The effect of leucodepletion on leucocyte activation, pulmonary inflammation and respiratory index in surgery for coronary revascularisation: a prospective randomised study

Leucocyte activation is central to end-organ damage that occurs during cardiac surgery under cardiopulmonary bypass (CPB). Exhaled nitric oxide (NO) increases in inflammatory lung conditions and has been proposed as a marker of pulmonary inflammation during CPB. This study examined the effect of leucodepletion on leucocyte activation, pulmonary inflammation and oxygenation in patients undergoing coronary revascularisation. Fifty low-risk patients undergoing first time coronary artery bypass graft (CABG) were randomised to two groups. Twenty-five patients had an arterial line leucocyte-depleting filter and 25 controls had a standard filter. Arterial blood samples were taken before CPB, 5 and 30 min on CPB, 5 min after aortic clamp removal and 6 h post-operatively. Activated leucocytes were identified with Nitroblue Tetrazolium staining. NO was sampled via an endotracheal teflon tube 15 min after median sternotomy before CPB and 30 min after discontinuation of CPB using a real-time chemiluminescense analyser. Respiratory index (alveolar-arterial oxygenation index, AaOI) was calculated before CPB, 1, 2, 4, 8 and 18 h post-operatively. Clinical outcome end-points were also recorded. Results: Total and activated leucocyte counts were significantly lower following leucodepletion during CPB (P