An observational study of therapeutic bronchoscopy in critical hypoxaemic ventilated patients with COVID-19 at Mediclinic Midstream Private Hospital in Pretoria, South Africa
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the novel coronavirus which causes COVID-19. At the time of writing (24th August 2020) and since its initial detection, more than 23 605 542 cases have been confirmed and 812 757 people have died worldwide. In South Africa, the number of confirmed cases has continued to rise and is currently standing at 609 773 with 13 059 deaths since the first cases were reported in March 2020.
Eighty-one percent of patients with COVID-19 are asymptomatic while 14.1% present with severe disease and 4% are critically ill and require mechanical ventilation.
However, despite the continued global rise in mortality since the outbreak of SARS-CoV-2 in Wuhan, China in 2019, the highly infectious nature of the virus has resulted in limited use of bronchoscopy. It is being utilised primarily for diagnostic or management purposes in non-COVID-19 patients.
COVID-19 patients who require mechanical ventilation have been classified into two phenotypes according to Gattinoni and these have been incorporated into the Surviving Sepsis Guideline: the L- and H-type. The L-type is characterised by low elastance (high compliance), is easy to ventilate, has low lung recruitability and may respond to early proning. The H-type is characterised by high elastance (low compliance) that resembles more closely patients with typical acute respiratory distress syndrome (ARDS) and is potentially recruitable.
The H-type may have a higher mortality with most patients requiring further interventions such as proning, airway pressure release ventilation (APRV) or even extracorporeal membrane oxygenation (ECMO).
The L-type theoretically can progress to the H type over time. Some of these patients in the L- or H- categories fail to improve their oxygenation despite optimal chemotherapy and mechanical ventilation. These patients have a prolonged ventilatory course, often complicated by secondary hospital-acquired sepsis with an associated high mortality.
It has been presumed that this represents a combination of irreversible pulmonary fibrosis and microvascular pulmonary thrombosis.
Currently, there are no studies to support the use of flexible fibreoptic bronchoscopy (FFB) as a therapeutic tool in these patients primarily because there is no obvious evidence of atelectasis or dynamic hyperinflation suggesting airway pathology. We nevertheless decided to perform FFB after the point of maximal care had been reached without improvement in oxygenation to assess the status of the airways and to see whether there would be an impact on oxygenation.
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