Purpose
This study evaluated the clinical effects of Heated humidified high flow nasal cannula (HHHFNC) treatment in pediatric patients with respiratory disease and respiratory insufficiency.

Methods
We retrospectively reviewed the medical records for the clinical features and tests performed in patients admitted to the Chungnam University Hospital pediatric ward and treated with HHHFNC between July 2014 and December 2018. We evaluated the effects of HHHFNC treatment in patients with bronchiolitis treated with oxygen using nasal prong.

Results
The 136 children treated with HHHFNC during the study period and the median age was 8 months. Among the 136 patients, 39 (28.7%) were diagnosed with bronchiolitis and pneumonia, 42 (30.9%) with pneumonia, 28 (20.6%) with bronchiolitis, 3 (2.2%) with epilepsy. Thirty-five patients (25.7%) had underlying neurological disorders. Fifty one (37.5%) received invasive ventilator treatment. After HHHFNC treatment, venous blood gas analysis (VBGA) showed a pH increase from 7.32 to 7.37 (P<0.05) and a decrease in partial pressure of carbon dioxide (pCO2) from 53.1 to 46.2 mmHg (P<0.05). The respiratory rate had decreased from 46.3 to 43.3/minute (P<0.05). There were no statistically significant differences in hospital stay duration or ICU admission rates between the HHHFNC treatment and control (oxygen therapy with nasal prong) patients with bronchiolitis before the introduction of HHHFNC.

Conclusion
In this study, in various diseases leading to pediatric respiratory insufficiency, HHHFNC treatment may improve physiologic parameters at pediatric ward. HHHFNC was also effective in patients with underlying neurological disorders and those with respiratory insufficiency from non-respiratory infectious disease.