ABSTRACT
Background: Continuous positive airway pressure (CPAP) can improve oxygenation in severe COVID-19 pneumonia. Objective(s): To assess whether CPAP-associated improvements in oxygenation can inform clinical outcomes in patients with severe COVID-19 pneumonia. Method(s): Retrospective study in patients with severe COVID-19 pneumonia treated with CPAP in three academic respiratory units in Milan, Italy. Arterial gas analysis obtained before and 1 hour after starting CPAP. CPAP failure defined as either death in the respiratory units while on CPAP or need for intubation. Result(s): 211 patients (mean age 64 years, 74% males) were included. Baseline median PaO2was 68 (57-83) mmHg, PaO2/FiO2(P/F) ratio was 129 (91-179) mmHg and alveolar-arterial (A-a) O2 gradient was 310 (177-559) mmHg. On CPAP, PaO2and P/F increased to 100 (79-141) (p<0.001) and 195 (132-257;p<0.001) mmHg and A-a gradient decreased to 240 (188-308;p<0.001) mmHg. 42 (19.9%) patients died in the respiratory units while on CPAP and 51 (24.2%) required intubation. There was a substantial overlap of baseline and CPAP-associated values of PaO2, P/F ratio and A-a gradient in CPAP failures and successes (Figure). CPAP-associated changes in PaO2, P/F ratio and A-a gradient in both groups were similar. Conclusion(s): CPAP-associated improvements in oxygenation cannot be used to inform clinical outcomes of the individual patient with severe COVID-19 pneumonia.
ABSTRACT
To evaluate outcomes of COVID-19 patients with pneumonia-related hypoxaemic acute respiratory failure (hARF) undergoing continuous positive airway pressure therapy (CPAP) treatment, hence, a multicentre, observational, prospective study was conducted between 7 March 2020 and 21 April 2020 in three high-dependency units (HDU) at two hospitals in Milan, Italy. The primary outcome was CPAP failure defined as the occurrence of either intubation or death due to any cause during hospital high-dependency units (HDU) stay while secondary outcomes included the weaning from CPAP to oxygen therapy (CPAP success), all-cause in-hospital and 30-day mortality. A total of 157 patients with hARF (median (IQR) PaO2/FIO2 ratio 142.9 (96.7-203.2)) underwent helmet CPAP with an initial median (IQR) FIO2 of 0.6 (0.5-0.6) and mean positive end-expiratory pressure (PEEP) of 10.8+or-2.3 cmH<sub>2</sub>O. The most prevalent comorbidities were arterial hypertension (44.0%), diabetes (22.9%), ischaemic cardiac disease (17.2%) and chronic arrhythmia (10.8%). Hypoxaemia generally improved when CPAP treatment was initiated: median (IQR) values of PaO2/FIO2 ratio at baseline on oxygen therapy (142.9 (96.7-203.2)) significantly improved when helmet CPAP was used after 6 h (205.6 (140.0-271.1), p<0.0001). However, an increase of at least 30% in PaO2/FIO2 ratio during helmet CPAP application in comparison to oxygen therapy was found only in 52% of the population. Median (IQR) duration of helmet CPAP treatment was 6 days. Only 4 patients discontinued helmet CPAP because of intolerance. CPAP failure was observed in 70 (44.6%) patients: 34 (21.7%) were intubated and 36 (22.9%) died during the HDU stay. 87 (55.4%) patients improved during the HDU stay, weaned to oxygen therapy and transferred to the general ward. No patients were intubated during the first hours after CPAP initiation or under high emergency conditions. Among those who died in HDU, pneumonia-related deaths were detected in 26 patients, while non-pneumonia related in 10 patients, including pulmonary embolisms (n=5), end-stage renal failure (n=2), cerebrovascular accident (n=1), end-stage heart failure (n=1) and septic shock (n=1). Among the 34 patients who were intubated in HDU and transferred to the ICU, nine (26.5%) died. A total of 65 (41.4%) patients had a Do-Not-Intubate (DNI) status on HDU admission: 36 died and 29 survived. At the multivariable analysis, CPAP failure was associated with the severity of pneumonia on admission (HR (95% CI) 2.9 (1.3-6.2), p=0.009) and higher baseline values of interleukin-6 (HR (95% CI) 1.0 (1.0-1.0), p<0.009). The all-cause in-hospital and 30-day mortality rates were 28.7% and 28.0%, respectively.