Macklin Effect in the Current Pandemic: A Pathological Sequelae or Ventilator-Associated Lung Injury

ABSTRACT

Aim and background: SARS-CoV-2 pandemic questioned many basic concepts in medicine. COVID-19 affects many organ systems despite the lung being the primary affected organ. ARDS management is challenging and a new complication during the management adds to the burden. Macklin described a pathophysiological process by which air escaped through the ruptured alveolar basement membrane causing pneumomediastinum. The occurrence of air leak syndromes (ALS) in COVID-19 made us investigate the disease and its association with the complication. Objective: To observe the clinicopathological profile of patients who developed air leak syndrome during the second wave of the pandemic. Materials and methods: A retrospective analysis was conducted on SARSCoV- 2 patients admitted to ICU due to ARDS. The study included patients admitted from March to June 2021 with rTPCR positive test for SARS-CoV-2 illness and diagnosed to have ARDS as defined by the Berlin criteria. We analyzed 195 cases admitted in the ICU who met the above criteria and received protocolised care as per national and institutional guidelines. Cases who received ventilatory support either as HFNO (high flow nasal oxygenation), NIV (noninvasive ventilation), or invasive mechanical ventilation as per ARDS NET protocol and developed ALS were included. Demographic and clinical profiles of patients and laboratory parameters like acute phase reactants, haemogram, and serum creatinine were analysed. Results: 5.6% of patients were diagnosed to have air leak syndrome, which includes subcutaneous emphysema, pneumomediastinum, pneumopericardium, and pneumothorax. 81% of the cases were men. The average age was 44.8 years. 90% of the patients had no pre-existing lung pathology or respiratory comorbidity. 81.8% did not have a documented history of smoking. 63.33% of patients had other preexisting co-morbidities. 27.2% of patients had more than one comorbidity with diabetes mellitus being the most common. The average time to develop air leak syndrome was 6 days. 81% of the patients received mechanical ventilation, 2 patients were only on HFNO. 90% of the patients were prone in view of severe ARDS. From air leak syndromes mentioned above, 72.2% developed pneumothorax, 63.3% of the patients developed subcutaneous emphysema, 54.5% of the patients developed pneumomediastinum, and 9% developed pneumopericardium. 1 patient (9%) developed the complete spectrum of ALS. 63% of the patients developed 2 or more entities of the air leak, i.e., subcutaneous emphysema, pneumomediastinum, pneumopericardium, and pneumothorax. Acute phase reactants were elevated in all patients who developed ALS. There was neutrophil predominance in the haemogram. Only one patient developed AKI. Another compelling finding was the development of secondary infection, the majority was respiratory tract infections (81%) followed by urinary tract infections. Candiduria was observed in 36.6% of patients. The average duration of stay was 21.6 days. The mortality rate was 63%. 4 patients were discharged who had an average time to resolution of 8 days. Conclusion: COVID-19 is majorly a self-limiting disease. Secondary bacterial infection and poor oxygenation was major finding in our study. Development of ALS in a previously normal lung with no preexisting lung pathology points towards the need to conclude ALS and viral pneumonias.