Heart Rate Variability Analysis for the Prediction of Hypotension during Spinal Anesthesia in Programmed Cesarean Surgery and its Relation with Fetal Cord Acid-base Equilibrium

In this paper the ability of linear and nonlinear heart rate variability (HRV) indices to predict hypotension during spinal anesthesia in programmed cesarean is studied, as well as their relation with fetal cord values. A database consisting of the ECG recordings of 40 pregnant women is analyzed. Recordings include the following positions: lateral decubitus (LD), supine decubitus (SD), sitting position (SP) and recovery from Valsalva maneuver (RV). Classical temporal, spectral and non-linear HRV indices were calculated. Univariate analysis shows significant hypotension association: maternal age, gestational age, sample (SampEn) and approximate entropy (ApEn) in SD, the difference in SampEn, ApEn and correlation dimension (D-2) values between positions SD and LD, and the difference in total power between SD and SP. Data from fetal cord study show that hypotension is associated with an increase in arterial lactic acid. The difference in SampEn, ApEn and D2 values between SD and LD are associated with venous lactic acid. A logistic regression model was used for the prediction of hypotension reaching balanced accuracy of 89.7%.