Barotrauma in mechanically ventilated patients with Coronavirus disease 2019: a survey of 38 hospitals in Lombardy, Italy

Effect of decreasing PEEP on hyperinflation and collapse in COVID-19: A computed tomography study

BACKGROUND

High positive end-expiratory pressure (PEEP>10 cmH2O) is commonly used in mechanically ventilated hypoxemic patients with COVID-19. However, some epidemiological and physiological studies indirectly suggest that using a lower PEEP may primarily and beneficially decrease lung hyperinflation in this population. Herein we directly quantified the effect of decreasing PEEP from 15 to 10 cmH2O on lung hyperinflation and collapse in mechanically ventilated patients with COVID-19.

METHODS

Twenty mechanically ventilated patients with COVID-19 underwent a lung computed tomography (CT) at PEEP of 15 and 10 cmH2O. The effect of decreasing PEEP on lung hyperinflation and collapse was directly quantified as the change in the over-aerated (density below -900 HU) and non-aerated (density above -100 HU) lung volumes. The net response to decreasing PEEP was computed as the sum of the change in those two compartments and expressed as the change in the "pathologic" lung volume. If the pathologic lung volume decreased (i.e., hyperinflation decreased more than collapse increased) when PEEP was decreased, the net response was considered positive; otherwise, it was considered negative.

RESULTS

On average, the ratio of arterial tension to inspiratory fraction of oxygen (PaO2:FiO2) in the overall study population was 137 (119-162) mmHg. In 11 (55%) patients, the net response to decreasing PEEP was positive. Their over-aerated lung volume decreased by 159 (98-186) mL, while the non-aerated lung volume increased by only 58 (31-91) mL. In nine (45%) patients, the net response was negative. Their over-aerated lung volume decreased by 46 (18-72) mL, but their non-aerated lung volume increased by 107 (44-121) mL.

CONCLUSION

In 20 patients with COVID-19 the net response to decreasing PEEP, as assessed with lung CT, was variable. In approximately half of them it was positive (and possibly beneficial), with a decrease in hyperinflation larger than the increase in collapse.

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.

Lung response to prone positioning in mechanically-ventilated patients with COVID-19

BACKGROUND

Prone positioning improves survival in moderate-to-severe acute respiratory distress syndrome (ARDS) unrelated to the novel coronavirus disease (COVID-19). This benefit is probably mediated by a decrease in alveolar collapse and hyperinflation and a more homogeneous distribution of lung aeration, with fewer harms from mechanical ventilation. In this preliminary physiological study we aimed to verify whether prone positioning causes analogue changes in lung aeration in COVID-19. A positive result would support prone positioning even in this other population.

METHODS

Fifteen mechanically-ventilated patients with COVID-19 underwent a lung computed tomography in the supine and prone position with a constant positive end-expiratory pressure (PEEP) within three days of endotracheal intubation. Using quantitative analysis, we measured the volume of the non-aerated, poorly-aerated, well-aerated, and over-aerated compartments and the gas-to-tissue ratio of the ten vertical levels of the lung. In addition, we expressed the heterogeneity of lung aeration with the standardized median absolute deviation of the ten vertical gas-to-tissue ratios, with lower values indicating less heterogeneity.

RESULTS

By the time of the study, PEEP was 12 (10-14) cmH2O and the PaO2:FiO2 107 (84-173) mmHg in the supine position. With prone positioning, the volume of the non-aerated compartment decreased by 82 (26-147) ml, of the poorly-aerated compartment increased by 82 (53-174) ml, of the normally-aerated compartment did not significantly change, and of the over-aerated compartment decreased by 28 (11-186) ml. In eight (53%) patients, the volume of the over-aerated compartment decreased more than the volume of the non-aerated compartment. The gas-to-tissue ratio of the ten vertical levels of the lung decreased by 0.34 (0.25-0.49) ml/g per level in the supine position and by 0.03 (- 0.11 to 0.14) ml/g in the prone position (p < 0.001). The standardized median absolute deviation of the gas-to-tissue ratios of those ten levels decreased in all patients, from 0.55 (0.50-0.71) to 0.20 (0.14-0.27) (p < 0.001).

CONCLUSIONS

In fifteen patients with COVID-19, prone positioning decreased alveolar collapse, hyperinflation, and homogenized lung aeration. A similar response has been observed in other ARDS, where prone positioning improves outcome. Therefore, our data provide a pathophysiological rationale to support prone positioning even in COVID-19.

Incidence, clinical characteristics and outcome of barotrauma in critically ill patients with COVID-19: a systematic review and meta-analysis

INTRODUCTION

Barotrauma is rare in patients with acute respiratory distress syndrome undergoing mechanical ventilation. Its incidence seems increased among critically ill COVID-19 patients. We performed a systematic review and meta-analysis to investigate the incidence, risk factors and clinical outcomes of barotrauma among critically ill COVID-19 patients EVIDENCE ACQUISITION: PubMed was searched from March 1st, 2020 to August 31st, 2021; case series and retrospective cohort studies concerning barotrauma in adult critically ill COVID-19 patients, either hospitalized in the Intensive Care Unit (ICU) or invasively ventilated were included. Primary outcome was the incidence of barotrauma in COVID-19 versus non-COVID-19 patients. Secondary outcomes were clinical characteristics, ventilator parameters, mortality and length of stay between patients with and without barotrauma.

EVIDENCE SYNTHESIS

We identified 21 studies (six case series, 15 retrospective cohorts). The overall incidence of barotrauma was 11 [95% CI: 8-14]% in critically ill COVID-19 patients, vs. 2 [1-3]% in non-COVID-19, P<0.001; the incidence in mechanically ventilated patients was 14 [11-17]% vs. 4 [2-5]% non-COVID-19 patients, P<0.001. There were no differences in demographic, clinical, ventilatory parameters between patients who did and did not develop barotrauma, while, on average, protective ventilation criteria were always respected. Among COVID-19 patients, those with barotrauma had a higher mortality (60 [55-66] vs. 48 [42-54]%, P<0.001) and a longer ICU length of stay (20 [14-26] vs. 13 [10,5-16] days, P=0.03).

CONCLUSIONS

Barotrauma is a frequent complication in critically ill COVID-19 patients and is associated with a poor prognosis. Since lung protective ventilation was delivered, the ventilatory management might not be the sole factor in the development of barotrauma.

Risk Factors for Pulmonary Air Leak and Clinical Prognosis in Patients With COVID-19 Related Acute Respiratory Failure: A Retrospective Matched Control Study

Background

The role of excessive inspiratory effort in promoting alveolar and pleural rupture resulting in air leak (AL) in patients with SARS-CoV-2 induced acute respiratory failure (ARF) while on spontaneous breathing is undetermined.

Methods

Among all patients with COVID-19 related ARF admitted to a respiratory intensive care unit (RICU) and receiving non-invasive respiratory support, those developing an AL were and matched 1:1 [by means of PaO2/FiO2 ratio, age, body mass index-BMI and subsequent organ failure assessment (SOFA)] with a comparable population who did not (NAL group). Esophageal pressure (ΔP_es) and dynamic transpulmonary pressure (ΔP_L) swings were compared between groups. Risk factors affecting AL onset were evaluated. The composite outcome of ventilator-free-days (VFD) at day 28 (including ETI, mortality, tracheostomy) was compared between groups.

Results

Air leak and NAL groups (n = 28) showed similar ΔP_es, whereas AL had higher ΔP_L (20 [16–21] and 17 [11–20], p = 0.01, respectively). Higher ΔP_L (OR = 1.5 95%CI[1–1.8], p = 0.01), positive end-expiratory pressure (OR = 2.4 95%CI[1.2–5.9], p = 0.04) and pressure support (OR = 1.8 95%CI[1.1–3.5], p = 0.03), D-dimer on admission (OR = 2.1 95%CI[1.3–9.8], p = 0.03), and features suggestive of consolidation on computed tomography scan (OR = 3.8 95%CI[1.1–15], p = 0.04) were all significantly associated with AL. A lower VFD score resulted in a higher risk (HR = 3.7 95%CI [1.2–11.3], p = 0.01) in the AL group compared with NAL. RICU stay and 90-day mortality were also higher in the AL group compared with NAL.

Conclusion

In spontaneously breathing patients with COVID-19 related ARF, higher levels of ΔP_L, blood D-dimer, NIV delivery pressures and a consolidative lung pattern were associated with AL onset.

An Imaging Overview of COVID-19 ARDS in ICU Patients and Its Complications: A Pictorial Review

A significant proportion of patients with COVID-19 pneumonia could develop acute respiratory distress syndrome (ARDS), thus requiring mechanical ventilation, and resulting in a high rate of intensive care unit (ICU) admission. Several complications can arise during an ICU stay, from both COVID-19 infection and the respiratory supporting system, including barotraumas (pneumothorax and pneumomediastinum), superimposed pneumonia, coagulation disorders (pulmonary embolism, venous thromboembolism, hemorrhages and acute ischemic stroke), abdominal involvement (acute mesenteric ischemia, pancreatitis and acute kidney injury) and sarcopenia. Imaging plays a pivotal role in the detection and monitoring of ICU complications and is expanding even to prognosis prediction. The present pictorial review describes the clinicopathological and radiological findings of COVID-19 ARDS in ICU patients and discusses the imaging features of complications related to invasive ventilation support, as well as those of COVID-19 itself in this particularly fragile population. Radiologists need to be familiar with COVID-19's possible extra-pulmonary complications and, through reliable and constant monitoring, guide therapeutic decisions. Moreover, as more research is pursued and the pathophysiology of COVID-19 is increasingly understood, the role of imaging must evolve accordingly, expanding from the diagnosis and subsequent management of patients to prognosis prediction.

Clinical and organizational factors associated with mortality during the peak of first COVID-19 wave: the global UNITE-COVID study

PURPOSE

To accommodate the unprecedented number of critically ill patients with pneumonia caused by coronavirus disease 2019 (COVID-19) expansion of the capacity of intensive care unit (ICU) to clinical areas not previously used for critical care was necessary. We describe the global burden of COVID-19 admissions and the clinical and organizational characteristics associated with outcomes in critically ill COVID-19 patients.

METHODS

Multicenter, international, point prevalence study, including adult patients with SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) and a diagnosis of COVID-19 admitted to ICU between February 15th and May 15th, 2020.

RESULTS

4994 patients from 280 ICUs in 46 countries were included. Included ICUs increased their total capacity from 4931 to 7630 beds, deploying personnel from other areas. Overall, 1986 (39.8%) patients were admitted to surge capacity beds. Invasive ventilation at admission was present in 2325 (46.5%) patients and was required during ICU stay in 85.8% of patients. 60-day mortality was 33.9% (IQR across units: 20%-50%) and ICU mortality 32.7%. Older age, invasive mechanical ventilation, and acute kidney injury (AKI) were associated with increased mortality. These associations were also confirmed specifically in mechanically ventilated patients. Admission to surge capacity beds was not associated with mortality, even after controlling for other factors.

CONCLUSIONS

ICUs responded to the increase in COVID-19 patients by increasing bed availability and staff, admitting up to 40% of patients in surge capacity beds. Although mortality in this population was high, admission to a surge capacity bed was not associated with increased mortality. Older age, invasive mechanical ventilation, and AKI were identified as the strongest predictors of mortality.

Research on SARS-COV-2 pandemic: a narrative review focused on the Italian contribution

Background

Since late 2019, a severe acute respiratory syndrome, caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has spread with overwhelming speed causing over 214 million confirmed infections and more than 4.5 million deaths worldwide. In this framework, Italy had the second highest number of SARS-CoV-2 infections worldwide, and the largest number of deaths. A global effort of both the scientific community and governments has been undertaken to stem the pandemic. The aim of this paper is to perform a narrative review of the Italian contribution to the scientific literature regarding intensive care management of patients suffering from COVID-19, being one of the first western countries to face an outbreak of SARS-CoV-2 infection.

Main body

We performed a narrative review of the literature, dedicating particular attention and a dedicated paragraph to ventilatory support management, chest imaging findings, biomarkers, possible pharmacological interventions, bacterial superinfections, prognosis and non-clinical key aspects such as communication and interaction with relatives.

Conclusions

Many colleagues, nurses and patients died leaving their families alone. To all of them, we send our thoughts and dedicate these pages.

Lung response to a higher positive end-expiratory pressure in mechanically ventilated patients with COVID-19

Background

International guidelines suggest using a higher (> 10 cm H₂O) positive end-expiratory pressure (PEEP) in patients with moderate-to-severe ARDS due to COVID-19. However, even if oxygenation generally improves with a higher PEEP, compliance, and Paco₂ frequently do not, as if recruitment was small.

Research Question

Is the potential for lung recruitment small in patients with early ARDS due to COVID-19?

Study Design and Methods

Forty patients with ARDS due to COVID-19 were studied in the supine position within 3 days of endotracheal intubation. They all underwent a PEEP trial, in which oxygenation, compliance, and Paco₂ were measured with 5, 10, and 15 cm H₂O of PEEP, and all other ventilatory settings unchanged. Twenty underwent a whole-lung static CT scan at 5 and 45 cm H₂O, and the other 20 at 5 and 15 cm H₂O of airway pressure. Recruitment and hyperinflation were defined as a decrease in the volume of the non-aerated (density above −100 HU) and an increase in the volume of the over-aerated (density below −900 HU) lung compartments, respectively.

Results

From 5 to 15 cm H₂O, oxygenation improved in 36 (90%) patients but compliance only in 11 (28%) and Paco₂ only in 14 (35%). From 5 to 45 cm H₂O, recruitment was 351 (161-462) mL and hyperinflation 465 (220-681) mL. From 5 to 15 cm H₂O, recruitment was 168 (110-202) mL and hyperinflation 121 (63-270) mL. Hyperinflation variably developed in all patients and exceeded recruitment in more than half of them.

Interpretation

Patients with early ARDS due to COVID-19, ventilated in the supine position, present with a large potential for lung recruitment. Even so, their compliance and Paco₂ do not generally improve with a higher PEEP, possibly because of hyperinflation.

Barotrauma during non-invasive ventilation for acute respiratory distress syndrome caused by COVID-19: a balance between risks and benefits

Ventilatory support is vital for the management of severe forms of COVID-19. Non-invasive ventilation is often used in patients who do not meet criteria for intubation or when invasive ventilation is not available, especially in a pandemic when resources are limited. Despite non-invasive ventilation providing effective respiratory support for some forms of acute respiratory failure, data about its effectiveness in patients with viral-related pneumonia are inconclusive. Acute respiratory distress syndrome caused by severe acute respiratory syndrome-coronavirus 2 infection causes life-threatening respiratory failure, weakening the lung parenchyma and increasing the risk of barotrauma. Pulmonary barotrauma results from positive pressure ventilation leading to elevated transalveolar pressure, and in turn to alveolar rupture and leakage of air into the extra-alveolar tissue. This article reviews the literature regarding the use of non-invasive ventilation in patients with acute respiratory failure associated with COVID-19 and other epidemic or pandemic viral infections and the related risk of barotrauma.