Tracheal intubation conditions after one minute: rocuronium and vecuronium, alone and in combination

Rocuronium is a recently introduced nondepolarising neuromuscular blocking agent with a rapid onset and intermediate duration of action. Experimental observations have suggested that during onset it acts synergistically with other nondepolarising agents, but that at a steady state the combined action is additive. In order to investigate whether synergism during onset produces a clinical benefit we performed the following study of tracheal intubation conditions. Consenting patients presenting for elective surgery which required tracheal intubation were randomly allocated to receive a standard anaesthetic and either a twice ED₉₅ dose of rocuronium, or vecuronium, or an equipotent mixture of both drugs. Tracheal intubation conditions were assessed after 60 s and scored as excellent, good, poor or impossible. The conditions produced in the rocuronium and the mixture groups were similar and both were significantly better than those of vecuronium. Excellent intubation conditions were achieved in 57% of the rocuronium group, 70% of the mixture group and 27% of the vecuronium group. We conclude that a mixture of rocuronium and vecuronium acts synergistically during the early part of their action and a mixture containing one ED₉₅ of both agents provides comparable conditions for tracheal intubation as an equipotent dose of rocuronium.