Background and aim: Remifentanil is an ultra-short-acting opioid, increasingly used today in neuroanesthesia and neurointensive care. Its characteristics make remifentanil a potentially ideal agent, but previous data have cast a shadow on this opioid, supporting potentially toxic effects on the ischemic brain. The aim of the present concise review is to survey available up-to-date information on the effects of remifentanil on the central nervous system.



Method: A MEDLINE search within the past seven years for available up-to-date information on remifentanil and brain was performed.



Results: Concise up-to-date information on the effects of remifentanil on the central nervous system was reported, with a particular emphasis on the following topics: cerebral metabolism, electroencephalogram, electrocorticography, motor-evoked potentials, regional cerebral blood flow, cerebral blood flow velocity, arterial hypotension and hypertension, intracranial pressure, cerebral perfusion pressure, cerebral autoregulation, cerebrovascular CO2 reactivity, cerebrospinal fluid, painful stimulation, analgesia and hyperalgesia, neuroprotection, neurotoxicity and hypothermia.



Conclusion: The knowledge of the influence of remifentanil on brain functions is crucial before routine use in neuroanesthesia to improve anesthesia performance and patient safety as well as outcome.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1399-6576.2007.01566.x

Remifentanil and the brain.

In patients with severe traumatic brain injury, bronchotracheal toilet may be accompanied by deleterious variations in intracranial pressure (ICP). To avoid these effects, IV opioids have been proposed. Twenty mechanically-ventilated patients received 3 ascending IV doses of remifentanil: dose 1 (1 microg/kg bolus, 0.25 microg/kg/min infusion); dose 2 (2 microg/kg bolus, 0.5 microg/kg/min infusion); and dose 3: (4 microg/kg bolus, 1 microg/kg/min infusion). Endotracheal suction was performed 20 min after the beginning of infusion to assess coughing. Heart rate, ICP, mean arterial blood pressure (MAP), cerebral perfusion pressure (CPP), middle cerebral artery mean flow velocity (V(MCA)), and bispectral index were monitored throughout the 30-min study period. Twelve, 15, and 19 patients receiving dose 1, 2, and 3, respectively, required vasopressors to maintain CPP >60 mm Hg. Suctioning resulted in coughing in 16, 15, and 5 patients receiving dose 1, 2, and 3, respectively. An increase in ICP, without change in V(MCA), corresponded to the reduction in MAP consistent with the preservation of autoregulation. Remifentanil used as a continuous infusion in head-injured patients is not an effective drug to block responses to suctioning.

The effects of remifentanil on endotracheal suctioning-induced increases in intracranial pressure in head-injured patients

Aim: A double blind, randomized, controlled, study was designed to compare the efficacy of single bolus doses of Fentanyl (2μg/kg) or Lignocaine (1.5 mg/kg) for attenuation of pressor response to laryngoscopy and endotracheal intubation (ETI). Methods: Ninety patients received either fentanyl or lignocaine or saline 5 minutes before intubation. Rest of the procedure was standardized. Results: The fentanyl group showed significantly lesser rise (5.46%) in HR compared to lignocaine (16.23%) (p=0.018) and Control group (43.68%) (p=0.000). The rise persisted for 2, 5 and 10 minutes in fentanyl, lignocaine & control groups respectively. The lignocaine group showed lesser rise in SBP (12.1%) compared to Control group (25.8%) (p=0.000) at intubation. The rise persisted for 3 minutes and 10 minutes in lignocaine and control groups respectively. The fentanyl group showed significant decrease in SBP after administration, which came back to normal at 1 to 3 minutes following intubation and again decreased 4 minutes after intubation. In the control group 50% of the patients had hypertension and 80% had tachycardia by definition, while no adverse effects were noted in lignocaine and fentanyl groups. Conclusion:Lignocaine and fentanyl both attenuated the rise in pulse rate, though fentanyl was better. Lignocaine attenuated the rise in blood pressure with intubation whereas fentanyl prevented it totally.

https://print.ispub.com/api/0/ispub-article/10964

Attenuation Of The Hemodynamic Response To Endotracheal Intubation: Fentanyl Versus Lignocaine

care to children with neurologic pathologies. The cerebral physiology is influenced by the developmental stage of the child. The understanding of the effects of anesthetic agents on the physiology of cerebral vasculature in the pediatric population has significantly increased in the past decade allowing a more rationale decision making in anesthesia management. Although no single anesthetic technique can be recommended, sound knowledge of the principles of cerebral physiology and anesthetic neuropharmacology will facilitate the care of pediatric neurosurgical patients.

/pdf/impact-of-anesthetic-agents-on-cerebrovascular-physiology-in-3d38pdl5qh.pdf

Impact of anesthetic agents on cerebrovascular physiology in children.

Purpose of review Remifentanil has now reached maturity, as reflected by the increasing number of clinical papers relating to its use. Its position among anaesthetic drugs is now better understood, and this review will attempt to place it in the context of current clinical practice. Recent findings and summary Propofol reduces the initial distribution of remifentanil, leading to higher concentrations during induction. Propofol and remifentanil administered together at sedative doses display a major synergistic interaction on the respiratory drive. Remifentanil accelerates the penetration of sevoflurane to its site of effect. The risk of intraoperative awareness seems to be low when remifentanil is associated to very low concentrations of hypnotic drugs, but this field warrants further investigation. Acute tolerance to opioids and its prevention remain controversial. Summary Remifentanil is the opioid of choice for tracheal intubation without muscle relaxants. It provides an alternative to regional anaesthesia in labour pain control. Target-controlled infusion may further improve the administration of remifentanil.

remifentanil: an update

Controlling the cerebral and systemic hemodynamic responses to laryngoscopy and tracheal intubation may play a role in determining clinical outcome in pediatric neurosurgical patients. This study compared the effects of remifentanil and fentanyl on cerebral blood flow velocity (CBFV) and hemodynamic profile during laryngoscopy and tracheal intubation in children under sevoflurane anesthesia. Sixty healthy children aged two to six years undergoing dental surgery under general anesthesia were enrolled. Each child was randomly assigned to receive a remifentanil or fentanyl infusion, at a rate of 0.75, 1.0, or 1.5 μg·kg−1·min−1 after induction of anesthesia with 2% sevoflurane. Middle cerebral artery blood flow velocity was measured by transcranial Doppler (TCD) sonography Once a baseline set of hemodynamic variables and TCD measurements were recorded, the opioid infusion was started. Measurements were taken at two-minute intervals, starting four minutes prior to laryngoscopy until four minutes following naso-tracheal intubation. Remifentanil caused a more significant decrease in mean arterial pressure and CBFV prior to tracheal intubation than did fentanyl (P < 0.001). During laryngoscopy and for two minutes following tracheal intubation, CBFV increased in all remifentanil groups (P < 0.05), whereas it remained stable in all fentanyl groups. This study suggests that fentanyl was more effective than remifentanil at preventing increases in CBFV during and immediately following laryngoscopy and tracheal intubation in children undergoing sevoflurane anesthesia. Fentanyl also seemed to provide a more stable hemodynamic profile prior to laryngoscopy and tracheal intubation when compared to remifentanil.

/pdf/fentanyl-is-more-effective-than-remifentanil-at-preventing-me27bxwfzl.pdf

Claude Abdallah

Papers

Fentanyl is more effective than remifentanil at preventing increases in cerebral blood flow velocity during intubation in children.