Nasal high flow therapy and PtCO₂ in stable COPD: A randomized controlled cross‐over trial

Abstract

Background and objective: Hypercapnia is associated with worse clinical outcomes in exacerbations of COPD. The present study aimed to determine the effects of nasal high flow (NHF) therapy on transcutaneous partial pressure of carbon dioxide (PtCO 2 ) in stable COPD patients. Methods: In a single-blind randomized controlled crossover trial, 48 participants with COPD were allocated in random order to all of four 20 min interventions: NHF at 15 L/min, 30 L/min and 45 L/min or breathing room air with each intervention followed by a washout period of 15 min. The primary outcome measure was PtCO 2 at 20 min, adjusted for baseline PtCO 2 . Secondary outcomes included respiratory rate at 20 min, adjusted for baseline. Results: The mean (95% CI) change in PtCO 2 at 20 min was −0.6 mm Hg (−1.1 to 0.0), P = 0.06; −1.3 mm Hg (−1.9 to 0.8), P < 0.001; and −2.4 mm Hg (−2.9 to −1.8), P < 0.001; for NHF at 15 L/min, 30 L/min and 45 L/min compared with room air, respectively. The mean (95% CI) change in respiratory rate at 20 min was −1.5 (−2.7 to −0.3), P = 0.02; −4.1 (−5.3 to −2.9), P < 0.001; and −4.3 (−5.5 to −3.1), P < 0.001; breaths per minute compared with room air, respectively. Conclusion: NHF results in a small flow-dependent reduction in PtCO 2 and respiratory rate in patients with stable COPD.

Comparison of high flow nasal cannula with noninvasive ventilation in chronic obstructive pulmonary disease patients with hypercapnia in preventing postextubation respiratory failure: A pilot randomized controlled trial

“…Braunlich et al () found that PCO 2 decreased more with 30 L/min than 20 L/min ( p < 0.03) in 54 stable COPD patients with PCO 2 >55 mmHg. In our study, the median flow was 50 L/min, which was found to decrease PCO 2 more than 30 L/min (McKinstry et al, ).…”

“…HFNC was also found to be more comfortable than NIV in our study, which is consistent with the finding by Pisani et al (). In a study by McKinstry et al (), participants expressed that HFNC was easy to use and moisture in the nasal passage was comfortable; 30 L/min was preferred to 15 or 45 L/min. Patient comfort or tolerability plays an important role in the effects of NIV or HFNC.…”

“…In a study by McKinstry et al (2018), participants expressed that HFNC was easy to use and moisture in the nasal passage was comfortable; 30 L/min was preferred to 15 or 45 L/min. Patient comfort or tolerability plays an important role in the effects of NIV or HFNC.…”

“…Thus, the role of HFNC in weaning COPD with hypercapnia is still unclear. Physiological studies reported that the high velocity of the gas could rinse the dead space of the upper airway and reduce carbon dioxide rebreathing (Biselli et al, 2018), to improve alveolar ventilation in COPD, which ultimately improves dyspnea and arterial blood gases (ABGs; Braunlich, Mauersberger, & Wirtz, 2018;McKinstry et al, 2018;Pisani et al, 2017). In the retrospective comparison of HFNC to NIV in postextubation patients by Yoo et al (2016), a subgroup analysis of partial pressure of PaCO 2 >45 mmHg patients showed that reintubation rate and ICU mortality did not differ significantly.…”

Non‐invasive ventilation or high‐flow oxygen therapy: When to choose one over the other?

“…Ventilatory support is the main physiological effect expected from treatment during a COPD exacerbation. HFOT contributes to reduced respiratory efforts by the PEEP effect and by the reduction of functional dead space through washout in the upper airways contributing to partial pressure of CO 2 (pCO 2 ) reduction . Increased tidal volume and decreased respiratory rate are other physiological effects of HFOT favouring a reduction in the work of breathing in acute hypercapnic respiratory failure …”