Target concentrations of remifentanil with propofol to blunt coughing during intubation, cuff inflation, and tracheal suctioning

Background. The target blood concentrations of propofol and remifentanil, when used in combination, required to blunt the cough response to tracheal intubation, cuff inflation, and tracheal suctioning without neuromuscular blocking agents are not known. Methods. In a randomized prospective study, 81 patients were enrolled to determine which of three target remifentanil blood concentrations was required to blunt coughing during intubation, cuff inflation, and tracheal suctioning. Anaesthesia was achieved with propofol at a steady effect-site concentration of 3.5 μg ml^-1. The target blood remifentanil concentrations were 5, 10, or 15 ng ml^-1. These concentrations were maintained for 12 min before intubation. Results. There was no cough response to intubation in more than 74% of patients and no significant difference in the incidence of coughing with intubation between the three groups. Significant difference in coughing, diminishing with increasing remifentanil target concentration, was observed with cuff inflation (P = 0.04) and tracheal suctioning (P = 0.007). Bradycardia and hypotension was more frequent with the remifentanil target concentration of 15 ng ml^-1. Tracheal suctioning resulted in more coughing than intubation (P=0.01) or cuff inflation (P=0.004). Conclusion. Target remifentanil blood concentrations of 5, 10, and 15 ng ml^-1 associated with a 3.5 μg ml^-1 propofol target blood concentration provided good intubating conditions and absence of cough about 75% of the time. Higher target remifentanil concentrations were associated with less coughing during tracheal tube cuff inflation and tracheal suctioning.