One anesthesiologist directing one or two overlapping surgical cases appears to be the optimal ratio for best patient outcomes, a large retrospective study of registry data suggests.
“In this cohort study, increasing overlapping anesthesiologist coverage was associated with increased surgical patient morbidity and mortality, despite treatment bias for healthier patients and lower-risk operations,” lead study author Michael L. Burns, MD, PhD, of the Department of Anesthesiology of the University of Michigan in Ann Arbor, and his colleagues write.
“These findings suggest potential consequences of overlapping anesthesiologist responsibilities in perioperative team models and should be considered in clinical coverage efforts,” they conclude.
As reported in JAMA Surgery, Burns and his colleagues examined whether differences in anesthesiologist staffing ratios may be linked with surgical patient morbidity and mortality.
Surgical Outcomes From Electronic Health Records
The researchers focused on a common clinical care team model: one anesthesiologist who oversees multiple simultaneous operations and supervises the anesthesia clinicians (certified registered nurse anesthetists, anesthesia assistants, or anesthesiology residents) working in each operating room.
The researchers analyzed the outcomes of 578,815 adult patients whose data were included in the Multicenter Perioperative Outcomes Group electronic health record registry. The patients averaged around 56 years of age, roughly half were female, and all underwent major noncardiac inpatient surgical procedures between 2010 and 2017 at 23 academic and private hospitals in the US.
After matching surgical procedures according to anesthesiologist staffing ratio, 48,555 patients were treated by an anesthesiologist tending to that case alone, 247,057 patients by an anesthesiologist directing one to two overlapping cases, 216,193, by an anesthesiologist directing two to three overlapping cases, and 67,010 by an anesthesiologist directing three to four overlapping cases.
The researchers used anesthesiologist sign-in and sign-out times to calculate a continuous time-weighted average staffing ratio variable for each operation. They applied propensity score-matching methods to create balanced sample groups with respect to patient-, operative-, and hospital-level confounders.
The authors set the primary outcome as a composite of 30-day mortality and six major surgical morbidities — bleeding, cardiac, respiratory, gastrointestinal, urinary, and infectious complications.
More Cases, More Worse Outcomes
Increasing anesthesiologist coverage responsibilities was linked with increased risk for risk-adjusted surgical patient morbidity and mortality.
Compared with patients whose anesthesiologist directed between one and two overlapping operations, those whose anesthesiologist directed teams during two to three overlapping operations had a 4% relative increase in risk-adjusted mortality and morbidity (5.06% vs 5.25%; adjusted odds ratio (AOR) 1.04; 95% CI, 1.01-1.08).
Patients whose anesthesiologist directed between three and four overlapping operations had a 14% increase in risk-adjusted mortality and morbidity (5.06% vs 5.75%; AOR 1.15; 95% CI, 1.09-1.21).
“When 100,000 operations, which is typical annually for a major medical center, are considered, the increase in risk from 5.06% to 5.75% that we observed would translate to an additional 690 operations with adverse outcomes,” the authors write.
Increasing Strain on Anesthesiologist Work Force Projected
Bradford D. Winters, MD, PhD, FCCM, division director of adult critical care medicine at Johns Hopkins University School of Medicine, Baltimore, Maryland, told Medscape Medical News that these results about the US healthcare system are very concerning.
“We are in for a rough ride,” he predicted.
“The health system is rapidly heading into an across-the-board staffing crisis, accelerated and exacerbated by the COVID-19 pandemic,” Winters, who was not involved in the study, said in an email.
“Surgery is particularly vulnerable because an aging population will consume more surgical services, and the drive to meet that burden in the face of a dwindling anesthesiologist workforce will stretch staffing models to a breaking point,” he said.
While thinly stretched staffing may lead to worse patient outcomes, he added, decreasing overlap to only one to two operations may lead to long delays for patients waiting to have nonemergent and nonurgent procedures.
“A team approach will have a better distribution of workload and responsibilities and likely result in a better outcome,” advised Winters. “Being solo puts all the workload on one person, which to me seems just as risky for poor outcome as being responsible for supervising too many teams.”
Study Raises Important Questions
Meena Bhatia, MD, FASA, vice chair of clinical operations in the Department of Anesthesiology at the University of North Carolina School of Medicine in Chapel Hill, said in an email that the study authors ask an important question, and that the results, “if true, may have substantial public health implications and huge staffing implications.”
Bhatia, who also was not involved in the study, pointed out its limitations, including the lack of accounting for cardiac, transplant, and other complex surgeries, the exclusion of cases staffed by residents in training, and the omission of anesthesia care for specific complications.
“The American Society of Anesthesiology supports the safety of the anesthesia care team model, recognizing that patient acuity and provider experience are important factors that may influence what the appropriate staffing ratio may ultimately be,” she said.
“Delivering safe and efficient care remains our highest priority,” Bhatia notes. “This report, which raises good questions that are yet to be fully understood and answered, deserves attention.”
In an accompanying editorial, Martin Almquist, MD, PhD, of the Department of Surgery at Skåne University Hospital in Lund, Sweden, writes that this study adds to the growing literature that highlights the importance of the anesthesiologist for postsurgical outcomes.
The results suggest that the level of experience of the anesthesia team is important, Almquist says. Low staffing levels are linked with increased burnout and higher turnover of nursing staff, he said.
“Anesthesia is not only indispensable for surgery,” he writes, “but how anesthesia is carried out, and by whom, is also of paramount importance.”
Two study authors and the editorial author report financial relationships with pharmaceutical companies. Winters and Bhatia report having no relevant financial relationships. The study did not receive commercial support.
JAMA Surgery. Published online July 20, 2022. Abstract; Editorial.
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