Journal article
Airflow mechanics in models of equine obstructive airway disease under conditions simulating exercise
Research in veterinary science, Vol.62(3), pp.205-211
1997
Handle:
https://hdl.handle.net/2376/113526
PMID: 9300535
Abstract
Effects of respiratory tract obstructions on ventilatory mechanics in horses exercising at high speeds were tested with a fibreglass replica of the airways (nares to mainstem bronchi) of an adult horse. Segmental pressures were recorded at six sites along the model at four different unidirectional flows (1300 – 4100 litre min
−1), and the respective resistances (R) to airflow were calculated. The external nares and the larynx made the greatest contributions to the total resistance (R
TOT) when no obstruction was present. Modifying the model to simulate severe pharyngeal lymphoid hyperplasia (
PLH) had no effect on R at the larynx or at any point in the trachea under these flow conditions. Two 16 litre anaesthetic rebreathing bags were attached to the bronchial end of the model, and tidal ventilation generated by a piston pump. Upper (nares to pharynx) and lower tract R (R
U and R
L) and R
TOT, and dynamic compliance were determined for pump volumes (V
p) of six and 12 litres, at pumping frequencies (f
p) of 20 – 100 min
−1 while the airway was clear, and after modifying it to simulate either
PLH or partial bronchial obstruction. Model condition had no effect on R
U. However, R
L and R
TOT were higher in the
PLH simulated condition when f
p ≥ 90 and V
P = 12 litres (P<0·05). This suggested that severe
PLH may significantly interfere with airflow distal to the site of the lesions during high frequency, high volume ventilation of the type seen in galloping horses. With partial bronchial obstruction R
L and R
TOT were increased when f
p>34 with each V
p. The applicability of the model was verified by comparing results from the unobstructed state with those from normal horses exercising on a treadmill.
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Details
- Title
- Airflow mechanics in models of equine obstructive airway disease under conditions simulating exercise
- Creators
- W.M Bayly - Department of Veterinary Clinical Sciences, Washington State University, Pullman, Washington, USAR.F Slocombe - School of Veterinary Science, University of Melbourne, Parkville, Victoria, Australia
- Publication Details
- Research in veterinary science, Vol.62(3), pp.205-211
- Academic Unit
- Veterinary Clinical Sciences, Department of
- Publisher
- Elsevier India Pvt Ltd
- Identifiers
- 99900548143301842
- Language
- English
- Resource Type
- Journal article