• Savino Spadaro, Salvatore Grasso, Dan Stieper Karbing, Alberto Fogagnolo, Marco Contoli, Giacomo Bollini, Riccardo Ragazzi, Gilda Cinnella, Marco Verri, Narciso Giorgio Cavallesco, Stephen Edward Rees, and Carlo Alberto Volta.
• From the Department of Morphology, Surgery and Experimental Medicine, Intensive Care Unit, Sant'Anna Hospital, Ferrara, Italy (S.S., A.F., G.B., R.R., M.V., N.G.C., C.A.V.); Department of Emergency and Organ Transplant, Aldo Moro University of Bari, Bari, Italy (S.G.); Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark (D.S.K., S.E.R.); Research Centre on Asthma and Chronic Obstructive Pulmonary Disease, Department of Medical Sciences, University of Ferrara, Ferrara, Italy (M.C.); and Department of Anesthesia and Intensive care, University of Foggia, Foggia, Italy (G.C.).
• Anesthesiology. 2018 Mar 1; 128 (3): 531-538.

BackgroundArterial oxygenation is often impaired during one-lung ventilation, due to both pulmonary shunt and atelectasis. The use of low tidal volume (VT) (5 ml/kg predicted body weight) in the context of a lung-protective approach exacerbates atelectasis. This study sought to determine the combined physiologic effects of positive end-expiratory pressure and low VT during one-lung ventilation.MethodsData from 41 patients studied during general anesthesia for thoracic surgery were collected and analyzed. Shunt fraction, high V/Q and respiratory mechanics were measured at positive end-expiratory pressure 0 cm H2O during bilateral lung ventilation and one-lung ventilation and, subsequently, during one-lung ventilation at 5 or 10 cm H2O of positive end-expiratory pressure. Shunt fraction and high V/Q were measured using variation of inspired oxygen fraction and measurement of respiratory gas concentration and arterial blood gas. The level of positive end-expiratory pressure was applied in random order and maintained for 15 min before measurements.ResultsDuring one-lung ventilation, increasing positive end-expiratory pressure from 0 cm H2O to 5 cm H2O and 10 cm H2O resulted in a shunt fraction decrease of 5% (0 to 11) and 11% (5 to 16), respectively (P < 0.001). The PaO2/FIO2 ratio increased significantly only at a positive end-expiratory pressure of 10 cm H2O (P < 0.001). Driving pressure decreased from 16 ± 3 cm H2O at a positive end-expiratory pressure of 0 cm H2O to 12 ± 3 cm H2O at a positive end-expiratory pressure of 10 cm H2O (P < 0.001). The high V/Q ratio did not change.ConclusionsDuring low VT one-lung ventilation, high positive end-expiratory pressure levels improve pulmonary function without increasing high V/Q and reduce driving pressure.

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