Physiological and quantitative CT-scan characterization of COVID-19 and typical ARDS: a matched cohort study.
case_control · Level III
Where this comes from
- Record sourced from PubMed, PMID 33089348.
- Also identified by DOI 10.1007/s00134-020-06281-2 and PMC identifier 7577365.
- Licence recorded as CC BY-NC.
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Abstract
To investigate whether COVID-19-ARDS differs from all-cause ARDS. Thirty-two consecutive, mechanically ventilated COVID-19-ARDS patients were compared to two historical ARDS sub-populations 1:1 matched for PaO<sub>2</sub>/FiO<sub>2</sub> or for compliance of the respiratory system. Gas exchange, hemodynamics and respiratory mechanics were recorded at 5 and 15 cmH<sub>2</sub>O PEEP. CT scan variables were measured at 5 cmH<sub>2</sub>O PEEP. Anthropometric characteristics were similar in COVID-19-ARDS, PaO<sub>2</sub>/FiO<sub>2</sub>-matched-ARDS and Compliance-matched-ARDS. The PaO<sub>2</sub>/FiO<sub>2</sub>-matched-ARDS and COVID-19-ARDS populations (both with PaO<sub>2</sub>/FiO<sub>2</sub> 106 ± 59 mmHg) had different respiratory system compliances (Crs) (39 ± 11 vs 49.9 ± 15.4 ml/cmH<sub>2</sub>O, p = 0.03). The Compliance-matched-ARDS and COVID-19-ARDS had similar Crs (50.1 ± 15.7 and 49.9 ± 15.4 ml/cmH<sub>2</sub>O, respectively) but significantly lower PaO<sub>2</sub>/FiO<sub>2</sub> for the same Crs (160 ± 62 vs 106.5 ± 59.6 mmHg, p < 0.001). The three populations had similar lung weights but COVID-19-ARDS had significantly higher lung gas volume (PaO<sub>2</sub>/FiO<sub>2</sub>-matched-ARDS 930 ± 644 ml, COVID-19-ARDS 1670 ± 791 ml and Compliance-matched-ARDS 1301 ± 627 ml, p < 0.05). The venous admixture was significantly related to the non-aerated tissue in PaO<sub>2</sub>/FiO<sub>2</sub>-matched-ARDS and Compliance-matched-ARDS (p < 0.001) but unrelated in COVID-19-ARDS (p = 0.75), suggesting that hypoxemia was not only due to the extent of non-aerated tissue. Increasing PEEP from 5 to 15 cmH<sub>2</sub>O improved oxygenation in all groups. However, while lung mechanics and dead space improved in PaO<sub>2</sub>/FiO<sub>2</sub>-matched-ARDS, suggesting recruitment as primary mechanism, they remained unmodified or worsened in COVID-19-ARDS and Compliance-matched-ARDS, suggesting lower recruitment potential and/or blood flow redistribution. COVID-19-ARDS is a subset of ARDS characterized overall by higher compliance and lung gas volume for a given PaO<sub>2</sub>/FiO<sub>2</sub>, at least when considered within the timeframe of our study.
Medical subject headings
- COVID-19
- Respiratory Distress Syndrome