Nasal high flow therapy and PtCO(2) in stable COPD: A randomized controlled cross-over trial.

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 (PtCO2 ) in stable COPD patients. In a single-blind randomized controlled cross-over 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 PtCO2 at 20 min, adjusted for baseline PtCO2 . Secondary outcomes included respiratory rate at 20 min, adjusted for baseline. The mean (95% CI) change in PtCO2 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. NHF results in a small flow-dependent reduction in PtCO2 and respiratory rate in patients with stable COPD.

McKinstry S ，Pilcher J ，Bardsley G ，Berry J ，Van de Hei S ，Braithwaite I ，Fingleton J ，Weatherall M ，Beasley R ... -  《-》

Physiological effects of titrated oxygen via nasal high-flow cannulae in COPD exacerbations: A randomized controlled cross-over trial.

Increased arterial carbon dioxide tension (PaCO2 ) is an important complication of acute exacerbations of COPD. The effects of nasal high-flow cannulae (NHF) on PaCO2 in patients with COPD exacerbations, and whether this therapy should be used in this clinical situation, are less certain. We aimed to investigate the effect of NHF on PaCO2 in patients admitted to hospital with a COPD exacerbation. We performed a single-centre randomized controlled cross-over trial in 24 hospital inpatients with acute exacerbations of COPD receiving oxygen via standard nasal prongs (SNPs). Patients received both supplemental oxygen via NHF (35 L/min) and SNP for 30 min each, with oxygen titrated to maintain the patient's baseline oxygen saturation, measured by pulse oximetry (SpO2 ). Interventions were administered in random order with a minimum 15-min washout between interventions. The primary outcome was difference in transcutaneous carbon dioxide tension (PtCO2 ) at 30 min adjusted for time zero. The difference in PtCO2 adjusted for time zero was lower after 30 min for NHF compared with SNP (-1.4 mm Hg (95% CI: -2.2 to -0.6), P = 0.001). There was no difference in SpO2 at 30 min (-0.02% (95% CI: -0.8 to 0.7), P = 0.96). The reduction in respiratory rate for NHF at 30 min was not statistically significant (-2.0 breaths/min (95% CI: -4.5 to 0.4), P = 0.099). Short-term use of NHF results in a small reduction in PtCO2 compared with SNP in patients with acute exacerbations of COPD, but whether this is clinically significant is uncertain.

Pilcher J ，Eastlake L ，Richards M ，Power S ，Cripps T ，Bibby S ，Braithwaite I ，Weatherall M ，Beasley R ... -  《-》

Nasal high-flow therapy compared with non-invasive ventilation in COPD patients with chronic respiratory failure: A randomized controlled cross-over trial.

Non-invasive ventilation (NIV) is part of the standard of care for hypercapnic respiratory failure secondary to COPD, but may be poorly tolerated. Preliminary evidence suggests nasal high-flow (NHF) therapy may improve hypercapnia in COPD and be well tolerated. We compared NHF and NIV in people with COPD and chronic hypercapnic respiratory failure. Single-blind randomized controlled two-way cross-over single-centre trial was conducted in New Zealand. Twenty-four participants with stable hypercapnic COPD received: NHF at 45 L/min and NIV at 15/4 cm H2 O, each for 60 min with a 15-min washout in between. The primary outcome was transcutaneous partial pressure of carbon dioxide (PtCO2 ) at 60 min, adjusted for baseline. NIV reduced the PtCO2 more than NHF (mean (SD) at 60 min by -5.3 (5.0) vs -2.5 (3.5) mm Hg; difference: -2.8 (-5.0 to -0.5) P = 0.021). Difference across all time points was -2.5 mm Hg (95% CI -4.5 to -0.5, P = 0.016). There was no significant difference in the proportion of participants with a reduction of PtCO2  ≥ 4 or ≥ 8 mm Hg. Participants rated NHF significantly better for ease of application, comfort and fit. In stable COPD patients with chronic hypercapnia, NIV resulted in a greater reduction in PtCO2 compared with NHF, which was of uncertain clinical significance. NHF was better tolerated than NIV and may be a therapeutic option for some people with hypercapnic respiratory failure. ACTRN12616001701415 at www.anzctr.org.au.

McKinstry S ，Singer J ，Baarsma JP ，Weatherall M ，Beasley R ，Fingleton J ... -  《-》

The effect of 50% oxygen on PtCO(2) in patients with stable COPD, bronchiectasis, and neuromuscular disease or kyphoscoliosis: randomised cross-over trials.

Pilcher J ，Thayabaran D ，Ebmeier S ，Williams M ，Back G ，Collie H ，Richards M ，Bibby S ，Semprini R ，Weatherall M ，Beasley R ... -  《BMC Pulmonary Medicine》

Nasal highflow improves ventilation in patients with COPD.

Bräunlich J ，Köhler M ，Wirtz H 《International Journal of Chronic Obstructive Pulmonary Disease》