Normothermic perfusion and lung function after cardiopulmonary bypass: effects in pulmonary risk patients

Abstract

Fifty patients at risk for postoperative lung dysfunction and undergoing elective coronary revascularization have been randomly assigned to receive normothermic (36°C) perfusion with warm heart protection (NP group) or hypothermic (28°C) perfusion with cold heart protection (HP group). Lung function before and after cardiopulmonary bypass (CPB) was studied through the determination of the intrapulmonary shunt ( Qs/ Qt), the alveolo-arterial oxygen gradient (A-aΔO₂), and the artero-alveolar carbon dioxide gradient (a-AΔCO₂). The Q _s /Q _t after CPB was significantly lower in the NP group (27.1 ± 2.6 vs 35.7 ± 2.3) as well as the A-aΔO₂ (50.2 ± 1.5 vs 57.6 ±2.4); both data returned to comparable between the groups after 3 h in the intensive care unit. The a-AΔCO₂ was significantly lower after CPB in the NP group (5.2 ± 0.74 vs 8.2 ± 0.8). Hospital stay and mortality were comparable in the two groups; intubation time and rate of early extubation showed a trend in favour of the NP group; the rate of patients suffering hypoxia and/or hypercapnia after extubation was significantly lower in the NP group (12%) versus the HP group (44%). Normothermia seems to exert a protective effect against lung dysfunction after CPB. The absence of a rewarming injury associated with reperfusion, a limitation of the hypothermic-induced vasoconstriction due to local cooling of the lung and a better compliance of the normothermic lung are hypothesized as beneficial effects of the ‘all-warm’ strategy.