Canadian Health and Care Mall: Smoking and Timing of Cessation

December 20, 2015 Category: Smoking

SmokersSmoking has been found to be a risk factor for the development of postoperative complications after many types of surgery, even in the absence of underlying chronic lung disease. The relative risk of complications after surgery for smokers compared to nonsmokers has been reported to increase from 1.4-fold to 4.3-fold. Smoking cessation prior to surgery is widely encouraged, but the value of stopping only a few days to weeks prior to an operation is not known. A decrease in postoperative pulmonary complications due to smoking cessation is thought to be related to physiologic improvement in ciliary action, macrophage activity, and small airways function, as well as a decrease in sputum production, These changes can take weeks to months to occur.

Some studies have suggested that stopping smoking only a few weeks prior to surgery may lead to an unexpected or paradoxical increase in the rate of pulmonary complications, and recommendations have been made that surgery should be delayed for 8 weeks after smoking cessation.

COPDThe effect of smoking and the time of smoking cessation on postoperative pulmonary complications in patients undergoing thoracotomy for primary or secondary lung tumors is unclear. Many of these patients, particularly those with primary lung cancer, are current or past smokers, and some have COPD. Since the extent of lung resection may affect outcome, lung-sparing surgery, such as wedge resection, is often preferentially performed in those with marginal pulmonary reserve, making risk prediction difficult. Only one retrospective study has looked at patients undergoing thoracotomy for lung cancer and found that it took 5 weeks of smoking abstinence for complications in smokers to decrease to the level of ex-smokers. The complication rate was highest in those who quit smoking within 4 weeks of surgery, Since patients who are potentially capable of undergoing resection proceed to surgery as quickly as is feasible, the impact of quitting the smoking of cigarettes in the preoperative period on postoperative complications is an important issue. We undertook this prospective study to clarify the relationship of postoperative pulmonary complications to smoking history and the timing of smoking cessation in those scheduled to undergo the anatomical resection of primary or secondary lung tumors. Smoking may lead to different severe disorders. But to what – the answer may be found here on official website – Canadian Health&Care Mall.

postoperative pulmonary complicationsConsecutive thoracic surgical patients who were > 18 years old, and were scheduled to undergo thoracotomy for the treatment of primary or secondary lung tumors at Memorial Sloan Kettering Cancer Center between September 1999 to November 2001, were prospectively recruited. The protocol was approved by the institutional review board, and patients gave written consent. Patients were excluded from the study for undergoing a second surgery during the same hospital admission, or for undergoing concomitant rib, chest wall, diaphragmatic, pericardial, or pleural resections. Smoking status (ie, number of years smoked, packs per day, timing of smoking cessation, and nicotine replacement therapy) was determined by a questionnaire that was administered at the time of surgery by a research assistant. Patients were assured that answers would not be communicated to the care team. The groups studied were as follows: nonsmokers; past quitters, who stopped smoking > 2 months before surgery; recent quitters, who stopped smoking > 1 week and < 2 months before surgery; and ongoing smokers, who smoked to within the week of undergoing surgery or did not stop smoking. Patients received standard general anesthesia and postoperative analgesia, which was surgeon-specific, and consisted of IV morphine patient-controlled analgesia (n = 93) or epidural fentanyl patient-controlled analgesia (n = 207).

The following postoperative pulmonary complications were considered as study end points and were recorded throughout the hospital stay: respiratory failure requiring ICU admission and/or intubation; pneumonia (new pulmonary infiltrate with fever treated with IV antibiotics); atelectasis requiring bronchoscopy (need determined by the surgical team); pulmonary embolism (diagnosed by CT scan and treated); and the need for supplemental oxygen at hospital discharge. No patient had required the use of oxygen prior to undergoing surgery. Transient hypoxemia and bronchospasm were not study end points. Once discharged from the hospital, an investigator or research nurse monitored patients for complications for 30 days from the time of surgery and queried patients about intercurrent hospitalizations or emergency department visits.

FEV1Statistical Analysis

We anticipated that the ratio of subjects with complications to subjects without complications in the study population would be 1:4. The required sample size for detecting a difference of 0.125 with 0.80 power between smokers and nonsmokers was 300 patients. The distribution of clinical characteristics, smoking history, pulmonary complications, and length of stay in categories of smoking cessation were compared using the x2 test, Fisher exact test, t test, or analysis of variance, as appropriate. The overall pulmonary complication and pneumonia rates were compared between nonsmokers and all smokers, and also among the categories of smokers. Continuous variables are presented as the mean ± SD and median (range), as some distributions were skewed. Multivariate analysis of the joint effects of prognostic factors was studied using stepwise logistic regression. All variables whose univariate tests resulted in a p value of < 0.2 were considered in the multivariate analysis model. Box-Cox transformations were applied to pack-years of cigarette smoking and length of hospital stay to reduce skewness. Imputation was employed for a small number of missing values. Two missing values of packs of cigarettes smoked per day were imputed by gender-adjusted median values to compute the total number of pack-years. Six missing percent predicted values for diffusing capacity of the lung for carbon monoxide (Dlco) were imputed from a linear regression on FEV1 percent predicted values. Fourteen missing Dlco and FEV1 percent predicted values were excluded from multivariant prognostic factor analysis for pulmonary complications. All test results with a p value of < 0.05 were considered to indicate statistical significance. A statistical software package (SAS, release 9.0; SAS Institute; Cary, NC) was used for all analyses.

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