Barotrauma in COVID 19: Incidence, pathophysiology, and effect on prognosis

Chest X-ray at Emergency Admission and Potential Association with Barotrauma in Mechanically Ventilated Patients: Experience from the Italian Core of the First Pandemic Peak

Barotrauma occurs in a significant number of patients with COVID-19 interstitial pneumonia undergoing mechanical ventilation. The aim of the current study was to investigate whether the Brixia score (BS) calculated on chest-X-rays acquired at the Emergency Room was associated with barotrauma. We retrospectively evaluated 117 SARS-CoV-2 patients presented to the Emergency Department (ED) and then admitted to the intensive care unit (ICU) for mechanical ventilation between February and April 2020. Subjects were divided into two groups according to the occurrence of barotrauma during their hospitalization. CXRs performed at ED admittance were assessed using the Brixia score. Distribution of barotrauma (pneumomediastinum, pneumothorax, subcutaneous emphysema) was identified in chest CT scans. Thirty-eight subjects (32.5%) developed barotrauma (25 pneumomediastinum, 24 pneumothorax, 24 subcutaneous emphysema). In the barotrauma group we observed higher Brixia score values compared to the non-barotrauma group (mean value 12.18 vs. 9.28), and logistic regression analysis confirmed that Brixia score is associated with the risk of barotrauma. In this work, we also evaluated the relationship between barotrauma and clinical and ventilatory parameters: SOFA score calculated at ICU admittance and number of days of non-invasive ventilation (NIV) prior to intubation emerged as other potential predictors of barotrauma.

Optimized ventilation power to avoid VILI

The effort to minimize VILI risk must be multi-pronged. The need to adequately ventilate, a key determinant of hazardous power, is reduced by judicious permissive hypercapnia, reduction of innate oxygen demand, and by prone body positioning that promotes both efficient pulmonary gas exchange and homogenous distributions of local stress. Modifiable ventilator-related determinants of lung protection include reductions of tidal volume, plateau pressure, driving pressure, PEEP, inspiratory flow amplitude and profile (using longer inspiration to expiration ratios), and ventilation frequency. Underappreciated conditional cofactors of importance to modulate the impact of local specific power may include lower vascular pressures and blood flows. Employed together, these measures modulate ventilation power with the intent to avoid VILI while achieving clinically acceptable targets for pulmonary gas exchange.

From pressure to tension: a model of damaging inflation stress

Although the stretch that generates ventilator-induced lung injury (VILI) occurs within the peripheral tissue that encloses the alveolar space, airway pressures and volumes monitor the gas within the interior core of the lung unit, not its cellular enclosure. Measured pressures (plateau pressure, positive end-expiratory pressure, and driving pressure) and tidal volumes paint a highly relevant but incomplete picture of forces that act on the lung tissues themselves. Convenient and clinically useful measures of the airspace, such as pressure and volume, neglect the partitioning of tidal elastic energy into the increments of tension and surface area that constitute actual stress and strain at the alveolar margins. More sharply focused determinants of VILI require estimates of absolute alveolar dimension and morphology and the lung's unstressed volume at rest. We present a highly simplified but informative mathematical model that translates the radial energy of pressure and volume of the airspace into its surface energy components. In doing so it elaborates conceptual relationships that highlight the forces tending to cause end-tidal hyperinflation of aerated units within the 'baby lung' of acute respiratory distress syndrome (ARDS).

Effects of pulmonary air leak on patients with coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis

BACKGROUND

Coronavirus disease 2019 (COVID-19) has posed increasing challenges to global health systems. We aimed to understand the effects of pulmonary air leak (PAL), including pneumothorax, pneumomediastinum and subcutaneous emphysema, on patients with COVID-19.

METHODS

We searched PubMed, Embase and Web of Science for data and performed a meta-analysis with a random-effects model using Stata 14.0. This meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Thirty-five articles were included in the meta-analysis. The data came from 14 countries and included 3,047 COVID-19 patients with PAL, 11,3679 COVID-19 patients without PAL and 361 non-COVID-19 patients with PAL. We found that the incidence of PAL was much higher in COVID-19 patients than in non-COVID-19 patients (odds ratio (OR) = 6.13, 95% CI: 2.09-18.00). We found that the group of COVID-19 patients with PAL had a longer hospital stay (standardized mean difference (SMD) = 0.79, 95% CI: 0.27-1.30) and intensive care unit (ICU) stay (SMD = 0.51, 95% CI: 0.19-0.83) and comprised more ICU (OR = 15.16, 95% CI: 6.51-35.29) and mechanical ventilation patients (OR = 5.52, 95% CI: 1.69-17.99); furthermore, the mortality rate was also higher (OR = 2.62, 95% CI: 1.80-3.82).

CONCLUSIONS

Patients with lung injuries caused by COVID-19 may develop PAL. COVID-19 patients with PAL require more medical resources, have more serious conditions and have worse clinical outcomes.

PROSPERO REGISTRATION NUMBER

CRD42022365047.

Occurrence, Risk Factors, and Outcomes of Pulmonary Barotrauma in Critically Ill COVID-19 Patients: A Retrospective Cohort Study

Objective

Pulmonary barotrauma has been frequently observed in patients with COVID-19 who present with acute hypoxemic respiratory failure. This study evaluated the prevalence, risk factors, and outcomes of barotrauma in patients with COVID-19 requiring ICU admission.

Methods

This retrospective cohort study included patients with confirmed COVID-19 who were admitted to an adult ICU between March and December 2020. We compared patients who had barotrauma with those who did not. A multivariable logistic regression analysis was performed to determine the predictors of barotrauma and hospital mortality.

Results

Of 481 patients in the study cohort, 49 (10.2%, 95% confidence interval: 7.6-13.2%) developed barotrauma on a median of 4 days after ICU admission. Barotrauma manifested as pneumothorax (N = 21), pneumomediastinum (N = 25), and subcutaneous emphysema (N = 25) with frequent overlap. Chronic comorbidities and inflammatory markers were similar in both patient groups. Barotrauma occurred in 4/132 patients (3.0%) who received noninvasive ventilation without intubation, and in 43/280 patients (15.4%) who received invasive mechanical ventilation. Invasive mechanical ventilation was the only risk factor for barotrauma (odds ratio: 14.558, 95% confidence interval: 1.833-115.601). Patients with barotrauma had higher hospital mortality (69.4% versus 37.0%; p < 0.0001) and longer duration of mechanical ventilation and ICU stay. Barotrauma was an independent predictor of hospital mortality (odds ratio: 2.784, 95% confidence interval: 1.310-5.918).

Conclusion

s. Barotrauma was common in critical COVID-19, with invasive mechanical ventilation being the most prominent risk factor. Barotrauma was associated with poorer clinical outcomes and was an independent predictor of hospital mortality.