Respiratory mechanics and mechanical power during low vs. high positive end-expiratory pressure in obese surgical patients - A sub-study of the PROBESE randomized controlled trial.
Scharffenberg M., Mandelli M., Bluth T., Simonassi F., Wittenstein J., Teichmann R., Birr K., Kiss T., Ball L., Pelosi P., Schultz MJ., Gama de Abreu M., Huhle R., PROBESE-investigators None., Protective Ventilation Network None., Clinical Trials Network of the European Society of Anaesthesiology and Intensive Care None.
Study objectiveWe aimed to characterize intra-operative mechanical ventilation with low or high positive end-expiratory pressure (PEEP) and recruitment manoeuvres (RM) regarding intra-tidal recruitment/derecruitment and overdistension using non-linear respiratory mechanics, and mechanical power in obese surgical patients enrolled in the PROBESE trial.DesignProspective, two-centre substudy of the international, multicentre, two-arm, randomized-controlled PROBESE trial.SettingOperating rooms of two European University Hospitals.PatientsForty-eight adult obese patients undergoing abdominal surgery.InterventionsIntra-operative protective ventilation with either PEEP of 12 cmH2O and repeated RM (HighPEEP+RM) or 4 cmH2O without RM (LowPEEP).MeasurementsThe index of intra-tidal recruitment/de-recruitment and overdistension (%E2) as well as airway pressure, tidal volume (VT), respiratory rate (RR), resistance, elastance, and mechanical power (MP) were calculated from respiratory signals recorded after anesthesia induction, 1 h thereafter, and end of surgery (EOS).Main resultsTwenty-four patients were analyzed in each group. PEEP was higher (mean ± SD, 11.7 ± 0.4 vs. 3.7 ± 0.6 cmH2O, P 2O, P T and RR did not differ significantly (7.3 ± 0.6 vs. 7.4 ± 0.8 ml∙kg-1, P = 0.835; and 14.6 ± 2.5 vs. 15.7 ± 2.0 min-1, P = 0.150, respectively). %E2 was higher in HighPEEP+RM than in LowPEEP following induction (-3.1 ± 7.2 vs. -12.4 ± 10.2%; P 2O∙l∙s-2, P = 0.009; and 15.7 ± 5.5 vs. 28.5 ± 8.4 cmH2O∙l, P -1, P ConclusionsIn this sub-cohort of PROBESE, intra-operative ventilation with high PEEP and RM reduced intra-tidal recruitment/de-recruitment as well as driving pressure, elastance, resistance, and mechanical power, as compared with low PEEP.Trial registrationThe PROBESE study was registered at www.Clinicaltrialsgov, identifier: NCT02148692 (submission for registration on May 23, 2014).