title: Use of volumetric capnography to identify pulmonary dysfunction in horses with and without clinically apparent recurrent airway obstruction.
abstract: OBJECTIVE
  To investigate whether volumetric capnography indices could be used to differentiate between horses without recurrent airway obstruction (RAO) and horses with RAO that were in clinical remission or that had clinically apparent RAO.
  
  
  METHODS
  70 adult Swiss Warmblood horses (20 used for pleasure riding and 50 used for dressage or show jumping).
  
  
  METHODS
  Horses were allocated to 4 groups on the basis of history, clinical signs, results of endoscopy, and cytologic findings (group 1, 21 healthy horses; group 2, 22 horses with RAO that were in remission; group 3, 16 horses with mild RAO; group 4, 11 horses with exacerbated RAO). Expiratory volume and CO2 curves were recorded by use of a computerized ultrasonic spirometer. Volumetric capnograms were plotted, and derived indices were calculated.
  
  
  RESULTS
  Dead-space volume (VD) was calculated by use of the Bohr equation (VD(Bohr)) and for physiologic VD (VD(phys)). Ratios for VD(Bohr) to expiratory tidal volume (VT) and VD(phys) to V(T) as well as an index of effective CO2 elimination were significantly different among groups of horses. Age and use of the horses also significantly affected volumetric capnography indices.
  
  
  CONCLUSIONS
  Ratios of VD(Bohr) to VT and VD(phys) to VT as well as an index of effective CO2 elimination were sufficiently sensitive measures to distinguish between healthy horses and horses with RAO in remission. To optimize the ability of volumetric capnography indices to differentiate among horses in heterogeneous populations, it is important to account for effects of age and specific use of the horses.
authors.affiliation: Department of Equine Internal Medicine, Faculty of Veterinary Medicine, University of Berne, Länggasstr 124, CH-3012 Berne, Switzerland.
authors.forename: Conny P
authors.initials: CP
authors.lastname: Herholz
authors.forename: Vinzenz
authors.initials: V
authors.lastname: Gerber
authors.forename: Peter
authors.initials: P
authors.lastname: Tschudi
authors.forename: Reto
authors.initials: R
authors.lastname: Straub
authors.forename: Andrea
authors.initials: A
authors.lastname: Imhof
authors.forename: André
authors.initials: A
authors.lastname: Busato
mesh_terms: D000375:Aging; D000402:Airway Obstruction / Q000150:complications* / Q000175:diagnosis / Q000662:veterinary*; D000818:Animals; D019296:Capnography / Q000379:methods* / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D008171:Lung Diseases / Q000150:complications / Q000175:diagnosis* / Q000662:veterinary*; D008297:Male; D011237:Predictive Value of Tests