Abstract
Objective:Many patients with coronavirus disease 2019 (COVID-19) need mechanical ventilation secondary to acute respiratory distress syndrome. Information on the respiratory system mechanical characteristics of this disease is limited. The aim of this study is to describe the respiratory system mechanical properties of ventilated COVID-19 patients.Design, Setting, and Patients:Patients consecutively admitted to the medical intensive care unit at the University of Iowa Hospitals and Clinics in Iowa City, USA, from April 19 to May 1, 2020, were prospectively studied; final date of follow-up was May 1, 2020.Measurements:At the time of first patient contact, ventilator information was collected including mode, settings, peak airway pressure, plateau pressure, and total positive end expiratory pressure. Indices of airflow resistance and respiratory system compliance were calculated and analyzed.Main Results:The mean age of the patients was 58 years. 6 out of 12 (50%) patients were female. Of the 21 laboratory-confirmed COVID-19 patients on invasive mechanical ventilation, 9 patients who were actively breathing on the ventilator were excluded. All the patients included were on volume-control mode. Mean [±standard deviation] ventilator indices were: resistive pressure 19 [±4] cmH2O, airway resistance 20 [±4] cmH2O/L/s, and respiratory system static compliance 39 [±16] ml/cmH2O. These values are consistent with abnormally elevated resistance to airflow and reduced respiratory system compliance. Analysis of flow waveform graphics revealed a pattern consistent with airflow obstruction in all patients.Conclusions:Severe respiratory failure due to COVID-19 is regularly associated with airflow obstruction.
Highlights
In December 2019, the first patients with pneumonia due to a new species of coronavirus were admitted to hospitals in Wuhan, China.[1]Since SARS-CoV-2 virus has spread across the world, leading to a pandemic of the associated disease, COVID-19.A significant proportion of patients with COVID-19 develop severe respiratory disease and may require admission to the intensive care unit (ICU) and mechanical ventilation.[2,3,4]Patients with COVID-19 pneumonia requiring mechanical ventilation typically fulfill the diagnostic criteria for the acute respiratory distress syndrome (ARDS).[5]
Adult subjects with ARDS due to COVID-19 pneumonia ventilated in the medical ICU between April 19 and May 1, 2020 were prospectively identified during usual ICU care
Airway resistance was calculated as peak pressure (Ppeak) minus plateau pressure (Pplat) divided by inspiratory flow rate
Summary
In December 2019, the first patients with pneumonia due to a new species of coronavirus Gas exchange may be impaired out of proportion to mechanical abnormalities (“happy hypoxia”)[6] and respiratory system compliance is relatively preserved.[7] Gattinoni and colleagues have hypothesized 2 distinct phenotypes of lung failure in COVID-19: L-type with low elastance and H-type with high elastance.[8] These peculiar features may affect treatment choices, such as levels of positive end expiratory pressure (PEEP) or strategies for delivering lung-protective ventilation These characteristics offer clues to pathophysiology of lung failure in COVID-19 pneumonia and could point to new therapies. Sometimes with evident end-expiratory flow) were present so often that we hypothesize that airflow obstruction is an integral part of COVID-19-related lung failure
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