title: Evaluation of an acute focal epidural mass model to characterize the intracranial pressure-volume relationship in healthy Beagles.
abstract: OBJECTIVE
  To characterize the intracranial pressure-volume relationship (ICPVR) in dogs by use of an acute frontal-parietal mass lesion model.
  
  
  METHODS
  7 healthy adult female Beagles.
  
  
  METHODS
  Dogs were anesthetized with isoflurane to achieve a surgical plane of anesthesia. A fiberoptic intracranial pressure (ICP) monitor was inserted to a depth of 1 cm in the parenchyma of the right frontal-parietal region of the brain. A Foley balloon-tipped catheter was placed in the epidural space of the left frontal-parietal area through a separate 1-cm burr hole. Baseline measurements were obtained with the balloon deflated. The balloon was then inflated incrementally with 0.5 mL of 0.9% NaCl solution every 10 minutes until ICP exceeded mean arterial blood pressure. Nonlinear regression analysis with 2-factor and 3-factor exponential equations was used to characterize the ICPVR.
  
  
  RESULTS
  The mean baseline ICP was 11 mm Hg, with a 95% confidence interval of 2 to 20 mm Hg. The ICPVR was well characterized by 2-factor or 3-factor exponential equations for all dogs (R² > 0.93). Balloon volumes of > 1. 2 mL were associated with ICP > 20 mm Hg.
  
  
  CONCLUSIONS
  Characterization of the ICPVR may provide clinically useful information regarding the safety of obtaining CSF from the atlanto-occipital space or implantation of brachytherapy catheters and for determining the need for decompressive craniectomy in dogs with acute intracranial disease. High ICP should be suspected in dogs that have an acute frontal-parietal mass lesion estimated to exceed 2% of the brain volume.
authors.affiliation: Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47906, USA. rpacker@purdue.edu
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Packer
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Simmons
authors.forename: Nichol M
authors.initials: NM
authors.lastname: Davis
authors.forename: Peter D
authors.initials: PD
authors.lastname: Constable
mesh_terms: D000818:Animals; D001794:Blood Pressure; D001927:Brain Diseases / Q000503:physiopathology; D004195:Disease Models, Animal; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D004824:Epidural Space / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate; D007427:Intracranial Pressure / Q000502:physiology*; D008991:Monitoring, Physiologic / Q000379:methods / Q000662:veterinary