[The effect of priming dose of vecuronium on the diaphragm and the hypothenar muscle].

We studied the relaxation property of priming or precurarization vecuronium dose (0.015 mg.kg-1) on the diaphragm and the abductor digiti minimi muscle in 8 healthy patients undergoing elective surgery. Patients had control ventilation (PETCO2: 35 - 40 mmHg) by the laryngeal mask under "thiopental-fentanyl-oxygen" anesthesia. Supra-maximal single twitch stimulation with 1 Hz frequency was applied to right phrenic and ulnar nerves. Electromyographic response was recorded using NEC Synax ER1100 (NEC, Sanei, Tokyo, Japan) by surface electrodes in the 8 th intercostal space and the hypothenar. Time to maximum blockade at the diaphragm was 189 +/- 37 sec, compared with 314 +/- 39 at the abductor digiti minimi muscle (P < 0.01). This result suggests that we should be careful about the respiratory state of primed or precurarized patients with small dose of vecuronium such as 0.015 mg.kg-1 administration.