Propranolol in neurosurgical patients with sinus tachycardia. Cardiovascular effects and mode of use.

Cardiac rate (CR) and systolic arterial blood pressure (ABP) response to the intravenous injection of one, two, or three mg propranolol were recorded in 77 patients with traumatic, neoplastic, or haemorrhagic intracranial lesions and sinus tachycardia. In most patients tachycardia occurred with no cause except the intracranial lesion; in the other patients induction of general anaesthesia or surgical procedures on the brain appeared to have an initiating role. A central imbalance, with increased sympathetic cardiotropic influences is suggested and discussed. (I) First administrations of propranolol always reduced CR but had different effects on ABP from case to case; in all the patients 2.05 +/- 0.84 mg of drug lowered CR by 28 +/- 14/min (P less than 0.01), and ABP by 4.7 +/- 11 torr. CR decrease and ABP changes were without relation to the injected dose. Previous digitalization (desacetyllanatoside C) did not modify CR response to propranolol but reduced (P less than 0.05) its arterial hypotensive action. Positive correlations were found between basal CR and CR decrease (P less than 0.01), basal CR and ABP changes (P less than 0.01), CR decrease and ABP changes (P less than 0.05). Halothane appeared to potentiate CR response (P less than 0.01). (II) CR effect was less when the same dose of propranolol was repeated within 90 min (P less than or equal to 0.05). Usefulness and the mode of use of propranolol were critically evaluated.