Opioids and adjuvant drugs

Abstract

Anesthetic agents can alter cerebral hemodynamics, which can improve or worsen intracranial conditions during surgical procedures. The effects of opioids and other adjuvant analgesics on cerebral hemodynamics are presented in this chapter. Opioids: Although reports differ, cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) remain unaltered or are modestly increased with the administration of clinical doses of opioids, but supraclinical doses of opioids decrease both CBF and CMRO2. However, the cerebrovascular response to a change in mean arterial pressure (MAP) or arterial carbon dioxide tension is unaffected by opioids. Opioids do not increase intracranial pressure (ICP) directly. These findings suggest that clinical doses of opioids can be used safely for neuroanesthesia. The impact of opioids on an ischemic cerebrospinal injury is also discussed. Adjuvant analgesics: A substantial dose of lidocaine may decrease CMRO2. Indomethacin, but not other cyclooxygenase inhibitors, decreases CBF and ICP without decreasing MAP.