Περίληψη:
Introduction
We aimed to compare acute mechanical and metabolic responses of the
diaphragm and rib cage inspiratory muscles during two different types of
respiratory loading in patients with chronic obstructive pulmonary
disease. Methods
In 16 patients (age, 65 +/- 13 yr; 56% male; forced expiratory volume
in the first second, 60 +/- 6%pred; maximum inspiratory pressure, 82
+/- 5%pred), assessments of respiratory muscle EMG, esophageal pressure
(Pes) and gastric pressures, breathing pattern, and noninvasive
assessments of systemic (VO2, cardiac output, oxygen delivery and
extraction) and respiratory muscle hemodynamic and oxygenation responses
(blood flow index, oxygen delivery index, deoxyhemoglobin concentration,
and tissues oxygen saturation [StiO(2)]), were performed during
hyperpnea and loaded breathing. Results
During hyperpnea, breathing frequency, minute ventilation, esophageal
and diaphragm pressure-time product per minute, cardiac output, and VO2
were higher than during loaded breathing (P < 0.05). Average inspiratory
Pes and transdiaphragmatic pressure per breath, scalene (SCA),
sternocleidomastoid, and intercostal muscle activation were higher
during loading breathing compared with hyperpnea (P < 0.05). Higher
transdiaphragmatic pressure during loaded breathing compared with
hyperpnea was mostly due to higher inspiratory Pes (P < 0.05). Diaphragm
activation, inspiratory and expiratory gastric pressures, and rectus
abdominis muscle activation did not differ between the two conditions (P
> 0.05). SCA-blood flow index and oxygen delivery index were lower, and
SCA-deoxyhemoglobin concentration was higher during loaded breathing
compared with hyperpnea. Furthermore, SCA and intercostal muscle StiO(2)
were lower during loaded breathing compared with hyperpnea (P < 0.05).
Conclusion
Greater inspiratory muscle effort during loaded breathing evoked larger
rib cage and neck muscle activation compared with hyperpnea. In
addition, lower SCA and intercostal muscle StiO(2) during loaded
breathing compared with hyperpnea indicates a mismatch between
inspiratory muscle oxygen delivery and utilization induced by the former
condition.
Συγγραφείς:
Rodrigues, Antenor
Louvaris, Zafeiris
Dacha, Sauwaluk and
Janssens, Wim
Pitta, Fabio
Vogiatizis, Ioannis
Gosselink,
Rik
Langer, Daniel
