Anesthesia Alert: How Does Wildfire Smoke Impact Anesthesia?

New research ignites discussion about protocols for high-risk patients.

Should anesthesia providers in areas where wildfires are burning change their practices to account for the possible effects of extremely poor air quality on their patients?

That question and many others are being asked in the wake of an article published last month in the Online First edition of Anesthesiology, the peer-reviewed journal of the American Society of Anesthesiologists (ASA).

Senior Author Vijay Krishnamoorthy, MD, MPH, PhD, chief of the Critical Care Medicine Division and associate professor of anesthesiology and population health sciences at Duke University School of Medicine in Durham, N.C., says exposure to wildfire smoke can damage the heart, lungs and other organs, and lead to potentially worsening outcomes for patients undergoing anesthesia and surgery.

Spreading like wildfire

According to ASA, nearly 100 wildfires were raging in August, burning more than two million acres across the U.S., and recent data suggests the number of wildfires will grow by 30% by 2050.

Dr. Krishnamoorthy and his colleagues recognize an increasingly urgent need to determine exactly how exposure to wildfire smoke negatively affects patients undergoing anesthesia and surgery and their ultimate outcomes. Just as importantly, they believe guidance should be developed on how providers can best manage such patients perioperatively.

They report that wildfire smoke exposure can exacerbate some patients’ existing comorbidities and chronic diseases. It poses significant risks to those with preexisting heart and lung disease, obese patients, infants and young children, the elderly and other vulnerable groups. It is known to cause inflammation, worsen heart and lung disease, and impact pregnancy outcomes.

Anyone familiar with the harm surgical smoke exposure can cause will immediately recognize the toxic nature of wildfire smoke, which contains a mix of fine particles and chemicals that produce inflammation and oxidative stress. Researchers say exposure is proven to impact patients with cardiovascular disease, possibly contributing to heart attack, heart rhythm abnormalities, heart failure or stroke.

The ‘known knowns’ of wildfire smoke exposure

“What’s currently known is that the increase in wildfires is slowly but surely occurring across the world,” says Dr. Krishnamoorthy. “We also know for sure that certain patients are vulnerable to worse outcomes during periods of high wildfire smoke — the very elderly, the very young, the pregnant population and patients with a significant chronic disease, particularly cardiopulmonary disease. We know that, among those patients, and in these settings, we have certainly observed greater exacerbations of stroke, cardiac disease, pulmonary disease and pregnancy outcomes.”

What’s unknown right now is how anesthesia providers and the surgical centers where they work should handle high-risk patients in the midst of, or in the wake of, a wildfire in their area. Just what clinical steps to avoid adverse outcomes should anesthesia providers take with their patients and protocols in response to a wildfire that is impacting (or has recently impacted) their area? The answer is that, right now, we just don’t know, says Dr. Krishnamoorthy. Little is known about the relationship between wildfire smoke exposure, anesthesia and surgery.

“More research is needed to guide what specific operational changes need to take place,” says Krishnamoorthy. “Not only to increase awareness about the impacts of wildfire smoke on acute illness, but also to hopefully contribute to setting a research agenda for this topic that I hope will inform more robust guidelines to truly guide patient care.”

Dr. Krishnamoorthy’s research group is doing its part to fill those gaps through a mathematical model they are developing that aims to link geographic smoke exposure data to databases that include surgical outcomes. The team hopes that this and other lines of research will help providers develop guidelines for assessing and managing patient risks.

“While I think the perioperative community definitely appreciates the impact of climate change on society, I think understanding the specific impacts on perioperative care is less appreciated,” says Dr. Krishnamoorthy. “That was one of the big goals of the paper, just to put this on the radar.” For now, Dr. Krishnamoorthy and others in the industry are making their best educated guesses on how to better ensure patient safety during times of wildfire. “At this point, we want to make sure the patient is not having an exacerbation of any of their chronic disease during a period of high wildfire smoke,” he says. “Additionally, we would potentially want to consider closer monitoring of these patients in the perioperative setting.”

Dr. Krishnamoorthy believes that most patients should be able to safely undergo most elective surgeries during times of wildfire. “I think the groups we should be thinking about are the very vulnerable patient population groups, especially in areas of very high wildfire exposure,” he says.

In practice

Michael A. MacKinnon, DNP, FNP-C, CRNA, owner of MacKinnon Anesthesia in Show Low, Ariz., says he has seen wildfire smoke exposure cause major respiratory issues in already compromised patients. Once, he and his colleagues evacuated patients from a hospital due to a wildfire in the area. Another time, his facility was placed on “get set” status as it began “snowing” ash outside.

“Currently, we do not have any specific protocols in place solely for addressing the impacts of wildfire smoke inhalation in the perioperative setting,” he says. “However, during wildfire season when air quality is particularly poor, we elevate our clinical awareness regarding patients with certain respiratory conditions that are especially vulnerable to exacerbation from smoke inhalation.”

Dr. MacKinnon says that while chronic obstructive pulmonary disease and asthma are the more commonly recognized conditions to consider, diseases such as interstitial lung disease, bronchiectasis, pulmonary fibrosis and certain forms of restrictive lung disease can also be significantly impacted by wildfire smoke exposure. Patients with cardiovascular comorbidities such as congestive heart failure or ischemic heart disease can experience worsened symptoms due to the systemic inflammatory response triggered by inhaled particulate matter, he adds. “Though there isn’t a formal policy, we take a more cautious approach in evaluating patients with these conditions during fire season,” he says.

That cautious approach entails heightened vigilance during pre-op assessments, with careful attention to recent exacerbations, changes in medication usage or new symptoms that could indicate impaired respiratory function.

“For patients with these at-risk conditions, we might consider additional pulmonary function tests or chest imaging depending on the severity of their symptoms and overall risk profile,” says Dr. MacKinnon. “Intraoperatively, we remain mindful of the potential for increased airway reactivity and the need for meticulous management of ventilation.”

Dr. MacKinnon fully agrees with Dr. Krishnamoorthy that further research is needed. “It could lead to better-defined protocols, evidence-based guidelines and, ultimately, improved patient outcomes. The clinical experiences of those of us on the front lines certainly suggest that further investigation is needed,” he says. OSM