Not. Stromberg et N. Nelson, THORACOABDOMINAL ASYNCHRONY IN SMALL CHILDREN WITH LUNG-DISEASE - METHODOLOGICAL ASPECTS AND THE RELATIONSHIP TO LUNG-MECHANICS, Clinical physiology, 18(5), 1998, pp. 447-456
Thoracoabdominal asynchrony (TAA) has been regarded as a clinical sign
of lung disease. A measure of TAA is the phase angle (phi) between ri
bcage (RC) and abdominal (ABD) respiratory motion. The aim of this stu
dy was to assess the effect of the points chosen for phi calculation.
The influence of correct respiratory timing was assessed by calculatin
g TAA. indices using a pneumotachometer (PTM) as timing reference and
using the calibrated respiratory inductive plethysmograph (RIP) signal
for respiratory timing. The relationship between TAA and lung mechani
cs was studied in 15 young children 9 months to 2.5 years of age with
a wide span of restrictive and/or obstructive lung disease. phi as cal
culated from mid-RC points was poorly related to phi as calculated fro
m the top RC and ABD positions, indicating non-sinusoidal respiratory
motions. The estimation of the TAA indices depended on correct respira
tory timing, which in the case of severe asynchrony cannot be inferred
from the RIP signals alone. An external source for respiratory timing
, such as the airway flow measured by a PTM, is needed. The degree of
asynchronous chest wall movement was only a weak indicator of patholog
ical lung mechanics. We conclude that the usefulness of TAA indices as
indicators of impaired lung mechanics is limited by the sensitivity t
o the points used for their calculation (phi) and the need of an exter
nal source for respiratory timing. It was therefore not surprising tha
t a rather weak relationship was seen between TAA indices and lung mec
hanics.