HFNC a reasonable first option for patients with mild acute hypercapnic respiratory failure

High-flow nasal cannula (HFNC) oxygen therapy may be a reasonable initial treatment option for patients presenting with mild  acute hypercapnic respiratory failure, a Queensland study suggests.

The treatment proved effective and better tolerated than non-invasive ventilation (NIV) in real world use according to results from a retrospective audit carried out by respiratory physicians at The Prince Charles Hospital, Brisbane.

However their report on HFNC and NIV usage in 69 admissions for  acute hypercapnic respiratory failure at the hospital’s thoracic medicine unit found that HFNC may be less suited for obese patients and those with sleep disordered breathing.

In an article published in the Internal Medicine Journal they noted that HFNC proved to be safe and effective in normalising blood gas  parameters for most patients with mild acute hypercapnic respiratory failure.  There were no significant differences in length of stay, mortality or readmission observed for patients treated initially with HFNC and those treated with NIV.

The patients had a mean age was 69 and had a variety of diagnoses including COPD 955%), heart failure (36%) and pneumonia (9%). Patients treated with NIV group were

more likely to have an admission diagnosis of sleep disordered breathing than those treated with HFNC (48% vs 14%).

HFNC treatment had an average flow rate of 40L/min (range 20 to 60L/min), while NIV settings were titrated to an average inspiratory pressure of 15.0cmH2O and average expiratory pressure of  6.6cmH2O.

In both groups, mean arterial pCO2  improved significantly (-10 mmHg) from baseline, with no difference seen between groups.

Complications occurred in four patients treated with NIV (8.8%), including two pressure injuries and two  cases of poor tolerance of positive pressure therapy.

Six patients transitioned from HFNC to NIV, and the study authors said it was notable that two of the three obese patients with comorbid obstructive sleep apnoea (OSA) or obesity hypoventilation syndrome (OHS) treated with HFNC first failed treatment with significant  nocturnal desaturation as the main concern.

“With little data regarding use of HFNC in obese patients with OSA/OHS and acute hypercapnic respiratory failure, it may be difficult to accurately predict whether HFNC

would be sufficient to overcome respiratory workloads, hypoventilation and impairments of gas exchange for a prolonged period of time,” they wrote.

“We would suggest such patients with mild hypercapnic respiratory failure are closely monitored if undergoing a trial with HFNC,” they added.

The study investigators said their retrospective audit was provided support for a prospective trial of HFNC in larger numbers of patients with acute hypercapnic respiratory failure.

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