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.

Hello world! Let’s Talk About Wound Irrigation…

Editor’s Note: Welcome to Prescience, a blog focused on the science of surgical site infection (SSI). Since Prescient Surgical was founded to explore the potential benefits of surgical wound irrigation, I thought this would be an excellent first topic to explore. To that end, I invited Prescient Surgical’s Co-founders, Dr. Insoo Suh and Dr. Mark Welton, to provide some grounding context and present an overview of the literature on surgical wound irrigation.

Surgical Wound infection: A “perfect storm”
As is the case with many clinical problems, wound infection is a multifactorial disease with numerous identified risk factors. However, as Cheadle (2006) details in an informative review, these risk factors can be broken down into three broad categories (1):

  1. The patient. It is well-established that a patient’s underlying medical condition affects the risk of developing surgical complications including wound infection. Pre-existing medical conditions such as advanced age, poor nutritional status, diabetes, coronary artery disease, obesity, and previous abdominal surgery and/or irradiation have clearly been demonstrated to increase the likelihood of wound infection in surgical patients. A patient’s inherent immune status also directly affects the ability of a wound to fight off infection and properly heal. Although important, these risk factors as a whole are generally secondary to the fundamental mechanisms causing wound infection. In addition, these comorbidities are inherent to the makeup of the patient, and are therefore less amenable to significant improvement in a short time frame (other than making sure that they do not significantly worsen in the perioperative period).
  2. The microbe. By definition, a wound infection requires the presence of a responsible invasive organism, usually bacterial; therefore, the type of microbe that contaminates the wound edges is perhaps the most fundamental factor in the development of wound infection. Generally, wound infections from “clean” operations (those that do not violate the aerodigestive tract) are due to organisms that normally reside on the skin, such as Staphylococcus and Streptococcus species. On the other hand, operations that violate the GI tract (such as colorectal surgery) release millions of fecal organisms (E. coli, Klebsiella, Proteus, etc.), which are then responsible for the majority of wound infections in these procedures. As detailed below, antibiotics represent an active strategy to counteract and destroy bacteria.
  3. The operation. The setting in which the potential inciting events for wound infection occur is also profoundly important. Factors that either increase the patient’s physiologic stress response (e.g. tissue ischemia, increased blood loss, inadvertent hypothermia, etc.) or increase the exposure of the wound to the possibility of contamination (e.g. longer operative time, increased incision length, improper skin prep/sterilization, operations that expose the wound to contaminating intestinal contents, etc.) are known to increase the likelihood of wound infection. Some of these factors are highly dependent on the technical prowess of the individual surgeon or the inherent difficulty of the operative task, and are therefore difficult to control. However, some factors – namely, contact contamination – are critical factors that can be modified and improved through a standardized approach.

Continue reading “Hello world! Let’s Talk About Wound Irrigation…”