A study conducted at the University Medical Centre Freiburg, Germany, has shown that small amounts of carbon monoxide (CO) could reduce lung inflammation. The discovery was made while researchers sought a new drug therapy for patients who may experience life-threatening lung injury during cardiopulmonary bypass surgery (CPB).

Approximately 2% of cardiac surgery patients suffer from life-threatening lung injuries during surgery. This might sound low, but the mortality rate for these same patients exceeds 60%.

“Cardiac surgery is one of the most extreme situations a patient can face,” says Torsten Loop, MD, “although a heart-lung machine ensures that organs are supplied with blood—and therefore oxygen—the nature of heart surgery means that normal operation of the lungs is impaired, potentially resulting in lung injury.”

While large doses of CO limit the ability of the blood to carry oxygen, this study shows that low doses can protect against tissue injury.

“Our findings support that inhaled CO provides anti-inflammatory effects in the lungs and decreases the instance of cell death during CPB,” says Loop. “Of greater importance, these effects occurred when CO was administered as a pretreatment with the advantage of short exposure time, which limits how avidly CO can bind to hemoglobin.”

The study used low doses of inhaled CO in pig models while employing beating-heart CPB. Human studies examining the effectiveness of CO on organ function have not yet been conducted, but, these findings could help push researchers in that direction.

The study is featured in this month’s issue of Anesthesiology.