9. SMOKING

Smoking is a major risk factor for perioperative complications.

Cigarette smoking is a major cause of coronary heart disease and an important cause of cerebrovascular disease. It is the single most important cause of cancer mortality in the United States, accounting for 30% of all cancer deaths. Cigarette smoking also is a major cause of chonic obstructive pulmonary disease and is associated with an increased risk of pneumonia and postoperative respiratory complications.

The anaesthetist must be aware of the damage that smoking can do to a patient’s health.

Recommendation

Patients who smoke should be encouraged to stop smoking at least six to eight weeks (ideally 6 months) before surgery.

Even stopping smoking for 12 hours before surgery is of some benefit.

Physiological Effects

More than 4000 substances have been found in cigarette smoke.

Cigarette smoke contains 2 to 6% carbon monoxide. Smoking increases the amount of carboxyhaemoglobin in the blood. The range of carboxyhaemoglobin levels in smokers is 2 to 15%. As the half-life of carboxyhaemoglobin is only four hours, 12 hours of stopping smoking will greatly reduce its levels, improve oxygen content and reverse the negative inotropic and arrhythmic effects. The polycythaemia takes several days to reverse.

Nicotine increases heart rate, blood pressure and causes peripheral vasoconstriction. These effects improve after 12 to 24 hours of stopping smoking.

Smoking also causes increased secretion of mucus in the lungs. The airways are narrowed and the lungs ability to remove mucus is reduced by smoking so smokers tend to become hypoxic more quickly. It takes 6 weeks before the mucus production in the lungs returns to normal.

Smoking also has an adverse effect on the patient’s immune system. It takes 6 months before a patients immune system returns to normal.

One year after stopping smoking there is a marked reduction in the patient’s risk of myocardial infarction.