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

This study is being conducted to evaluate if wearing a non-invasive breathing support device over the chest/abdomen improves markers of breathing in patients with lung injury requiring high-flow oxygen. The breathing support device consists of a plastic shell that sits over the chest and abdomen and connects to a vacuum that helps the chest expand with breathing. This breathing support is known as continuous negative external pressure (CNEP). Study findings will help determine if this breathing support device might be useful for patients with acute hypoxemic respiratory failure (AHRF).

Inclusion Criteria:Acute hypoxemic respiratory failureNon-cardiogenic airspace opacities on chest radiograph or computed tomography (CT) scanHigh-flow nasal cannula (flow ≥ 30 LPM) initiated within last 96 hours (4 days)FiO2 ≥ 40%SpO2 ≥ 92%Exclusion Criteria:Age < 18 yearsDo-not-intubate orderAnatomical factor predisposing to poor fit of cuirass (e.g. severe kyphosis or scoliosis)Use of cuirass precluded, e.g. due to:Clinically prescribed prone positioningTense ascitesSevere abdominal painAbdominal wound or surgeryPregnancyAgitated deliriumPrior intubation during hospital stayCardiogenic pulmonary edemaExacerbation of asthma or COPDChronic lung disease, including:Interstitial lung diseaseCystic fibrosisLung mass, lung cancer, or metastasis to the lungLung transplant recipientAny disease that requires home oxygenGlasgow coma score < 15Chest tube, pneumothorax, or pneumomediastinumImplantable electrical device (e.g. pacemaker, defibrillator, neurostimulator)Unreliable pulse-oximetry tracingImminent intubationAnticipated 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