Acute Responses to Oxygen Delivery via High Flow Nasal Cannula in Patients with Severe Chronic Obstructive Pulmonary Disease-HFNC and Severe COPD.

Amy H Attaway,Srinivasan Dasarathy,Jihane Faress,Frank Jacono

doi:10.3390/jcm10091814

Amy H Attaway, Srinivasan Dasarathy + Show 2 more

Open Access

https://doi.org/10.3390/jcm10091814

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Abstract

Differences in oxygen delivery methods to treat hypoxemia have the potential to worsen CO2 retention in chronic obstructive lung disease (COPD). Oxygen administration using high flow nasal cannula (HFNC) has multiple physiological benefits in treating respiratory failure including reductions in PaCO2 in a flow-dependent manner. We hypothesized that patients with COPD would develop worsening hypercapnia if oxygen fraction was increased without increasing flow rate. We evaluated the acute response to HFNC in subjects with severe COPD when flow remained constant and inspired oxygen was increased. In total, 11 subjects with severe COPD (FEV1 < 50%) on supplemental oxygen with baseline normocapnia (PaCO2 < 45 mm Hg; n = 5) and hypercapnia (PaCO2 ≥ 45 mm Hg; n = 6) were studied. Arterial blood gas responses were studied at three timepoints: Baseline, HFNC at a flow rate of 30 L/min at resting oxygen supplementation for 1 h, and FiO2 30% above baseline with the same flow rate for the next hour. The primary endpoint was the change in PaCO2 from baseline. No significant changes in PaCO2 were noted in response to HFNC applied at baseline FiO2 in the normocapnic and hypercapnic group. At HFNC with FiO2 30% above baseline, the normocapnic group did not show a change in PaCO2 (baseline: 38.9 ± 1.8 mm Hg; HFNC at higher FiO2: 38.8 ± 3.1 mm Hg; p = 0.93), but the hypercapnic group demonstrated significant increase in PaCO2 (baseline: 58.2 ± 9.3 mm Hg; HFNC at higher FiO2: 63.3 ± 10.9 mm Hg; p = 0.025). We observed worsening hypercapnia in severe COPD patients and baseline hypercapnia who received increased oxygen fraction when flow remained constant. These data show the need for careful titration of oxygen therapy in COPD patients, particularly those with baseline hypercapnia when flow rate is unchanged.

Highlights

Recent randomized control trials have reported decreased mortality at 90 days of high flow nasal cannula (HFNC) compared to NIPPV and conventional oxygen in the treatment of acute hypoxemic respiratory failure [1] and reduced rates of reintubation at 72 h when compared to conventional oxygen devices or NIPPV [2,10]
We hypothesized that patients with COPD would develop worsening hypercapnia if oxygen fraction was increased without increasing flow rate
On supplemental oxygen, we identified that patients with baseline hypercapnia were at risk for worsening hypercapnia when oxygen was delivered with HFNC when the oxygen fraction was increased by 30% but the flow rate remained unchanged

Summary

Introduction

High flow nasal cannula (HFNC) is a potent adjunctive therapy for patients with acute hypoxemic respiratory failure in the ICU [1,2]. HFNC has emerged as an alternative to and less invasive treatment for respiratory failure than noninvasive positive pressure (NIPPV) or invasive mechanical ventilation (IMV) [9]. Recent randomized control trials have reported decreased mortality at 90 days of HFNC compared to NIPPV and conventional oxygen in the treatment of acute hypoxemic respiratory failure [1] and reduced rates of reintubation at 72 h when compared to conventional oxygen devices or NIPPV [2,10]. Computer modeling has suggested that incorporating HFNC as a strategy for patients could result in greater mechanical ventilator availability and potentially fewer deaths [18] during the COVID-19 pandemic

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