“Anesthesia-related adverse events (AEs) in obstetric populations in developed countries are infrequent but may be associated with significant maternal and neonatal morbidity and mortality,” explains Leyla Baghirzada, MD, MPH, FRCPC. “Anesthesia-related morbidity has been identified as a fitting and effective indicator for obstetric care quality and could serve as a patient safety indicator during childbirth. However, studies on AEs of obstetric anesthesia and analgesia are limited. In addition, there is no dedicated obstetric anesthesia registry in Canada. This creates obstacles when conducting an informed consent discussion regarding the risks of obstetric anesthesia, as well as while dealing with medical and legal issues.”

For a paper published in the Canadian Journal of Anaesthesia, Dr. Baghirzada and colleagues aimed to determine the frequency, temporal trend, and risk factors of anesthesia-related AEs during hospitalization for delivery. The researchers conducted a retrospective, population-based study that utilized the hospitalization database of the Canadian Institute for Health Information for all parturients (gestation ≥20 weeks) hospitalized for childbirth from April 2004 to March 2017. Correlations between hospitalizations with an anesthesia-related AE and patient characteristics, delivery method, and modality of anesthesia were evaluated with multivariate logistic regression.

Trend of Adverse Events Has Decreased

Dr. Baghirzada and colleagues found that 1 in every 311 hospitalizations for delivery was associated with anesthesia-related AE during the 13-year study period, although this trend has decreased over time. “This finding was reassuring given the changing obstetric population such as advanced maternal age and increasing rate of obesity in parturients,” Dr. Baghirzada says. “No deaths were clearly ascribed to anesthesia-related AEs. Postdural puncture headache was the most common anesthesia-related AE in parturients receiving neuraxial anesthesia, as was failed or difficult intubation in those receiving general anesthesia.”

Although the cumulative rate of serious anesthesia-related AEs appears to be concentrated in the top three most common events, the individual risk of conditions comprising these events is very low, Dr. Baghirzada points out. “For example, the risk of one of the most dreaded complications of obstetric anesthesia, aspiration pneumonitis, is only 0.8 per 100,000 patients. During the past 30 years, aspiration in women who are pregnant has markedly declined, primarily due to advances in obstetrical anesthesia. The standard use of regional anesthesia for most women in labor and increased awareness among anesthesia providers regarding the high risk of aspiration and potential difficult airway management in parturients has increased the safety in this population (Table).” She adds that care has also improved due to advances in airway management devices. The routine utilization of pulse oximetry, capnography, and difficult airway algorithms have also helped to mitigate the risks associated with general anesthesia in parturients.

Need for a Serious Complication Registry

“Our primary objective, to establish the incidences of serious complications related to obstetric anesthesia, was achieved with a reasonable degree of certainty,” Dr. Baghirzada says. “In contrast, there were too few serious complications in each category captured during the study period to identify associated risk factors. Therefore, although it is not feasible to create evidence-based practice advisories from the results, they can be used to facilitate discussions about informed consent and to make practical recommendations. For example, the most common complication was spinal- and epidural-induced headache. This necessitates some interventions to reduce the likelihood of this complication, such as preprocedural ultrasound landmarking or adequate teaching and simulation of the technique.”
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Dr. Baghirzada and colleagues note an interesting observation about the feasibility of determining the rate of anesthesia-related AEs for individual practitioners in a hospital setting using an administrative database in combination with hospital-specific intervention rates and staffing patterns. “More research is needed to validate the model, however,” she says. “Acquiring information on additional complications is a worthwhile patient safety goal. Next steps include the creation of a national obstetric anesthesia database and a serious complication registry.”