Use of the impulse oscillometry system for testing pulmonary function during methacholine bronchoprovocation in horses.
OBJECTIVE
To compare sensitivity of the impulse oscillometry system (IOS) with that of the conventional reference technique (CRT; ie, esophageal balloon method) for pulmonary function testing in horses.


METHODS
10 horses (4 healthy; 6 with recurrent airway obstruction [heaves] in remission).


METHODS
Healthy horses (group-A horses) and heaves-affected horses (group-B horses) were housed in a controlled environment. At each step of a methacholine bronchoprovocation test, threshold concentration (TC(2SD); results in a 2-fold increase in SD of a value) and sensitivity index (SI) were determined for respiratory tract system resistance (R(rs)) and respiratory tract system reactance (X(rs)) at 5 to 20 Hz by use of IOS and for total pulmonary resistance (RL) and dynamic lung compliance (C(dyn)), by use of CRT.


RESULTS
Bronchoconstriction resulted in an increase in R(rs) at 5 Hz (R(5Hz)) and a decrease in X(rs) at all frequencies. Most sensitive parameters were X(rs) at 5 Hz (X(5Hz)), R(5Hz), and R(5Hz):R(10Hz) ratio; RL and the provocation concentration of methacholine resulting in a 35% decrease in dynamic compliance (PC(35)C(dyn)) were significantly less sensitive than these IOS parameters. The TC(2SD) for X(rs) at 5 and 10 Hz was significantly lower in group-B horses, compared with group-A horses. The lowest TC(2SD) was obtained for X(5Hz) in group-B horses and R(5Hz) in group-A horses.


CONCLUSIONS
In contrast to CRT parameters, IOS parameters were significantly more sensitive for testing pulmonary function. The IOS provides a practical and noninvasive pulmonary function test that may be useful in assessing subclinical changes in horses.
van Erck
Emmanuelle
E
Laboratory for Functional Investigation, Department of Physiology, Faculty of Veterinary Medicine, University of Liège, Bat B42, Sart Tilman, B-4000 Liège, Belgium.
Votion
Dominique M
DM
Kirschvink
Nathalie
N
Art
Tatiana
T
Lekeux
Pierre
P
D000402:Airway Obstruction / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D001985:Bronchial Provocation Tests / Q000379:methods / Q000662:veterinary*; D006734:Horse Diseases / Q000503:physiopathology*; D006736:Horses / Q000502:physiology*; D007700:Kinetics; D009991:Oscillometry; D012016:Reference Values; D012129:Respiratory Function Tests / Q000662:veterinary*