title: Controlled mechanical ventilation with constant positive end-expiratory pressure and alveolar recruitment manoeuvres during anaesthesia in laterally or dorsally recumbent horses.
abstract: OBJECTIVE
  To compare the effects of controlled mechanical ventilation (CMV) and constant positive end-expiratory pressure (PEEP) and interposed recruitment manoeuvres (RMs) with those of CMV without PEEP on gas exchange during general anaesthesia and the early recovery period.
  
  
  METHODS
  Prospective, randomized clinical trial.
  
  
  METHODS
  A total of 48 Warmblood horses undergoing elective surgery in lateral (Lat) (n = 24) or dorsal (Dors) (n = 24) recumbency.
  
  
  METHODS
  Premedication (romifidine), induction (diazepam and ketamine) and maintenance (isoflurane in oxygen) were identical in all horses. Groups Lat- CMV and Dors-CMV (each n = 12) were ventilated using CMV. Groups Lat-RM and Dors-RM (each n = 12) were ventilated using CMV with constant PEEP (10 cmH2O) and intermittent RMs (three consecutive breaths with peak inspiratory pressure of 60 cmH2O, 80 cmH2O and 60 cmH2O, respectively). RMs were applied as required to maintain PaO2at > 400 mmHg (> 53.3 kPa). Dobutamine was given to maintain mean arterial blood pressure at > 60 mmHg. Physiological parameters were recorded every 10 minutes. Arterial blood gases were measured intra- and postoperatively. Statistical analyses were conducted using analyses of variance (anova),t tests and the Mann-Whitney U-test.
  
  
  RESULTS
  Horses in Dors-RM had higher PaO2values [478 ± 35 mmHg (63.7 ± 4.6 kPa)] than horses in Dors-CMV [324 ± 45 mmHg (43.2 ± 6 kPa)] during anaesthesia and the early recovery period. There were no differences between horses in groups Lat-CMV and Lat-RM. Other measured parameters did not differ between groups.
  
  
  CONCLUSIONS
  Ventilation with CMV, constant PEEP and interposed RM provided improved arterial oxygenation in horses in dorsal recumbency that lasted into the early recovery period, but had no benefit in horses in lateral recumbency. This mode of ventilation may provide a clinically practicable method of improving oxygenation in anaesthetized horses, especially in dorsal recumbency.
authors.affiliation: Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany. Electronic address: klaus.hopster@tiho-hannover.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Hopster
authors.affiliation: Department of Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Rohn
authors.affiliation: Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Ohnesorge
authors.affiliation: Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany; Centre for Systems Neuroscience Hannover, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
authors.forename: Sabine B R
authors.initials: SBR
authors.lastname: Kästner
mesh_terms: D000768:Anesthesia, General / Q000379:methods / Q000662:veterinary*; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D045422:Continuous Positive Airway Pressure / Q000379:methods / Q000662:veterinary*; D003975:Diazepam; D017558:Elective Surgical Procedures / Q000379:methods / Q000662:veterinary*; D006736:Horses; D007093:Imidazoles; D007530:Isoflurane; D007649:Ketamine; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D056888:Patient Positioning / Q000379:methods / Q000662:veterinary*; D011175:Positive-Pressure Respiration / Q000662:veterinary; D018467:Positive-Pressure Respiration, Intrinsic / Q000662:veterinary; D011229:Preanesthetic Medication / Q000662:veterinary; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000502:physiology*; D012121:Respiration, Artificial / Q000662:veterinary*
chemical_list: D007093:Imidazoles; D007649:Ketamine; C076257:romifidine; D007530:Isoflurane; D003975:Diazepam; D010100:Oxygen
keywords: controlled mechanical ventilation; equine anaesthesia; oxygenation; positive end-expiratory pressure; recruitment manoeuvres; ventilation