Effect of Anesthetics on ICP

Anesthetic agents can have profound effects on systemic hemodynamics and cerebral circulation:

Anesthetic Agents	MAP	CMRO2	CBF	Cerebrovascular Autoregulation	CSF Production	Response to
						ICP	Hypervent	Seizures
Inhalation:    Halothane    Enflurane    Isoflurane    N2O	¯¯ ¯¯ ¯¯ «/¯	¯ ¯ ¯¯ ?¯	?¯	Abolished Abolished Maintained ?Maintained	¯ « ?	?	« « « ?	No Yes* No No
Intravenous:    Thiopental    Etomidate    Fentanyl	¯¯ ¯ ¯	¯¯ ¯ «/¯	¯ ¯ «/¯	Maintained Maintained Maintained	« ? «	¯ ¯ «	¯ ¯ ¯	No ? Yes (high dose)

· Increase CBF

• All inhaled agents and ketamine
• Enflurane – lowers seizure threshold)
• Nitrous oxide – Least increase in CBF, no vasodilation
• Isoflurane – small increase in CBF
• Decrease CBF
• All IV agents except ketamine
• Thiopental – cardiodepressant
• Etomidate – suppresses adrenal response to stress
• Cerebral metabolism changes with CBF – all IV decrease CBF (except ketamine), all inhaled increase CBF (nitrous least)