Physiological Effects of Continuous Negative External Pressure for Acute Hypoxemic Respiratory Failure

Inclusion Criteria: * Age 18 years or older * Acute hypoxemic respiratory failure * Non-cardiogenic airspace opacities on chest radiograph or computed tomography (CT) scan * High-flow nasal cannula (flow ≥ 30 LPM) initiated within last 96 hours (4 days) * FiO2 ≥ 40% * SpO2 ≥ 92% Exclusion Criteria: * Do-not-intubate order * Anatomical factor predisposing to poor fit of cuirass (e.g. severe kyphosis or scoliosis) * Use of cuirass precluded, e.g. due to: * Clinically prescribed prone positioning * Tense ascites * Severe abdominal pain * Abdominal wound or surgery * Pregnancy * Agitated delirium * Prior intubation during hospital stay * Cardiogenic pulmonary edema * Exacerbation of asthma or COPD * Chronic lung disease, including: * Interstitial lung disease * Cystic fibrosis * Lung mass, lung cancer, or metastasis to the lung * Lung transplant recipient * Any disease that requires home oxygen * Glasgow coma score \< 15 * Chest tube, pneumothorax, or pneumomediastinum * Hemodynamic instability (mean arterial pressure \< 55 mmHg or norepinephrine-equivalent vasopressor requirement \> 0.1mcg/kg/min) * Implantable electrical device (e.g. pacemaker, defibrillator, neurostimulator) * Unreliable pulse-oximetry tracing * Imminent intubation * Anticipated lack of patient availability to complete study procedures (e.g. due to planned clinical procedure such as CT scan or dialysis during potential time of study) * Attending physician refusal