Background: Humidified high flow nasal cannula (HFNC) has been shown to be an effective respiratory support therapy in
both primary and post-extubation patients with Type 1 respiratory failure (T1RF). Clinical outcomes using HFNC in patients with
hypercapnic respiratory failure or Type 2 respiratory failure (T2RF) are less well understood as research to date has frequently
excluded hypercapnic patients. However, there is growing evidence that suggests HFNC could be beneficial in patients with T2RF.
Aims: To describe the outcome of patients with T2RF who received primary HFNC and to elaborate a safe algorithm for its use.
Methods: We conducted a retrospective observational study on the use of HFNC as a primary treatment in 102 (n=102)
consecutive subjects admitted to the Intensive Care Unit (ICU) from August 2015 to June 2017. Vital signs and arterial blood gases
were evaluated before, one hour and 6 hours after initiation HFNC and their need for escalation of therapy was collected from
Results: In T2RF patients it was observed that HFNC was successful in 51.28%, and despite escalation, 90% of subjects were
successfully discharged from hospital. Need for escalation of therapy was observed at 24.56 hours of treatment with HFNC. In our
population, in both T1RF and T2RF, those with a pH<7.30 and a RR≥30 prior and one-hour post initiation of HFNC were more likely
to require escalation of therapy and, these parameters had 97% specificity and 80% predictive value.
Conclusion: HFNC could be cautiously used as primary therapy in hypercapnic respiratory failure. The clinical parameters:
pH<7.30 and a RR≥30, prior and post initiation of HFNC, allow a risk stratification of subjects and a safe guide in case of needing an
escalation of therapy.
Keywords: Humidified high flow nasal cannula; Respiratory high flow therapy; High flow oxygen therapy; High flow nasal cannula
oxygen therapy; Heated humidified high flow therapy; Type 2 respiratory failure