COVID-19 ARDS Is Characterized by Increased Dead Space Ventilation Compared With Non-COVID ARDS.

BACKGROUND: ARDS in patients with coronavirus disease 2019 (COVID-19) is characterized by microcirculatory alterations in the pulmonary vascular bed, which could increase dead-space ventilation more than in non-COVID-19 ARDS. We aimed to establish if dead-space ventilation is different in patients with COVID-19 ARDS when compared with patients with non-COVID-19 ARDS. METHODS: A total of 187 subjects with COVID-19 ARDS and 178 subjects with non-COVID-19 ARDS who were undergoing invasive mechanical ventilation were included in the study. The association between the ARDS types and dead-space ventilation, compliance of the respiratory system, subjects' characteristics, organ failures, and mechanical ventilation was evaluated by using data collected in the first 24 h of mechanical ventilation. RESULTS: Corrected minute ventilation (V˙E), a dead-space ventilation surrogate, was higher in the subjects with COVID-19 ARDS versus in those with non-COVID-19 ARDS (median [interquartile range] 12.6 [10.2-15.8] L/min vs 9.4 [7.5-11.6] L/min; P < .001). Increased corrected V˙E was independently associated with COVID-19 ARDS (odds ratio 1.24, 95% CI 1.07-1.47; P = .007). The best compliance of the respiratory system, obtained after testing different PEEPs, was similar between the subjects with COVID-19 ARDS and the subjects with non-COVID-19 ARDS (mean ± SD 38 ± 11 mL/cm H2O vs 37 ± 11 mL/cm H2O, respectively; P = .61). The subjects with COVID-19 ARDS received higher median (interquartile range) PEEP (12 [10-14] cm H2O vs 8 [5-9] cm H2O; P < .001) and lower median (interquartile range) tidal volume (5.8 [5.5-6.3] mL/kg vs 6.6 [6.1-7.3] mL/kg; P < .001) than the subjects with non-COVID-19 ARDS, being these differences maintained at multivariable analysis. In the multivariable analysis, the subjects with COVID-19 ARDS showed a lower risk of anamnestic arterial hypertension (odds ratio 0.18, 95% CI 0.07-0.45; P < .001) and lower neurologic sequential organ failure assessment score (odds ratio 0.16, 95% CI 0.09-0.27; P < .001) than the subjects with non-COVID-19 ARDS. CONCLUSIONS: Indirect measurements of dead space were higher in subjects with COVID-19 ARDS compared with subjects with non-COVID-19 ARDS. The best compliance of the respiratory system was similar in both ARDS forms provided that different PEEPs were applied. A wide range of compliance is present in every ARDS type; therefore, the setting of mechanical ventilation should be individualized patient by patient and not based on the etiology of ARDS.

Pneumomediastinum and subcutaneous emphysema in COVID-19: barotrauma or lung frailty?

BACKGROUND: In mechanically ventilated acute respiratory distress syndrome (ARDS) patients infected with the novel coronavirus disease (COVID-19), we frequently recognised the development of pneumomediastinum and/or subcutaneous emphysema despite employing a protective mechanical ventilation strategy. The purpose of this study was to determine if the incidence of pneumomediastinum/subcutaneous emphysema in COVID-19 patients was higher than in ARDS patients without COVID-19 and if this difference could be attributed to barotrauma or to lung frailty. METHODS: We identified both a cohort of patients with ARDS and COVID-19 (CoV-ARDS), and a cohort of patients with ARDS from other causes (noCoV-ARDS).Patients with CoV-ARDS were admitted to an intensive care unit (ICU) during the COVID-19 pandemic and had microbiologically confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. NoCoV-ARDS was identified by an ARDS diagnosis in the 5 years before the COVID-19 pandemic period. RESULTS: Pneumomediastinum/subcutaneous emphysema occurred in 23 out of 169 (13.6%) patients with CoV-ARDS and in three out of 163 (1.9%) patients with noCoV-ARDS (p<0.001). Mortality was 56.5% in CoV-ARDS patients with pneumomediastinum/subcutaneous emphysema and 50% in patients without pneumomediastinum (p=0.46).CoV-ARDS patients had a high incidence of pneumomediastinum/subcutaneous emphysema despite the use of low tidal volume (5.9±0.8 mL·kg-1 ideal body weight) and low airway pressure (plateau pressure 23±4 cmH2O). CONCLUSIONS: We observed a seven-fold increase in pneumomediastinum/subcutaneous emphysema in CoV-ARDS. An increased lung frailty in CoV-ARDS could explain this finding more than barotrauma, which, according to its etymology, refers to high transpulmonary pressure.

Thromboprophylaxis with enoxaparin is associated with a lower death rate in patients hospitalized with SARS-CoV-2 infection. A cohort study.

BACKGROUND: Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) infection is associated with hypercoagulability caused by direct invasion of endothelial cells and\or proinflammatory cytokine release. Thromboprophylaxis with enoxaparin is recommended by current guidelines, but evidence is still weak. The aim of this study was to assess the impact of thromboprophylaxis with enoxaparin on hospital mortality in patients admitted for Coronavirus disease 2019 (COVID-19). The effects of enoxaparin on intensive care admission and hospital length-of-stay were evaluated as secondary outcomes. METHODS: Observational cohort study, with data collected from patients admitted to Poliambulanza Foundation with positive real time reverse transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2 from 20th February to 10th May 2020. Multivariate logistic regression with overlap weight propensity score was used to model hospital mortality and intensive care admission, hospital length-of-stay was analyzed with a multivariate Poisson regression. Seven hundred and ninety nine (57%) patients who received enoxaparin at least once during the hospitalization were included in the enoxaparin cohort, 604 (43%) patients who did not were included in the control cohort. FINDINGS: At the adjusted analysis enoxaparin was associated with lower in-hospital mortality (Odds Ratio 0·53, 95% C.I. 0·40-0·70) compared with no enoxaparin treatment. Hospital length-of-stay was longer for patients treated with enoxaparin (Incidence Rate Ratios 1·45, 95% C.I. 1·36-1·54). Enoxaparin treatment was associated with reduced risk of intensive care admission at the adjusted analysis (Odds Ratio 0·48, 95% C.I. 0·32-0·69). INTERPRETATION: This study shows that treatment with enoxaparin during hospital stay is associated with a lower death rate and, while results from randomized clinical trials are still pending, this study supports the use of thromboprophylaxis with enoxaparin in all patients admitted for COVID-19. Moreover, when enoxaparin is used on the wards, it reduces the risk of Intensive Care Unit admission.

Impact of Azithromycin and/or Hydroxychloroquine on Hospital Mortality in COVID-19.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has led to widespread use of hydroxychloroquine and azithromycin despite the lack of conclusive evidence for their safety and efficacy. We evaluated the association between treatment with hydroxychloroquine and/or azithromycin and hospital mortality as the primary outcome. We compared the hospital mortality of patients treated with hydroxychloroquine alone, azithromycin alone, or their combination to the mortality of patients who received neither drug. A logistic multivariate model with overlap weight propensity score was used for estimation of odds ratios (ORs) with 95% confidence intervals (95% CIs). One thousand four hundred and three patients with SARS-CoV-2 infection were admitted to the hospital. At the time of the analysis, the outcome was available for 1376 (98%) of them. Five hundred and eighty-seven patients (42%) received azithromycin and 377 patients (27%) received hydroxychloroquine, alone or in combination. In-hospital mortality was 26%. After the adjusted analysis, azithromycin alone was associated with lower mortality (OR 0.60, 95% CI 0.42-0.85) compared to no treatment. Hydroxychloroquine alone (OR 0.76, 95% CI 0.53-1.08) and the combination of azithromycin and hydroxychloroquine (OR 1.13, 95% CI 0.77-1.69) were not associated with hospital mortality. In this cohort of patients, azithromycin alone was associated with lower hospital mortality but hydroxychloroquine was not associated with increased or reduced mortality. While we await randomized clinical trials, these data support the use of azithromycin in novel coronavirus disease 2019 (COVID-19) and can contribute to better understanding of its role in further meta-analyses.