Interaction between postoperative shivering and hyperalgesia caused by high-dose remifentanil

Area of Science:

• Anesthesiology
• Pharmacology
• Pain Management

Background:

• High-dose remifentanil anesthesia is linked to opioid-induced hyperalgesia (OIH) and postanesthetic shivering (PAS).
• N-methyl-d-aspartate (NMDA) receptor antagonists can prevent these adverse effects.
• The study investigates the correlation between OIH and PAS induced by high-dose remifentanil and the impact of low-dose ketamine.

Purpose of the Study:

• To examine the relationship between OIH and PAS caused by high-dose remifentanil.
• To evaluate the efficacy of low-dose ketamine in mitigating OIH and PAS.
• To explore the potential shared mechanisms underlying these remifentanil-induced effects.

Main Methods:

• Seventy-five patients undergoing gynecologic surgery were randomized into three groups.
• Groups received different intraoperative remifentanil dosages (0.1 µg/kg/min or 0.3 µg/kg/min).
• One group received high-dose remifentanil plus low-dose ketamine (0.25 mg/kg bolus and 5 µg/kg/min infusion).

Main Results:

• Post-anesthetic shivering (PAS) and hyperalgesia were significantly higher in the high-dose remifentanil group compared to others.
• PAS showed significant correlations with OIH, including tactile pain thresholds and hyperalgesia extent in high-dose remifentanil groups.
• Key outcomes like temperature, time to first analgesic, pain scores, and morphine consumption were comparable across groups.

Conclusions:

• Opioid-induced hyperalgesia (OIH) and postanesthetic shivering (PAS) are associated with high-dose remifentanil.
• These effects are significantly correlated and can be attenuated by low-dose ketamine.
• A shared mechanism, potentially involving central glutamatergic system activation via NMDA receptors, likely underlies these remifentanil-induced effects.