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Intracranial elastance in isoflurane-anesthetized horses
Robert J Brosnan1, Richard A LeCouteur, Eugene P Steffey
1Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
American Journal of Veterinary Research
|September 1, 2004
Summary
High intracranial pressure (ICP) in anesthetized horses during spontaneous ventilation (SV) correlates with increased intracranial elastance. Small volume changes significantly impact ICP, potentially worsening intracranial hypertension.
Area of Science:
- Veterinary Anesthesiology
- Equine Physiology
- Intracranial Pressure Dynamics
Background:
- Anesthetized horses can experience elevated intracranial pressure (ICP).
- Understanding intracranial elastance is crucial for managing ICP during anesthesia.
Purpose of the Study:
- To investigate the relationship between high ICP during spontaneous ventilation (SV) and intracranial elastance in anesthetized horses.
- To assess how intracranial volume changes affect ICP under specific anesthetic conditions.
Main Methods:
- Six adult horses were anesthetized with isoflurane for 5 hours.
- Intracranial pressure (ICP) and arterial blood pressure were measured.
- Cerebrospinal fluid (CSF) was removed in aliquots during SV to determine intracranial elastance via pressure-volume curves.
Main Results:
- Intracranial elastance varied significantly (0.2–3.7 mm Hg/mL).
- Steeper pressure-volume curves were observed after initial CSF removal, indicating increased elastance.
- A second-order relationship was found between SV ICP and initial intracranial elastance.
Conclusions:
- In isoflurane-anesthetized horses, minor intracranial volume fluctuations can lead to substantial ICP increases.
- Elevated intracranial elastance may worsen existing intracranial hypertension.
- Compensatory fluid shifts suggest sustained increases in intracranial volume during anesthesia.