Multimodal non-invasive monitoring to apply an open lung approach strategy in morbidly obese patients during bariatric surgery

To evaluate the use of non-invasive variables for monitoring an open-lung approach (OLA) strategy in bariatric surgery. Twelve morbidly obese patients undergoing bariatric surgery received a baseline protective ventilation with 8 cmH2O of positive-end expiratory pressure (PEEP). Then, the OLA strategy was applied consisting in lung recruitment followed by a decremental PEEP trial, from 20 to 8 cmH2O, in steps of 2 cmH2O to find the lung’s closing pressure. Baseline ventilation was then resumed setting open lung PEEP (OL-PEEP) at 2 cmH2O above this pressure. The multimodal non-invasive variables used for monitoring OLA consisted in pulse oximetry (SpO2), respiratory compliance (Crs), end-expiratory lung volume measured by a capnodynamic method (EELVCO2), and esophageal manometry. OL-PEEP was detected at 15.9 ± 1.7 cmH2O corresponding to a positive end-expiratory transpulmonary pressure (PL,ee) of 0.9 ± 1.1 cmH2O. ROC analysis showed that SpO2 was more accurate (AUC 0.92, IC95% 0.87–0.97) than Crs (AUC 0.76, IC95% 0.87–0.97) and EELVCO2 (AUC 0.73, IC95% 0.64–0.82) to detect the lung’s closing pressure according to the change of PL,ee from positive to negative values. Compared to baseline ventilation with 8 cmH2O of PEEP, OLA increased EELVCO2 (1309 ± 517 vs. 2177 ± 679 mL) and decreased driving pressure (18.3 ± 2.2 vs. 10.1 ± 1.7 cmH2O), estimated shunt (17.7 ± 3.4 vs. 4.2 ± 1.4%), lung strain (0.39 ± 0.07 vs. 0.22 ± 0.06) and lung elastance (28.4 ± 5.8 vs. 15.3 ± 4.3 cmH2O/L), respectively; all p < 0.0001. The OLA strategy can be monitored using noninvasive variables during bariatric surgery. This strategy decreased lung strain, elastance and driving pressure compared with standard protective ventilatory settings.Fil: Tusman, Gerardo. Fundación Medica de Mar del Plata. Hospital Privado de Comunidad; ArgentinaFil: Acosta, Cecilia Maria. Fundación Medica de Mar del Plata. Hospital Privado de Comunidad; ArgentinaFil: Ochoa, Marcos Raúl. Fundación Medica de Mar del Plata. Hospital Privado de Comunidad; ArgentinaFil: Böhm, Stephan H.. Universität Rostock; AlemaniaFil: Gogniat, Emiliano. Sociedad Argentina de Cuidados Intensivos; ArgentinaFil: Martinez Arca, Jorge. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Eléctrica. Laboratorio de Bioingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Scandurra, Adriana Gabriela. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Eléctrica. Laboratorio de Bioingeniería; ArgentinaFil: Madorno, Matías. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Ferrando, Carlos. Hospital Clínico Barcelona; EspañaFil: Suarez Sipmann, Fernando. Universidad Autonoma de Madrid. Hospital Universitario de la Princesa; España. Centro de Investigación Biomédica en Red de Enfermedades Respiratorias; España. Uppsala Universitet; Sueci