Gerald W. Black

Uptake of volatile anaesthetics in children.

The uptake of halothane is known to be more rapid in children than in adults, but comparable clinical data regarding other inhalational anaesthetics are not available. In this study, the rates of uptake of halothane, enflurane, isoflurane and methoxyflurane were compared in children of different ages. Expired (FE′) and inspired (FI) vapour concentrations were measured with an infrared analyser, and FE′/FI ratios were used to determine rates of uptake. Uptake rates of halothane, enflurane and methoxyflurane were more rapid in the younger than in the older children, but age had no effect on the uptake of isoflurane which was uniformly rapid in all the children studied.

A Comparative Study of the Haemostatic Properties and Cardiovascular Effects of Adrenaline and Ornipressin in Children during Enflurane Anaesthesia

In a randomised, double‐blind trial, haemostatic and cardiovascular effects of ornipressin and adrenaline were compared in 30 children requiring surgery for “bat‐ear” deformity. Mean total blood loss was 14.3 ml with ornipressin and 11.7 ml with adrenaline, this difference being insignificant. There was a significant and progressive reduction in mean heart rate in children who received ornipressin. from 134 to 116 bpm (P<0.0.5). and a significant rise from 127 to 134 bpm (P<0.05) with adrenaline. Mean systolic pressure was unaltered by ornipressin but was significantly increased from 97 to 105 mmHg (P<0.05) in children receiving adrenaline. Ornipressin is as effective a haemostatic agent as adrenaline and the rises in heart rate and systolic pressure associated with adrenaline, which are factors known to predispose to the onset of ventricular dysrhythmias, do not occur with ornipressin.

A comparative study of enflurane and halothane in children

Equipotent concentrations of enflurane and halothane inhaled by children caused substantial hypotension and respiratory depression, these changes being more pronounced with the former agent.

A Comparison of Cardiac Rhythm During Halothane and Methoxyflurane Anaesthesia at Normal and Elevated Levels of PaCO2

Changes in cardiac rhythm were studied at normal and elevated levels of PaCO2 during the inhalation of 1.5 per cent halothane and 1.5 per cent methoxyflurane in sixteen normal children. With halothane idioventricular rhythm developed in each of eight children at PCO2 levels ranging from 104 mm Hg to greater than 150 mm Hg. Normal sinus rhythm persisted in the presence of comparable degrees of respiratory acidosis in the children receiving methoxyflurane. It is suggested that myocardial sensitisation to the effects of catecholamines is minimal during anaesthesia with the latter agent.

A review of the cardiovascular effects of halothane

Halothane has been used in clinical anasthesia for over three years, but there is incomplete agreement on its cardiovascular effects and many conflicting reports have appeared in the literature. It is difficult to evaluate many of the conclusions drawn from published work owing to the number of variables present in the studies, e.g. preansesthetic medication, use of other anasthetic agents, variations in respiratory pattern and the effects of surgical intervention. In this communication, an attempt is made to review the present day knowledge of the cardiovascular effects of halothane and to endeavour to reconcile some of the apparently contradictory findings. It is necessary, first of all, to refer to some of the actions of halothane on other systems, as these modify its effect on the circulation. It was appreciated early that some degree of respiratory depression was inevitable during halothane anzsthesia, particularly if an opiate was given as pre-anasthetic medicationl. This must lead to hypercarbia with a resulting effect on peripheral resistance and circulating catechol amines. Controlled respiration, initiated to compensate the depressant action of the halothane, can affect venous return and arterial blood pressure. While anasthesia with cyclopropane or ether is accompanied by a riseincirculating catechol amines, this is not observed with halothanez. Hence, the stimulating action of adrenaline and nor-adrenaline on the heart muscle and blood vessels will not be manifest during the use of this drug. The pin point pupils frequently found during anaesthesia and the failure of halothane to produce a rise in blood sugar3, support the finding2 that the sympatho-adrenal response is not increased by halothane.

Circulatory and respiratory effects of ether, halothane and the azeotrope mixture*

The cardiovascular and respiratory depressant properties of anasthetic concentrations of halothane have been demonstrated by Raventbs 1, Johnstonez, Hall and Norris3 and others. An azeotropic mixture of halothane and ether has been described by Hudon, Jacques and Boivin4 who claim that the addition of ether modifies these depressant effects. This was not the experience of Raventbs and Dee5 who found that the azeotrope caused comparable degrees of bradycardia, hypotension and respiratory depression to halothane iii the dog. However, Dobkin and his colleagues were impressed by the absence of depression found with the mixture in man6 and in the dog, as compared with halothane. It may well be that species variation accounts for these conflicting reports and so it was thought desirable to investigate the problem further in the human subject. Some physical characteristics of halothane and the azeotrope are shown in T A B L E 1.

Reversal of non-depolarising neuromuscular block in children: a comparison of atropine and glycopyrrolate in a mixture with neostigmine.

Atrapine and glycopyrrolate were compared when given in a mixture with neostigmine for the reversal of non‐depolarising neuromuscular block in children. Glycopyrrolate was an effective antimuscarinic agent and could be safely used as an alternative to atropine, although the advantages in this age group were not as marked as have been observed in adults.

Anaesthesia for Rammstedt's operation.

Examination of the literature indicates that there is no standard technique for anaesthesia in Rammstedt’s operation. The operation appears to lie between minor and major surgery. Some authorities regard it as a minor procedure requiring only local analgesia which may be reinforced by various medicants administered on a teat in order to comfort and settle the baby when the abdomen is opened. Others treat the operation as a major one and administer general anaesthesia, ether and cyclopropane being mainly used. Other writers have changed their methods in the course of time, for example from a local to a general technique or to a combination of both. C. A. Nafel has employed general anasthesia in approximately 85 per cent of cases, but in those babies who are under par, and are poor surgical risks, 0.5 per cent procaine hydrochloride is used by infiltration. In addition, when local analgesia is used Nafe gives Igr (0.065g) of phenobarbital by rectum, thirty minutes before operation. His choice of general anresthesia has always been open