[Therapeutic possibilities of sympathoadrenergic reactions during general anesthesia using sublingual application of...

Strong surgical stimulation (for e. g. sternotomy, mediastinal preparation and aortic dissection in heart surgery) leads to an adrenergic reaction with the so-called haemodynamic break-through phenomenon. The inhibition of this reaction by means of narcotics is always connected with a dangerous decrease of cardiac index. Therefore, the sublingual application of nitroglycerin (GTN: 7 micrograms/kg), well established in the therapy of angina pectoris, was used as a rapidly applicable alternative. Patients with coronary heart disease under neuroleptanaesthesia (n = 10) were investigated in comparison to volunteers (n = 5). Beside the registration of haemodynamic parameters by invasive monitoring, the determination of arterial plasma concentrations of GTN and its metabolites 1.2- and 1.3-glyceryl dinitrate (GDN) were performed using gas-chromatographic technique. Using the same doses the haemodynamic changes are more marked and of longer duration in the anaesthetised patients than in the awake volunteers. The cause seems to be the higher and longer detectable active concentrations of GTN and GDN (the average maximum GTN concentrations greater than 0.5 ng/ml still after 12 minutes in contrast to 7 minutes). After discussing various different pharmacokinetic possibilities this effect is probably related to the simple fact of an improved resorption of the drug in the anaesthetised patient (no salivation, no swallow movements). On the basis of this investigation the sublingual application of GTN is a very useful therapy for the blockade of sympathoadrenergic reactions under anaesthesia, but the commonly used doses of GTN has to be reduced by half (3-4 micrograms/kg).