Pulse oximeter derived Perfusion index as a non-invasive predictor of hypotension following spinal anesthesia in lower segment Caesarean section; an observational study.

Abstract

Background: Spinal anesthesia is the preferred anaesthetic technique for conducting lower segment Caesarean section. Besides being advantageous spinal anesthesia is not totally free of adverse effects, with hypotension being one of the common adverse effects. An ability to predict which parturient will develop severe hypotension would enable adequate preparation preoperatively for better fetal and maternal outcomes.

OBJECTIVE (S) : To evaluate: The correlation between baseline perfusion index (PI) and the incidence of hypotension following spinal anesthesia in LSCS.

The ability of PI to predict vasopressor requirements following spinal anesthesia for LSCS.

STUDY DESIGN: An Observational Study.

PARTICIPANTS: 327 uncomplicated parturients aged 20 to 35 years, posted for elective LSCS under spinal anesthesia.

METHODS: Participants were divided into two groups based on baseline PI. Group I of 158 (PI≤3.5) and group II of 169 (PI>3.5) parturients. NIBP, heart rate, respiratory rate, SpO2, and perfusion index were recorded at 2 minutes intervals after the subarachnoid block up to 20 minutes and then at 5 minutes intervals till the end of surgery.

RESULTS: The occurrence and severity of hypotension were higher in parturients with baseline PI >3.5. The incidence of hypotension was 13.3% and 73.4% in groups I and II, respectively. The vasopressors requirement (median dose of phenylephrine 25mcg and 75mcg in group I and II respectively) and IV fluid consumption was higher in group II as compared to group I (P < 0.001) . The sensitivity and specificity of baseline PI >3.5 to predict hypotension after spinal anesthesia for LSCS was 75.3% and 85.5%, respectively.

CONCLUSIONS: PI can be used for predicting hypotension in parturients undergoing LSCS under spinal anesthesia, with baseline PI >3.5 indicating a higher risk of developing hypotension.

IMPLICATIONS: Simple non-invasive tool to identify parturients at risk of hypotension.