Smoking has some immediate effects on the heart and lungs such as decreasing the amount of available oxygen, increasing the need for oxygen, narrowing the airways, and increasing the mucus in the airways. It can also cause spasms in blood vessels which can interrupt blood flow to vital areas like the brain and heart. These factors are never beneficial but they can be particularly harmful in people undergoing surgery that requires anesthesia. In fact, they are probably the reason that people who smoke are more likely to have complications after surgery than those who do not smoke.
Researchers wanted to know the specific effects on heart complications, lung complications, or death after surgery in people who were current smokers or those that had stopped smoking at least a year before. The study, published in JAMA, found that people who had smoked but quit for a year or more had a lower risk of surgical complications than those who were currently smoking.
The cohort study included 607,558 people undergoing major surgery in hospitals in the United States, Canada, Lebanon and United Arab Emirates. The patients were followed for 30 days after the surgery for the appearance of any vascular problems like heart attack and stroke, respiratory problems like pneumonia or need for ventilation, and death.
The study found that:
- Non-smokers had lowest risk of arterial and respiratory complications.
- Current smokers, compared nonsmokers and those that had quit for at least 1 year, had:
- Increased risk of vascular complications
- Increased risk of respiratory complications
- Increased risk of mortality
- Patients that had quit smoking for at least 1 year had
- Lower risk of vascular and respiratory complications compared to current smokers
- Higher risk of vascular and respiratory complications compared to nonsmokers
- Lower risk of death than current smokers
- No greater risk of death than nonsmokers
- Higher rates and longer time smoking was associated with increased risk of vascular and respiratory complications
The study also separated patients in to those that had current heart disease, chronic obstructive pulmonary disease, and cancer and those that did not. The increased risk with smoking was consistent whether these diseases were present or not.
The study is a cohort study which is an observational study. This means researchers find similar patients, collect information, and observe the outcomes, they do not try to control the involved factors. As a results, observational studies can not determine a cause and effect, instead they indicate a potential relationship between two factors. Risk factors for smoking have been well studied and it is reasonable to see a link between post operative heart and lung complications and smoking. This study supports this connection and reports that even smokers without current pulmonary or heart disease were at higher risk.
The good news is that those who quit smoking were able to reduce their risk of complications. If you are a current smoker and are planning to have major surgery, talk to your surgical team about your options. The length of time to your surgery and how long you have been smoking may play a role in your team's recommendations.
Musallam K, Rosendaal F, et al. Smoking and the Risk of Mortality and Vascular and Respiratory Events in Patients Undergoing Major Surgery. JAMA Surg. 2013;():1-8.
Last reviewed August 2013 by Michael Woods, MD
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