Mechanisms of improvement of respiratory failure in patients with COPD treated with NIV.

Title: Mechanisms of improvement of respiratory failure in patients with COPD treated with NIV.
Authors: Nickol, AH
Hart, N
Hopkinson, NS
Hamnegård, C-H
Moxham, J
Simonds, A
Polkey, MI
Item Type: Journal Article
Abstract: BACKGROUND: Noninvasive ventilation (NIV) improves gas-exchange and symptoms in selected chronic obstructive pulmonary disease (COPD) patients with hypercapnic respiratory failure. We hypothesized NIV reverses respiratory failure by one or all of increased ventilatory response to carbon-dioxide, reduced respiratory muscle fatigue, or improved pulmonary mechanics. METHODS: Nineteen stable COPD patients (forced expiratory volume in one second 35% predicted) were studied at baseline (DO), 5-8 days (D5) and 3 months (3M) after starting NIV. RESULTS: Ventilator use was 6.2 (3.7) hours per night at D5 and 3.4 (1.6) at 3M (p = 0.12). Mean (SD) daytime arterial carbon-dioxide tension (PaCO2) was reduced from 7.4 (1.2) kPa to 7.0 (1.1) kPa at D5 and 6.5 (1.1) kPa at 3M (p = 0.001). Total lung capacity decreased from 107 (28) % predicted to 103 (28) at D5 and 103 (27) % predicted at 3M (p = 0.035). At D5 there was an increase in the hypercapnic ventilatory response and some volitional measures of inspiratory and expiratory muscle strength, but not isolated diaphragmatic strength whether assessed by volitional or nonvolitional methods. CONCLUSION: These findings suggest decreased gas trapping and increased ventilatory sensitivity to CO2 are the principal mechanism underlying improvements in gas-exchange in patients with COPD following NIV. Changes in some volitional but not nonvolitional muscle strength measures may reflect improved patient effort.
Issue Date: 4-Nov-2008
ISSN: 1176-9106
Start Page: 453
End Page: 462
Journal / Book Title: Int J Chron Obstruct Pulmon Dis
Volume: 3
Issue: 3
Copyright Statement: © 2008 Nickol et al, publisher and licensee Dove Medical Press Ltd. This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited.
Keywords: Aged
Middle Aged
Muscle Strength
Prospective Studies
Pulmonary Disease, Chronic Obstructive
Pulmonary Gas Exchange
Respiration, Artificial
Respiratory Mechanics
Respiratory Muscles
1102 Cardiovascular Medicine And Haematology
Respiratory System
Publication Status: Published
Conference Place: New Zealand
Appears in Collections:National Heart and Lung Institute
Airway Disease
Faculty of Medicine

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