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Updated: Jan 28, 2026

Surfactant Depletion Combined with Injurious Ventilation Results in a Reproducible Model of the Acute Respiratory Distress Syndrome ARDS
Published on: April 7, 2021
Ultra-protective mechanical ventilation without extra-corporeal carbon dioxide removal for acute respiratory distress
Hariharan Regunath1,2, Nathanial Moulton3, Daniel Woolery1
1Department of Medicine, Division of Pulmonary, Critical Care and Environmental Medicine, University of Missouri, Columbia, MO, USA.
Background:
Tidal hyperinflation can still occur with mechanical ventilation using low tidal volume (LVT) (6 mL/kg predicted body weight (PBW)) in acute respiratory distress syndrome (ARDS), despite a well-demonstrated reduction in mortality.
Methods:
Retrospective chart review from August 2012 to October 2014. Inclusion: Age >18years, PaO2/FiO2<200 with bilateral pulmonary infiltrates, absent heart failure, and ultra-protective mechanical ventilation (UPMV) defined as tidal volume (VT) <6 mL/kg PBW. Exclusion: UPMV use for <24 h. Demographics, admission Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, arterial blood gas, serum bicarbonate, ventilator parameters for pre-, during, and post-UPMV periods including modes, VT, peak inspiratory pressure (PIP), plateau pressure (Pplat), driving pressure, etc. were gathered. We compared lab and ventilator data for pre-, during, and post-UPMV periods.
Results:
Fifteen patients (male:female = 7:8, age 42.13 ± 11.29 years) satisfied criteria, APACHEII 20.6 ± 7.1, mean days in intensive care unit and hospitalization were 18.5 ± 8.85 and 20.81 ± 9.78 days, 9 (60%) received paralysis and 7 (46.67%) required inotropes. Eleven patients had echocardiogram, 7 (63.64%) demonstrated right ventricular volume or pressure overload. Eleven patients (73.33%) survived. During-UPMV, VT ranged 2-5 mL/kg PBW(3.99 ± 0.73), the arterial partial pressure of carbon dioxide (PaCO2) was higher than pre-UPMV values (84.81 ± 18.95 cmH2O vs. 69.16 ± 33.09 cmH2O), but pH was comparable and none received extracorporeal carbon dioxide removal (ECCO2-R). The positive end-expiratory pressure (14.18 ± 7.56 vs. 12.31 ± 6.84 cmH2O), PIP (38.21 ± 12.89 vs. 32.59 ± 9.88), and mean airway pressures (19.98 ± 7.61 vs. 17.48 ± 6.7 cm H2O) were higher during UPMV, but Pplat and PaO2/FiO2 were comparable during- and pre-UPMV. Driving pressure was observed to be higher in those who died than who survived (24.18 ± 12.36 vs. 13.42 ± 3.25).
Conclusion:
UPMV alone may be a safe alternative option for ARDS patients in centers without ECCO2-R.
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