Increased risk of unintentional dural puncture in night-time obstetric epidural anesthesia

Purpose: To evaluate the experience of the operator and the time of epidural anesthesia as factors contributing to unintentional dural puncture (UDP). Methods: In a prospective analysis of recorded cases of UDP the following variables were recorded: maternal height, weight, and weight gain, type of personnel providing epidural analgesia, number of attempts, and hour of the epidural procedure. Work time was divided into day-time (8 AM to 7 PM) and night-time (7 PM to 8 AM), according to the change of coverage of the delivery suite. Night-time was divided into first (7 PM to midnight) and second parts (midnight to 8 AM). Relative risk was used to compare the incidence of UDP among different work-times. Results: A total of 1489 consecutive epidural procedures were considered. The incidence of dural puncture was 0.8% (12 cases). The relative risk was higher for night-time than day-time (risk ratio 6.33; 95% confidence interval, 1.39 to 28.80; P = 0.006). Seven cases were caused by three operators with poor expertise, and five by two skilled obstetric anesthesiologists. Conclusion: Operator experience and hour of procedure appear to be two important risk factors of UDP. The increased risk of UDP in night-work could result from human factors such as fatigue, sleep deprivation or interruption.