Discriminating between CPAP success and failure in COVID-19 patients with severe respiratory failure

 

Discriminating between CPAP success and failure in COVID-19 patients with severe respiratory failure

 

By: Pietro Arina, Beatrice Baso, Valeria Moro, Hemani Patel, Gareth Ambler on behalf of the UCL Critical Care COVID-19 Research Group

Intensive Care Medicine (2020) Published: 16 November 2020

 

Research letter

Continuous positive airways pressure (CPAP) treatment was used increasingly in the UK and elsewhere for coronavirus disease 2019 (COVID-19) to avoid the need for mechanical ventilation [1,2,3]. Early identification of patients benefitting from CPAP would assist decision making however we found that intensive care unit (ICU) admission respiratory parameters (rate, PaO2/FiO2 ratio) were poorly discriminatory. Using electronic healthcare records we retrospectively studied COVID-19 patients admitted to the University College London Hospital ICU between 8 March and 5 June 2020 in moderate-to-severe respiratory failure who received initial management with CPAP to see whether better prognosticators could be identified.

Comparison of demographic, clinical and biochemical parameters measured on ICU admission was made between patients adjudged CPAP success (hospital survival with CPAP alone) or failure (either death where CPAP was a ceiling of treatment, or need for mechanical ventilation regardless of hospital outcome). Requirement for other organ support was also compared. Patients managed on CPAP in non-ICU wards were excluded as detailed clinical and lab data were often lacking.

Of 108 within-hospital admissions, 93 (86%) received CPAP as initial respiratory failure management (median[IQR] PaO2/FiO2 ratio 13 [10–18] kPa) (Supplementary Fig. 1). Thirty-two (34%) were adjudged CPAP successes and 61 (66%) failures (14 deaths (23%) with CPAP as the ceiling of treatment, 47 (77%) requiring invasive ventilation of whom 26 died). Demographics and ICU admission values of respiratory rate, inspired oxygen concentration (FiO2) and PaO2/FiO2 ratio were similar between groups (Supplementary data). Admission values of C-reactive protein (CRP) (p < 0.0001), N Terminal-pro-B-type natriuretic peptide (NT-proBNP) (p < 0.001), troponin-T (p < 0.001) and D-dimers (p < 0.05) were significantly higher in CPAP failure patients (Fig. 1). Other organ support was only required for CPAP failure patients receiving invasive ventilation (46 vasopressors, 28 renal replacement therapy), but none for CPAP successes. At 6 h post-CPAP the PaO2/FiO2 ratio rose by 76.7% (37.9 to 99.8%) in CPAP success patients but only by 38.1% (−24.4 to 100.5) in the failure group (p = 0.015)…