Tobacco use in surgical patients

Published on 07/02/2015 by admin

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Tobacco use in surgical patients

Yu Shi, MD, MPH and David O. Warner, MD

Approximately 20% of adults in the United States smoke cigarettes, and each year an estimated 10 million smokers undergo surgical procedures. Chronic and acute exposures to cigarette smoke cause profound changes in physiology that increase the perioperative risk of cardiovascular, pulmonary, and wound-related complications occurring (Figure 107-1). Thus, the knowledge of how smoking and abstinence from cigarettes affect perioperative physiology is of practical importance. This chapter will review (1) why smokers should maintain perioperative abstinence from smoking for as long as possible, (2) why surgery provides a good opportunity to quit smoking permanently, and (3) how anesthesiologists can help their patients quit smoking.

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Figure 107-1 Mechanisms of how cigarette smoking increases perioperative risk. CO, Carbon monoxide.

Smoking abstinence and perioperative outcomes

Although some of the effects of smoking are irreversible (e.g., airway damage in chronic obstructive pulmonary disease), abstinence from smoking can improve the function of many organ systems and reduce the risk of perioperative complications. The amount of time needed for the body to recover from the reversible effects of smoking varies widely. However, the effects of many smoke constituents are transient. For example, nicotine has a short half-life (∼1-2 h), so that plasma nicotine levels are very low after 8 to 12 h of abstinence.

Cardiovascular outcomes

Smoking is a major risk factor for cardiovascular diseases. In the long term, abstinence from smoking decreases the risk for all-cause death in smokers with coronary artery disease by approximately one third. Smoking a cigarette acutely increases myocardial O2 consumption by increasing heart rate, blood pressure, and myocardial contractility. These effects are likely mediated primarily by nicotine, which both increases sympathetic outflow and directly contracts some (but not all) peripheral vessels. The carbon monoxide in cigarette smoke binds to hemoglobin and shifts the oxyhemoglobin dissociation curve to the left, interfering with O2 release. These effects all contribute to an increased risk of myocardial ischemia. During anesthesia, the frequency of ischemia, as assessed by the electrocardiogram, is well correlated with exhaled carbon monoxide levels. This suggests that smoking in the immediate preoperative period increases acute cardiovascular risk and that even brief preoperative abstinence may benefit the heart because carbon monoxide values fall rapidly after abstinence from smoking (within about 12 h). As the effects of nicotine and carbon monoxide dissipate, the risks of acute ischemia may also quickly decrease as myocardial O2 demand decreases and O2 supply increases. After 12 h of abstinence, maximum exercise capacity, a measure of overall cardiovascular function, is significantly increased.

Respiratory outcomes

Smoking is a major cause of pulmonary diseases. For example, chronic obstructive pulmonary disease develops in about 15% of smokers. Even those smokers who do not develop clinical lung disease show acceleration in the normal age-related declines in pulmonary function. Smoking induces an inflammatory state in the lung, causing goblet cell hyperplasia, smooth muscle hyperplasia, fibrosis, and structural epithelial abnormalities. Smoking affects both the volume and composition of mucus and decreases mucociliary clearance. All of these abnormalities predispose smokers to a greater frequency of pulmonary infections and reactive airway disease. Smoking status is a consistent risk factor for several perioperative pulmonary complications, including bronchospasm and pneumonia. Even relatively low-level exposure to smoke has clinical consequences; for example, children exposed to secondhand smoke have an increased rate of upper airway complications.

Despite the inflammatory response induced by cigarette smoke, important elements of lung defenses against infection are impaired during anesthesia to a greater degree in smokers compared with nonsmokers. Lung recovery from chronic smoke exposure is a complex process. Symptoms of cough and wheezing decrease within weeks of abstinence. Goblet cell hyperplasia, mucus production, and mucociliary clearance also improve. As a result of this recovery, abstinence decreases the risk of perioperative pulmonary complications, but it appears that several months of abstinence are required for maximal benefit. However, it is not true that brief abstinence from smoking prior to surgery increases the risk of pulmonary complications. This belief was based on the idea that quitting smoking produces a transient increase in cough and mucus production, which is also not true. Thus, although the longer the duration of preoperative abstinence the better, smokers should never be discouraged from quitting at any time, even if only briefly before surgery.

Wound-healing and bone-healing outcomes

Smokers are more likely to develop postoperative wound-related complications, such as dehiscence and infection, especially in procedures that require undermining of the skin, such as plastic surgery. This is likely caused in part by smoking-induced decreases in tissue oxygenation, which is an important determinant of wound healing. Cigarette smoke may also directly affect the function of fibroblasts and immune cells, which play important roles in the healing process. Microvascular disease caused by smoking may also interfere with angiogenesis via impaired release of substances, such as nitric oxide, that are important for wound repair. For this reason, some surgical specialists (especially plastic surgeons) refuse to perform cosmetic procedures unless their patients at least temporarily stop smoking. Smoking has significant effects on bone metabolism and is a major risk factor for osteoporosis. Smoking increases the risk for nonunion of spinal fusions, and the healing of fractures and ligaments may also be impaired in smokers. There is now strong evidence that abstinence can reduce wound-related complications, such as wound infections. The duration of preoperative abstinence required for benefit is not known. However, because tissue oxygenation is a primary determinant of risk, and because tissue oxygenation improves quickly with the cessation of smoking, there is good reason to believe that even brief periods of abstinence would be beneficial. It is important for patients to maintain postoperative abstinence for the first week after surgery to allow for the initial stages of the healing process to occur.

Surgery represents an excellent opportunity for smoking cessation

As discussed previously, even a brief abstinence from smoking before surgery may decrease the risk for perioperative complications. The results of a recent meta-analysis suggest that preoperative intervention on smoking cessation reduces postoperative complications (risk ratio: 0.70, 95% confidence interval 0.56, 0.88). Another reason that patients should try to quit smoking around the time of surgery is that surgery is a “teachable moment” that motivates individuals to change smoking behavior—undergoing a major surgical procedure doubles the rate of spontaneous quitting. Also, studies suggest that symptoms of nicotine withdrawal do not consistently occur in the perioperative period. For example, smokers do not report greater increases in stress over the perioperative period, compared with nonsmokers. Regardless of whether the lack of increased stress occurs because of opioids given postoperatively or the fact that patients are out of their normal environments that usually provide cues for smoking, patients can be encouraged to maintain perioperative abstinence from cigarettes without fearing that this will contribute to the stress caused by the surgical experience itself. Because smoking is the most common preventable cause of premature death, surgery is, thus, an excellent opportunity to promote the long-term health of surgical patients.

Helping patients quit smoking

Treatment of tobacco dependence involves both behavioral counseling (to address the habit of smoking) and pharmacotherapy (to address nicotine addiction) (Figure 107-2). Even brief advice to stop smoking offered by physicians increases quit rates. More intensive counseling further increases quit rates. It may not be practical for anesthesiologists to deliver intensive behavioral interventions, as most are not trained to do so and time is limited in busy clinical practices; however, anesthesiologists can refer patients to other existing services, such as telephone quitlines, which are available in all states (1-800-QUIT-NOW) and can provide assistance and follow-up at low or no cost to smokers attempting to quit. Pharmacotherapy helps smokers treat symptoms of nicotine withdrawal, including cravings for cigarettes. Nicotine replacement therapy (NRT) in the forms of gum, inhaler, patch, and lozenges is effective in promoting abstinence, with many forms available without prescription. NRT does not produce adverse cardiac effects in healthy smokers and is safe in patients with cardiovascular diseases. There is no evidence that therapeutic doses of NRT in humans affect wound healing; therefore, current evidence supports the safety of NRT for surgical patients. Good success in maintaining abstinence has been reported with a combination of pharmacotherapy (bupropion SR or varenicline tartrate) and psychotherapy (e.g., individual, group, or telephone-based therapy).

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Figure 107-2 Summary of methods to help patients quit smoking. (Modified from Warner DO. Helping surgical patients quit smoking: Why, when, and how. Anesth Analg. 2005;101:481-487.)

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