Modification of Respiratory Drive and Lung Stress by Level of Support Pressure and ECMO Sweep Gas Flow in Patients With Severe COVID-19-Associated Acute Respiratory Distress Syndrome: an Exploratory Retrospective Analysis.

OBJECTIVES

Patients with severe acute respiratory distress syndrome (ARDS) often exhibit an unusually strong respiratory drive, which predisposes them to effort-induced lung injury. Careful titration of support pressure via the ventilator and carbon dioxide removal via extracorporeal membrane oxygenation (ECMO) may attenuate respiratory drive and lung stress.

DESIGN

A retrospective cohort study.

SETTING

At a single center, a university hospital.

PARTICIPANTS

Ten patients with severe COVID-19-associated ARDS (CARDS) on venovenous ECMO therapy.

INTERVENTIONS

Assessment of the effect of titrated support pressure and titrated ECMO sweep gas flow on respiratory drive and lung stress in spontaneously breathing patients during ECMO therapy.

MEASUREMENTS AND MAIN RESULTS

Airway occlusion pressure (P) and the total swing of the transpulmonary pressure were determined as surrogate parameters of respiratory drive and lung stress. Ventilator-mediated elevation of support pressure decreased P but increased transpulmonary driving pressure, airway pressure, tidal volume, and end-inspiratory transpulmonary occlusion pressure. The increase in ECMO sweep gas flow lowered P, transpulmonary pressures, tidal volume, and respiratory frequency linearly.

CONCLUSIONS

In patients with CARDS on pressure support ventilation, even moderate support pressure may lead to overassistance during assisted ventilation, which is only reflected by advanced monitoring of respiratory mechanics. Modifying carbon dioxide removal via the extracorporeal system profoundly affects respiratory effort and mechanics. Spontaneously breathing patients with CARDS may benefit from consequent carbon dioxide removal.