Effectiveness of high-flow nasal cannula oxygen therapy for acute respiratory failure with hypercapnia

Heated and humidified high-flow nasal cannula (HFNC) oxygen therapy has recently been introduced for hypoxic respiratory failure. However, it has not been well-evaluated for acute respiratory failure with hypercapnia.

This retrospective study included acute respiratory failure patients with hypercapnia in the medical intensive care unit (MICU) from April 2011 to February 2013, who required HFNC oxygen therapy for hypoxemia. Respiratory parameters were recorded and arterial blood gas analyses conducted before, and at 1 and 24 h after initiation of HFNC oxygen therapy.

Thirty-three patients were studied [median age, 72 years; range, 17-85 years; men, 24 (72.7%)]. Pneumonia (36.4%) and acute exacerbation of chronic obstructive pulmonary disease (33.4%) were the most common reasons for oxygen therapy. Most patients (60.6%) received oxygen therapy via nasal prong before HFNC application. The mean fraction of inspired oxygen (FiO₂) and HFNC flow rate were 0.45±0.2 and 41.1±7.1 L/min, respectively; mean duration of application was 3.6±4.1 days. The partial pressure of arterial carbon dioxide (PaCO₂) was 55.0±12.2 mmHg at admission, and increased by approximately 1.0±7.7 mmHg with conventional oxygen therapy. In contrast, with HFNC therapy, PaCO₂ decreased by 4.2±5.5 and 3.7±10.8 mmHg in 1 and 24 h, respectively, resulting in significant improvement in hypercapnia (P=0.006 and 0.062, respectively).

HFNC oxygen therapy with sufficient FiO₂ to maintain a normal partial pressure of arterial oxygen (PaO₂) significantly reduced PaCO₂ in acute respiratory failure with hypercapnia.