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Effects of changes in power setting of an ultrasonic aspirator on amount of damage to the cerebral cortex of healthy dogs

Rodney S. BagleyDepartment of Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164- 6610.

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Michael L. HarringtonDepartment of Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164- 6610.
Present address is Animal Neurology and Neurosurgery, 9200 Red-Wood NE, No. C313, Redmond, WA 98052.

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John M. GayDepartment of Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164- 6610.

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Gena M. SilverDepartment of Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164- 6610.
Present address is the Massachusetts Veterinary Referral Hospital, 21 Cabot Rd, Woburn, MA 01804.

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Abstract

Objective—To determine the minimal ultrasonic aspirator pressure necessary to damage the cerebral cortex of healthy dogs.

Animals—9 mixed-breed dogs.

Procedure—The study comprised 2 parts. In part A, 6 dogs were euthanatized immediately prior to the experiment. In part B, 3 dogs were anesthetized for recording of physiologic variables. In both parts, craniectomy and durotomy were performed to bilaterally expose the lateral aspect of the cerebral cortex. An ultrasonic aspirator was placed in contact with various areas of the cerebral cortex, and aspirator power was altered (10, 20, 30, and 40%). Duration of contact at each power was 5 and 10 seconds. Subsequently, gross morphologic and histologic damage was assessed in the cortex.

Results—Gross observations for all dogs were similar. At 10% power, visible or histologic damage was not evident in the cortex. At 20% power, the cortex was slightly indented from contact with the hand piece; however, cortical disruption was not evident. Cortical disruption was initially detectable at 30% power in some dogs and was consistently evident at 40% power in both sets of dogs.

Conclusions and Clinical Relevance—Ultrasonic aspirator power of < 20% created minimal acute morphologic damage to the cortex. Power settings between 20 and 30% may superficially damage the cerebral cortex in healthy dogs, whereas 40% power consistently damages the cerebral cortex. Knowledge of the degree of damage to cerebral cortex caused by various amounts of power for ultrasonic aspirators will allow surgeons to avoid damaging normal brain tissues during surgery. (Am J Vet Res 2001;62: 248–251)

Abstract

Objective—To determine the minimal ultrasonic aspirator pressure necessary to damage the cerebral cortex of healthy dogs.

Animals—9 mixed-breed dogs.

Procedure—The study comprised 2 parts. In part A, 6 dogs were euthanatized immediately prior to the experiment. In part B, 3 dogs were anesthetized for recording of physiologic variables. In both parts, craniectomy and durotomy were performed to bilaterally expose the lateral aspect of the cerebral cortex. An ultrasonic aspirator was placed in contact with various areas of the cerebral cortex, and aspirator power was altered (10, 20, 30, and 40%). Duration of contact at each power was 5 and 10 seconds. Subsequently, gross morphologic and histologic damage was assessed in the cortex.

Results—Gross observations for all dogs were similar. At 10% power, visible or histologic damage was not evident in the cortex. At 20% power, the cortex was slightly indented from contact with the hand piece; however, cortical disruption was not evident. Cortical disruption was initially detectable at 30% power in some dogs and was consistently evident at 40% power in both sets of dogs.

Conclusions and Clinical Relevance—Ultrasonic aspirator power of < 20% created minimal acute morphologic damage to the cortex. Power settings between 20 and 30% may superficially damage the cerebral cortex in healthy dogs, whereas 40% power consistently damages the cerebral cortex. Knowledge of the degree of damage to cerebral cortex caused by various amounts of power for ultrasonic aspirators will allow surgeons to avoid damaging normal brain tissues during surgery. (Am J Vet Res 2001;62: 248–251)