Anesthesia-related adverse events in obstetric patients: a population-based study in Canada

Background Anesthesia-related complications in obstetric patients could be catastrophic and impact the lives of both the parturient and the neonate. The objective of this study was to determine the frequency, temporal trend, and risk factors of anesthesia-related adverse events during hospitalization for delivery in Canada. Methods This retrospective population-based study utilized the hospitalization database of the Canadian Institute for Health Information for all parturients (gestation >= 20 weeks) in Canada (except Quebec) hospitalized for childbirth from April 2004 to March 2017. Complications were identified by the enhanced Canadian version of the tenth revision of the International Statistical Classification of Diseases and Related Health Problems codes. Data were summarized with descriptive statistics. Associations between hospitalizations with an anesthesia-related adverse event and patient characteristics, delivery method, and modality of anesthesia were assessed using multivariate logistic regression. Results Among 2,601,034 hospitalizations (3,194,875 interventions), 8,361 anesthesia-related adverse events occurred over a 13-year period (262 per 100,000 interventions; 95% confidence interval [CI], 256 to 267), with a significant decline over time (P \ 0.001). These were two-fold and seven-fold higher per 100,000 interventions with general (488; 95% CI, 438 to 542) and general plus neuraxial (1,476; 95% CI, 1,284 to 1,689) anesthesia compared with neuraxial anesthesia alone (225; 95% CI, 219 to 230). Serious adverse events constituted 9% of all adverse events. The most common adverse event was spinal and epidural anesthesia-induced headache (6,908/8,361; 83%); the overall rate of failed or difficult intubations was low (201/8,361; 2%). Anesthesia-related events were more likely in those who had a Cesarean delivery compared with vaginal delivery (odds ratio [OR], 1.12; 95% CI, 1.06 to 1.18) and general anesthesia compared with neuraxial anesthesia (OR, 1.71; 95% CI, 1.53 to 1.93). Noteworthy associations were found between any anesthesia-related adverse events and cardiomyopathy (OR, 8.34; 95% CI, 2.59 to 26.83), eclampsia (OR, 3.11; 95% CI, 1.95 to 4.97), and obstructive sleep apnea (OR, 1.91; 95% CI, 1.66 to 2.19). Conclusion The incidence of anesthesia-related adverse events in obstetric patients in Canada is low and declining. High vigilance is required in parturients undergoing Cesarean delivery, receiving general anesthesia, and those with pre-existing medical conditions.