Читать книгу Manual of Equine Anesthesia and Analgesia - Группа авторов - Страница 337

 Anesthetic drugs can modify cerebral blood flow and cerebral metabolic rate (see Table 6.1).

 These changes can be affected by the presence or absence of intracranial pathology, and may also be influenced by hypoxemic or hypercapnic states.

 Isoflurane increases ICP in normal horses, and this is exacerbated by a prolonged duration of anesthesia, by hypoventilation (increased PaCO2), and if the head is positioned below heart level.

 Isoflurane preserves autoregulation even at moderate‐deep levels of anesthesia in healthy horses and a cerebral blood flow of 33 ml/100 g/minute, regardless of mean arterial pressure in the 60–100 mmHg range.

 Dobutamine infusion was not found to increase ICP in normal horses.

 Spinal cord perfusion was found to decrease during isoflurane anesthesia, and dobutamine infusion may decrease perfusion further.

 However, hypotension and decreased ability to autoregulate cerebral perfusion caused by older volatile anesthetics such as halothane may cause rare neurological complications in normal horses.

 Cerebral vasodilation with volatile anesthetics is a problem in disease states when high ICP is already present. The increase in blood volume within the cranium could increase ICP further.

 Drugs which produce a degree of cerebral vasoconstriction may be more useful, especially if they also decrease cerebral metabolic rate (e.g. α2 agonists and propofol).