Adverse Events and Factors Associated With Potentially Avoidable Use of General Anesthesia in Cesarean Deliveries

Jean Guglielminotti, M.D., Ph.D.; Ruth Landau, M.D.; Guohua Li, M.D., Dr.PH.

Disclosures

Anesthesiology. 2019;130(6):912-922. 

In This Article

Discussion

In this 12-year study, we analyzed risks, time trends, and risk factors for potentially avoidable general anesthesia for cesarean delivery. The major findings were the following: (1) a high proportion of potentially avoidable general anesthesia among all general anesthesia cases (44%); (2) a decrease over time in potentially avoidable general anesthesia cases except in minority women and in high-volume hospitals; (3) a significant increase in the risk of serious adverse events when cesarean delivery was performed with general anesthesia compared with neuraxial anesthesia; and (4) several patient- and hospital-level factors associated with potentially avoidable general anesthesia, with some of them directly actionable.

Risk of Adverse Events Associated With General Anesthesia

Contrary to previous research, we did not observe an increased risk of death or cardiac arrest associated with general anesthesia compared with neuraxial anesthesia.[1,2] This apparent discrepancy can be explained by the exclusion in our analysis of discharges recording severe comorbidities and high-risk obstetrical situations (Charlson comorbidity index at or above 2 or comorbidity index for obstetric patients at or above 3), which are strongly associated with the risk of near-miss maternal morbidity or mortality.[19] However, we observed a significantly increased risk of anesthesia-related complications (overall and severe) and surgical site infections. It confirms previous research on the risks associated with general anesthesia for cesarean delivery and extends it to cases of potentially avoidable general anesthesia.[3,4]

Increased risk of surgical infection associated with general anesthesia has also been reported in planned orthopedic surgery. The increased risk associated with general anesthesia in cesarean delivery may not only be related to the urgency of the procedure. Several mechanisms have been suggested to account for the decreased risk of surgical infection associated with neuraxial techniques.[20] They include an attenuated inflammatory response to surgery, an improvement in tissue oxygenation through the vasodilation induced by neuraxial techniques, and an enhanced postoperative analgesia with a decrease in pain-associated autonomic response and subsequent vasoconstriction. In addition, we extend the previously reported association between neuraxial techniques and decreased risk of venous thromboembolic events to cesarean deliveries.[21] This decreased risk is thought to be related to improved blood flow through the legs secondary to sympathectomy-induced vasodilatation. Venous thromboembolic disease is a leading cause of maternal morbidity and mortality in the United States and one of the three priority conditions targeted by the National Partnership for Maternal Safety to decrease maternal morbidity and mortality.[22,23]

Whereas increased risks of anesthesia-related complications, surgical site infection, and venous thromboembolic events associated with general anesthesia could be considered acceptable when general anesthesia was clinically indicated and could not have been avoided, risks would be less acceptable when general anesthesia was potentially avoidable. In other words, efforts to reduce the use of general anesthesia for cesarean delivery should probably target cases without a recorded clinical indication.

Temporal Trends

We observed a 14% decrease in the occurrence of potentially avoidable use of general anesthesia for cesarean delivery. This indicates that obstetric anesthesia providers have increasingly favored neuraxial over general anesthesia for cesarean delivery, as recommended by the successive American Society of Anesthesiologists Practice Guidelines for Obstetric Anesthesia.[6,7] However, we observed an increase in the utilization of general anesthesia in minority women and no change in high-volume hospitals.

Using 1999 to 2002 data, Butwick et al.[11] reported racial disparities in the use of general anesthesia for cesarean delivery with a higher use of general anesthesia in African American women. Similarly, a lower use of neuraxial labor analgesia in minority women has been repeatedly reported.[24] In this study, we observed that racial disparities in anesthesia care are increasing over time. One hypothesis for this finding is a lower increase in the use of labor neuraxial analgesia in minority women compared with nonminority women. However, in the current study, we observed an increase in the use of labor neuraxial analgesia for both minority and nonminority women, suggesting that the increased utilization of general anesthesia observed in minority patients is related to other mechanisms.

Contrasting with a decreased utilization of general anesthesia in low- and intermediate-volume hospitals, we observed no change in high-volume hospitals. This trend was also observed for cesarean deliveries with a recorded indication for general anesthesia (Supplemental Digital Content Table 10, http://links.lww.com/ALN/B862). It may reflect the redistribution of high-risk patients (i.e., women with severe comorbidities) or high-risk deliveries (e.g., previous cesarean delivery) to high-volume centers (regionalization of care).

Patient-level Factors Associated With General Anesthesia

We confirm previous research on patient-level factors that identified higher odds of general anesthesia in younger women, minority women, Medicaid beneficiaries, women with preexisting or pregnancy-associated conditions, women admitted during weekend, and women with a nonelective admission.[9,11,25,26] Although many of these factors do not seem easily amenable, some of them could indicate areas for possible actions such as younger maternal age and admission during weekend.

Previous studies suggests that younger patients spontaneously tend to favor general anesthesia for a surgical procedure, especially younger patients.[27,28] Lower anticipated and actual use of neuraxial analgesia during labor is also reported in younger women.[29] Provision of antenatal information about the benefits and risks of neuraxial analgesia intrapartum and neuraxial versus general anesthesia for cesarean delivery may help reduce the general anesthesia use in this population.

Increased use of general anesthesia in women admitted during weekend could be related to the commonly called "weekend effect" or worse outcomes in patients admitted on Saturday or Sunday.[30] Possible mechanisms accounting for this weekend effect include difference in patient case mix and suboptimal quality of care resulting from reduction in staffing or presence of less experienced providers.[31] A 2015 survey of obstetric anesthesia directors in academic center reports that up to 60% hospitals do not have an in-house dedicated team for the labor and delivery unit during weekends, indicating a change in staffing composition and likely experience.[32] Because our multilevel model adjusts for case mix, we suggest that increased use of general anesthesia during weekend may be related to understaffing or provision of care by less experienced physicians.[33,34]

Hospital-level Factors Associated With General Anesthesia

Hospital-level factors associated with the use of general anesthesia have not previously been thoroughly evaluated, with only one recent study indicating a higher proportion of general anesthesia in university hospitals.[9] In the current study, we confirm a higher use of general anesthesia in university hospitals and identified higher annual volume of delivery, higher proportion of high-risk pregnancy, lower labor neuraxial analgesia rate, and neonatal level-of-care designations 1 or 3 as new risk factors. Similar to patient-level factors, many of the hospital-level factors associated with general anesthesia are beyond the control of the anesthesiologists except for the utilization of neuraxial techniques during labor.

We found that in hospitals with a lower labor epidural analgesia rate, the general anesthesia rate for cesarean delivery was significantly higher. The exact mechanisms accounting for a low labor neuraxial analgesia rate in some hospitals are difficult to determine using administrative data. One explanation is that, with a low epidural analgesia rate, the experience and expertise of anesthesia providers may be limited, which results in their preference to perform general anesthesia for cesarean deliveries. Another explanation is the lack of availability of a dedicated anesthesia team for obstetric anesthesia care, and the low epidural analgesia rate is a surrogate marker for lack of 24/7 anesthesia services, which increases the likelihood of general anesthesia for urgent or even less urgent cesarean deliveries. In other words, labor epidural analgesia rate could be less a measure of clinician experience but rather physical presence and involvement on the labor and delivery unit and intensity of services.[35] Because general anesthesia without a clinical indication was associated with a higher risk of adverse events, this finding should be viewed as a strong incentive to target quality assurance programs to hospitals with a low use of neuraxial techniques such as developing dedicated staffing for the labor and delivery unit. Free from duties outside of this unit, dedicated teams could improve the intensity of services.

Limitations of the Study

We acknowledge several limitations to our study. First, we had to apply ICD-9-CM codes and not individual chart review for the definition of exposure and the lack of or presence of a clinical indication for general anesthesia for cesarean delivery. It is therefore possible that a case may have had a clinical indication that was not captured by ICD-9-CM coding (either by missing code or a clinical circumstance not recorded appropriately). Furthermore, some factors associated with the use of general anesthesia are not available in administrative data, such as (1) patients' request for general anesthesia (or refusal of neuraxial anesthesia) and (2) a nonfunctional epidural catheter for intrapartum cesarean delivery or a general anesthetic being needed for rescue of a failed neuraxial anesthetic. Therefore, a proportion of general anesthesia cases may have been attributable to patient refusal of neuraxial analgesia/anesthesia, or rescue general anesthesia if neuraxial anesthesia was not adequate for cesarean delivery (either because of emergent intrapartum cesarean delivery or simply because of a failed neuraxial anesthetic). Several studies suggest that patient refusal represents a small proportion of general anesthesia for cesarean delivery cases.[10,26] For example, in a series of 98 cases of general anesthesia for cesarean delivery in an academic hospital, Palanisamy et al.[26] report that patient refusal of neuraxial technique accounted for only 1% of the cases. However, the incidence of failed epidural catheter is much higher and up to 12% in a recent study.[36] Another limitation is that our analysis is limited to practice in New York State because it is the only Healthcare Cost and Utilization Project participating state that provides information on anesthesia care; therefore, our findings may not be generalizable because of marked variations in anesthesia care between states. Indeed, Butwick et al.[37] reported the current overall labor neuraxial analgesia rate in the United States to be 73%, but with a minimum of 37% in the state of Maine and a maximum of 80% in the state of Utah. From an analytical standpoint, although we limited our study sample to women without a recorded clinical indication for general anesthesia, adjusted for a large set of confounders using propensity score weighting, and conducted sensitivity analyses to test the robustness of our main analysis, we cannot exclude some residual confounding in the estimate of the adjusted odds of adverse events associated with general anesthesia compared with neuraxial anesthesia. Last, we cannot report on the influence of the anesthesia provider on general anesthesia use without a recorded clinical indication; nonobstetric anesthesiologist care has been associated with an increased use of general anesthesia for cesarean delivery through failed intrapartum conversion of labor epidural analgesia into surgical anesthesia.[34,38,39] Unfortunately, we do not have any information about anesthesia providers' characteristics.

Conclusions

In this cohort, we identified that 44% of general anesthesia cases for cesarean delivery were potentially avoidable, which was associated with an increased risk of maternal adverse events, including venous thromboembolic events. A low hospital-level use of neuraxial techniques during labor was one of the strongest predictors of potentially avoidable use of general anesthesia for cesarean delivery.

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