Changes in Plasma Glycine Concentration in General Anesthesia With Remifentanil: A Prospective Observational Pilot...

Area of Science:

• Anesthesiology and Pharmacology
• Neuroscience
• Pain Management

Background:

• Remifentanil anesthesia is linked to postanesthetic shivering (PAS) and opioid-induced hyperalgesia (OIH).
• Both PAS and OIH may involve N-methyl-D-aspartate (NMDA) receptor signaling, with glycine acting as a co-agonist.
• Commercial remifentanil contains glycine, prompting investigation into perioperative glycine level changes.

Purpose of the Study:

• To determine if general anesthesia using glycine-containing remifentanil elevates plasma glycine levels.
• To analyze the perioperative course of plasma glycine concentrations.

Main Methods:

• Prospective observational study in 10 adult patients undergoing elective pancreaticoduodenectomy.
• Balanced anesthesia with desflurane, propofol, and remifentanil (containing glycine).
• Plasma glycine measured at six time points; postanesthetic shivering, pain, and delirium assessed exploratorily.

Main Results:

• Plasma glycine levels did not significantly increase during remifentanil infusion.
• Glycine levels were significantly lower at 2 and 3 hours post-remifentanil compared to pre-induction.
• One patient showed elevated glycine despite preserved organ function; study lacked power for clinical outcome associations.

Conclusions:

• Glycine-containing remifentanil anesthesia did not elevate plasma glycine in most patients with preserved organ function.
• The findings limit the assessment of NMDA receptor-mediated mechanisms for PAS and OIH in this context.
• Further research should explore high-concentration remifentanil or concomitant glycine formulations.