Sevoflurane, a new volatile anesthetic agent, is of great potential interest in pediatric anesthesia. Its use for ENT surgery in children was compared with halothane in this study. Altogether 40 children participated in the investigation. In 18 (median age 4.2 years), halothane was used. The remainder (median age 4.0 years) were anesthetized with sevoflurane. After rectal premedication with midazolam and atropine, anesthesia was induced by mask (the agent in O2/N2O, 40/60) using a Mapleson D system. The trachea was intubated without the use of muscle relaxants and the children were then allowed to breathe spontaneously at fresh gas flows set high enough to avoid rebreathing. Hemoglobine oxygen saturation (SpO2), inspired and expired gas concentrations, respiratory rate (RR), heart rate (HR), ECG and blood pressure were followed. Equianesthetic concentrations of the agents were used and induction characteristics were comparable between the two agents. RR and end-tidal CO2 tensions were similar in the two groups. HR and systolic blood pressures were, however, higher with sevoflurane. Cardiac arrhythmias were seen more frequently with halothane (61%) than with sevoflurane (5%). During emergence, postoperative nausea/vomiting was more frequent after halothane anesthesia. Initially, postoperative excitement occurred more often after sevoflurane, when paracetamol was given during anesthesia, which was reduced (P < 0.01) when paracetamol was given at the time for premedication. It is concluded that sevoflurane is an excellent induction agent, and maintains heart rate and systolic blood pressure better than when halothane is used. The incidence of cardiac arrhythmia is lower with sevoflurane than with halothane.(ABSTRACT TRUNCATED AT 250 WORDS)

Eight harrier dogs received an i.v. infusion of halothane dissolved 1:9 in a fat emulsion for i.v. nutrition (Intralipid, Vitrum). The rate of infusion was adjusted to maintain end-tidal halothane concentrations of 0.7% and 1.4%. At 1.4%, mean arterial pressure decreased to 76 +/- 8 mmHg (10.1 +/- 1.0 kPa) (mean +/- s.e.mean) from a pre-infusion value of 122 +/- 6 mmHg (16.2 +/- 0.8 kPa) (P less than 0.01). The concomitant decrease in cardiac output was 39% and left ventricular maximum dp/dt decreased by 50% (P less than 0.01). Changes in systemic vascular resistance and pulmonary arterial pressure were small. The haemodynamic responses during halothane inhalation, to corresponding end-tidal concentrations, were similar. Arterial and mixed venous halothane concentration increased in proportion to end-tidal concentration. There were no changes in arterial PO2 during the halothane-in-fat infusion. Triglyceride concentrations in plasma increased 12-fold. Haemodynamic recovery after the infusion was fast. We conclude that the halothane-in-fat infusion caused a dose-dependent depression of myocardial contractility and arterial pressure, similar to that seen during inhalation, and that end-tidal concentration could be used for control of the infusion rate.

The anaesthetic properties of a halothane-in-fat solution given either as a single i.v. dose or as a continuous i.v. infusion were investigated in rats. 0.3 ml of a 5% solution of halothane in fat emulsion was injected i.v. into 15 awake rats. At the end of the 30 s injection, all rats had collapsed from the upright position and showed no response to a firmly applied tail clamp. Breathing usually became shallow and irregular just after injection. Two rats died. In the surviving rats, movement in response to clamping of the tail reappeared after some 30 s (range 15-90 s). The rats regained the upright position after about 100 s, and appeared fully awake about 3 min (range 2-5 min) after injection. Surviving rats behaved normally after the experiment, and gained in weight. They were killed 1-29 days later. The lungs, kidneys, heart, brain and liver had a normal macroscopic and microscopic appearance. In a second set of experiments (n = 9), a 10% solution of halothane was continuously infused i.v. (3.75 microliters min-1). The anaesthetic depth, as well as the mean arterial pressure, heart rate, respiratory rate and arterial PCO2 and PO2 were similar to values observed during inhalation of halothane in air at an inspired concentration of 1.1%. By doubling the infusion rate, MAP was reduced by 23%. It was easy to adjust anaethestic depth by changing the infusion rate and recovery was fast.

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In 48 children subjected to adenoidectomy, comparisons of airway problems, heart rates, cardiac arrhythmias, ventilation and stress hormone reactions were studied during halothane, enflurane and isoflurane anaesthesia. Sixteen children were anaesthetized with either of the three agents and eight patients in each group received diazepam 0.25 mg kg-1 and atropine 0.015 mg kg-1 rectally (DA) as premedication and the remainder diazepam 0.5 mg kg-1, morphine 0.15 mg kg-1 and scopolamine 0.01 mg kg-1 (DMS) rectally. All children were intubated and breathing spontaneously. Equianaesthetic inspired concentrations of halothane, enflurane and isoflurane were used. Airway problems were of the same magnitude during halothane and isoflurane anaesthesia but were less frequent with both agents compared with enflurane anaesthesia. DMS reduced the number of airway reactions in all groups. Respiratory rates were uninfluenced by anaesthesia, intubation and surgery during enflurane anaesthesia. Cardiac arrhythmias were less frequent with enflurane and isoflurane than with halothane. Plasma ACTH and cortisol were similar with all three agents. During induction of anaesthesia in the DA-premedicated halothane group, however, plasma catecholamines were higher than in the group which received DMS, in contrast to the findings during enflurane and isoflurane anaesthesia. The DMS premedication decreased the response of plasma ACTH, cortisol and plasma catecholamines to surgery.