Manual Versus Target-Controlled Infusion Remifentanil Administration in Spontaneously Breathing Patients

BACKGROUND: The combination of propofol-remifentanil for procedural deep sedation in spontaneously breathing patients is characterized by the frequent incidence of side effects, especially respiratory depression. These side effects may be due to either the drug combination or the drug delivery technique. Target-controlled infusion (TCI) might optimize drug delivery. In this prospective, randomized, double-blind study in patients undergoing elective colonoscopy, we thus tried to answer two questions: first, if adding remifentanil to propofol surpasses the disadvantages of the combination of these two products, and second, if administration of remifentanil via TO decreases the incidence of side effects, compared to manually controlled administration. METHODS: Patients undergoing elective colonoscopy were randomly assigned to receive remifentanil via manually controlled continuous infusion (MCI) (0.125 mu g . kg(-1) . min(-1) for 2 min followed by a continuous infusion of 0.05 mu g . kg(-1) . min(-1)), TCI remifentanil (1 ng/mL), or placebo (normal saline either as TCI: or manual infusion of equivalent rate). All patients received TO propofol, adjusted to a target concentration level that provided deep sedation in which patients were not responsive to verbal commands, but maintained spontaneous ventilation without assistance. RESULTS: Significantly more patients in the placebo group showed movement, cough and hiccup, which transiently interfered with the examination. There were no clinically significant differences in hemodynamic or recovery variables among all groups. Remifentanil administered via TO resulted in a decrease in propofol requirements. The incidence of hypopnea and apnea was less frequent when remifentanil was administered via TCI compared to MCI (TCI n = 7, MCI n = 16, P < 0.05). CONCLUSION: The combination of remifentanil and propofol for deep sedation in spontaneously breathing patients, offered better conditions for colonoscopy than propofol used as a single drug. Remifentanil administered via TCI resulted in a decrease in propofol dosing and in a lower incidence in apnea and respiratory depression (TCI n = 7, MCI n = 16, P < 0.05), compared to manually controlled administration of remifentanil.