Journal Article

Effectiveness of nasal highflow in hypercapnic COPD patients is flow and leakage dependent

Bräunlich, Jens, Wirtz, Hubert, Mauersberger, Friederike

2018

Overview

Background Nasal Highflow (NHF) delivers a humidified and heated airflow via nasal prongs. Current data provide evidence for efficacy of NHF in patients with hypoxemic respiratory failure. Preliminary data suggest that NHF may decrease hypercapnia in hypercapnic respiratory failure. The aim of this study was to evaluate the mechanism of NHF mediated PCO 2 reduction in patients with chronic obstructive pulmonary disease (COPD). Methods In 36 hypercapnic COPD patients (PCO 2  > 45 mmHg), hypercapnia was evaluated by capillary gas sampling 1 h after NHF breathing under four conditions A to D with different flow rates and different degrees of leakage (A = 20 L/min, low leakage, two prongs, both inside; B = 40 L/min, low leakage, two prongs, both inside; C = 40 L/min, high leakage, two prongs, one outside and open; D = 40 L/min, high leakage, two prongs, one outside and closed). Under identical conditions, mean airway pressure was measured in the hypopharynx of 10 COPD patients. Results Hypercapnia significantly decreased in all patients. In patients with capillary PCO 2  > 55 mmHg ( n  = 26), PCO 2 additionally decreased significantly by increased leakage and/or flow rate in comparison to lower leakage/ flow rate conditions (A = 94.2 ± 8.2%; B = 93.5 ± 4.4%; C = 90.5 ± 7.2%; D = 86.8 ± 3.8%). The highest mean airway pressure was observed in patients breathing under condition B (2.3 ± 1.6 mbar; p  < 0.05). Conclusions This study demonstrates effective PCO 2 reduction with NHF therapy in stable hypercapnic COPD patients. This effect does not correlate with an increase in mean airway pressure but with increased leakage and airflow, indicating airway wash out and reduction of functional dead space as important mechanisms of NHF therapy. These results may be useful when considering NHF treatment in hypercapnic COPD patients. Trial registration Clinical Trials: NCT02504814; First posted July 22, 2015.

• Publisher: BioMed Central,BioMed Central Ltd,BMC
• Subject: Aged / Blood Gas Analysis / Cannula / Carbon Dioxide / Care and treatment / COPD / COPD and occupational lung disease / Critical Care Medicine / Equipment and supplies / Female / Humans / Hypercapnia / Hypercapnia - etiology / Hypercapnia - therapy / Intensive / Internal Medicine / Lung diseases, Obstructive / Male / Medicine / Medicine & Public Health / Middle Aged / Nasal high flow / Noninvasive Ventilation - methods / Nose / Partial Pressure / Pneumology/Respiratory System / Prospective Studies / Pulmonary Disease, Chronic Obstructive - complications / Pulmonary Disease, Chronic Obstructive - therapy / Research Article / Respiratory therapy / Type II respiratory failure / Wash-out