Heart Rate Variability in Pregnant Women before Programmed Cesarean Intervention

Abstract

Background: Heart rate variability (HRV) indices have shown ability for hypotension prediction during spinal anaesthesia in pregnant women programmed for cesarean only the same day of the surgery but not the previous day. Objective: To study changes in linear and nonlinear HRV indices of pregnant women programmed for cesarean between the previous day and the surgery day. Methods: Previous day recordings (PDR) and surgery day recordings (SDR) of 71 pregnant women programmed for cesarean have been studied during the following conditions: lateral decubitus (LD), supine decubitus (SD) and Valsalva maneuver recovery (VR). Linear HRV indices include classical temporal and spectral indices. Nonlinear HRV indices consist of sample and approximate entropy and correlation dimension (D ₂). Results: Some linear HRV indices show very significant increases (p < 0.01) in SDR with respect to PDR: HRM in VR, SDNN in LD and SD, power in the very low frequency band in LD, power in the low frequency band in LD and SD. On the contrary, nonlinear HRV indices show a decrease in almost every condition and index in SDR with respect to PDR, being only statistically significant for D ₂ in SD (p < 0.01). Conclusions: The increase in the former linear indices and the decrease in nonlinear indices the surgery day with respect to the previous day can be attributable to the stress induced by the imminent surgery.