Background Nasal high flow (NHF) delivers warmed humidified oxygen up to 65L/min and is commonly used in intensive care units (ICU). In a non-critical care settings it can provide a bridge to ICU for hypoxic patients, and symptom palliation for those unsuitable for escalation.
Evidence to support NHF use in a non-critical care setting is limited. We aimed to review patient selection and clinical outcomes for individuals commenced on NHF over two winter periods, in order to highlight prognostic indicators and develop a clinical guideline.
Method We performed a retrospective review of 93 cases managed with NHF September-December in 2014 and 2015 in a medium sized DGH. Patients were included regardless of diagnosis and treatment escalation plan. Data was collected on patient demographics, diagnosis, management and clinical outcome. Results described as %(n).
Results 93 patients (mean age 71.2 yrs, SD 14.8). Presenting complaint: Pneumonia 57.0% (53), Aspiration pneumonia 4.3% (4), Pulmonary embolism 4.3% (4), Pulmonary oedema 3.2% (3), Interstitial Lung Disease 3.2% (3), other diagnoses 28.0% (26). Clinical indication: Hypoxia 64.5% (60), hypoxia and work of breathing 14.0% (13), work of breathing alone 7.5% (7) and palliation 14.0% (13).
42 patients (45%) were assessed by ICU, of which 21 patients were deemed appropriate [mean age 65 yrs (40–84)]. 62% (13) were intubated. 81% (17) survived to discharge; 5.9% (1) required LTOT. No significant correlation was present between flow rates and mortality (p = 0.7).
72 patients (77.4%) were managed in non-critical care settings [mean age 72.7 yrs (28–99)]. 48.6% (35) survived to discharge, 14.3% (5) required LTOT and 5.7% (2) died within 30 days of discharge. Flow rates ranged 20–65 L/min. In non-ICU patients, survival was negatively correlated with increasing flow rates (r = −0.86). Patients requiring ≥60 L/min had an 86% mortality rate (p = 0.0001).
Conclusion Mortality rates were higher in patients managed on NHF in a non-critical care setting. A negative correlation was present between flow rates and survival outside of ICU. This may be explained by an older patient cohort, associated comorbidities and premorbid performance status. However this information could help guide clinical decision making in acutely unwell patients with limited escalation options.