Individualized lung recruitment maneuver guided by pulse-oximetry in anesthetized patients undergoing laparoscopy: a feasibility study

BackgroundWe conducted this study to test whether pulse-oximetry hemoglobin saturation (SpO(2)) can personalize the implementation of an open-lung approach during laparoscopy. Thirty patients with SpO(2)97% on room-air before anesthesia were studied. After anesthesia and capnoperitoneum the FIO2 was reduced to 0.21. Those patients whose SpO(2) decreased below 97% - an indication of shunt related to atelectasis - completed the following phases: (1) First recruitment maneuver (RM), until reaching lungs opening pressure, defined as the inspiratory pressure level yielding a SpO(2) 97%; (2) decremental positive end-expiratory (PEEP) titration trial until reaching lungs closing pressure defined as the PEEP level yielding a SpO(2)<97%; (3) second RM and, (4) ongoing ventilation with PEEP adjusted above the detected closing pressure. ResultsWhen breathing air, in 24 of 30 patients SpO(2) was <97%, PaO2/FIO2?53.3kPa and negative end-expiratory transpulmonary pressure (PTP-EE). The mean (SD) opening pressures were found at 40 (5) and 33 (4)cmH(2)O during the first and second RM, respectively (P<0.001; 95% CI: 3.2-7.7). The closing pressure was found at 11 (5)cmH(2)O. This SpO(2)-guided approach increased PTP-EE (from -6.4 to 1.2cmH(2)O, P<0.001) and PaO2/FIO2 (from 30.3 to 58.1kPa, P<0.001) while decreased driving pressure (from 18 to 10cmH(2)O, P<0.001). SpO(2) discriminated the lung's opening and closing pressures with accuracy taking the reference parameter PTP-EE (area under the receiver-operating-curve of 0.89, 95% CI: 0.80-0.99). ConclusionThe non-invasive SpO(2) monitoring can help to individualize an open-lung approach, including all involved steps, from the identification of those patients who can benefit from recruitment, the identification of opening and closing pressures to the subsequent monitoring of an open-lung condition.