Left-ventricular performance, volumes, and catecholamine responses during anaesthesia induction--monitoring by combined radionuclide cardiography and right heart catheterization.

Sequential radionuclide imaging and continuous recording of arterial and right heart pressures were carried out during anaesthesia with midazolam 0.2 mg kg-1, pancuronium 0.15 mg kg-1 and fentanyl 10 micrograms kg-1 in eight patients with normal cardiopulmonary status scheduled for craniotomy. The aim was to examine how a stress-free anaesthetic induction tailored to protect against the hypertension and tachycardia provoked by laryngoscopy and intubation influenced left-ventricular performance, left-ventricular loading conditions and plasma catecholamine concentrations. During the 20-min study period no significant changes were observed in heart rate, left-ventricular ejection fraction, ratio of peak systolic pressure to left-ventricular end-systolic volume, pulmonary capillary wedge pressure, left-ventricular end-systolic volume, cardiac output, dopamine and noradrenaline concentrations. Except for a minor increase in mean arterial pressure after laryngoscopy and intubation, mean arterial pressure decreased 24%, left-ventricular end-diastolic volume decreased 15%, and left-ventricular stroke volume decreased 21%. Central venous pressure increased by 75% but there was no parallel increase in pulmonary wedge pressure, which in turn did not reflect the alterations in ventricular end-diastolic volume. Plasma adrenaline concentrations decreased significantly (66%). The chosen induction regimen preserved global left-ventricular pump function during laryngoscopy and intubation without any activation of the sympathetic nervous system. Central venous and pulmonary wedge pressures were unreliable in the assessment of ventricular preload during induction of general anaesthesia.