Risk factors for failure to extend labor epidural analgesia to epidural anesthesia for Cesarean section

To identify parturients at risk of inability to extend labor epidural analgesia in whom alternative methods of anesthesia should be considered for Cesarean section (CS).

For 6 months, we prospectively studied women undergoing CS with a functioning epidural catheter in place from the delivery ward. All parturients received the same epidural protocol: bolus of bupivacaine 0.1% and fentanyl, followed by bupivacaine 0.1% and fentanyl (2 microg/ml) 10-15 ml/h and an additional 5 ml of bupivacaine 0.125% as top-up according to patient request. Sixteen milliliters of lidocaine 2%, 1 ml of bicarbonate and 100 microg of fentanyl were given for CS. Failed epidural analgesia was defined as the need to convert to general anesthesia.

Of the 101 parturients studied, 20 (19.8%) required conversion to general anesthesia. In univariate analysis, the likelihood of failed epidural anesthesia was inversely correlated with parturient age (P = 0.014) and directly correlated with pre-pregnancy weight (P = 0.019), weight at the end of pregnancy (P = 0.003), body mass index at the end of pregnancy (P = 0.0004), gestational week (P = 0.008), number of top-ups (P = 0.0004) and visual analog scale (VAS) score 2 h before CS (P = 0.03). In multivariate analysis, the number of top-ups in the delivery ward was the best predictor of epidural anesthesia failure (odds ratio, 4.39; P = 0.005).

Younger, more obese parturients at a higher gestational week, requiring more top-ups during labor and having a higher VAS score in the 2 h before CS are at risk for inability to extend labor epidural analgesia to epidural anesthesia for CS.