Corrected Proof Iran J Pediatr. 2016 December; 26(6):e92269. Published online 2019 November 19. doi: 10.5812/ijp.92269. Research Article 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 Ana Dragoljub Mandras 1, * , Ivan Soldatovic 2 , Maja Sujica 1 , Vesna Stevanovic 1 , Dejan Markovic 3 , Zoran Paunovic 4 and Predrag Minic 5 1 Department of Anesthesiology and Intensive Care Therapy, Institute for Mother and Child Health Care, Belgrade, Serbia 2 Institute for Medical Statistics and Informatics, Medical Faculty University of Belgrade, Belgrade, Serbia 3 Department of Anesthesiology, Clinic for Cardiovascular Surgery, Clinical Center of Serbia, Belgrade, Serbia 4 Department of Orthopedics, Institute for Mother and Child Health Care, Belgrade, Serbia 5 Depratment of Pulmonolgy, Institute for Mother and Child Health Care, Belgrade, Serbia * Corresponding author: Department of Anesthesiology and Intensive Care Therapy, Institute for Mother and Child Health Care, Laze jovanovica Porcija 1/2, 11080 Zemun, Belgrade, Serbia. Tel: +381-642549637, Email: ana_mandras@yahoo.com Received 2019 April 14; Revised 2019 September 22; Accepted 2019 October 08. Abstract 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 cmH2 O 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 cmH2 O (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 (ΔPaO2 /FiO2 -30.3 vs. 0.52; P < 0.001; ΔP(A-a)O2 6.7 vs. -1.0; P < 0.001) and within interven- tional 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 cmH2 O improves oxygenation, reduces intrapulmonary shunt without causing hemody- namic instability in preschool children during general anesthesia. Keywords: Oxygenation, Intrapulmonary Shunt, Hypotension, Positive End-Expiratory Pressure 1. Background Mechanical ventilation promotes alveolar derecruit- ment, atelectasis and increases physiological intrapul- monary shunt (1, 2). This can lead to impaired oxygen ex- change. Positive end-expiratory pressure (PEEP) is used to counteract alveolar derecruitment and improve oxygen exchange. Literature data from human and animal stud- ies show overall positive effect of PEEP on lung function (3-7). On the other hand, PEEP exerts negative hemody- namic effects. As distending pressure PEEP increases in- trathoracic pressure, decreases venous return and cardiac output in normovolemic and hypovolemic patients (8). De- pending on speed of titration and PEEP level these effects can be more or less clinically apparent (4, 7, 9). Slow PEEP titration up to 20 cmH 2 O during 15 minutes achieved re- cruitment, improved gas exchange and decreased intra- pulmonary shunt without circulatory depression (4, 7). Copyright © 2019, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.