Am. J. Respir. Crit. Care Med.,
Volume 161, Number 5, May 2000, 1754-1756
Detection of Positional Airway Obstruction in Neonates
by Acoustic Reflection
PIERRE-HENRI
JARREAU,
BRUNO
LOUIS,
LUC
DESFRÈRE,
PIERRE W.
BLANCHARD,
DANIEL
ISABEY,
ALAIN
HARF,
and
GUY
MORIETTE
Service de Médecine Néonatale de Port-Royal, Centre Hospitalier Universitaire Cochin, Assistance Publique-Hôpitaux de Paris-Université Paris V,
Paris; and Institut National de la Santé et de la Recherche Médicale INSERM U 492, and Service de Physiologie-Explorations fonctionnelles,
Centre Hospitalier Universitaire Henri Mondor, Assistance Publique-Hôpitaux de Paris-Université Paris XII, Créteil, France
In neonates intubated with an uncuffed endotracheal tube (ETT),
positional changes of the head may induce obstruction (side position-related ETT obstruction [SPRO]) due to abutment of the beveled distal ETT orifice against the tracheal wall. We studied whether the acoustic reflection (ACR) method, a 4-s measurement that maps cross-sectional area as a function of the distance along the ETT and the airways, could detect SPRO. Eleven preterm newborns intubated with 2.5-mm ETTs and clinically suspected of having SPRO were studied with the head oriented to the left and to
the right. In all patients there was a marked decrease in the ACR-measured area beyond the distal tip of the ETT in the presence of
obstruction (decrease = 38 ± 22% [mean ± SD] of the ETT inside
area), while the ACR-measured area increased markedly in the absence of obstruction (increase = 49 ± 17%). For six of the 11 infants, we also recorded the maximal flow produced by a set mechanical inflation pressure. This maximal flow decreased in the
presence of obstruction (decrease = 47 ± 18%), and was constantly associated with a decrease in ACR-measured area beyond
the ETT. In conclusion, ACR measurement is an efficient method
for diagnosing positional ETT obstruction in intubated newborns.
