Eighteen thyrotoxic patients receiving chronic treatment with propranolol (160 mg/day) were studied to determine the relationship between plasma propranolol concentration and drug effect. There was a considerable interindividual variability in both the plasma propranolol steady state concentration and the degree of beta-adrenergic blockade. The plasma propranolol steady state concentration correlated significantly with both beta-adrenergic blockage and weight change but not with the degree of subjective improvement. In a group of 40 patients, including 10 severely thyrotoxic patients, who had the dosage of propranolol titrated objectively preoperatively to bring about a greater than 25% reduction in exercise heart rate at the end of a dosage interval, no case of thyroid storm was encountered. Many patients, the younger and severely thyrotoxic in particular, require doses in excess of 160 mg/day to achieve this degree of beta-adrenergic blockade.

The perioperative course of 44 hyperthyroid patients prepared for surgery with propranolol alone, including 11 with severe thyrotoxicosis was compared to that of 20 euthyroid patients prepared for surgery with carbimazole. Conventional propranolol at a dosage of 160 mg/day was frequently insufficient to produce a high degree of beta-adrenergic blockade, particularly in severely thyrotoxic patients. A greater than 25 per cent reduction in sitting pulse rate was associated with a high degree of beta-blockade. The clinical course of patients with mild or moderate thyrotoxicosis was similar to that of the patients prepared with carbimazole. In contrast, the course of severely thyrotoxic patients was complicated and, in addition to a higher preoperative propranolol dosage, these patients commonly required supplemental propranolol after operation. Although thyroid crisis did not occur in any patient, we cannot recommend the use of propranolol alone for the severely thyrotoxic patient.

Correspondence tion with oral lorazepam 2 4 mg, 2 hours preoperatively. induction of anaesthesia with fentanyl (2-5 pg/kg). droperidol (up to 70 pg/kg). sleep dose of either thiopentone or etomidate, alcuronium or atracurium. the passage of a cuffed orotracheal tube and maintenance of anaesthesia with oxygen and nitrous oxide with intermittent positive pressure ventilation of the lungs.Our experience has reinforced our opinion that monitoring of the electrocardiograph of all patients under anaesthesia is mandatory. This can present problems with the young or older uncooperative patient and the services of anaesthetists are frequently sought in these circumstances, often in situations remote from the operating theatres. A major difficulty with many current techniques of basal sedation is that of unpredictability. The patients may not be adequately sedated for the procedure to be undertaken, or they may become too severely depressed to be safely lelt unattended. One technique which overcomes some of these problems uses gauhahydroxybutyrate, a drug which is widely used in Europe but has enjoyed little or no popularity in this country.' Gammahydroxybutyrate used alone does not provide surgical anaesthesia. It has little or no analgesic action and any painful stimulus may provoke brisk reflex movement and may induce vomiting. It is, however, eminently suitable for provision of sedation for non-painful procedures, and has been shown to be a satisfactory agent to employ in cardiac catheterisation.2 Thirty chihiren presenting either for evoked response audiometry or for cerebral computerised axial tomography were d a t e d using the following technique. Their ages ranged between 2 months and 12 years.Children over a year old were premedicated with oral trimcpradnc tartrate 1.7 m a g and atropine 0.03 mg/kg up to a maximum of 0.6 mg.Children less than 12 months old did not receive any(1 mg/kg) followed immediately by gammahydroxybutyric acid (40 mg/kg) administered intravenously through a 25-gauge indwelling needle. A further increment of gammahydroxybutyric acid (10 mg/kg) was given intravenously, half an hour after induction if the examination was not nearing completion at that time. All patients breathed air except for a 2-year-old with a ventricular septa1 defect who was given 30% oxygen by face mask. Each child was observed continuously throughout the procedure. Full resuscitative facilities were always immediately available.The airway was maintained without any sign of obstruction in all but two patients. These two both had anatomical abnormalities of the upper airway. One had a very large tongue associated with Down's syndrome, while the other suffered from periodic airway obstruction caused by very large palatine tonsils. In both cases . the,obstruction was relieved by the insertion of a pharyngeal airway. Two other patients developed moderate bradycardia which responded to intravenous atropine.After the examination patients were nursed on their side in a recovery area until crying or speaking on stimulation. Fro...

SummaryThe administration of beta-adrenoceptor As the clinical features of hyperthyroidism closely resemble those of increased sympathetic activity, it has been believed for many years that the disease may be due to a disorder of the autonomic nervous system. Attempts have been made to reduce the sympathetic component of hyperthyroidism by surgical' (cervical sympathectomy) or medical2. (catecholamine depleting drugs) means. Following the development of beta-adrenoceptor blocking agents their use in this disease was therefore a logical one. Although the evidence for sympathetic overactivity in hyperthyroidism has recently been in dispute, beta-blocking drug therapy has been proved to alleviate effectively many of the symptoms of hyperthyroidism that have been attributed to sympathetic overactivity. A high frequency of adverse reactions associated with the first betablocking drug, pr~nethalol,~ caused its use to be discontinued. Several controlled clinical trials on its successor propranolol, however, soon demonstrated its beneficial effects in hyperthyroidism. 5,