Does diathermy smoke contaminate processed salvaged blood in cardiac surgery?

A cell salvage device is used in cardiac surgery with the aim of reducing allogeneic blood transfusion. Suction of blood from the operating field used for the device is often accompanied by diathermy smoke. There is limited published research to know if this blood is then contaminated with clinically significant levels of harmful chemicals from this smoke. Postoperative cardiac surgery patients are already physiologically vulnerable, making the optimization of salvaged blood worth considering.

Ten patients who had cardiac surgery using a cell salvage device from a single institution had samples taken from the processed blood just prior to transfusion. Samples were tested for carbon monoxide (CO), cyanide and benzene. Results were compared to preoperative co-oximetry results and normal adult laboratory reference ranges. Demographic data about the patients was collected, including the type of operation, gender, age, body mass index, smoking status and amount of salvaged blood collected and processed.

Primary surgery was coronary artery bypass grafting (CABG) in three patients, mitral valve repair or replacement in three patients and one each of aortic valve replacement (AVR)/CABG, AVR/plication of the aorta, CABG/external wrapping of the aorta and valve-sparing root replacement. None were smokers. Neither the blood CO level prior to surgery nor in the processed salvaged blood was above the normal limit of 2% for non-smokers. There was no processed blood benzene found. Cyanide levels in the processed blood ranged from 1.8 to 44.1 μmol/l (where <8 μmol/l is considered within the normal adult laboratory limit).

Despite the obvious limitations of the current study, it shows that cyanide levels can be found many times the normal level in processed salvaged blood. Whilst the total dose of cyanide is small, the potential impact may be clinically significant due to cyanide's effect on mitochondrial metabolism in the heart and brain.