title: Use of continuous positive airway pressure (CPAP) to optimise oxygenation in anaesthetised horses--a clinical study.
abstract: BACKGROUND
  Hypoxaemia is a common problem during equine anaesthesia. Continuous positive airway pressure (CPAP) is a ventilation mode routinely employed in man to overcome hypoxaemia but has not been objectively assessed in horses.
  
  
  OBJECTIVE
  To test the effects of CPAP on oxygenation and its indices in anaesthetised horses in a clinical setting.
  
  
  METHODS
  Twenty-four healthy horses requiring anaesthesia in dorsal recumbency were anaesthetised using a standard protocol. Following orotracheal intubation and connection to an anaesthetic machine capable of applying CPAP, horses were randomly allocated to ventilate at physiological airway pressure measured at the airway opening (Group PAP) or to receive CPAP of 8 cmH2O (Group CPAP). Arterial blood gas analysis was performed as soon as arterial cannulation was achieved and 30, 60 and 90 min after induction. If PaCO2 increased above 9.31 kPa controlled ventilation was initiated. Groups were compared using a general linear model.
  
  
  RESULTS
  Horses receiving CPAP had significantly higher PaO2 and calculated oxygen indices than horses receiving PAP. No significant differences in ventilation indices were observed between the 2 groups. Eight horses receiving PAP and 5 receiving CPAP required controlled ventilation. No differences in dobutamine requirements or mean arterial pressures were recorded.
  
  
  CONCLUSIONS
  Continuous positive airway pressure of 8 cmH2O improved oxygenation indices in dorsally recumbent horses without significantly influencing ventilation.
  
  
  CONCLUSIONS
  Continuous positive airway pressure reduces the incidence of hypoxaemia in anaesthetised horses. Further research is warranted to elucidate the effects of CPAP on the cardiovascular system.
authors.affiliation: Division of Anaesthesiology, Vetsuisse-Faculty, University of Zürich, Zürich, Switzerland. mmosing@vetclinics.uzh.ch
authors.forename: M
authors.initials: M
authors.lastname: Mosing
authors.forename: M
authors.initials: M
authors.lastname: Rysnik
authors.forename: D
authors.initials: D
authors.lastname: Bardell
authors.forename: P J
authors.initials: PJ
authors.lastname: Cripps
authors.forename: P
authors.initials: P
authors.lastname: MacFarlane
mesh_terms: D000768:Anesthesia, General / Q000662:veterinary*; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D002245:Carbon Dioxide / Q000097:blood; D045422:Continuous Positive Airway Pressure / Q000662:veterinary*; D005260:Female; D006736:Horses / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D010313:Partial Pressure; D012129:Respiratory Function Tests / Q000662:veterinary
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen