Respiratory and haemodynamic changes during decremental open lung positive end-expiratory pressure titration in patients with acute respiratory distress syndrome

Abstract

IntroductionTo investigate haemodynamic and respiratory changes during lung recruitment and decremental positive end-expiratory pressure (PEEP) titration for open lung ventilation in patients with acute respiratory distress syndrome (ARDS) a prospective, clinical trial was performed involving 12 adult patients with ARDS treated in the surgical intensive care unit in a university hospital.MethodsA software programme (Open Lung Tool™) incorporated into a standard ventilator controlled the recruitment (pressure-controlled ventilation with fixed PEEP at 20 cmH2O and increased driving pressures at 20, 25 and 30 cmH2O for two minutes each) and PEEP titration (PEEP lowered by 2 cmH2O every two minutes, with tidal volume set at 6 ml/kg). The open lung PEEP (OL-PEEP) was defined as the PEEP level yielding maximum dynamic respiratory compliance plus 2 cmH2O. Gas exchange, respiratory mechanics and central haemodynamics using the Pulse Contour Cardiac Output Monitor (PiCCO™), as well as transoesophageal echocardiography were measured at the following steps: at baseline (T0); during the final recruitment step with PEEP at 20 cmH2O and driving pressure at 30 cmH2O, (T20/30); at OL-PEEP, following another recruitment manoeuvre (TOLP).ResultsThe ratio of partial pressure of arterial oxygen (PaO2) to fraction of inspired oxygen (FiO2) increased from T0 to TOLP (120 ± 59 versus 146 ± 64 mmHg, P < 0.005), as did dynamic respiratory compliance (23 ± 5 versus 27 ± 6 ml/cmH2O, P < 0.005). At constant PEEP (14 ± 3 cmH2O) and tidal volumes, peak inspiratory pressure decreased (32 ± 3 versus 29 ± 3 cmH2O, P < 0.005), although partial pressure of arterial carbon dioxide (PaCO2) was unchanged (58 ± 22 versus 53 ± 18 mmHg). No significant decrease in mean arterial pressure, stroke volume or cardiac output occurred during the recruitment (T20/30). However, left ventricular end-diastolic area decreased at T20/30 due to a decrease in the left ventricular end-diastolic septal-lateral diameter, while right ventricular end-diastolic area increased. Right ventricular function, estimated by the right ventricular Tei-index, deteriorated during the recruitment manoeuvre, but improved at TOLP.ConclusionsA standardised open lung strategy increased oxygenation and improved respiratory system compliance. No major haemodynamic compromise was observed, although the increase in right ventricular Tei-index and right ventricular end-diastolic area and the decrease in left ventricular end-diastolic septal-lateral diameter during the recruitment suggested an increased right ventricular stress and strain. Right ventricular function was significantly improved at TOLP compared with T0, although left ventricular function was unchanged, indicating effective lung volume optimisation.

Thulium laser vaporesection versus standard transurethral resection of the prostate: A randomized trial with transpulmonary thermodilution hemodynamic monitoring

“…The PiCCO apparatus was set up for the intermittent transpulmonary thermodilution technique, which initially injected 20 mL of iced saline into the central venous catheter before the first set of measurements, and then repeated the injection three times to obtain the mean parameters. 11 Hemodynamic data were collected before and 1 h after the surgery.…”

“…11 The PiCCO was used to monitor the hemodynamic parameters and intravascular volume in all patients. Hemodynamic data were the primary outcome of the present study.…”

Decremental PEEP Titration: A Step Away From the Table

“…This is not a new approach to determining an optimal level of PEEP. [7][8][9][10][11][12] However, a quick look at the available evidence may leave clinicians questioning the usefulness of this method. In the provided Table of decremental PEEP studies there are noticeable differences in titration methods, monitored values, methods for prior recruitment, as well as what the "optimal" level of PEEP should be post procedure.…”

Recrutamento alveolar em pacientes no pós-operatório imediato de cirurgia cardíaca

“…PEEP provides higher alveolar stability after the recruitment. The ideal PEEP can be determined by the best gas exchange point, in other words, 2 cmH2O above the lower inflection point of pressure-volume curve of the respiratory system, observing the hemodynamic stability [10,20,26 Benefits Studies have shown that alveolar recruitment strategies can improve respiratory function in the postoperative period of cardiac surgery by reducing atelectasis and intrapulmonary shunt, improving ventilation-perfusion ratio and, consequently, arterial oxygenation [11,13,16].…”