ANESTHESIOLOGISTS do not need to be reminded of the devastating consequences of cigarette smoking. Our practices are affected on a near-daily basis—we often care for patients who require surgery for diseases caused by smoking, and we manage smoking-related perioperative morbidity such as respiratory complications. Usually, we successfully deal with these challenges and deliver these patients safely back to their families. However, the consequences of smoking do not end at the recovery room door. Surgeons have long maintained that the healing of surgical wounds is impaired in smokers, and most clinical and experimental studies confirm that smoking status is a risk factor for wound dehiscence and infections.1–6Two important recent prospective studies show that preoperative abstinence from smoking can reduce the risk of wound-related complications. These studies, one in orthopedic surgery patients7and one in volunteers,8found dramatic reductions in the frequency of wound-related complications when smokers quit from 4 to 8 weeks before surgery. These studies did not address whether more brief periods of abstinence also reduce risk. In this issue of Anesthesiology, Kuri et al. 9attempt to answer this question.
Why is wound healing impaired in smokers? Clinical studies suggest that wounds requiring wide surgical undermining, such as facelifts, are particularly vulnerable.4,10,11This implies that decreased tissue oxygenation, an important determinant of wound healing,12may be a key factor. Smoking a cigarette decreases subcutaneous oxygen tension in humans,13consistent with the ability of smoke constituents, such as nicotine and carbon monoxide, to produce peripheral vasoconstriction and to impair the capacity of hemoglobin to carry oxygen, respectively. However, many other factors could also contribute. Nicotine or other components of cigarette smoke could directly affect the function of cells such as fibroblasts and immune cells important to healing,14,15although recent evidence suggests that the topical application of nicotine to wounds may in fact stimulate angiogenesis and accelerate wound healing.16Microvascular disease caused by smoking may also interfere with angiogenesis via impaired release of mediators such as nitric oxide that are important for wound repair.17,18
To the extent that impaired wound healing is caused by the acute pharmacologic effects of smoke constituents, even relatively brief periods of abstinence should be beneficial. For example, concentrations of nicotine and carboxyhemoglobin decrease dramatically within 12 h after the last cigarette.19If changes in immune function or endothelial function are involved, a longer period may be required for full benefit. Studies attempting to determine how the duration of abstinence affects perioperative risk are inherently difficult, given that it is almost impossible to implement the optimal study design of randomly assigning patients to different durations of abstinence from cigarettes. Rather, studies depend on spontaneous changes in smoking behavior to obtain varying abstinence durations. This raises the possibility of selection bias. Smokers with more severe disease or those undergoing more extensive medical procedures are more likely to quit smoking.20,21Therefore, characteristics of patients who are able to quit within a few weeks of surgery may differ in important ways from those who continue to smoke.
Accepting this limitation, Kuri et al. examined a patient population with both a high prevalence of smoking and a high rate of wound-related complications—patients requiring resection of head and neck cancers, followed by free flap reconstruction. Although a retrospective study, with the problems inherent in such a design, determination of smoking history and ascertainment of wound-related complications were appropriately conservative, and other patient characteristics were nicely matched. “Smokers” were defined as those patients who had smoked within a week. Because no information is given regarding how many of these patients had quit before hospital admission, the effects of brief periods of abstinence (< 1 week) could not be evaluated. In multivariate analysis, odds ratios for patients reporting at least 1 week of preoperative abstinence indicated at least a threefold decrease in risk for wound-related complications (defined as an event requiring surgical intervention postoperatively) for all grouping of durations, although this was not statistically significant for those reporting 1–3 weeks of abstinence. This lack of significance is the basis of the authors’ conclusion that 3 weeks of abstinence is required for benefit, but is more likely a function of relatively small numbers of patients studied. Presentation of the frequency of impaired wound healing as a function of a 3-week moving time average suggested that risk declined steadily over approximately the first 6 weeks of abstinence, although this analysis permits no statistical conclusions and itself demonstrates considerable variability (e.g. , the sudden appearance of a high frequency of complications at 7–10 weeks of abstinence). What seems clear is that the longer the duration of abstinence the better, as supported by a separate analysis showing a significant correlation between the duration of abstinence and wound-related complications. The inability to define a clear threshold for the duration of abstinence that confers benefit mirrors studies that examine the influence of preoperative abstinence duration on pulmonary risk. These studies also could only conclude that “longer is better,”22–25suggesting that several months of abstinence is necessary for full benefit.
Although the data of Kuri et al. do not provide definitive answers to the question of how long is long enough to significantly reduce the risk of wound-related complications, their study is a valuable addition to the body of evidence suggesting that preoperative smoking cessation can improve perioperative outcomes. However, the most important question may not be the optimal duration of preoperative abstinence but whether smokers can maintain long-term abstinence after surgery, because even if preoperative abstinence had no effect on perioperative outcomes, we should still help our surgical patients quit smoking. Increasing evidence suggests that surgery represents a golden opportunity for smokers to quit, with great benefit to their health.26–28For example, even in the absence of any interventions by medical personnel, the rate of spontaneous quitting is increased in surgical patients compared with the general population of smokers, especially in those undergoing more extensive procedures.28Effective tobacco interventions, modeled on those currently available in ambulatory settings, could take advantage of this natural tendency and further increase quit rates. Surgery could thus serve as a “teachable moment” to promote prolonged abstinence, if only we will take the time to teach.29A recent survey suggests that surgeons and anesthesiologists are not consistently doing so.26This is not surprising, because few surgical specialists are familiar with the dramatic advances that have occurred during the past 20 yr in the treatment of tobacco dependence.30There are now methods of proven efficacy that can at least double the chances that smokers will quit.30Optimal application of these techniques to the surgical setting will require answers to several questions. How can surgeons and anesthesiologists best incorporate tobacco interventions into their busy practices? How can surgical patients effectively access other resources such as “quitlines” and nicotine treatment specialists? Is it safe to use nicotine replacement therapy in surgical patients? In the meantime, simply asking about tobacco use and providing strong, personalized, and consistent advice that patients abstain for as long as possible before and after surgery are steps that anesthesiologists can take now to help their patients deal with tobacco dependence—if we accept that it is our responsibility to do so.
Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota. warner.david@mayo.edu
