COMPARISON OF THE CARDIOVASCULAR EFFECTS OF BOLUS V . INCREMENTAL ADMINISTRATION OF THIOPENTONE

Abstract

Twenty unpremedicated patients (ASA grade I) were assigned randomly to receive thiopentone in 50-mg increments every 15 s until loss of lash reflex (group I) or as a 4-mg kg⁻1 bolus (group II). Arterial pressure, heart rate, systolic time intervals and end-tidal carbon dioxide were measured in the control state and then every 30 s. The mean dose of thiopentone in group I was 5.58±1.24 (SD) mg kg⁻1 which was significantly larger than in group II (P< 0.001). Both groups exhibited similar decreases in arterial pressure and increases in heart rates. The degree of cardiac depression revealed from measurement of the systolic time intervals, indexed for heart rate, was equal in the two groups.