Pulse Transit Time Variability Predicts Severe Hypotension after Spinal Anesthesia for Elective Cesarean Delivery

Hypotension after spinal anesthesia for elective cesarean delivery may be harmful. This article first proposed pulse transit time variability (PTTV) analysis could be applied in the preoperative assessment of its risk. 42 patients were classified into groups of Mild, Moderate and Severe. Frequency domain analysis was performed on the day before surgery using autoregressive model. We divided the frequency band according to the troughs and extracted relevant parameters of power spectrum, while differences between groups were evaluated by t-test. The results indicating significant differences are presented in PR5, PR1/PR5, PR3/PR5 and PR4/PR5, with their discriminant accuracy on the 42 patients reaching 80.77% in low-BP group and 75% in norm-BP group. We conclude PTTV analysis can help predict the risk of hypotension on the day before surgery and the physiological mechanism is mainly due to parasympathetic regulation.