Background The utility of heated and humidified high-flow nasal oxygen (HFNO) for severe COVID-19-related hypoxaemic respiratory failure (HRF), particularly in s``ettings with limited access to intensive care unit (ICU) resources, remains unclear, and predictors of outcome have been poorly studied. Methods We included consecutive patients with COVID-19-related HRF treated with HFNO at two tertiary hospitals in Cape Town, South Africa. The primary outcome was the proportion of patients who were successfully weaned from HFNO, whilst failure comprised intubation or death on HFNO. Findings The median (IQR) arterial oxygen partial pressure to fraction inspired oxygen ratio (P a O2/FiO 2 ) was 68 (54–92) in 293 enroled patients. Of these, 137/293 (47%) of patients [P a O2/FiO 2 76 (63–93)] were successfully weaned from HFNO. The median duration of HFNO was 6 (3–9) in those successfully treated versus 2 (1–5) days in those who failed ( p <0.001). A higher ratio of oxygen saturation/FiO2 to respiratory rate within 6 h (ROX-6 score) after HFNO commencement was associated with HFNO success (ROX-6; AHR 0.43, 0.31–0.60), as was use of steroids (AHR 0.35, 95%CI 0.19–0.64). A ROX-6 score of ≥3.7 was 80% predictive of successful weaning whilst ROX-6 ≤ 2.2 was 74% predictive of failure. In total, 139 patents (52%) survived to hospital discharge, whilst mortality amongst HFNO failures with outcomes was 129/140 (92%). Interpretation In a resource-constrained setting, HFNO for severe COVID-19 HRF is feasible and more almost half of those who receive it can be successfully weaned without the need for mechanical ventilation.

Background: The utility of heated and humidified high-flow nasal oxygen (HFNO) for severe COVID-19related hypoxaemic respiratory failure (HRF), particularly in settings with limited access to intensive care unit (ICU) resources, remains unclear, and predictors of outcome have been poorly studied. Methods: We included consecutive patients with COVID-19-related HRF treated with HFNO at two tertiary hospitals in Cape Town, South Africa. The primary outcome was the proportion of patients who were successfully weaned from HFNO, whilst failure comprised intubation or death on HFNO. Findings: The median (IQR) arterial oxygen partial pressure to fraction inspired oxygen ratio (P a O2/FiO 2 ) was 68 (54À92) in 293 enroled patients. Of these, 137/293 (47%) of patients [P a O2/FiO 2 76 (63À93)] were successfully weaned from HFNO. The median duration of HFNO was 6 (3À9) in those successfully treated versus 2 (1À5) days in those who failed (p<0.001). A higher ratio of oxygen saturation/FiO2 to respiratory rate within 6 h (ROX-6 score) after HFNO commencement was associated with HFNO success (ROX-6; AHR 0.43, 0.31À0.60), as was use of steroids (AHR 0.35, 95%CI 0.19À0.64). A ROX-6 score of 3.7 was 80% predictive of successful weaning whilst ROX-6 2.2 was 74% predictive of failure. In total, 139 patents (52%) survived to hospital discharge, whilst mortality amongst HFNO failures with outcomes was 129/140 (92%). Interpretation: In a resource-constrained setting, HFNO for severe COVID-19 HRF is feasible and more almost half of those who receive it can be successfully weaned without the need for mechanical ventilation.

Background: During the outbreak of coronavirus disease 2019 (COVID-19) many studies have investigated laboratory biomarkers in management and prognostication of COVID-19 patients, however to date, few have investigated arterial blood gas (ABG), acid-base and blood pressure (BP) patterns. The aim of the study is to assess the ABG and acid-base patterns, BP findings and their association with the outcomes of COVID-19 patients admitted to an intensive care unit (ICU). Methods: A single-centre retrospective, observational study in a dedicated COVID-19 ICU in Cape Town, South Africa. Admission ABG, serum electrolytes, renal function and BP readings performed on COVID-19 patients admitted between 26 March and 2 June 2020 were analysed and compared between survivors and non-survivors. Results: A total of 56 ICU patients had admission ABG performed at the time of ICU admission. An alkalaemia (pH > 7.45) was observed in 36 (64.3%) patients. A higher arterial pH [median 7.48 (IQR: 7.45-7.51 vs. 7.46 (IQR: 7.40-7.48), p=0.049] and partial pressure of oxygen in arterial blood [PaO2; median 7.9kPa (IQR 7.3- 9.6) vs. 6.5kPa (IQR: 5.2-7.3), p=<0.001] were significantly associated with survival. Survivors also tended to have a higher systolic BP [median: 144mmHg (IQR: 134- 152) vs. 139mmHg (IQR: 125-142), p=0.078] and higher arterial HCO3 [median: 28.0mmol/L (IQR: 25.7- 28.8) vs. 26.3mmol/L (IQR: 24.3-27.9); p=0.059). Conclusions: The majority of the study population admitted to ICU had an alkalaemia on ABG. A higher pH and lower PaO2 on ABG analysis were significantly associated with survival.

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