Surgical Infection in the Age of Minimally-Invasive Surgery

Today marks about 4 years since Prescient Surgical was founded, conveniently marked by the company’s incorporation in the fine state of Delaware. After a full year of exploring various unmet needs in hyperkalemia to Raynaud’s phenomenon as Innovation Fellows in the Stanford Biodesign program, the founding team began to rally around what we called “The SSI Project.” With strong support from the surgical community at Stanford and beyond, and under full sail with the trade winds of public reporting and fines implemented with the Affordable Care Act, it was clear we were chasing down a critical unsolved problem in surgery that required immediate attention.

Naturally, I remain convinced of that fact today, and am thrilled by the progress we’ve made as a company and community towards reducing surgical site infection. Yet from the moment we began this journey, the requisite gauntlet of venture capitalists, health systems, BigCo’s, and physician interaction have buffeted us with a recurring, unseemly paradox that I’d like to address here—mainly, that the evolution of minimally invasive surgical techniques (predominantly laparoscopic surgery) has all but eliminated SSI.

Well…so why do we still see so many infections? Is it because laparoscopic / MIS techniques are in fact a panacea, but have not yet been fully adopted? Probably not, and for the past 5 years at ASCRS we’ve seen laparoscopic adoption in colorectal surgery stagnate at around 30-40%, even as the video game generation enters its prime. Laparoscopic techniques simply aren’t or can’t be used in the majority of some of the most complex surgeries.

In my position I am privileged with access to some of the world’s greatest minds in surgery, and I’m hearing a consistent belief that the next decade of surgical development will be about OR safety, not necessarily OR “MIS-ness.” One prominent single-port laparoscopic surgeon put it this way—“The impact in cholecystectomy was enormous, but when you look at more complex procedures like colectomy, you are taking out a colon, you are extracorporealizing a contaminated specimen. It’s fundamentally invasive, and within that big-picture context, MIS techniques offer real, but comparatively diminished benefits.” He advocates MIS “right-sizing,” that is mitigating patient risk in ways that might include laparoscopy when appropriate as opposed to the uncompromising pursuit of a near-incisionless nirvana. I was surprised to hear this from a surgeon that could perform a single-port colectomy wth one hand tied behind his back! It’s all about striking a balance between the risk and global invasiveness of each surgery with the each surgeon’s ability to perform it effectively and efficiently.

Is it because there are large financial interests that would like you to believe that the increased costs of laparoscopic surgery are justified by unilateral improvements in surgical care? Perhaps. I would never question the net benefit of laparoscopic approaches, but particularly when it comes to SSI, the data are mixed, and high SSI rates persist.

Consider Covidien / Medtronic’s clinical dossier summarizing the benefits of laparoscopic approaches in colorectal surgery (http://www.medtronic.com/content/dam/covidien/library/us/en/clinical-procedural-therapy/colorectal/colorectal-global-value-dossier.pdf):

“Surgical Site Infection: Rates of surgical site infection are consistently lower (often significantly) with laparoscopic colorectal surgery than open colorectal Surgery.”

Covidien data

By “often significantly,” Medtronic means that studies do not always show this benefit with statistical significance, and at times have been associated with higher infection rates in colon surgery. Though the weight of evidence supports the notion that laparoscopic approaches reduce the risk of SSI, there are still infections in laparoscopic surgery (perhaps 4-17% based on the data presented by Medtronic, though the most recent studies, and NSQIP rates at high-volume laparoscopic centers would suggest rates of 7-12%, and prospective studies generally find rates of 15-20%+). We shouldn’t be surprised either. However small, the resulting incisions are still prone to intraoperative contamination and reduced immunological activity. Even with laparoscopic approaches, a comprehensive wound care plan is warranted.

In the News: Closing the Stable Door After the Horse has Bolted

Thanks to Google Alerts, I recently came across an article published by the folks at MedPage Today reporting on an algorithm developed by Dr. Cromwell at The University of Iowa  Hospital and Clinics touted to cut surgical site infections (SSI) by 58%. Results of that magnitude certainly pique my interest, so I did some internet sleuthing to learn more, and eventually came across a more thorough review on the WSJ CIO Blog and an unpublished manuscript describing their approach.

Although predictive analytics for surgical site infection isn’t in itself novel (NSQIP developed a patient risk assessment tool, for example), the novelty of Cromwell’s approach seems to be rooted in the strength of their data analytics and committment to incorporate detailed intraoperative factors into the assessment.

From the WSJ post:

“During surgery, as the surgeon closes up the patient’s abdomen, the circulating nurse logs onto a Web portal for the software and enters real-time data such as patient blood loss during the operation, the wound classification and whether it was contaminated, said Dr. Cromwell.”

The theory is that if caregivers are armed with this information before patients leave the operating room, doctors can create a plan to reduce the subsequent risk of infection by “altering medication or using different techniques in treating the wound.” The reader is left to wonder what those medications or techniques might be, especially when the physiology of wound healing dictates that infection prevention strategies are severely impaired after the incision is closed due to fibrosis and encapsulation of infectious material (Surgical Infections, March 2013).

Regardless, I think Cromwell is on to something here, because the events of operation itself represent the best opportunity to reduce risk. But assessing these predictive variables at closure is a bit like closing the stable door after the horse has bolted. A better approach would be to make sure the stable door is closed to begin with.

As an illustrative example, consider the Cromwell’s results: factors associated with increased risk of infection include certain patient zip codes, ostomy creation, higher wound class (i.e. wound contamination), higher ASA score, higher total # of procedures (per patient), surgical apgar score, and open procedural approach. We highlighted the importance of wound contamination in an earlier post, and would further maintain that of these factors, wound class (i.e. wound contamination) is the only one under direct control of the surgeon. So why aren’t we doing more to prevent wound contamination? We could start by directing powerful analytical tools like those developed by Cromwell towards the operative field.