High flow nasal cannula (HFNC) treatment likely reduces acute exacerbations in patients with chronic obstructive pulmonary disease (COPD) and chronic hypercapnia and may also reduce hospitalization admissions, according to systematic review and meta-analysis study findings published in Respiratory Medicine.
Noninvasive ventilation (long-term oxygen therapy) is standard care in patients with COPD and chronic hypercapnia according to current international guidelines; however, use of HFNC in this patient population has not been addressed by guidelines. Therefore,
investigators sought to characterize the differences between HFNC home care vs standard care in patients with COPD and chronic hypercapnia respiratory failure. Primary endpoints included acute exacerbations, hospitalizations, change in St. George Respiratory Questionnaire (SGRQ), and all-cause mortality.
The investigators conducted this systematic review and meta-analysis searching Cochrane CENTRAL, SCOPUS, MEDLINE, EMBASE, and Clinicaltrials.gov from inception through mid-July 2023 for randomized clinical trials that included stable adult patients with COPD (ie, those who did not have exacerbations in the month prior to the study) who initiated HFNC and used it for at least 1 month.
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Near future guideline panels will need to address whether HFNC is appropriate given the existing body of evidence, which patients could be selected, and the types of monitoring required to ensure safe practice.
The meta-analysis included 4 randomized trials of 440 patients (predominantly men) with average ages ranging from 67 to 75 years. All patients had been stable (with flow rates ranging from as low as 20 L/min to 40 L/min). Baseline forced expiratory volume in 1 second (FEV1) percent predicted ranged from 26% to 45%; the highest average baseline carbon dioxide (CO2) was 51.9 mmHg and the lowest was 48.3 mmHg. For 3 trials, the follow-up period was 12 months, and 1 trial had 15-month follow-up period.
High risk of bias was found in all trials for acute exacerbations. Deviations from intended interventions produced risk for bias in all trials, and missing data caused risk for bias in 2 trials.
The investigators found acute exacerbations are probably reduced with HFNC compared with standard care (relative risk [RR], 0.77; 95% CI, 0.66-0.89; moderate certainty). This finding suggests that for every 1000 patients, HFNC use results in 69 fewer exacerbations (range, 33 to 102; I2=17%).
The meta-analysis also found that hospital admissions may be reduced with HFNC vs standard care (RR, 0.87; 95% CI, 0.69-1.09; low certainty;). This finding suggests that for every 1000 patients, HFNC use results in 20 fewer hospital admissions (range 14 to 47; I2=0%).
The SGRQ score may be reduced (mean difference, -8.12 units; 95% CI, -13.30 to -2.95; low certainty), suggesting that quality of life might improve with HFNC; however, substantial heterogeneity was found (I2=71%).
The investigators noted mortality may not be affected by HFNC compared with standard care (RR, 1.22; 95% CI, 0.64-2.35; low certainty; I2=0%).
Systematic review and meta-analysis limitations include basing most outcomes on low to moderate certainty evidence, variation in HFNC settings across trials, and the inclusion of only patients with mild hypercapnia.
“HFNC probably reduces acute exacerbations and might reduce hospital admissions in COPD patients with chronic hypercapnia. However, its effect on mortality is uncertain,” the study authors concluded. “Near future guideline panels will need to address whether HFNC is appropriate given the existing body of evidence, which patients could be selected, and the types of monitoring required to ensure safe practice,” said the investigators.
