RAPID INHALATION INDUCTION WITH HALOTHANE NITROUS-OXIDE FOR MYASTHENIC PATIENTS

Rapid inhalation induction (RII) was successfully employed for patient s without myopathy. Inhalatory agents can be used for anaesthetic indu ction of myasthenics, avoiding the use of neuromuscular blocking agent s. We studied the use of RII in 15 myasthenics (MG) and in 15 normal s ubjects (nMG), measuring induction time (TI), cardiorespiratory effect s, complications, and evaluated the patient's reaction to RII. The pat ients were submitted to elective transsternal thymectomly (MG) and gyn aecological or lower abdominal surgery (nMG). No premedication was use d. After preoxygenation, RII war starred using a mixture of 4% halotha ne and O-2:N2O (1:2). They performed three vital capacity breaths, fol lowed by normal spontaneous ventilation. ?he TI was assessed by timing the loss of verbal command (TLVC) and loss of eyelid reflex (TLER). S ystolic and diastolic pressure, pulse oximetry, capnometry, respirator y rate (RR) and heart rate (HR) were measured during induction at each minute, for four minutes. After a postanaesthetic questionnaire only two normal subjects did not like the RII technique. Mean values for TL VC and TLER were 67 and 73 sec for MG and 64 and 69 sec for nMG, respe ctively. There was no change in HR for MG or blood pressure. The RR in creased in both groups, but no change in PETCO(2) was observed; SaO2 w as >97%. In conclusion, RII can be performed rapidly and safely in mya sthenic patients and is a technique that should be considered for the induction of anaesthesia in myasthenic patients.