INDIANAPOLIS – Intraoperative temperature proved unrelated to the risk of surgical site infection following major colorectal surgery in a large patient series.
This finding undercuts the rationale for normothermia as a process measure that’s part of the Surgical Care Improvement Project (SCIP) sponsored by CMS in partnership with the American College of Surgeons and other organizations.
Dr. Genevieve Melton-Meaux
"Our study suggests that perioperative normothermia is not independently associated in and of itself with reduced surgical site infections after colorectal surgery, and this as a process measure may have limited utility in actually decreasing SSIs. We believe that efforts in other areas may be more efficacious," Dr. Genevieve B. Melton-Meaux said at the annual meeting of the American Surgical Association.
She hastened to add that she and her coinvestigators are by no means saying intraoperative warming is unimportant. Indeed, there is compelling evidence that warming has physiologic benefit. Also, it has been shown that intraoperative hypothermia boosts SSI risk by about three-fold (N. Engl. J. Med. 1996; 334:1209-15). But the investigators take issue with the SCIP quality measure mandating documentation of a temperature of exactly 36° C at the end of a surgical case, given that their study demonstrated that this metric had no correlation with SSI rate.
"Our message and belief is that warming is a good thing and hypothermia is not a good thing. Warming is indeed something that should be done," emphasized Dr. Melton-Meaux, a colorectal surgeon at the University of Minnesota, Minneapolis.
She presented an analysis of continuously measured intraoperative temperature data recorded via anesthesia information system in 1,008 adults who underwent major colorectal procedures at the Cleveland Clinic during a recent 1-year period. Roughly two-thirds of the patients had either a partial colectomy, a proctectomy, or total abdominal colectomy. The mean operating time was 173 minutes, and 22% of patients had a laparoscopic approach. The anesthesia information system, Dr. Melton-Meaux observed, is a hitherto largely untapped rich data source for research, since it records temperature and other physiologic data throughout the operation.
Active rewarming was performed in 92% of cases. A total of 91% of patients received an antibiotic within 1 hour prior to incision, in accord with another SCIP performance measure. The mean and median intraoperative temperature was 36.0° C, with an ending temperature of 36.3° C.
The 30-day SSI rate was 17.4%, including an organ/space infection rate of 8.5%. Neither maximum, minimum, median, nor ending temperature differed significantly among patients who developed an SSI and those who didn’t. In a multivariate analysis, the only factors significantly associated with SSI risk were preoperative diabetes, which carried a 1.9-fold increased risk; laparoscopic approach, which was associated with a 41% reduction in risk; and estimated blood loss.
Discussant Dr. Mary T. Hawn characterized the temperature study as an indictment of SCIP.
"Colorectal surgery, as we all know, has been a major focus of the Surgical Care Improvement Project. Yet despite rapid adoption and standardization of some aspects of perioperative care, there is little if any evidence that any meaningful improvements in outcomes have been realized. And the evidence to support many of the SCIP metrics is limited. For instance, the evidence to support the use of prophylactic antibiotics is based upon extensive Level 1 data, but that data is on whether or not the patient received the antibiotic, not whether it was given within 60 minutes prior to incision," said Dr. Hawn of the University of Alabama at Birmingham.
She added that it’s incumbent upon surgeons themselves to develop the evidence for alternative metrics that more meaningfully measure true surgical quality.
"If you Google ‘SCIP normothermia measure,’ the first three sites that come up are companies selling these devices, so I think we need to study them," the surgeon said.
Other audience members decried the fact that hospitals are spending millions of dollars to be compliant with quality scorecards based in large part upon SCIP process measures of unproven value.
"Are we ready to recommend to CMS that they modify their indirect attempts to alter the practice of medicine by telling us exactly what we ought to do with temperature?" commented Dr. Kenneth L. Mattox, professor and vice chairman of the department of surgery at Baylor College of Medicine, Houston.
Dr. Melton-Meaux commented, "I think the intention behind the process measures is the right one: that we should be implementing system-wide best practices. But I think what has happened inadvertently, especially because SCIP has become part of value-based purchasing, is we are all playing a game. We are playing to the measure rather than really focusing on delivering better care and better outcomes."