Anesthesia, Surgery and Long-Term Outcomes

nesthesiologists are recognized leaders in seeking ways to improve patient safety. To date most of our efforts have been focused on reducing the likelihood of adverse events in the immediate perioperative period. Over the last few years, several threads of information have been coalescing that suggest anesthesia and surgery may influence adverse outcomes occurring remote from the perioperative period (greater than 30 days) and which are not directly related to a specific complication of the surgery.

Long-term outcome following anesthesia and surgery was the subject of the Fall 2003 and Spring 2004 APSF Newsletters.^1,2 As detailed in these newsletter articles, there are a variety of reasons to think that mortality, and presumably morbidity, can be affected by perioperative events and that inflammation could be a key element in such occurrences. Furthermore, it is becoming increasingly recognized that specific genotypes may predict adverse perioperative outcomes.

APSF convened an experts workshop led by Anesthesia Patient Safety Foundation (APSF) Secretary David M. Gaba, M.D., to discuss issues related to long-term postoperative outcomes. Thirty experts representing anesthesiology, surgery, cardiology, epidemiology, immunology and administrative agencies attended this conference in Boston, Massachusetts, on September 21-22, 2004. (Participant names and a full report of the conference are available on the APSF Web site at <www.apsf.org>.)

It was proposed that the perioperative inflammatory/immune response may be a potential biological link to long-term outcomes after anesthesia and surgery. It is conceivable that the inflammatory response to surgery may amplify proinflammatory cell mechanisms of certain disease states, such as coronary artery disease, and hence contribute to disease acceleration and adverse postoperative events. Furthermore it was proposed that certain patients or patient populations may exhibit an exaggerated inflammatory response to surgery and/or delayed resolution to the preoperative immune status. If true these patients may be at even greater risk of experiencing postoperative complications. It is not well established whether anesthetic drugs, other aspects of anesthetic technique or physiologic occurrences during surgery could be potent triggers for abnormal inflammation.

In addition to risk factors presented by patients’ underlying disease and presence of hypotension and/or tachycardia, there was discussion of provocative but very preliminary data suggesting that depth of anesthesia as reflected by brain-wave monitoring was a predictor of long-term postoperative outcome. One suggestion was that depth of anesthesia was merely a marker for patients with a different (perhaps genetically determined) physiologic state manifesting as enhanced autonomic system activity. These individuals might be more likely to be treated with higher levels of hypnotics or volatile anesthetics based on clinical signs during anesthesia.

Interpretation of data on perioperative beta-blockers is complex and controversial. While there have been multiple randomized trials — and there is a consensus for beta-blockade (possibly also for clonidine) for patients with known cardiac disease having vascular surgery — it is still open to considerable debate whether or not this is beneficial for broader use. Nonetheless a number of these studies suggest that treatments only in the perioperative period (a few days to weeks) can have long-lasting effects.

Conclusions reached by the participants, which will serve as the bases for future analysis and action include:

1. Historically surgeons and anesthesiologists have largely felt that their actions only have immediate or near-term consequences. The participants felt it was distinctly possible that there are events occurring during surgery that have lasting effects and may have a long-term impact on how long you live.

2. There should be studies of large numbers of patients to better identify risk factors for the occurrence of adverse long-term outcomes as well as for short-term complications. It was suggested that the advent of anesthesia information management systems (AIMS) could make it easier to link intraoperative events to both short-term and long-term outcomes.

3. Inflammation has been implicated in many disease processes, and it is definitely possible that there exists a relationship between inflammation and the long-term outcomes associated with surgery and anesthesia. Studies are needed both on the basic biology of inflammation and on the specifics of this biology in the setting of anesthesia and surgery.

References:

1. Eger SE, Monk TG, Mayfield JB, Head CA. Can we alter long-term outcome? The role of anesthetic management and the inflammatory response. APSF Newsletter. Fall 2003.

2. Eger SE, Monk TG, Mayfield JB, Head CA. Can we alter long-term outcome? The role of inflammation and immunity in the perioperative period (Part II). APSF Newsletter. Spring 2004.

Robert K. Stoelting, M.D., Indianapolis, Indiana, is President of the Anesthesia Patient Safety Foundation.