Sedation with alfentanil and propofol for rhizotomies
Background: Patient safety during sedation for closed rhizotomies is improved when analgesia is optimised, rather than relying on deep sedation for patient comfort. This retrospective study determined the appropriate effect-site concentration (Ce) for alfentanil, in combination with a constant propofol infusion, for optimal pain control during sedation for closed rhizotomies. Airway maintenance is ensured by keeping patients responsive to verbal commands, albeit at the price of inevitable ventilatory depression.
Method: The records of patients who received rhizotomies over a six-month period were studied retrospectively. Sixty-three outpatients were included. Patients rated the level of analgesia with each needle placement. If the Ce for alfentanil was adequate, it was kept constant. Otherwise, it was increased in 5 ng/ml increments with each needle placement until analgesia was effective, or up to the maximum Ce for alfentanil of 100 ng/ml. Propofol infusion at a constant Ce of 200 ng/ml was added.
Results: Forty-eight per cent of patients reported being comfortable at a Ce for alfentanil of 70–75 ng/ml. Only 5% of patients requested the maximum Ce for alfentanil of 100 ng/ml. All of the patients experienced ventilatory depression, but a patent airway was maintained. The haemodynamic observations were within normal limits. According to the ward records, 16% of the patients complained of nausea, and there was one incident of vomiting.
Conclusion: Combining alfentanil at a Ce for alfentanil of 70–100 ng/ml with propofol at 200 ng/ml is a safe and effective method for analgesia during sedation for closed rhizotomies.
Keywords: alfentanil, analgesia, procedural sedation, propofol, rhizotomy, target-controlled infusion