Effects of ventilation and isoflurane end-tidal concentration on intracranial and cerebral perfusion pressures in horses

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Abstract

Objective - To measure the effects of isoflurane end-tidal concentration and mode of ventilation (spontaneous vs controlled) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in horses. Animals - 6 adult horses of various breeds. Procedures - Anesthesia was induced and maintained with isoflurane in O2 in 6 healthy, unmedicated, adult horses. Using a subarachnoid strain gauge transducer, ICP was measured. Blood gas tensions and carotid artery pressures also were measured. Four isoflurane doses were studied, corresponding to the following multiples of the minimum alveolar concentration (MAC): 1.0 MAC, 1.2 MAC, 1.4 MAC, and 1.6 MAC. Data were collected during controlled ventilation and spontaneous ventilation at each dose. Results - Increasing isoflurane end-tidal concentration induced significant dose-dependent decreases in mean arterial pressure (MAP) and CPP but no change in ICP. Hypercapnic spontaneous ventilation caused significant increases in MAP and ICP compared with normocapnic controlled ventilation; no change in CPP was observed. Conclusions and Clinical Relevance - Hypercapnia likely increases cerebral blood flow (CBF) by maintaining CPP in the face of presumed cerebral vasodilation in healthy anesthetized horses. The effect of isoflurane dose on CBF, however, remains unresolved because it depends on the opposing influences of a decrease in CCP and cerebral vasodilation.

Original languageEnglish (US)
Pages (from-to)21-25
Number of pages5
JournalAmerican Journal of Veterinary Research
Volume64
Issue number1
DOIs
StatePublished - Jan 1 2003

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Cerebrovascular Circulation
Isoflurane
isoflurane
Horses
Ventilation
Intracranial Pressure
horses
Vasodilation
Arterial Pressure
vasodilation
Hypercapnia
dosage
blood flow
Transducers
Carotid Arteries
Anesthesia
Gases
hypercapnia
horse breeds
Pressure

ASJC Scopus subject areas

  • veterinary(all)

Cite this

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title = "Effects of ventilation and isoflurane end-tidal concentration on intracranial and cerebral perfusion pressures in horses",
abstract = "Objective - To measure the effects of isoflurane end-tidal concentration and mode of ventilation (spontaneous vs controlled) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in horses. Animals - 6 adult horses of various breeds. Procedures - Anesthesia was induced and maintained with isoflurane in O2 in 6 healthy, unmedicated, adult horses. Using a subarachnoid strain gauge transducer, ICP was measured. Blood gas tensions and carotid artery pressures also were measured. Four isoflurane doses were studied, corresponding to the following multiples of the minimum alveolar concentration (MAC): 1.0 MAC, 1.2 MAC, 1.4 MAC, and 1.6 MAC. Data were collected during controlled ventilation and spontaneous ventilation at each dose. Results - Increasing isoflurane end-tidal concentration induced significant dose-dependent decreases in mean arterial pressure (MAP) and CPP but no change in ICP. Hypercapnic spontaneous ventilation caused significant increases in MAP and ICP compared with normocapnic controlled ventilation; no change in CPP was observed. Conclusions and Clinical Relevance - Hypercapnia likely increases cerebral blood flow (CBF) by maintaining CPP in the face of presumed cerebral vasodilation in healthy anesthetized horses. The effect of isoflurane dose on CBF, however, remains unresolved because it depends on the opposing influences of a decrease in CCP and cerebral vasodilation.",
author = "Brosnan, {Robert J} and Eugene Steffey and Lecouteur, {Richard A} and Ayako Imai and Farver, {Thomas B} and Kortz, {Greg D.}",
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AU - Steffey, Eugene

AU - Lecouteur, Richard A

AU - Imai, Ayako

AU - Farver, Thomas B

AU - Kortz, Greg D.

PY - 2003/1/1

Y1 - 2003/1/1

N2 - Objective - To measure the effects of isoflurane end-tidal concentration and mode of ventilation (spontaneous vs controlled) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in horses. Animals - 6 adult horses of various breeds. Procedures - Anesthesia was induced and maintained with isoflurane in O2 in 6 healthy, unmedicated, adult horses. Using a subarachnoid strain gauge transducer, ICP was measured. Blood gas tensions and carotid artery pressures also were measured. Four isoflurane doses were studied, corresponding to the following multiples of the minimum alveolar concentration (MAC): 1.0 MAC, 1.2 MAC, 1.4 MAC, and 1.6 MAC. Data were collected during controlled ventilation and spontaneous ventilation at each dose. Results - Increasing isoflurane end-tidal concentration induced significant dose-dependent decreases in mean arterial pressure (MAP) and CPP but no change in ICP. Hypercapnic spontaneous ventilation caused significant increases in MAP and ICP compared with normocapnic controlled ventilation; no change in CPP was observed. Conclusions and Clinical Relevance - Hypercapnia likely increases cerebral blood flow (CBF) by maintaining CPP in the face of presumed cerebral vasodilation in healthy anesthetized horses. The effect of isoflurane dose on CBF, however, remains unresolved because it depends on the opposing influences of a decrease in CCP and cerebral vasodilation.

AB - Objective - To measure the effects of isoflurane end-tidal concentration and mode of ventilation (spontaneous vs controlled) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in horses. Animals - 6 adult horses of various breeds. Procedures - Anesthesia was induced and maintained with isoflurane in O2 in 6 healthy, unmedicated, adult horses. Using a subarachnoid strain gauge transducer, ICP was measured. Blood gas tensions and carotid artery pressures also were measured. Four isoflurane doses were studied, corresponding to the following multiples of the minimum alveolar concentration (MAC): 1.0 MAC, 1.2 MAC, 1.4 MAC, and 1.6 MAC. Data were collected during controlled ventilation and spontaneous ventilation at each dose. Results - Increasing isoflurane end-tidal concentration induced significant dose-dependent decreases in mean arterial pressure (MAP) and CPP but no change in ICP. Hypercapnic spontaneous ventilation caused significant increases in MAP and ICP compared with normocapnic controlled ventilation; no change in CPP was observed. Conclusions and Clinical Relevance - Hypercapnia likely increases cerebral blood flow (CBF) by maintaining CPP in the face of presumed cerebral vasodilation in healthy anesthetized horses. The effect of isoflurane dose on CBF, however, remains unresolved because it depends on the opposing influences of a decrease in CCP and cerebral vasodilation.

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