As if the adverse effects of smoking weren’t terrible enough, new research proves that smokers and people exposed to secondhand smoke require more anesthesia and painkillers when undergoing operations in order to reach the same level of anesthesia as healthy non-smokers. Researchers have known that smoking increases the requirements for an anesthetic, but this is the first study to examine the effect of passive, or secondhand, smoke on anesthetic.

In the study, the authors examined 90 women who were having a total abdominal hysterectomy completed (which involves the removal of the uterus and cervix, often to treat cancer). The women were divided into three groups based on their level of exposure to smoke, which the researchers measured by serum cotinine — which is a metabolite of nicotine, and typically a marker of tobacco exposure. The first group were smokers, the second group were passive smokers, and the third group had never smoked and weren’t exposed to smoke.

The researchers then measured the effects of standard total intravenous anesthesia on the participants, measuring their level of consciousness and the total amount of anesthetic and painkiller used. They found that the smokers required anesthesia that was 38 percent more than the non-smokers, and 17 percent more than the passive smokers. The passive smokers, meanwhile, required 18 percent more anesthetic than the non-smoker group. When it came to the painkiller remifentanil that was administered to the patients, the smokers had 23 percent higher usage than the non-smokers.

“The amounts of anesthetic and painkiller required to ensure equal anesthetic depth in similar surgeries was higher in active smokers and passive smokers compared to non-smokers,” the authors concluded.

A 2000 study pointed to similar results. Researchers explained that tobacco smoke contains over 4,000 substances, most of which can cause cancer or be harmful in other ways, such as causing cardiovascular problems and increasing blood pressure. Cigarette smoke, in addition to messing with respiratory function while under anesthesia, interferes with drug metabolism. As a result, “Best is to stop smoking for at least eight weeks prior to surgery or, if not, at least 24 hours before surgery.”

Source: Ozturk E, et al. Euroanaesthesia meeting in Berlin. 2015.