Heart rate variability as a predictor of hypotension after spinal anesthesia in hypertensive patients

• Main Authors: Tae Dong Kweon, So Yeon Kim, Sung Ah Cho, Ji Hoon Kim, Young Ran Kang, Yang-Sik Shin
• Format: Article
• Language: English
• Published: Korean Society of Anesthesiologists 2013-10-01
• Series: Korean Journal of Anesthesiology
• Subjects: hypertension; hypotension; parasympathetic nervous system; spinal anesthesia; sympathetic nervous system
• Online Access: http://ekja.org/upload/pdf/kjae-65-317.pdf
• ISSN: 2005-6419; 2005-7563

BackgroundHypotension is a common phenomenon after spinal anesthesia in hypertensive patients. We investigated whether heart rate variability could predict the occurrence of hypotension after spinal anesthesia in hypertensive patients.MethodsForty-one patients undergoing spinal anesthesia were included. Heart rate variability was measured at five different time points such as before fluid loading (baseline), after fluid loading as well as 5 min, 15 min and 30 min after spinal anesthesia. Fluid loading was performed using 5 ml/kg of a crystalloid solution. Baseline total power and low to high frequency ratio (LF/HF) in predicting hypotension after spinal anesthesia were analyzed by calculating the area under the receiver operating characteristic curves (AUC).ResultsModerate hypotension, defined as a decrease of mean arterial pressure to below 20-30% of the baseline, occurred in 13 patients and severe hypotension, defined as a decrease of mean arterial pressure greater than 30% below the baseline, occurred in 7 patients. LF/HF ratiosand total powers did not significantly change after spinal anesthesia. AUCs of LF/HF ratio for predicting moderate hypotension was 0.685 (P = 0.074), severe hypotension was 0.579 (P = 0.560) and moderate or severe hypotension was 0.652 (P = 0.101), respectively. AUCs of total power for predicting moderate hypotension was 0.571 (P = 0.490), severe hypotension was 0.672 (P = 0.351) and moderate or severe hypotension was 0.509 (P = 0.924), respectively.ConclusionsHeart rate variability is not a reliable predictor of hypotension after spinal block in hypertensive patients whose sympathetic activity is already depressed.