Effects of smoking on pulmonary functions and arterial blood gases following coronary artery surgery in Turkish patients

The effects of smoking on postoperative lung volumes, arterial blood gas tensions, and pulmonary complications were studied prospectively in 213 consecutive Turkish patients undergoing elective coronary artery bypass graft surgery. One hundred and seventeen patients were current smokers (19 females, 98 males, mean age, 59.0+/-6.1 years, group 1) and 96 were nonsmokers (40 females, 56 males mean age, 59.6+/-5.8 years, group 2). Demographic data and the anesthesia and surgical methods were similar in both groups. Pulmonary function tests, arterial blood gas analyses, and chest radiographs were done preoperatively and postoperatively. Pulmonary complications were recorded. Postoperative partial arterial oxygen tension values in both groups revealed moderate hypoxemia which was more intense in smokers (decreased from preop. 82.0+/-7.8 mmHg to postop. 66.1+/-8.0 mmHg). Mean partial carbon dioxide tension increased significantly, remaining within acceptable limits (from 32.5+/-2.2 mmHg to 38.6+/-3.6 mmHg) in smokers following surgery. The postoperative pulmonary function test values decreased significantly in both groups but the deterioration in the smoking group was highly significant, except for FMFT. In the smokers, the preoperative mVC/pFVC (%) value was at the lower normal limit which indicates slight restrictive respiratory problems. Patients in both groups developed a severe restrictive ventilatory defect after coronary artery surgery (P<0.0001 for both), but this restriction was also statistically significant in the smoking group compared to nonsmokers after surgery (mVC/pFVC from 74.7+/-12.6% to 52.3+/-10.0% and 80.8+/-13.5% to 63.2+/-10.7%, in the smokers and nonsmokers, respectively). Also, the significantly greater decrease in the FEV1/FVC ratio in the smokers (from 75.4+/-12.2% to 72.2+/-11.5%) (P=0.037) was indicative of greater airway obstruction. Pulmonary complications developed in 20.5% (24 people) of the smokers and 10.4% (10 people) of the nonsmokers. The mean time to extubation, intensive care unit stay, and hospital stay for groups 1/2 were 19.9+/-11.5/14.1+/-4.3 hours (P<0.0001), 3.2+/-1.3/2.4+/-0.6 days (P<0.0001), and 14.1+/-4.4/12.5+/-2.4 days (P=0.0013), respectively. For the male group, we obtained results similar to those for the whole (males+females) study population and concluded that the observed differences in various parameters between smokers and nonsmokers were not due to gender. As a result, we revealed that cigarette smoking affects pulmonary functions by causing obstructive type respiratory problems and by worsening existing restrictive type respiratory problems postoperatively. The postoperative deterioration in blood gas measurements of smokers was also statistically significant compared with nonsmokers. In addition, the incidence of pulmonary complications in smokers was 2-fold greater than in nonsmokers and was related to the number of cigarettes consurned daily, leading to prolongation of the postoperative intubation period, and ICU and hospital stays.