title: Do Anesthetic Techniques Influence the Threshold for Glomerular Capillary Hemorrhage Induced in Rats by Contrast-Enhanced Diagnostic Ultrasound?
abstract: OBJECTIVE
  Glomerular capillary hemorrhage can be induced by ultrasonic cavitation during contrast-enhanced diagnostic ultrasound (US) exposure, an important nonthermal US bioeffect. Recent studies of pulmonary US exposure have shown that thresholds for another nonthermal bioeffect of US, pulmonary capillary hemorrhage, is strongly influenced by whether xylazine is included in the specific anesthetic technique. The objective of this study was to determine the influence of xylazine on contrast-enhanced diagnostic US-induced glomerular capillary hemorrhage.
  
  
  METHODS
  In this study, anesthesia with ketamine only was compared to ketamine plus xylazine for induction of glomerular capillary hemorrhage in rats by 1.6-MHz intermittent diagnostic US with a microsphere contrast agent (similar to Definity; Lantheus Medical Imaging, Inc, North Billerica, MA). Glomerular capillary hemorrhage was measured as a percentage of glomeruli with hemorrhage found in histologic sections for groups of rats scanned at different peak rarefactional pressure amplitudes.
  
  
  RESULTS
  There was a significant difference between the magnitude of the glomerular capillary hemorrhage between the anesthetics at 2.3 MPa, with 45.6% hemorrhage for ketamine only, increasing to 63.2% hemorrhage for ketamine plus xylazine (P < .001). However, the thresholds for the two anesthetic methods were virtually identical at 1.0 MPa, based on linear regression of the exposure response data.
  
  
  CONCLUSIONS
  Thresholds for contrast-enhanced diagnostic US-induced injury of the microvasculature appear to be minimally affected by anesthetic methods.
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan USA. douglm@umich.edu.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Miller
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Fabiilli
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan USA.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Dou
mesh_terms: D000758:Anesthesia / Q000379:methods*; D000778:Anesthetics, Dissociative; D000818:Animals; D002196:Capillaries; D003287:Contrast Media / Q000009:adverse effects*; D006470:Hemorrhage / Q000139:chemically induced*; D007649:Ketamine; D007678:Kidney Glomerulus / Q000098:blood supply*; D051381:Rats; D014463:Ultrasonography / Q000009:adverse effects*; D014991:Xylazine
chemical_list: D000778:Anesthetics, Dissociative; D003287:Contrast Media; D014991:Xylazine; D007649:Ketamine
keywords: contrast-enhanced diagnostic ultrasound; diagnostic ultrasound adverse effects; glomerular hemorrhage; ultrasonic cavitation biology