Dosage of neostigmine for reversal of rocuronium block from two levels of spontaneous recovery

Spontaneous recovery, and recovery following neostigmine 20, 35 or 50 mu g. kg(-1) administered at 10 or 25% of recovery of the first twitch of the tra in-of-four, was assessed in 80 patients after rocuronium administration und er continued isoflurane anaesthesia. In an additional 10 patients, isoflura ne administration was discontinued and neostigmine 35 or 50 mu g.kg(-1) was given at 10 or 25% recovery. The administration of neostigmine reduced the recovery times significantly. A neostigmine dose of 20 mu g.kg(-1) resulte d in slower recovery compared with the higher doses, particularly when reve rsal was attempted at a first twitch height of 10%. Higher doses of neostig mine given at a first twitch height of 25% resulted in rapid reversal of bl ock [mean (SD) times of 7.0 (4.8) and 6.4 (1.9) min with the 35 and 50 mu g .kg(-1) doses, respectively, for attaining a train-of-four ratio of 0.8]. D iscontinuing isoflurane did not alter recovery times. The incidence of emet ic symptoms did not differ between groups, including one group that receive d atropine instead of glycopyrronium in combination with neostigmine. We co nclude that rocuronium block can be antagonised safely using a neostigmine dose of 35 mu g.kg(-1), although recovery may be slightly slower if adminis tered at a first twitch of 10% of control.