Submitted on November 4, 2002
Accepted on June 6, 2003
The accuracy of noninvasive estimates of respiratory muscle effort during spontaneous breathing in restrictive diseases
Francisco Garcia-Rio1*, Jose M Pino1, Angeles Ruiz1, Salvador Diaz1, Concepcion Prados1, and Jose Villamor1
1 Servicio de Neumologia, Hospital Universitario La Paz, Madrid, Madrid, Spain
* To whom correspondence should be addressed. E-mail: fgr01m{at}jazzfree.com.
Mean inspiratory pressure (PI), estimated from the occlusion pressure at the mouth and the inspiratory time, is usefull as a noninvasive estimate of respiratory muscle effort during spontaneous breathing in normal subjects and patients with chronic obstructive pulmonary disease. The aim of this study was to compare the PI with respect to mean esophageal pressure (Pes) in patients with restrictive disorders. Eleven healthy volunteers, twelve patients with chest wall disease, fourteen patients with usual interstitial pneumonia and 17 patients with neuromuscular diseases were studied. PI, Pes and mean transdiaphragmatic pressure (Pdi) were simultaneously measured. Tension-time indices of diaphragm (TTdi) and inspiratory muscles (TTmu) were also determined. In neuromuscular patients, significant correlations were found between PI and Pes, PI and Pdi, and TTmu and TTdi. A moderate agreement between PI and Pes and between TTmu and TTdi was found. No significant correlation between these parameters was found in the other patient groups. These findings suggest that PI is a good surrogate for the invasive measurement of respiratory muscle effort during spontaneous breathing in neuromuscular patients.
