Risk factors for inadequate pain relief with labor epidurals – multivariate analysis, a prospective observational study.
Abstract Number: 19
Abstract Type: Original Research
Introduction: The reported percentage of failed or inadequate labor epidurals range from 0.9% to 24%. Inadequate relieve of labor pain may cause maternal dissatisfaction and inability to provide surgical anesthesia in cases of C-section. The aim of our study was to examine the affect of several factors on the incidence of inadequate pain relief with labor epidurals.
Methods: After institutional HIC approval and written informed consent was obtained, data was collected from 400 parturients. In all cases epidural catheters were inserted in a sitting position, using LOR technique with air or saline, at L2-L3, L4-L5 interspace with 17G Tuohy needle. The standard bolus of 0.125% bupivacaine with 10mcg/ml Fentanyl was given, followed by the infusion of 0.125% bupivacaine with 2.5mcg/ml Fentanyl solution at 8-10 ml/h. Pain was assessed 30 minutes after epidural insertion using a verbal pain scale (VPS) of 0 to 100. A score of 10 or more was considered as an inadequate analgesia. 20 independent factors were collected from each parturient. Data were analyzed using χ2 test, and multivariate analysis.
Results: 84 parturients (21%) had inadequate pain relief. Univariate analysis using χ2 test showed that previous failure of epidural analgesia, multiparity, oxytocin, cervical dilatation>7cm at insertion and paresthesia had statistically significant association with inadequate analgesia. (Table 1) A forward stepwise logistic regression model showed cervical dilatation > 7, previous failed epidurals and paresthesia were found to be the best predictors of inadequate epidural analgesia. (Table2)A classification table was constructed and showed that overall 80.8% of the epidurals were classified as successful by the model(Table 3).
Discussion : Our incidence of failed epidurals was 21% compared to reported range of 0.9% to 24%, and the odds ratio of inadequate pain relief was not increased with a less experienced operator as compared to Agaram study. The final model correctly classified 98% of the epidurals that provided effective analgesia; but classified only 14.3 % of that providing inadequate pain relief. The overall predictive rate with our model was 80% and a predictive score include three factors (previous failed epidural, cervical dilatation > 7 cm and paresthesia) with the greatest impact on the occurrence of inadequate epidurals. This information can be used to develop a predictive score and change practice resulting in fewer inadequate labor epidurals.