1 / 20

Remifentanil and the brain

Remifentanil and the brain. Acta Anaesthesiologica Scandinavica 2008; 52: 319-26 마취통증의학과 4 년차 전주연. Introduction. Remifentanil-based anesthesia Most desirable features of a neuroanesthetic regime Rapid anesthetic emergence

melania
Download Presentation

Remifentanil and the brain

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Remifentanil and the brain Acta Anaesthesiologica Scandinavica 2008; 52: 319-26 마취통증의학과 4년차 전주연

  2. Introduction • Remifentanil-based anesthesia • Most desirable features of a neuroanesthetic regime • Rapid anesthetic emergence • Delayed and recurring respiratory depression has not been reported • Low incidence of N/V (esp. the addition of propofol) • Up-to-date information on the effects of remifentanil on the CNS

  3. Cerebral metabolism • Opioids • Little or no effect on cerebral metabolism. • Remifentanil • Favorable effects on cerebral metabolism • Decreasing the cerebral metabolic rate of oxygen (CMRO2) • Cf) Large dose remifentanil • Increase CMRO2 in the temporal lobe from 6.29 to 7.68mg/100g/min

  4. Electroencephalogram (EEG) and electrocorticography (EcoG) • Very stable EEG during noxious stimulations. • Effect on BIS –controversial • Use of narcotic agents – confound measurements of depth of sedation or anesthesia • Sevoflurane-remifentanil – strongly synergistic for clinical sedation • BIS and A-line autoregressive index(AAI) are insensitive • Remifentanil to propofol affects BIS • only when a painful stimulus • Attenuated or abolished increases in EEG, BIS, auditory-evoked potentials and MAP during noxious stimulations

  5. Electroencephalogram (EEG) and electrocorticography (EcoG) • Effects of remi on the quality of intraop. EcoG • Sedative doses of this opioid • Minimal effects on EcoG spike activity • Continuous infusion of 0.1 μg/kg /min • Non-significant decrease in spike frequency with slowed background EcoG activity • Remifentanil enhances epileptiform activity • Facilitating localization of the epileptogenic zone and minimizing resection of nonepileptogenic eloquent brain tissue. • Opioid administration • Generalized tonic-clonic seizure like activity • So-called ‘opioid-seizure syndrome’

  6. Motor-evoked potentials (MEPs) • MEPs • Useful in preventing permanent neurological deficits during cranial and spinal procedures • Quality of MEPs • Depend on the stimulation pattern and technique of anesthesia. • Opioids, propofol and thiopental • Supress myogenic, but not neurogenic • Remifentanil • the least suppressive effects • Remifentanil with propofol • Enhances the quality of intraop. MEPs and allows recoding of myogenic potential

  7. Regional cerebral blood flow (rCBF) • rCBF changes • Dose-dependent manner in areas involved in pain processing • Low doses(0.05 μg/kg /min) • Increase in rCBF-lat.prefrontal cortices inf. Parietal cortices, and supplementary motor area • rCBF decreases in the basal mediofrontal cortex, cerebellum, sup. temporal lobe and midbrain gray matter. • Moderate doses(0.15 μg/kg /min) • rCBF increase in mediofrontal and ant. cingulate cortices, occipital lobe transition and caudal periventricular gray matter • Decrease in the inf. Parietal lobes

  8. Arterial hypotension and hypertension • Cerebral vascular system – admirable autoregulation • In neuroanesthesia – controlled hypotension, damaged brain may fail to compensation the reduction of MAP, with a subsequent risk of ischemia. • Remifentanil • increased incidence of hypotensive episodes(in comparison with other opioids) • ABP decreases by about 30% - more evident in aged, hypovolemic and obese patients • > 65yr – drug dosage must be reduced by 50% • Obese pt. – dose must be calcuated on the basis of ideal wt. and not on the actual wt. • Undergoing neurosurgery and receiving osmotic diuretics, simulating a hypovolemic-like clinical effect in the pt. – reduction of the dasage.

  9. Arterial hypotension and hypertension • Increased clinical experience • Patients are hemodynamically more stable • Decreased incidence of opioid-related adverse events. • TIVA c propofol-remifentanil ( compared with balanced anesthesia c sevo.-fentanyl) • Increased incidence of arterial hypertension requiring antihypertensive medication to maintain the MAP within 20% of the baseline.

  10. Intracranial pressure (ICP) • Infusion of remifentanil • Decreased ICP with minimal cerebral perfusion pressure(CPP) changes • Excision of supratentorial space-occupying lesions under conditions of a backgroud of isoflurane – no significant effect on ICP at a dose of either 0.5 or 1.0 μg/kg . • Neurosurgical ICU • Remifentanil use has been recommended for ICP control.

  11. Cerebral perfusion pressure (CPP) • Large doses of remifentanil • Reduce cerebral blood flow despite constant perfusion pressure. • Remifentanil (bolus of 0.5 μg/kg , followed by a continuous infusion 0.25 μg/kg /min for 20min) • on-top analgesia in head trauma pts. without adverse effects on cerebrovascular hemodynamics and CPP.

  12. Cerebral autoregulation • Remifentanil with propofol • Induces a dose-dependent low-flow state with preserved cerebral autoregulation • Autoregulatory index increased significantly • Low-flow state and the increase of cerebrovascular reactivity(CVR) – widens the autoregulatory plateau.

  13. Cerebrospinal fluid (CSF) • Rate of CSF formation(Vf) and resistance to reabsorption of CSF(Ra) • Very important as they influence CSF vol., ICP and intracranial elastance. • Independent of remifentanil dosage in rabbits. • Remifentanil dose of 0.1μg/kg /min under normocapnic condition • Systolic CSF peak velocity is not significantly altered in both animals and in healty human volunteers.

  14. Painful stimulation, analgesia and hyperalgesia • Difficult postop. pain management and promotion of hyperalgesia • Large-dose intraop. remifentanil can be associated with the development of hyperalgesia merely increasing sensitivity to noxious stimuli. • Different mechanisms of opioid-induced post-infusion anti-analgesia and secondary hyperalgesia. • Adequate pain therapy after TIVA with short-acting opioid drugs is mandatory.

  15. Neuroprotection • Cerebral ischemia • Excitotoxicity and neuronal death • Neuroprotective role of anesthetic agents. • Barbiturates and volatile agents, ketamine • Significant protective effects against ischemic injury • Endogenous opioid • Both neurodestructive and neuroprotective roles in CNS injury. • μ and k1 receptor – neuroprotective actions • k2 receptors –secondary injury responses • Remifentanil – potent synthetic μ-opioid agonist

  16. Neurotoxicity • Rat • Large dose μ-opioids are reported to produce limbic system hypermetabolism and histopathology. • Remifentanil infusion for 3h of 20-160μg/kg/min, dose-related EEG activation was evident. • In 19 out of 40 remifentanil treated rats, varying degrees of acute neuronal degeneration confined to the limbic system and its associated areas. • Physicians should be aware of these hazardous effects could occur during anesthesia or sedation.

  17. Hypothermia • Hypothermia • In selected patients to improve neuroprotection • Decreases clearance • Increased total remifentanil concentrations. • Elimination clearance decreases by 6.37% for each degree decrease from 37°C • Remifentanil infusion rate is reduced by 30% for each 5° decrease in temperature

  18. Conclusions • Aim of anesthesia • Providing brain relaxation, minimal interference with electrophysiological monitoring, rapid recovery, pt’s cooperation during surgery and neuroprotection • Combination of remifentanil with either an intravenous hypnotic or an inhalation agent – most satisfactory • Cerebral ischemia and neuroprotection • important issues for neurosurgeons, and the potential use of this opioid in neuroanesthesia and neurointensive management has been criticized. • But, Successive data have now emerged supporting and requiring other and more extensive research of remifentanil in the field of neuroprotection

  19. Conclusions • Neurocognitive effect of remifentanil • Disruption of cortical cholinergic NT • post-operative delirium and impaired memory function, increase in patient morbidity, delayed functional recovery and prolonged hospital stays. • Morphine and fentanyl, but not remifentanil, disrupt cholinergic NT. • Remifentanil • perfect titration of the analgesic effects to varying noxious stimulation intensities • rapid recovery • early assessment of postop. neurologic function. • Incidence of collateral effects of remi. –minimal. • Decreased hemodynamic variability, improved recovery profile and decreased incidence of opioid-related adverse events c increasing experience.

  20. Conclusions • Remifentanil - Ideal narcotic agent during neurosurgical procedure.

More Related