Respiratory resistance by end-inspiratory occlusion and forced
oscillations in intubated patients.
L., Beydon, P., Malassin[acute]e, A. M., Lorino, C., Mariette, F.,
Bonnet, A., Harf, and H., Lorino.
R[acute]eanimation chirurgicale, Service de Physiologie
-Explorations Fonctionnelles, and INSERM U296, H[circumflex]opital
Henri Mondor, 94010 Cr[acute]eteil, France
APStracts 2:0514A, 1995.
Measurement of respiratory impedance (Zrs) by the forced oscillation
technique (FOT) in intubated patients requires corrections for the
flow-dependent resistance, inertance, and air compression inside the
endotracheal tube (ETT). Recently we published a method to correct
Zrs for the mechanical contribution of the ETT. To validate this
correction, we compared the respiratory resistance obtained with this
method (Rfo) to the intrinsic (Rmin) and total (Rmax) resistances
measured by the airway occlusion technique (OCT) in 16 intubated
sedated-paralyzed ventilated patients. FOT was applied at functional
residual capacity in the 4-32 Hz frequency range, whereas OCT was
performed at the end of a normal constant-flow inspiration. Rmin
correlated with Rfo measured at 16 and 32 Hz (Rfo(16) = 1.10 x Rmin
+0.10 cm H2O x s x [lambda]-1, r = 0.96, p < 0.001; Rfo(32) =
0.93 x Rmin + 0.72 cm H2O x s x [lambda]-1, r = 0.97, p < 0.001
respectively). Rmax correlated Rfo at 4 Hz (Rfo(4) = 1.11 x Rmax
-1.48 cm H2O x s x [lambda]-1, r = 0.92, p < 0.001). We conclude
that the forced oscillation technique improved by corrections for the
behavior of the endotracheal tube is in good agreement with the
occlusion method in intubated patients.
Received 28 June 1995; accepted in final form 2 November 1995.
APS Manuscript Number A706-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95