title: Use of the impulse oscillometry system for testing pulmonary function during methacholine bronchoprovocation in horses.
abstract: 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.
authors: Laboratory for Functional Investigation, Department of Physiology, Faculty of Veterinary Medicine, University of Liège, Bat B42, Sart Tilman, B-4000 Liège, Belgium.
authors: Emmanuelle
authors: E
authors: van Erck
authors: Dominique M
authors: DM
authors: Votion
authors: Nathalie
authors: N
authors: Kirschvink
authors: Tatiana
authors: T
authors: Art
authors: Pierre
authors: P
authors: Lekeux
mesh_terms: 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*