CHRONOTROPIC VARIATION IN THE INCIDENCE OF INADVERTENT DURAL PUNCTURE IN PREGNANT WOMEN UNDERGOING LABOR EPIDURAL PLACEMENT
Abstract Number: S-29
Abstract Type: Original Research
Introduction: Postdural puncture headache (PDPH) is a complication of inadvertent dural puncture (IDP) during epidural placement. Proficiency with the technique is a standard goal for anesthesia residents with 32-60 attempts typically required to achieve 80-90% success. Variation by time (i.e. 24 hrs, day, month, year of training) may exist given the 24 hour-a-day, 7 day-a-week nature of obstetric anesthesia. We hypothesized that chronotropic variation would exist in the incidence of IDP.
Methods: This retrospective chart review identified all patients with IDP from January 1, 2009 to August 31, 2011 at our hospital. Cases of IDP were defined by presence of cerebrospinal fluid during epidural placement, presence of an indwelling spinal catheter, or diagnosed PDPH. PDPH following a routine spinal or combined spinal epidural technique were excluded. Procedural details, patient demographics, and the date, time, and level of practitioner training were collected. The incidence of IDP was analyzed as a function of time of day, day, month, and training year of the practitioner. Analysis was completed using nonlinear mixed effect modeling.
Results: A total of 159 patients were identified as having IDP during the study period. With 13,582 labor epidurals placed, an incidence of 1.17% was found. Differences were observed with the time of day (p<0.0001) with the peak and nadir occurring at 8:00 AM (2.3%) and 10:00 PM (0.2%), respectively. Although no differences were observed as a function of the day, variation in the monthly occurrence was present (p=0.0004) with the highest occurring in June (1.8%) and the lowest in November (0.6%). The number of IDP correlated with level-of-training (p<0.0001), highest with CA-2 residents (48), and lowest with CA-1 residents (35).
Discussion: Chronotropic variation in the incidence of IDP is present. The higher incidence of IDP in the morning and early afternoon do not appear to support the findings of errors associated with fatigue during overnight shifts, but may indicate that a “warm-up period” for epidural technique mastery exists. IDPs were more common in June when residents should have the most experience for their training level and in CA-2 residents more than CA-1 residents. These findings appear to refute the belief that CA-1 residents commit the most IDPs and may suggest that greater resident confidence or risk taking behavior or less attending oversight exists with more experienced residents.
Gander P, et al. Sleep Loss and Performance of Anaesthesia Trainees and Specialists. Chronobiol Int 2008;25:1077-91.
Kopacz DJ, et al. The regional anesthesia "learning curve". What is the minimum number of epidural and spinal blocks to reach consistency? Reg Anesth 1996; 21: 182-90.