Distribution of ventilation and oxygenation in surgical obese patients ventilated with high versus low positive end-expiratory pressure: A substudy of a randomised controlled trial

BACKGROUND Intra-operative ventilation using low/physiological tidal volume and positive end-expiratory pressure (PEEP) with periodic alveolar recruitment manoeuvres (ARMs) is recommended in obese surgery patients. OBJECTIVES To investigate the effects of PEEP levels and ARMs on ventilation distribution, oxygenation, haemodynamic parameters and cerebral oximetry. DESIGN A substudy of a randomised controlled trial. SETTING Tertiary medical centre in Geneva, Switzerland, between 2015 and 2018. PATIENTS One hundred and sixty-two patients with a BMI at least 35 kg per square metre undergoing elective open or laparoscopic surgery lasting at least 120 min. INTERVENTION Patients were randomised to PEEP of 4 cmH2O (n = 79) or PEEP of 12 cmH2O with hourly ARMs (n = 83). MAIN OUTCOME MEASURES The primary endpoint was the fraction of ventilation in the dependent lung as measured by electrical impedance tomography. Secondary endpoints were the oxygen saturation index (SaO2/FIO2 ratio), respiratory and haemodynamic parameters, and cerebral tissue oximetry. RESULTS Compared with low PEEP, high PEEP was associated with smaller intra-operative decreases in dependent lung ventilation [-11.2%; 95% confidence interval (CI) -8.7 to -13.7 vs. -13.9%; 95% CI -11.7 to -16.5; P = 0.029], oxygen saturation index (-49.6%; 95% CI -48.0 to -51.3 vs. -51.3%; 95% CI -49.6 to -53.1; P 
Source: European Journal of Anaesthesiology - Category: Anesthesiology Tags: Ventilation Source Type: research