Novel method of transpulmonary pressure measurement with an air-filled esophageal catheter

Abstract

\n Background\n\nThere is a strong rationale for proposing transpulmonary pressure-guided protective ventilation in acute respiratory distress syndrome (ARDS). The reference esophageal balloon catheter method requires complex in vivo calibration and dedicated ventilator with auxiliary pressure port. A simple, inexpensive, accurate and reproducible method of measuring esophageal pressure would greatly facilitate the measure of transpulmonary pressure to individualize protective ventilation in the intensive care unit.\nResults\n\nWe propose an air-filled esophageal catheter method without balloon, using disposable catheter and transducer that allows reproducible esophageal pressure measurements, and that does not require any specific ventilator equipment. We use a 49 cm-long thin low compliance polyvinyl 10 Fr suction catheter, positioned in the lower third of the esophagus and connected to an air-filled disposable blood pressure transducer bound to the monitor. To guarantee air transmission, the transducer is pressurized by an air-filled infusion bag allowing its integrated flush device to deliver continuous air flow and to obtain a stable esophageal waveform. Calibration requires simple zeroing the transducer open to atmospheric pressure. Esophageal pressures recorded on the monitoring are expressed in mmHg and need to be converted in cmH2O. We tested our novel method in 10 consecutive intubated patients with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. We calculated the target transpulmonary pressures for protective lung and diaphragm ventilation, both in passive and spontaneously breathing conditions. Esophageal to airway pressure change ratio was close to one in both conditions (median [P25;P75]\u2009=\u20090.94 [0.92;1.00] and 0.98 [0.96;1.01]). We adjusted ventilator settings towards recommended pressure targets to limit atelectrauma, barotrauma, inspiratory effort and lung stress, by modifying positive end-expiratory pressure, tidal volume, or inspiratory pressure accordingly.\nConclusions\n\nWe propose a simple, inexpensive and reproducible method for esophageal pressure monitoring with an air-filled esophageal catheter without balloon. It holds the promise of widespread bedside use of transpulmonary pressure-guided protective ventilation in patients with ARDS.