[Patient-ventilator interaction during noninvasive pressure supported spontaneous respiration in patients with hypercapnic COPD].
BACKGROUND
Noninvasive pressure support ventilation (NPSV) demands triggering with each breath. This study investigates the effects of NPSV via face mask on breathing pattern, ventilation and respiratory muscle loading in patients with hypercapnic stable COPD.


METHODS
7 patients (age 66 +/- 9 years; FEV1 43 +/- 13% predicted; PaO2 52 +/- 19 mmHg; PaCO2 58 +/- 12 mmHg) were included. The physiologic variables were evaluated during spontaneous breathing and at the end of a 60 minutes period with NPSV. Inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP) were adjusted to 12-14 cm H2O and 3 cm H2O, respectively. Respiratory muscle activity was measured as esophageal and transdiaphragmatic pressure time product (PTPes and PTPdi).


RESULTS
Non-triggering was observed only occasionally. Compared to unsupported spontaneous breathing NPSV improved ventilation: PaCO2 was reduced from 58 +/- 11 mmHg to 50 +/- 14 mmHg (p +/- 0.05). Respiratory muscles were unloaded by 30% (p +/- 0.05). Breathing frequency and breathing pattern did not change.


CONCLUSIONS
In patients with hypercapnic stable COPD NPSV effectively recognizes and supports breathing efforts. As a result ventilation is improved and respiratory muscles are unloaded.
Zentrum für Innere Medizin, Abteilung Medizinische Poliklinik, Zeitreihenlabor, Philipps-Universität, Marburg. pankow-berlin@t-online.de
W
W
Pankow
H
H
Becker
U
U
Köhler
H
H
Schneider
T
T
Penzel
J H
JH
Peter
D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology / Q000628:therapy*; D008173:Lung Diseases, Obstructive / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008397:Masks; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D012123:Pulmonary Ventilation / Q000502:physiology; D012132:Respiratory Muscles / Q000503:physiopathology; D014939:Work of Breathing / Q000502:physiology
D002245:Carbon Dioxide