A controlled investigation of propofol, thiopentone and methohexitone

This was a randomized study of 180 ASA physical status I and II patients, 60 in each group who received propofol (PROP), 2.5 mg . kg-1, thiopentone (THIO), 4 mg . kg-1, or methohexitone (METH), 1.5 mg . kg-1. Control values, followed by changes after induction and during a 3-min delay before intubation were recorded for the following parameters: heart rate (HR), systolic and diastolic blood pressures (SBP, DBP), respiratory rate (RR), end-tidal CO2 (PETCO2), and induction time (IT). In addition, the incidence of adverse reactions and time for recovery from anaesthesia were noted. The IT (mean +/- SE) was 35 +/- 1 sec for propofol, 35 +/- 1.2 sec for thiopentone and 34 +/- 1.4 sec for methohexitone. Ninety-three per cent of the PROP group fell asleep with one dose and required no additional doses. Fifty per cent of each of the THIO and METH groups required additional agents (p less than 0.05). METH was associated with the highest elevation in HR, PROP the least (p less than 0.05). PROP was associated with the most decrease in SBP and DBP and in addition respiratory depression (p less than 0.05). The incidence of injection pain or excitatory activity was equal in the three groups with the exception that 14 patients who received METH developed hiccoughs while none did in the other groups. PROP was associated with the most rapid recovery, particularly with respect to the orientation time. We conclude that PROP is an effective alternative to barbiturate induction and that the published recommended doses of THIO and METH are often ineffective.