Originally published by our sister publication, Anesthesiology News.

Increasing overlapping coverage by anesthesiologists for major noncardiac inpatient surgical procedures is linked to a significant rise in surgical patient morbidity and mortality, according to a retrospective study published online in JAMA Surgery (2022 Jul 20. doi:10.1001/jamasurg.2022.2804).

“How many overlapping rooms an anesthesiologist covers is an important consideration for staffing.” said first author Michael L. Burns, MD, PhD, an assistant professor of anesthesiology at the University of Michigan Medical School, in Ann Arbor. “We know the anesthesiology care team model is the most popular model in the United States, which is typically limited to one to four overlapping surgeries per individual anesthesiologist.”

Burns said anesthesiologists are aware that they have a busier schedule when they supervise more overlapping surgeries, “but we did not know if this perceived increase in workload leads to more patient risk.”

The matched cohort study comprised 866,453 adult patients who underwent major noncardiac inpatient surgery at one of 23 U.S. academic and private hospitals between January 2010 and October 2017.

Anesthesiologist sign-in and sign-out times were used to calculate a continuous, time-weighted staffing ratio; thus, each surgery was assigned a single value with decimals to reflect the level of overlapping coverage.

As an example, consider a single anesthesiologist covering two ORs, with one surgery lasting 60 minutes and the other 30 minutes. If the two operations overlapped completely, and once completed the second room was empty, the staffing ratio calculation for the 30-minute case would be 2.0 and for the 60-minute case 1.5.

Patients were divided into four groups: those receiving care from an anesthesiologist covering a single operation (group 1); those receiving care from an anesthesiologist covering more than one to a maximum of two overlapping operations (group 1-2); those receiving care from an anesthesiologist covering more than two to a maximum of three overlapping operations (group 2-3); and those receiving care from an anesthesiologist covering more than three to a maximum of four overlapping operations (group 3-4).

The primary composite outcome was 30-day mortality and six major surgical morbidities: cardiac, respiratory, gastrointestinal, urinary, bleeding and infectious complications.

Compared with patients in group 1-2, those in group 2-3 had a 4% relative increase in risk-adjusted mortality and morbidity (5.06% vs. 5.25%; P=0.02), and those in group 3-4 had a 14% increase in risk-adjusted mortality and morbidity (5.06% vs. 5.75%; P<0.001).

“The overall findings of increasing composite morbidity and mortality associated with increasing overlapping responsibilities was a surprise,” said Burns, also an assistant director of medical informatics and data analytics at the University of Michigan. “Given the many safety systems in place and the tendency to reserve increasing responsibilities for simpler cases or healthier patients, we did not expect to see a clinically meaningful connection.”

On the other hand, it was scientifically reassuring to observe a “dose-response” relationship in the effect size, when switching from two to three overlapping surgeries to three to four, according to Burns.

The increase in composite morbidity and mortality of 14% in group 3-4 “is a significant finding, but must be weighed along with staffing availability, costs and access-to-care considerations,” he said.

Because this is the first study to demonstrate the findings, “they need to be reproduced by other data sets and investigators,” Burns said. “However, given that the data support the intuitive concept that increasing clinical workloads may have care process impact, one should consider the results of our study when staffing ORs with anesthesia care team models.”

Furthermore, understanding how overlapping responsibilities might be causing the study’s observations, plus identifying the processes of care that are different when covering three to four ORs as opposed to one to two rooms, are essential, according to Burns.

More research is also required beyond the upper limit of four overlapping surgeries.

“It’s common sense that as an anesthesiologist is deployed to more and more rooms, it will have an effect on quality of care,” said Alan Kaye, MD, PhD, the vice chancellor at Louisiana State University Health Science Center, in Shreveport. “Unfortunately, a lot of decisions on manpower throughout the United States are driven by efficiency models and cost centers, when the two most important considerations are quality of care and best outcomes.”

One simple solution to decrease patient morbidity and mortality with overlapping cases is flexibility in deployment of manpower, according to Kaye, who was not a study author. A patient with an ASA physical status of IV, for example, “would be expected to have a lower staffing ratio than healthier, routine or easier surgeries,” he said.

Kaye noted that patient details usually are not reviewed when daily clinical deployments are made. “You rarely have the specifics about any one patient,” he said. “A patient may have what appears to be a fairly routine surgery, but in reality has a very significant comorbidity.”

—Bob Kronemyer