High Pleural Pressure Prevents Alveolar Overdistension and Hemodynamic Collapse in Acute Respiratory Distress Syndrome with Class III Obesity. A Clinical Trial

Abstract

Rationale: Obesity is characterized by elevated pleural pressure (P PL) and worsening atelectasis during mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Objectives: To determine the effects of lung recruitment maneuver (LRM) in the presence of elevated P PL on hemodynamics, left and right ventricular pressures and pulmonary vascular resistance. We hypothesized that elevated P PL protects the cardiovascular system against high airway pressures and prevents lung overdistension. Methods: First, an interventional crossover trial in adult subjects with ARDS and BMI≥35 kg/m 2 (n=21) was performed to explore the hemodynamic consequences of LRM. Second, cardiovascular function was studied during low/high PEEPs in a model of swine with ARDS and high P PL (n=9) versus healthy swine with normal P PL (n=6). Measurements and Main Results: Subjects with ARDS and obesity (BMI=57±12 kg/m 2) following LRM, required an increase in PEEP of 8[7, 10] cmH 2 O above traditional ARDSnet settings to improve lung function, oxygenation and ventilation/perfusion matching, without impairment of hemodynamics or right heart function. ARDS swine with high P PL demonstrated unchanged transmural left ventricle pressure and systemic blood pressure after LRM protocol. Pulmonary artery hypertension decreased 8[13, 4] mmHg, as did vascular resistance 1.5[2.2, 0.9] WU, and transmural right ventricle pressure 10[15, 6] mmHg during exhalation. LRM and PEEP decreased pulmonary vascular resistance and normalized ventilation/perfusion ratio.

Mechanical Ventilation in the Obese Patient: Compliance, Pleural Pressure, and Driving Pressure

“…Accordingly, in this issue of the Journal , to evaluate the hemodynamic consequences of higher levels of airway pressure in obese patients with acute respiratory distress syndrome (ARDS), De Santis Santiago and colleagues (pp. 575–584 ) ( 3 ) performed clinical and animal studies to determine if higher positive end-expiratory pressure (PEEP) can improve gas exchange without compromising hemodynamics.…”

Individualized Multimodal Physiologic Approach to Mechanical Ventilation in Patients With Obesity and Severe Acute Respiratory Distress Syndrome Reduced Venovenous Extracorporeal Membrane Oxygenation Utilization

“…Hypotension and hemodynamic stability have been a major clinical concern when high airway pressures are applied. In a recent study, De Santis Santiago et al ( 32 ) showed that levels of airway pressure that oppose high pleural pressure are well-tolerated hemodynamically in patients with class III obesity and recruitable lungs.…”

A rational approach on the use of extracorporeal membrane oxygenation in severe hypoxemia: advanced technology is not a panacea

“…In this group, the high prevalence of complete airway closure (> 41%), can make driving pressures unreliable [ 104 ]. Furthermore, the hemodynamic tolerance to high PEEP was found remarkably good in class III obese patients (mean BMI = 57 kg/m 2 ) [ 105 ]. The technique is largely neglected in daily practice, likely due to technical challenges.…”