Patients undergoing elective surgery are routinely told to stop smoking cigarettes weeks or even months before the procedure, due to the known relationship between cigarette smoke exposure and impaired wound healing.

Now, however, early research in rats suggests that electronic cigarette exposure may have the same negative impact on surgical wound healing.

Researchers conducted the skin-flap wound healing experiments on male rats exposed to smoke from traditional cigarettes and electronic cigarettes or no smoke at all.

Smoking and vaping appeared to be equally detrimental to wound healing and both were associated with a statistically significant increase in flap necrosis, compared with unexposed rats, Jeffrey Spiegel, MD, chief of the Facial Plastic Surgery Program at Boston University School of Medicine, and colleagues wrote online in JAMA Facial Plastic Surgery.

"To our knowledge, this study is the first to examine the association between e-cigarettes and wound healing," the team wrote ... "The exposed groups had the same degree of flap necrosis at similar nicotine levels; no substantial difference in wound healing was found when comparing the two groups, and no substantial difference in serum cotinine levels was observed."

Shaun Desai, MD, of Johns Hopkins Medicine in Baltimore, the author of an accompanying editorial, told MedPage Today that even though the data are preliminary, the results have influenced his pre-surgical patient counseling.

"Vaping wasn't really on my radar before I read this paper, and I don't think it's on the radar of many surgeons," he said. "And I don't think many patients are volunteering that they use e-cigarettes because they may not think it's relevant."

Desai wrote that patients should be asked about e-cigarette use before a surgical procedure, if possible: "Until further studies are completed, all e-cigarette use should be stopped 4 weeks prior to any surgical procedure, as recommended by the current literature for traditional cigarettes."

The cohort study was conducted on 45 male Sprague-Dawley rats randomized to one of three groups: negative control (n = 15), experimental (exposed to e-cigarette vapor; n = 15), and positive control (exposed to traditional cigarette smoke; n = 15).

Rats in the experimental and positive control groups were exposed to electronic cigarette vapor and traditional cigarette smoke in a smoking chamber for 30 minutes twice a day for 30 consecutive days.

The levels of serum cotinine were monitored and maintained between 150 and 200 ng/mL. After 30 days, random pattern dorsal skin flaps were raised. All 45 rats survived the surgical procedure and postoperative recovery, and all rats thrived and gained weight over the course of the study, the researchers reported.

Among their main findings:

The highest rate of flap necrosis was found in rats exposed to traditional cigarette smoke (positive control cohort), with a mean (SD) of 68.7% (8.6%), while the e-cigarette smoke exposed rats (experimental cohort) had a mean (SD) exposure of 65.9% (11.8%), and the negative control cohort had the least amount of flap necrosis, with a mean (SD) of 50.8% (9.4%)

The percentage of flap necrosis in the negative control rats (95% CI, 46.0-55.6; P<0.001) was substantially lower than that for both the positive control rats (95% CI, 64.3-73.0; P<0.001) and the experimental rats (95% CI, 59.9-71.8; P<0.001)

No statistically significant difference in flap necrosis was noted between the rats in the experimental cohort and the rats in the positive control cohort (95% CI, 59.9-71.8 vs 95% CI, 64.3-73.0; P=0.46)

Spiegel and co-authors noted that while the Sprague-Dawley rat is a verified pharmacokinetic model for cigarette smoking in humans, "it has not been verified for e-cigarette vaping."

"However, the marker of nicotine exposure, serum cotinine, was able to be reliably measured and tracked," the team added.

The study demonstrates "that e-cigarette vaping appears not to be safer than cigarette smoking in the context of wound healing and that both types of exposure appear to adversely affect healing from a surgical procedure.

"Surgeons are advised to appropriately counsel their patients and to regard those who use e-cigarettes as having equivalent perioperative healing risk as those who smoke cigarettes," the group concluded.