Predictors of Non-invasive Ventilation Response Do Not Indicate Response to High Flow Nasal Oxygen: A Bicentric Observational Study.
Abstract BackgroundIn patients receiving high flow nasal oxygen (HFNO), predicting chance of response is crucial in order to avoid unnecessary delay of intubation. Whether commonly used predictors of non-invasive ventilation (NIV) response may be as applicable for HFNO, is unclear.MethodsWe conducted a retrospective bi-centric analysis of adults treated with HFNO in two Austrian medical intensive care units from 01/2014 until 09/2017. Predictive value of respiratory rate, PaO2, PaCO2, SpO2, ROX index, pH, heart rate, base excess, SOFA-Score and SAPS III was analysed by means of logistic regression with HFNO responding as dependent variable. Calculations were also done separately in patients receiving HFNO as post-extubation support (Group A) and all other indications (Group B). ResultsWe registered 127 patients (m:f = 70:57, median age: 67 [IQR 53-77] years). Forty-eight patients (37.8%) received HFNO as post-extubation support and were assigned to group A. Seventy-nine patients (62.2%) received HFNO due to any other indication and were assigned to group B. Criteria of HFNO response were fulfilled by 42 patients (87.5%) of group A and 53 (67.1%) of group B patients.Whereas respiratory rate, PaO2, PaCO2, SpO2, pH, heart rate, base excess, SOFA-Score and SAPS III did not differ between responders and non-responders, ROX index showed significant association with HFNO success in all patients. With increasing ROX index, the odds for response increased (OR [95% CI]: baseline: 1.21 [1.05, 1.38], p = 0.0069, after 2 hours: 1.19 [1.05; 1.34], p = 0.0061, after 6 hours: 1.23 [1.06; 1.42], p = 0.0049). Subgroup analyses revealed similar odds ratios for ROX index (baseline: group A: 1.17 [0.90; 1.52], p = 0.24; group B: 1.22 [1.04; 1.43], p = 0.015; after 2 hours: 1.30 [0.94; 1.82], p = 0.12, group B: 1.18 [1.03; 1.34], p = 0.014; after 6 hours: 1.76 [1.01; 3.06], p = 0.047, group B: 1.19 [1.03; 1.37], p = 0.022). ConclusionsCriteria of HFNO success deviate from criteria for response to NIV. ROX index indicated HFNO response in a wide range of indications.