Perfusion index as a predictor of hypotension following spinal anaesthesia in lower segment caesarean section

Perfusion index (PI) is a new parameter tried for predicting hypotension during spinal anaesthesia for the lower segment caesarean section (LSCS). This study aimed at investigating the correlation between baseline perfusion index and incidence of hypotension following SAB in LSCS.

In this prospective observational study, 126 parturients were divided into two groups on the basis of baseline PI. Group I included parturients with PI of ≤3.5 and Group II, parturients with PI values >3.5. Spinal anaesthesia was performed with 10 mg of injection bupivacaine 0.5% (hyperbaric) at L3-L4 or L2-L3 interspace. Hypotension was defined as mean arterial pressure <65 mmHg. Statistical analysis was performed using Chi-square test, independent sample t-test and Mann-Whitney U-test. Regression analysis with Spearman's rank correlation coefficient was done to assess the correlation between baseline PI and hypotension. Receiver operating characteristic (ROC) curve was plotted for PI and occurrence of hypotension.

The incidence of hypotension in Group I was 10.5% compared to 71.42% in Group II (P < 0.001). There was significant correlation between baseline PI >3.5 and number of episodes of hypotension (r_s0.416, P < 0.001) and total dose of ephedrine (r_s0.567, P < 0.001). The sensitivity and specificity of baseline PI of 3.5 to predict hypotension was 69.84% and 89.29%, respectively. The area under the ROC curve for PI to predict hypotension was 0.848.

Baseline perfusion index >3.5 is associated with a higher incidence of hypotension following spinal anesthesia in elective LSCS.