High-flow nasal cannula therapy (HFNC) is effective and safe in patients older than 75 with acute respiratory failure (ARF) unrelated to COVID-19, investigators reported in Pulmonology.
The prospective, observational study assessed the efficacy and safety of HFNC in patients older than 75 years of age with ARF of any origin excluding COVID-19. Patients studied had ARF that was refractory to treatment with conventional oxygen therapy and/or intolerant to noninvasive ventilation or continuous positive airway pressure. Patients studied also did not meet criteria for admission to critical care units (ICUs).
Study participants were enrolled from November 2019 to November 2020 after being admitted to the emergency department (ED) with FiO2 of at least 35% after 24 hours of medical treatment and oxygenation by conventional systems. Participants also exhibited clinical deterioration, no improvement in dyspnea, tachypnea with respiratory rate (RR) greater than 25 bpm, or hypoxemia with pressure of arterial oxygen/fraction of inspired oxygen ratio (PaO2/FiO2) less than 300. A total of 200 patients were included in the study (mean age, 83 years; 61.9% women; body mass index, 31.1 kg/m2; Charlson Comorbidity Index, 4). About 64% were hypercapnic, and no patients had respiratory acidosis (pH 7.39).
The researchers obtained measurements of the following variables: dyspnea, RR, heart rate, blood pressure, oxygen saturation measured by oximetry (SpO2), PaO2, arterial carbon dioxide tension (PaCO2), bicarbonate, lactate, pH, FiO2, PaO2/FiO2 and SpO2/FiO2, ROX index (SpO2:FiO2/RR), and HFNC settings. The measurements were conducted 24 hours after treatment with conventional oxygenation (basal values) and at 60 minutes, 120 minutes, and 24 hours after beginning HFNC.
[High-flow nasal cannula therapy] in selected patients may be an alternative for elderly patients with ARF who remain hypoxemic and in respiratory distress after 24 hours of conventional treatment.
Significant improvement was observed at 60 minutes, 120 minutes, and 24 hours compared with baseline for RR, dyspnea, ROX index, PaO2/FiO2, SpO2/FiO2, and patient comfort. No changes occurred in PaCO2 or level of consciousness.
In independent analysis of the 128 patients with hypercapnia, significant improvement was observed at 60 minutes, 120 minutes, and 24 hours for RR, dyspnea, ROX index, PaO2/FiO2, SpO2/FiO2, and patient comfort. No significant change occurred in PaCO2 or deterioration in the level of consciousness.
HFNC was well tolerated, and the participants had significant improvement in comfort as assessed by the visual analog scale. Heat intolerance (37.5%) was the most common side effect of HFNC. A total of 10 patients died (5%), and progression of the triggering cause of ARF was the leading cause of death. Of the cohort, 7 patients (3.5%) were readmitted after 7 days and 17 (8.5%) after 30 days.
Limitations include the lack of a control group and randomization; potential selection bias due to the fact that the study was affected by the first waves of the COVID-19 pandemic; and the lack of patients presenting with respiratory acidosis, which limits application of the findings. Additionally, the study was conducted in a hospital that specialized in noninvasive respiratory support therapies dependent on the ED, so the generalizability of results may be limited.
“This is the study with the largest number of patients with these characteristics published to date and shows that the use of [high-flow nasal cannula therapy] in selected patients may be an alternative for elderly patients with ARF who remain hypoxemic and in respiratory distress after 24 hours of conventional treatment,” stated the researchers. “Randomized studies are needed to confirm these data and to provide higher quality evidence for the use of [high-flow nasal cannula therapy] in the elderly population.”