Walking with Non-Invasive Ventilation Does Not Prevent Exercise-Induced Hypoxaemia in Stable Hypercapnic COPD Patients.
BACKGROUND
Non-invasive positive pressure ventilation (NPPV) in addition to supplemental oxygen improves arterial oxygenation, walking distance and dyspnea when applied during exercise in stable hypercapnic COPD patients. The aim of the current study was to investigate whether NPPV without supplemental oxygen is capable of preventing severe exercise-induced hypoxemia in these patients when applied during walking.


RESULTS
15 stable hypercapnic COPD patients (FEV1 29.9 ± 15.9%) performed two 6-minute walk tests (6MWT) with a rollator in a randomized cross-over design: using either supplemental oxygen (2.4 ± 0.7 L/min) or NPPV (inspiratory/expiratory positive airway pressure of 28.2 ± 2.8 / 5.5 ± 1.5 mbar) without supplemental oxygen.


RESULTS
10 patients were able to complete both 6MWT. 6MWT with supplemental oxygen resulted in no changes for PO2 (pre: 67.3 ± 11.2 mmHg vs. post: 65.6 ± 12.0 mmHg, p = 0.72) whereas PCO2 increased (pre: 50.9 ± 8.1 mmHg vs. post: 54.3 ± 10.0 mmHg (p < 0.03). During 6MWT with NPPV PO2 significantly decreased from 66.8 ± 7.2 mmHg to 55.5 ± 10.6 mmHg (p < 0.02) whereas no changes occurred in PCO2 (pre: 50.6 ± 7.5 mmHg vs. post: 53.0 ± 7.1 mmHg; p = 0.17). Walking distance tended to be lower in 6MWT with NPPV compared to 6MWT with supplemental oxygen alone (318 ± 160 m vs. 377 ± 108 m; p = 0.08).


CONCLUSIONS
The use of NPPV during walking without the application of supplemental oxygen does not prevent exercise-induced hypoxemia in patients with stable hypercapnic COPD.
a Department of Pneumology, University Hospital , Freiburg , Germany.
David Johannes
DJ
Walker
a Department of Pneumology, University Hospital , Freiburg , Germany.
Stephan
S
Walterspacher
a Department of Pneumology, University Hospital , Freiburg , Germany.
Emelie
E
Ekkernkamp
b Department of Pneumology, Cologne Merheim Hospital, Kliniken der Stadt Köln gGmbH, Witten/Herdecke University , Germany.
Jan Hendrik
JH
Storre
b Department of Pneumology, Cologne Merheim Hospital, Kliniken der Stadt Köln gGmbH, Witten/Herdecke University , Germany.
Wolfram
W
Windisch
c Department of Cardiology, Pneumology, Angiology and Intensive Care Medicine, University Hospital , Aachen , Germany.
Michael
M
Dreher
D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D018592:Cross-Over Studies; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006935:Hypercapnia / Q000209:etiology; D000860:Hypoxia / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood; D010313:Partial Pressure; D011175:Positive-Pressure Respiration; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D016138:Walking / Q000502:physiology*
D002245:Carbon Dioxide; D010100:Oxygen
6-minute walk test; chronic obstructive pulmonary disease; exercise; non-invasive ventilation; respiratory muscle unloading