Physiological effects of a lung-recruiting strategy applied during one-lung ventilation.

Background: One-lung ventilation (OLV) affects respiratory mechanics and ventilation/perfusion matching, reducing functional residual capacity of the ventilated lung. While the application of a lung-recruiting manoeuvre (RM) on the ventilated lung has been shown to improve oxygenation, data regarding the impact of RM on respiratory mechanics are not available. Methods: Thirteen patients undergoing lung resection in lateral decubitus were studied. During OLV, a lungrecruiting strategy consisting in a RM lasting 1min followed by the application of positive end-expiratory pressure 5 cmH2O was applied to the ventilated lung. Haemodynamics, gas exchange and respiratory mechanics parameters were recorded on two-lung ventilation (TLVbaseline), OLV before and 20 min after the RM (OLVpre-RM, OLVpost-RM, respectively) and TLVend. Haemodynamics parameters were also recorded during the RM. Results: The PaO2/FiO2 ratio was 358 126 on TLVbaseline; it decreased to 235 113 on OLVpre-RM (Po0.01) increased to 351 120 on OLVpost-RM (Po0.01 vs. OLVpre-RM), and remain stable thereafter. During the RM, CI decreased from 3.04 0.7 l/m2 OLVpre-RM to 2.4 0.6 l/m2 (Po0.05), and returned to baseline on OLVpost-RM (3.1 0.7 l/m2, NS vs. OLVpre-RM). The RM resulted in alveolar recruitment and caused a significant decrease in static elastance of the dependent lung (16.6 8.9 cmH2O/ml OLVpost-RM vs. 22.3 8.1 cmH2O/ ml OLVpre-RM) (Po0.01). Conclusions: During OLV in lateral decubitus for thoracic surgery, application to the dependent lung a recruiting strategy significantly recruits the dependent lung, improving arterial oxygenation and respiratory mechanics until the end of surgery. However, the transient haemodynamic derangement occurring during the RM should be taken into account.