MIAMI BEACH – What do the timing of smoking cessation prior to surgery, reliable prediction of postoperative respiratory failure, and biomarkers that point to elevated postoperative myocardial infarction risk have in common? They emerged as some of the most prominent findings published in the past year, according to three experts in hospital medicine.
Dr. Gerald W. Smetana, Dr. Steven L. Cohn, and Dr. Paul J. Grant each selected studies of particular relevance to hospitalists and explained why during a panel presentation at a meeting on perioperative medicine sponsored by the University of Miami:
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• Preoperative Smoking Cessation. When a patient stops smoking up to 8 weeks before noncardiac surgery, it does not significantly change the total or pulmonary complication rates, according to a systematic literature review (Arch. Intern. Med. 2011;171:983-9).
"Many patients who quit smoking report they feel worse before they feel better," said Dr. Smetana, an attending in the general medicine division at Beth Israel Deaconess Medical Center, Boston.
Increased cough and sputum production are common right after quitting, he said. "This could be a plausible mechanism to explain why recent quitters might be at increased risk for postoperative pulmonary complications."
However, there was no statistically significant difference in total complications (relative risk of 0.78 for recent quitters, compared with a reference value of 1.0 for current smokers) in the nine eligible studies with 889 participants. Five of the trials assessed pulmonary complications, and found that recent quitters had a nonsignificant increased risk (RR, 1.18) compared with patients who continued to smoke.
Until there is consensus based on large randomized trials, stopping smoking before surgery can be considered safe, said Dr. Smetana, who is also on the medicine faculty at Harvard Medical School. In addition, longer periods of cessation are likely better than shorter ones. He added that despite the lack of a significant finding, it is still worthwhile to counsel patients because any time before surgery is a still a teachable moment for smoking cessation.
• Predicting Postoperative Pulmonary Failure. Type of procedure, emergency surgery, poor dependent functional status, sepsis, and higher American Society of Anesthesiologists classification were the five independent preoperative factors that significantly predicted postoperative respiratory failure in a multicenter database study (Chest 2011;140:1207-15).
The study included 211,410 participants undergoing all types of surgery. Mortality was 26% among those with postoperative respiratory failure, compared with 1% for unaffected patients. "This shows how important pulmonary complications can be," Dr. Smetana said.
Dr. Gerald W. Smetana
The researchers incorporated these five predictors into a surgical risk calculator that is downloadable for free.
Dr. Smetana said, "It is a nice tool that ... helps to stratify patients. It makes a difference in identifying which patients for which you will pull out all the stops."
• Preoperative Peptide Gauges Risk. Although multiple researchers have looked at preoperative B-type natriuretic peptide (BNP) as a predictor of postoperative cardiac events or death, there remain "a lot of unknowns for BNP at this point," said Dr. Cohn, director of the University of Miami Hospital Medical Consultation Service and professor of medicine at the University of Miami.
A recent meta-analysis may shed some light on the predictive value of BNP (J. Am. Coll. Cardiol. 2011;58:522-9). Investigators assessed five BNP studies with 632 patients to determine cutoff values for screening (high sensitivity) and diagnosis (high specificity), and an optimal value that combines both.
The researchers found that patients with BNP above the optimal cutoff point of 116 pg/mL had a significantly elevated risk for the composite outcome of nonfatal myocardial infarction or cardiovascular death (unadjusted odds ratio, 7.36). Compared with use of the Revised Cardiac Risk Index, the optimal BNP cutoff classification improved risk prediction by 58%. This means some patients moved to a more accurate ranking among the low-, intermediate- and high-risk categories, Dr. Cohn said.
• Troponin and Postoperative MI Risk. Myocardial infarction is the most common major, perioperative vascular complication, so investigators continue to search for an accurate way to identify high-risk patients. Some propose elevated serum levels of the protein troponin as a predictor, Dr. Cohn said, but the question remains: Would it change patient management and improve outcomes?
Researchers found that increased troponin after noncardiac surgery did in fact independently predict postoperative MI mortality in a meta-analysis (Anesthesiology 2011;114:796-806).
Elevated levels significantly predicted increased risk in the 14 studies with 3,318 patients overall (OR, 3.4). However, prediction within the first year was higher (OR, 6.7) compared with studies that measured troponin more than 12 months out (OR, 1.8).