Slow Positive End-Expiratory Pressure Titration During General Anesthesia with Muscle Paralysis Improves Lung Function Without Compromising Hemodynamic Stability in Preschool Children: A Randomized Control Clinical Trial

Background: Mechanical ventilation impairs oxygenation and increases intrapulmonary shunt. Positive end-expiratory pressure (PEEP) slows derecruitment, improves lung function but can compromise hemodynamics. Objectives: To asses slow PEEP titration effect on intrapulmonary shunt, oxygenation and hemodynamics in preschool children on mechanical ventilation under general anesthesia. Methods: This was a single tertiary care center an open-label, randomized parallel group controlled clinical trial. Study included 70 children, 3 - 7 years, ASA I and II, under general anesthesia for non-cardiothoracic surgery. Children were randomly allocated either to receive PEEP titration 5 - 11 cmH2O 20 minutes before the end of anesthesia (intervention group) or to be ventilated until the end of anesthesia with constant positive end-expiratory pressure of 3 cmH2O (control group). Main outcome measures were changes in oxygenation index (PaO2/FiO2) and alveolar-arterial gradient (P(A-a)O2) between and within groups and changes in systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) in interventional group during PEEP trial. Results: Seventy children were recruited and analyzed. P(A-a)O2 and PaO2/FiO2 improved in interventional group comparing to control as consequence of PEEP titration (PaO2/FiO2 -30.3 vs. 0.52; P < 0.001;P(A-a)O2 6.7 vs. -1.0; P < 0.001) and within interventional group before and after PEEP titration (PaO2/FiO2 522.0 vs. 552.3; P < 0.01; P(A-a)O2 20.1 vs. 13.3; P < 0.001). Hypotension and bradycardia were not documented. Conclusions: Slow PEEP titration up to 11 cmH2O improves oxygenation, reduces intrapulmonary shunt without causing hemodynamic instability in preschool children during general anesthesia.