Effects of hypercapnia, hypocapnia, and hyperoxemia on brain morphometrics determined by use of T1-weighted magnetic resonance imaging in isoflurane-anesthetized dogs.
Summary of "Effects of hypercapnia, hypocapnia, and hyperoxemia on brain morphometrics determined by use of T1-weighted magnetic resonance imaging in isoflurane-anesthetized dogs."
Objective-To evaluate the effects of various combinations of Paco(2) and Pao(2) values on brain morphometrics. Animals-6 healthy adult dogs. Procedures-A modified Latin square design for randomization was used. Dogs were anesthetized with propofol (6 to 8 mg/kg, IV), and anesthesia was maintained with isoflurane (1.7%) and atracurium (0.2 mg/kg, IV, q 30 min). Three targeted values of Paco(2) (20, 40, and 80 mm Hg) and 2 values of Pao(2) (100 and 500 mm Hg) were achieved in each dog, yielding 6 combinations during a single magnetic resonance (MR) imaging session. When the endpoints were reached, dogs were given at least 5 minutes for physiologic variables to stabilize before T1-weighted MR images were obtained. Total brain volume (TBV) and lateral ventricular volume (LVV) were calculated from manually drawn contours of areas of interest by use of a software program, with each dog serving as its own control animal. Three blinded investigators subjectively evaluated the lateral ventricular size (LVS) and the cerebral sulci width (CSW). Brain morphometric values were compared among the target blood gas states. Results-No significant differences in TBV were found among target states. The LVV was significantly greater during hypocapnia, compared with hypercapnia at the same Pao(2) value. With regard to the subjective evaluations, there were no significant differences among evaluators or among combinations of Pao(2) and Paco(2) values. Conclusions and Clinical Relevance-The changes observed in LVV during hypocapnia and hypercapnia may serve as a potential confounding factor when neuromorphometric evaluations are performed in anesthetized dogs. (Am J Vet Res 2010;71:1011-1018).
Affiliation
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Journal Details
This article was published in the following journal.
Name: American journal of veterinary research
ISSN: 0002-9645
Pages: 1011-8
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20807139
- DOI: http://dx.doi.org/10.2460/ajvr.71.9.1011
Medical and Biotech [MESH] Definitions
Threshold Limit Values
Standards for limiting worker exposure to airborne contaminants. They are the maximum concentration in air at which it is believed that a particular substance will not produce adverse health effects with repeated daily exposure. It can be a time-weighted average (TLV-TWA), a short-term value (TLV-STEL), or an instantaneous value (TLV-Ceiling). They are expressed either as parts per million (ppm) or milligram per cubic meter (mg/m3).
Multifactorial Inheritance
A phenotypic outcome (physical characteristic or disease predisposition) that is determined by more than one gene. Polygenic refers to those determined by many genes, while oligogenic refers to those determined by a few genes.
Hypocapnia
Clinical manifestation consisting of a deficiency of carbon dioxide in arterial blood.
Hypercapnia
A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood.
Brain Infarction
Tissue NECROSIS in any area of the brain, including the CEREBRAL HEMISPHERES, the CEREBELLUM, and the BRAIN STEM. Brain infarction is the result of a cascade of events initiated by inadequate blood flow through the brain that is followed by HYPOXIA and HYPOGLYCEMIA in brain tissue. Damage may be temporary, permanent, selective or pan-necrosis.
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