The increase in postoperative complications in smoking patients stems from the cardiovascular and respiratory effects of smoking. Elderly long-term smokers, in particular, are prone to postoperative lung infections and chest X-ray abnormalities in up to 53% of cases. Smokers have higher carboxyhemoglobin, which ranges from 3% to 15% depending on the degree and amount of smoking, and the increased carboxyhemoglobin concentration reduces hemoglobin-oxygen binding, which decreases arterial oxygen levels and shifts the oxyhemoglobin saturation curve to the left. In patients who smoke, oxygen delivery is reduced and tissue oxygen uptake is increased, resulting in lower mixed venous blood oxygen levels. Smoking patients with higher preoperative carboxyhemoglobin concentrations are at increased risk for intraoperative and postoperative complications. The cardiovascular dose-dependent effect of nicotine causes vasoconstriction of the body circulation, increased heart rate, and elevated blood pressure. Therefore, smoking patients should stop smoking for at least 12-18 hours preoperatively so that carboxyhemoglobin is cleared to 3 half-lives, and short-term abstinence in smokers is beneficial to the cardiovascular system, resulting in a decrease in blood pressure, heart rate, and blood catecholamine levels. Smoking cessation 4-6 weeks before surgery significantly reduces pulmonary complications.