Peroperative adenosine infusion reduces isoflurane concentrations during general anesthesia for shoulder surgery

Background: Adenosine (ADO), and stable analogs thereof, have been shown to exert antinociceptive action under experimental conditions in animals and in humans. The aim of this randomized double-blind placebo-controlled study was to evaluate if a low dose of intravenous (i.v.) ADO could reduce isoflurane requirements during joint-associated surgery, as an indication of antinociception in deep somatic pain.
Methods: Thirty-two patients, age 19–62 years, ASA I and II, scheduled for shoulder joint surgery, were assigned to receive an i.v. infusion of either adenosine, 80 μg kg^-1 min^-1, or placebo, during the surgical procedure. Anesthesia was maintained with isoflurane/N₂O/O₂ inhalation.
Results: The peroperative isoflurane concentration was significantly reduced at 50 minutes of surgery in the group receiving adenosine infusion. Also, the systolic blood pressure level was peroperatively more stable during adenosine infusion than during placebo. Other clinical parameters, such as pain, postoperative analgesic requirements and nausea, were not different between groups.
Conclusion: A peroperative infusion of a low dose of adenosine during shoulder joint surgery may reduce the peroperative isoflurane requirement.