Pneumothorax and barotrauma in invasively ventilated patients with COVID-19

The Macklin effect closely correlates with pneumomediastinum in acutely ill intubated patients with COVID-19 infection

PURPOSE

Patients with COVID-19 infection are frequently found to have pulmonary barotrauma. Recent work has identified the Macklin effect as a radiographic sign that often occurs in patients with COVID-19 and may correlate with barotrauma.

METHODS

We evaluated chest CT scans in COVID-19 positive mechanically ventilated patients for the Macklin effect and any type of pulmonary barotrauma. Patient charts were reviewed to identify demographic and clinical characteristics.

RESULTS

The Macklin effect on chest CT scan was identified in a total of 10/75 (13.3%) COVID-19 positive mechanically ventilated patients; 9 developed barotrauma. Patients with the Macklin effect on chest CT scan had a 90% rate of pneumomediastinum (p < 0.001) and a trend toward a higher rate of pneumothorax (60%, p = 0.09). Pneumothorax was most frequently omolateral to the site of the Macklin effect (83.3%).

CONCLUSION

The Macklin effect may be a strong radiographic biomarker for pulmonary barotrauma, most strongly correlating with pneumomediastinum. Studies in ARDS patients without COVID-19 are needed to validate this sign in a broader population. If validated in a broad population, future critical care treatment algorithms may include the Macklin sign for clinical decision making and prognostication.

Clinical use of Macklin-like radiological sign (Macklin effect): A systematic review

INTRODUCTION

Recent studies suggested that Macklin sign is a predictor of barotrauma in patients with acute respiratory distress syndrome (ARDS). We performed a systematic review to further characterize the clinical role of Macklin.

METHODS

PubMed, Scopus, Cochrane Central Register and Embase were searched for studies reporting data on Macklin. Studies without data on chest CT, pediatric studies, non-human and cadaver studies, case reports and series including <5 patients were excluded. The primary objective was to assess the number of patients with Macklin sign and barotrauma. Secondary objectives were: occurrence of Macklin in different populations, clinical use of Macklin, prognostic impact of Macklin.

RESULTS

Seven studies enrolling 979 patients were included. Macklin was present in 4-22% of COVID-19 patients. It was associated with barotrauma in 124/138 (89.8%) of cases. Macklin sign preceded barotrauma in 65/69 cases (94.2%) 3-8 days in advance. Four studies used Macklin as pathophysiological explanation for barotrauma, two studies as a predictor of barotrauma and one as a decision-making tool. Two studies suggested that Macklin is a strong predictor of barotrauma in ARDS patients and one study used Macklin sign to candidate high-risk ARDS patients to awake extracorporeal membrane oxygenation (ECMO). A possible correlation between Macklin and worse prognosis was suggested in two studies on COVID-19 and blunt chest trauma.

CONCLUSIONS

Increasing evidence suggests that Macklin sign anticipate barotrauma in patients with ARDS and there are initial reports on use of Macklin as a decision-making tool. Further studies investigating the role of Macklin sign in ARDS are justified.

Characteristics and risk factors for mortality in critically ill patients with COVID-19 receiving invasive mechanical ventilation: the experience of a private network in Sao Paulo, Brazil

Introduction

The use of invasive mechanical ventilation (IMV) in COVID-19 represents in an incremental burden to healthcare systems.

Aim of the study

We aimed to characterize patients hospitalized for COVID-19 who received IMV and identify risk factors for mortality in this population.

Material and Methods

A retrospective cohort study including consecutive adult patients admitted to a private network in Brazil who received IMV from March to October, 2020. A bidirectional stepwise logistic regression analysis was used to determine the risk factors for mortality.

Results

We included 215 patients, of which 96 died and 119 were discharged from ICU. The mean age was 62.7 ± 15.4 years and the most important comorbidities were hypertension (62.8%), obesity (50.7%) and diabetes (40%). Non-survivors had lower body mass index (BMI) (28.3 [25.5; 31.6] vs. 31.2 [28.3; 35], p<0.001, and a shorter duration from symptom onset to intubation (8.5 [6.0; 12] days vs. 10 [8.0; 12.5] days, p = 0.005). Multivariable regression analysis showed that the risk factors for mortality were age (OR: 1.07, 95% CI: 1.03 to 1.1, p < 0.001), creatinine level at the intubation date (OR: 3.28, 95% CI: 1.47 to 7.33, p = 0.004), BMI (OR: 0.91, 95% CI: 0.84 to 0.99, p = 0.033), lowest PF ratio within 48 hours post-intubation (OR: 0.988, 95% CI: 0.979 to 0.997, p = 0.011), barotrauma (OR: 5.18, 95% CI: 1.14 to 23.65, p = 0.034) and duration from symptom onset to intubation (OR: 0.76, 95% CI: 0.76 to 0.95, p = 0.006).

Conclusion

In our retrospective cohort we identified the main risk factors for mortality in COVID-19 patients receiving IMV: age, creatinine at the day of intubation, BMI, lowest PF ratio 48-hours post-intubation, barotrauma and duration from symptom onset to intubation.

Incidence and risk factors of COVID-19 associated pneumothorax

Background

Pneumothorax has been increasingly observed among patients with coronavirus disease-2019 (COVID-19) pneumonia, specifically in those patients who develop acute respiratory distress syndrome (ARDS). In this study, we sought to determine the incidence and potential risk factors of pneumothorax in critically ill adults with COVID-19.

Method

This retrospective cohort study included adult patients with laboratory-confirmed SARS-CoV-2 infection admitted to one of the adult intensive care units of a tertiary, academic teaching hospital from May 2020 through May 2021.

Results

Among 334 COVID-19 cases requiring ICU admission, the incidence of pneumothorax was 10% (33 patients). Patients who experienced pneumothorax more frequently required vasopressor support (28/33 [84%] vs. 191/301 [63%] P = 0.04), were more likely to be proned (25/33 [75%] vs. 111/301 [36%], P<0.001), and the presence of pneumothorax was associated with prolonged duration of mechanical ventilation; 21 (1–97) versus 7 (1–79) days, p<0.001 as well as prolonged hospital length of stay (29 [9–133] vs. 15 [1–90] days, P<0.001), but mortality was not significantly different between groups. Importantly, when we performed a Cox proportional hazard ratio (HR) model of multivariate parameters, we found that administration of tocilizumab significantly increased the risk of developing pneumothorax (HR = 10.7; CI [3.6–32], P<0.001).

Conclusion

Among 334 critically ill patients with COVID-19, the incidence of pneumothorax was 10%. Presence of pneumothorax was associated with prolonged duration of mechanical ventilation and length of hospital stay. Strikingly, receipt of tocilizumab was associated with an increased risk of developing pneumothorax.

Macklin effect on baseline chest CT scan accurately predicts barotrauma in COVID-19 patients

Purpose

To validate the role of Macklin effect on chest CT imaging in predicting subsequent occurrence of pneumomediastinum/pneumothorax (PMD/PNX) in COVID-19 patients.

Materials and methods

This is an observational, case-control study. Consecutive COVID-19 patients who underwent chest CT scan at hospital admission during the study time period (October 1st, 2020–April 31st, 2021) were identified. Macklin effect accuracy for prediction of spontaneous barotrauma was measured in terms of sensitivity, specificity, positive (PPV) and negative predictive values (NPV).

Results

Overall, 981 COVID-19 patients underwent chest CT scan at hospital arrival during the study time period; 698 patients had radiological signs of interstitial pneumonia and were considered for further evaluation. Among these, Macklin effect was found in 33 (4.7%), including all 32 patients who suffered from barotrauma lately during hospital stay (true positive rate: 96.9%); only 1/33 with Macklin effect did not develop barotrauma (false positive rate: 3.1%). No barotrauma event was recorded in patients without Macklin effect on baseline chest CT scan. Macklin effect yielded a sensitivity of 100% (95% CI: 89.1–100), a specificity of 99.85% (95% CI: 99.2–100), a PPV of 96.7% (95% CI: 80.8–99.5), a NPV of 100% and an accuracy of 99.8% (95% CI: 99.2–100) in predicting PMD/PNX, with a mean advance of 3.2 ± 2.5 days. Moreover, all Macklin-positive patients developed ARDS requiring ICU admission and, in 90.1% of cases, invasive mechanical ventilation.

Conclusions

Macklin effect has high accuracy in predicting PMD/PNX in COVID-19 patients; it is also an excellent predictor of disease severity.

Incidence and Clinical Features of Pneumomediastinum and Pneumothorax in COVID-19 Pneumonia

Background

Pneumothorax (PTX) and pneumomediastinum (PM), collectively termed here “air leak”, are now well described complications of severe COVID-19 pneumonia across several case series. The incidence is thought to be approximately 1% but is not definitively known.

Objectives

To report the incidence and describe the demographic features, risk factors and outcomes of patients with air leak as a complication of COVID-19.

Methods

A retrospective observational study on all adult patients with COVID-19 admitted to Watford General Hospital, West Hertfordshire NHS Trust between March 1st 2020 and Feb 28^th 2021. Patients with air leak were identified after reviewing both chest radiographs (CXRs) and axial imaging (CT Thorax) with confirmatory radiology reports inclusive of the terms PTX and/or PM.

Results

Air leak occurred with an incidence of 0.56%. Patients with air leak were younger and had evidence of more severe disease at presentation, including a higher median CRP and number of abnormal zones affected on chest radiograph. Asthma was a significant risk factor in the development of air leak (OR 13.4 [4.7-36.4]), both spontaneously and following positive pressure ventilation. CPAP and IMV were also associated with a greater than six fold increase in the risk of air leak (OR 6.4 [2.5-16.6] and 9.8 [3.7-27.8] respectively). PTX, with or without PM, in the context of COVID-19 pneumonia was almost universally fatal whereas those with alone PM had a lower risk of death.

Conclusion

Despite the global vaccination programme, patients continue to develop severe COVID-19 disease and may require respiratory support. This study demonstrates the importance of identifying that deterioration in such patients may be resultant from PTX or PM, particularly in asthmatics and those managed with positive pressure ventilation.

Veno-Venous Extracorporeal Membrane Oxygenation in Awake Non-Intubated Patients with COVID-19 ARDS at High Risk for Barotrauma

Objectives: To assess the efficacy of an awake venovenous extracorporeal membrane oxygenation (VV-ECMO) management strategy in preventing clinically relevant barotrauma in patients with coronavirus disease 2019 (COVID-19) with severe acute respiratory distress syndrome (ARDS) at high risk for pneumothorax (PNX)/pneumomediastinum (PMD), defined as the detection of the Macklin-like effect on chest computed tomography (CT) scan.

Design: A case series.

Setting: At the intensive care unit of a tertiary-care institution.

Participants: Seven patients with COVID-19-associated severe ARDS and Macklin-like radiologic sign on baseline chest CT.

Interventions: Primary VV-ECMO under spontaneous breathing instead of invasive mechanical ventilation (IMV). All patients received noninvasive ventilation or oxygen through a high-flow nasal cannula before and during ECMO support. The study authors collected data on cannulation strategy, clinical management, and outcome. Failure of awake VV-ECMO strategy was defined as the need for IMV due to worsening respiratory failure or delirium/agitation. The primary outcome was the development of PNX/PMD.

Measurements and Main Results: No patient developed PNX/PMD. The awake VV-ECMO strategy failed in 1 patient (14.3%). Severe complications were observed in 4 (57.1%) patients and were noted as the following: intracranial bleeding in 1 patient (14.3%), septic shock in 2 patients (28.6%), and secondary pulmonary infections in 3 patients (42.8%). Two patients died (28.6%), whereas 5 were successfully weaned off VV-ECMO and were discharged home.

Conclusions: VV-ECMO in awake and spontaneously breathing patients with severe COVID-19 ARDS may be a feasible and safe strategy to prevent the development of PNX/PMD in patients at high risk for this complication.

Protective ventilation in patients with acute respiratory distress syndrome related to COVID-19: always, sometimes or never?

PURPOSE OF REVIEW

To review current evidence on the pathophysiology of COVID-19-related acute respiratory distress syndrome (ARDS) and on the implementation of lung protective ventilation.

RECENT FINDINGS

Although multiple observations and physiological studies seem to show a different pathophysiological behaviour in COVID-19-ARDS compared with 'classical' ARDS, numerous studies on thousands of patients do not confirm these findings and COVID-19-ARDS indeed shares similar characteristics and interindividual heterogeneity with ARDS from other causes. Although still scarce, present evidence on the application of lung protective ventilation in COVID-19-ARDS shows that it is indeed consistently applied in ICUs worldwide with a possible signal towards better survival at least in one study. The levels of positive end-expiratory pressure (PEEP) usually applied in these patients are higher than in 'classical' ARDS, proposing once again the issue of PEEP personalization in hypoxemic patients. In the absence of robust evidence, careful evaluation of the patient is needed, and empiric settings should be oriented towards lower levels of PEEP.

SUMMARY

According to the present evidence, a lung protective strategy based on low tidal volume and plateau pressures is indicated in COVID-19-ARDS as in ARDS from other causes; however, there are still uncertainties on the appropriate levels of PEEP.

Incidence of Pneumothorax and Pneumomediastinum in 497 COVID-19 Patients with Moderate-Severe ARDS over a Year of the Pandemic: An Observational Study in an Italian Third Level COVID-19 Hospital

(1) Background: COVID-19 is a novel cause of acute respiratory distress syndrome (ARDS). Indeed, with the increase of ARDS cases due to the COVID-19 pandemic, there has also been an increase in the incidence of cases with pneumothorax (PNX) and pneumomediastinum (PNM). However, the incidence and the predictors of PNX/PMN in these patients are currently unclear and even conflicting. (2) Methods: The present observational study analyzed the incidence of barotrauma (PNX/PNM) in COVID-19 patients with moderate-severe ARDS hospitalized in a year of the pandemic, also focusing on the three waves occurring during the year, and treated with positive-pressure ventilation (PPV). We collected demographic and clinical data. (3) Results: During this period, 40 patients developed PNX/PNM. The overall incidence of barotrauma in all COVID-19 patients hospitalized in a year was 1.6%, and in those with moderate-severe ARDS in PPV was 7.2% and 3.8 events per 1000 positive-pressure ventilator days. The incidence of barotrauma in moderate-severe ARDS COVID-19 patients during the three waves was 7.8%, 7.4%, and 8.7%, respectively. Treatment with noninvasive respiratory support alone was associated with an incidence of barotrauma of 9.1% and 2.6 events per 1000 noninvasive ventilator days, of which 95% were admitted to the ICU after the event, due to a worsening of respiratory parameters. The incidence of barotrauma of ICU COVID-19 patients in invasive ventilation over a year was 5.8% and 2.7 events per 1000 invasive ventilator days. There was no significant difference in demographics and clinical features between the barotrauma and non-barotrauma group. The mortality was higher in the barotrauma group (17 patients died, 47.2%) than in the non-barotrauma group (170 patients died, 37%), although this difference was not statistically significant (p = 0.429). (4) Conclusions: The incidence of PNX/PNM in moderate-severe ARDS COVID-19 patients did not differ significantly between the three waves over a year, and does not appear to be very different from that in ARDS patients in the pre-COVID era. The barotrauma does not appear to significantly increase mortality in COVID-19 patients with moderate-severe ARDS if protective ventilation strategies are applied. Attention should be paid to the risk of barotrauma in COVID-19 patients in noninvasive ventilation because the event increases the probability of admission to the intensive care unit (ICU) and intubation.