arise from many different influences, probably the most consistent external modulator is respiration. At rest, the heart rate increases on inspiration and decreases on expiration, a phenomenon called respiratory sinus arrhythmia (RSA). Spectral analysis of heart rate offers good and reproducible estimate of RSA and BPV. Many studies have been conducted on the effects of respiration on HRV and BPV during awake subject breathing spontaneously. However, little is known as to whether respiratory rate modulates HRV and BPV during general anesthesia with mechanical ventilation. Here, we studied effects of respiratory rate on HRV and BPV during general anesthesia.
METHODS
We studied 40 patients undergoing general anesthesia with mechanical ventilation. Maintaining anesthesia with isoflurane, we recorded R-R interval and systolic blood pressure at respiratory rate of 15, 10 and 6 breaths/minute. Data was analyzed by the power spectral analyses of HRV and BPV, which were divided into low frequency (LF) and high frequency (HF) band. RESULTS: Respiratory rate did not affect RR interval, systolic blood pressure, and total spectral power HRV and BPV. Compared with its value at 15 breaths/minute, HF-HRV was significantly increased at 6 breaths/minute. HF-and LF-BPV at 6 breaths/minute were significantly increased versus 15 breaths/minute.
CONCLUSIONS
Respiratory rate modulates HRV and BPV during general anesthesia with mechanical ventilation. We suggest that respiratory rate should be considered and controlled in studies of cardiovascular variability during general anesthesia. |
| Key Words:
blood pressure variability; heart rate variability; respiratory rate |
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