Pulse Oximeter- A Visionary to Augur Hypotension at a Glance A Clinical Study Conducted in a Tertiary Care Institution in South India

Background: Hypotension during spinal anesthesia for cesarian delivery is a result of decreased vascular resistance due to sympathetic blockade and decreased cardiac output due to pooling of blood in blocked areas of the body. Change in baseline peripheral vascular tone due to pregnancy may affect the degree of such hypotension. The perfusion index derived from pulse oximeter has been used for assessing peripheral perfusion dynamics due to changes in peripheral vascular tone. Aim: To examine whether baseline perfusion index could predict the incidence of spinal anesthesia induced hypotension during caesarean delivery. Methods: 154 pregnant females in the gestational age group 36-40 weeks who are undergoing elective cesarian delivery with no comorbidities have been enrolled in this study. We collected the data using structured proforma and interpreted using ROC analysis to find optimal cut off value of baseline PI for prediction of hypotension Results: Baseline PI correlated with the percentage decrease in mean arterial pressure (r=0.662;p=0.000). The cut-off PI value of 2.65 identified parturients at risk for spinal anaesthesiainduced hypotension with a sensitivity of 91.6%, specificity of 70.4%, positive predictive value of 78.4%, negative predictive value 87.7% and accuracy of 81.8%. Baseline PI correlated with no of episodes of hypotension and no of times vasopressors used (p<0.005). Percentage of decrease in MAP correlated with parturient height and baseline MAP(p < 0.05). Conclusions: Baseline PI is associated with degree of hypotension after spinal anaesthesia for caesarean delivery. Baseline PI >2.65 can predict hypotension after spinal anaesthesia for caesarean delivery.