The Use of End-Tidal CO2 and Integrated Pulmonary Index to Predict Postspinal Hypotension in Cesarean Section

Purpose: Postspinal hypotension (PSH) is one of the most important complications in obstetric anesthesia, and early diagnosis and treatment reduces the risk of maternofetal complications. Integrated pulmonary index (IPI) is an algorithm that uses real-time measurements of four parameters: end tidal carbon dioxide (EtCO2), respiratory rate (RR), heart rate (HR) and peripheral oxygen saturation (SpO2). In this study, the effect of EtCO2 and IPI in predicting PSH was investigated. Methods: Patients scheduled for cesarean section under spinal anesthesia under elective conditions were included in the study. A capnography device (Capnostream 35; Medtronic, Inc.) was used for IPI assessment. A decrease of 20% or more in the baseline blood pressure value or a decrease in systolic blood pressure below 100 mmHg after spinal anesthesia was considered postspinal hypotension. The correlation between developing hypotension and EtCO 2 and IPI measurements was analyzed. Results: PSH developed in 63.4% of the 82 patients included in the study. EtCO 2 and IPI values decreased significantly compared to baseline values in patients who developed PSH. While IPI difference was not found to be an independent risk factor in predicting PSH, the amount of change in EtCO 2 was found to be diagnostic (AUC: 0.90 (0.83-0.97; p<0.001). According to the cut-off value of 2.5 for the amount of change in EtCO 2 , sensitivity was 80.8%, specificity 90.0%, positive predictive value 93.3% and negative predictive value 73.0%. Conclusion: EtCO 2 monitoring can be used as a reliable new technique for early diagnosis and treatment of postspinal hypotension in cesarean section. ClinicalTrials Registration: NCT05237856