Pulmonary artery perfusion versus no pulmonary per-fusion during cardiopulmonary bypass.

 During conventional cardiopulmonary bypass (CPB) there is no active perfusion of the pulmonary circulation and the mechanical ventilation is ceased leaving the lungs exposed to warm ischemia.   Pulmonary dysfunction is seen in varying degrees after major surgery, but more severe in cardiac surgery patients probably due to the effects of CPB. The evidence for effect and safety are limited, but active pulmonary artery perfusion during CPB could be beneficial for the patients' postoperative oxygenation. Our aim was in a randomised clinical trial to assess primarily the effect of pulmonary artery perfusion during CPB on postoperative oxygenation in patients diagnosed with chronic obstructive pulmonary disease (COPD), secondarily to assess other possible benefits and harms. Furthermore, we wanted in a systematic review with meta-analyses of all randomised clinical trials to investigate the pooled effects of pulmonary artery perfusion during CPB.  We planned and conducted a randomised, partly blinded, clinical trial assigning cardiac surgery patients diagnosed with COPD to receive pulmonary artery perfusion with oxygenated blood or histidine-tryptophan-ketoglutarate (HTK) solution compared to no pulmonary perfusion during CPB. The primary outcome was the oxygenation index measured during and after surgery. Secondary outcomes were intubation time, serious adverse events, days alive outside the intensive care unit and outside the hospital, 30- and 90-days mortality.  Secondly, we conducted a systematic review of randomised clinical trials comparing benefits and harms of using pulmonary artery perfusion versus no pulmonary perfusion during CPB pooling results in meta-analyses and trial sequential analyses (TSA).   Of the 90 randomised patients 89 were included in analysis of the primary outcome, the inverse oxygenation index, measured at a single time point 21 hours after CPB start and longitudinally 1, 3, 5, 7, and 21 hours after CPB start. At 21 hours, patients randomised to pulmonary artery perfusion with oxygenated blood had a higher inverse oxygenation index compared to patients randomised to no pulmonary perfusion during CPB (mean difference (MD) 0.94; 95% confidence interval (CI), 0.05 to 1.83; P=0.04). The inverse oxygenation index was also significantly higher at 21 hours after CPB start (MD 0.99; CI, 0.29 to 1.69; P=0.007), and longitudinally (P=0.009), for patients receiving pulmonary artery perfusion with oxygenated blood compared to pulmonary artery perfusion with HTK solution. This corresponds to a PaO