A new study found that soap was less effective than saline in debriding wounds.

Among the many wound types, open fractures present some especially delicate challenges to physicians and caregivers alike. When the bone breaks in this way, usually by extreme trauma, fragments then pierce the surrounding muscle and tissue.

As the American Academy of Orthopaedic Surgeons noted, open fractures can increase the rate of infection. In fact, according to a 2015 study published in the journal Acta Ortopedica Brasileira, the global infection rate for open fractures is just over 13 percent.

As a result, more scientists and wound care experts are continually taking measures to further reduce the likelihood of harmful infections. In a recent study published in the New England Journal of Medicine, a group of doctors outlined how saline could be an important tool in effective wound irrigation.

The mechanics of it all

This NEJM study was the result of four years of work by doctors and researchers from a number of hospitals and care centers across the globe – though it was chiefly organized by surgeons from South Carolina’s Greenville Health System. According to the research team, most doctors have two choices when it comes to both irrigation pressure and solution: low vs. high pressure, and soap vs. saline. While low pressure isn’t as effective as removing particulates, it doesn’t impede bone healing the same way high pressure delivery does. And though soap actively fights infections – unlike saline – it does tend to blend particulate into a messy, homogenous liquid. The only way for researchers to decide which solution was most effective was to pit soap against saline in real-life debridement procedures.

Setting up a FLOW

Between June 2009 and Sept. 2013, the team conducted a series of Fluid Lavage of Open Wounds (FLOW) trials. According to the ISRCTN Registry, FLOW is a standardized model involving multiple medical centers engaging in a blind factorial trial. In all, the team worked with 2,551 enrolled patients of varying ages and nationalities. Of that group, 859 were treated using high pressure and 846 underwent low-pressure treatments. In all, 1,276 people received irrigation with normal saline, while castile soap was used on 1,275 patients.

The results, the team said, were rather counterintuitive to what they originally theorized. The most substantial factor that physicians examined was the re-operation rate. This refers to secondary surgeries required following an infection. For soap, that rate was 14.8 percent compared to 11.6 percent with saline. Though that seems like a slim margin, the research team explained that it was statistically significant. As for pressure, high or low applications didn’t make much of a difference to the possibility of infection. This counters the conclusions of a 2005 study published in the journal Clinical Orthopaedics and Related Research, which stated that high pressure can increase infection rates by pushing bacteria directly into muscles.

Taking the next step

Dr. Kyle Jeray is the lead author of the NEJM and an orthopedic trauma surgeon at GHS. Speaking with The Greenville News, he said that the results of this study have huge ramifications in improving patients’ wound healing processes. He also noted that 250,000 people suffer open fractures each year in the U.S. alone.

“When we wash our hands, we use soap all the time, and in some ways it would make sense to use instead of normal saline,” he explained. “But soap is probably caustic to the tissues, muscle and bone. You end up with more damage to soft tissues, more problem with wound and bone healing. Normal saline is most effective. And this will eliminate the use of soap almost entirely for the 98 percent of wounds that don’t need it.” He mentioned that soap will still be required in some wounds, like those contaminated with grease.

Jeray said he believes this study will also reduce surgeons’ reliance on pulse lavage devices, which are used for debridement on bone surfaces. He went on to explain that saline could reduce usage by up to 10 percent. While that will be beneficial for all patients, Jeray and his co-authors specifically had military service members in mind. According to the U.S. Army Medical Department, almost 80 percent of all injuries are extremity-related, including open fractures.

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