High-flow nasal cannula oxygen in patients with haematological malignancy: a retrospective observational study.

Patients with haematological malignancies (HM) face high rates of intensive care unit (ICU) admission and mortality. High-flow nasal cannula oxygen (HFNCO) is increasingly used to support HM patients in ward settings, but there is limited evidence on the safety and efficacy of HFNCO in this group. We retrospectively reviewed all HM patients receiving ward-based HFNCO, supervised by a critical care outreach service (CCOS), from January 2014 to January 2019. We included 130 consecutive patients. Forty-three (33.1%) were weaned off HFNCO without ICU admission. Eighty-seven (66.9%) were admitted to ICU, 20 (23.3%) required non-invasive and 34 (39.5%) invasive mechanical ventilation. ICU and hospital mortality were 42% and 55% respectively. Initial FiO2 < 0.4 (OR 0.27, 95% CI 0.09-0.81, p = 0.019) and HFNCO use on the ward > 1 day (OR 0.16, 95% CI 0.04, 0.59, p = 0.006) were associated with reduced likelihood for ICU admission. Invasive ventilation was associated with reduced survival (OR 0.27, 95%CI 0.1-0.7, p = 0.007). No significant adverse events were reported. HM patients receiving ward-based HFNCO have higher rates of ICU admission, but comparable hospital mortality to those requiring CCOS review without respiratory support. Results should be interpreted cautiously, as the model proposed depends on the existence of CCOS.