Low-dose sevoflurane co-administered with propofol-based general anaesthesia obliterates intra-operative neurophysiological monitoring in an infant.

The influence of general anaesthetic agents on intra-operative neurophysiological monitoring in neonates and infants has rarely been reported. Propofol-based anaesthesia is recommended to avoid suppression of neurophysiological monitoring. However, the administration of propofol in children undergoing prolonged procedures, especially those younger than six months, should be carefully controlled due to the potential risk of propofol infusion syndrome. Adding a small dose of inhalational anaesthetic can be an option to reduce propofol requirements. Recent guidelines in Japan suggest limiting inhalational anaesthetics to less than 0.5 minimum alveolar concentrations when co-administered with low-dose propofol during intra-operative neuromonitoring. However, there is still insufficient evidence regarding the impact of sevoflurane on neurophysiological monitoring when co-administered with propofol in infants. This report describes a case of a three-month-old infant undergoing spinal lipoma resection in which there was a dramatic suppression of neurophysiological monitoring with the addition of 0.35-0.45% sevoflurane to propofol-based anaesthesia.

Postoperative pain management for pediatric urologic surgery.

The issues relating to postoperative pain management for pediatric urologic surgery have been discussed. Child development and the behavioral responses to pain have been reviewed, with emphasis on their relation to pain assessment in the pediatric patient. The benefits and limitations of various modalities for the treatment of postoperative pain have been reviewed, and their appropriate use for different urologic surgical procedures has been presented.

The influence of trimethaphan (Arfonad)-induced hypotension with and without spine distraction on canine spinal cord blood flow.

Controlled hypotension is used in scoliosis surgery to reduce the need for transfusion and to improve operating conditions, but there is concern that deliberate hypotension may decrease spinal cord blood flow (SCBF) and predispose the spinal cord to injury, particularly when it is distracted during Harrington instrumentation. To study the effect of deliberate hypotension on SCBF, the mean arterial pressure (MAP) was reduced to 50% of its normotensive value with trimethaphan (Arfonad) in dogs and the SCBF measured using the hydrogen washout technique with and without spine distraction. The SCBF was significantly reduced to half its normotensive value of 23.2 ml/min/100 gm to 11.4 ml/min/100 gm after hypotension was established. The SCBF remained significantly decreased compared with controls when measured at 30, 45, and 60 minutes following the induction of hypotension and also when hypotension was terminated. SCBF was not further reduced when 2 cm of spine distraction was added. These results show that induction of hypotension with trimethaphan is associated with a similar decrease in SCBF, which is maintained as long as the drug is used and that this effect continues after the drug is terminated and the MAP increases. Cautiously extrapolating these findings clinically would suggest that trimethaphan may not be the drug of choice for controlled hypotension during scoliosis surgery, despite its apparently favorable hemodynamic and hormonal responses.

The effect of trimethaphan-induced hypotension on canine spinal cord blood flow. Measurement at different cord levels using radiolabelled microspheres.

Controlled hypotension which is used during scoliosis surgery to improve operating conditions and minimize transfusion requirements may decrease spinal cord blood flow (SCBF). Previous studies using hydrogen washout, an invasive technique, have shown that trimethaphan-induced hypotension is associated with a decrease in SCBF, whereas hypotension induced with sodium nitroprusside or nitroglycerin is not. To determine whether the decrease seen with trimethaphan represented a generalized rather than regional spinal cord phenomenon, SCBF was measured at three separate cord levels (T2-3, 7-8, L2-3) using a noninvasive radionuclide-labelled microsphere technique. When the mean arterial pressure was reduced by 50%, SCBF decreased 35 to 45% at all levels of the cord examined, and remained at this reduced level during the period of hypotension. The results confirm that trimethaphan-induced hypotension is associated with a significant reduction in SCBF and that this occurs throughout the spinal cord during the period of hypotension.

Psychiatric sequelae of head injury.

The psychiatric problems which may arise following head injury are common, occurring in from 10-77% of cases. The behaviours manifest often impede the progress of treatment causing frustration to the staff, and continuing distress to the patient. To assist in their understanding, I will present the sorts of problems which may arise, with reference to the course of the symptoms and behaviour and to their management.

The fishing news.

The delivery of healthcare throughout the world is rapidly changing due to economic and other factors, both national and international. Psychiatry, a marginal and poorly understood profession in the community, is particularly vulnerable to these changes. Psychiatrists and their representing organisations, such as the Royal Australian and New Zealand College of Psychiatrists, have a key role in advocating for equitable, high standard care for their patients. They need to engage with other professionals involved in psychiatric care, patients and the community to ensure continuing development of services. By recognising the factors influencing psychiatric services, strategies to address them can be developed. Actions taken by the Royal Australian and New Zealand College are described.

Delayed vomiting after papavaretum in paediatric outpatient surgery.

The contribution of papavaretum to the incidence of vomiting observed in the 24 hours after paediatric outpatient anaesthesia was assessed in 129 children undergoing circumcision. Postoperative analgesia in all patients was achieved using caudal extradural blockade. The incidence of vomiting in the 24 hours after discharge from hospital was 56 per cent in those receiving papavaretum, compared with 15 per cent in those who did not (p less than 0.0001). The significance of this finding and the use of opiates in paediatric outpatient anaesthesia are discussed.

Single breath induction of anaesthesia, using a vital capacity breath of halothane, nitrous oxide and oxygen.

Inhalational induction of anaesthesia, using a single vital capacity breath of 4% halothane in 66% nitrous oxide and 33% oxygen was evaluated in 100 unpremedicated outpatients. The technique was found to be acceptable to most (91%) of the patients studied, with a mean (SD) induction time (measured from beginning of inspiration to loss of 'eyelash reflex') of 83(21) seconds. Relative cardiovascular stability was a notable finding of the technique, with a slight decrease in the mean arterial pressure of only 10%. Anaesthetic induction time was unaffected by age, weight or smoking habits. The technique of single breath induction is therefore proposed as a safe and acceptable alternative to intravenous induction in co-operative adult patients.

Comparative effects of halothane, enflurane, and isoflurane on atrioventricular conductivity and subsidiary pacemaker function in dogs.

This study compares effects of equipotent concentrations of halothane, enflurane, and isoflurane on atrioventricular (AV) function in dogs. Enflurane anesthesia was associated with more AV nodal depression, only at faster heart rates than either halothane or isoflurane. These rate-related effects are important in the genesis of supraventricular reentrant tachyarrhythmias. Subsidiary pacemaker function exhibited marked variability between and within animals with no demonstrable difference between anesthetic drugs. Enflurane has more depressant effects on AV nodal recovery properties than halothane or isoflurane; however, there were no differences demonstrated on slow AV nodal conduction. This suggests that enflurane would be the most effective volatile anesthetic in converting or slowing supraventricular tachyarrhythmias, while carrying no more risk of causing advanced heart block.

Anaesthetic management for caesarean section in a patient with uncorrected truncus arteriosus.

We describe the successful management of a 25-yr-old primigravida with uncorrected truncus arteriosus, requiring an urgent Caesarean section for delivery of a live infant and we discuss the rationale of using the chosen drug combination and the importance of adequate monitoring in selecting an anaesthetic technique based on the pathophysiology of the congenital cardiac lesion.

Recovery after single-breath halothane induction of anaesthesia in daycase patients. A comparison with thiopentone.

A single-breath technique of inhalational induction of anaesthesia allows intravenous induction agents to be avoided. We have investigated recovery from anaesthesia in 40 daycase patients, using tests of psychomotor function. Patients anaesthetised with inhalational induction awaken earlier than those who receive thiopentone, but not significantly earlier. There were no significant differences in postoperative psychomotor function between patients who received thiopentone and those who had inhalational inductions. Single-breath halothane, nitrous-oxide, oxygen induction is an alternative to intravenous induction in cooperative adults, but does not confer significant benefits in terms of recovery.

Hyperkinesis and diet: a double-blind crossover trial with a tartrazine challenge.

A pilot study was conducted on 22 children (19 boys and three girls) aged between four and eight years, who were selected as hyperactive on the basis of developmental history and clinical judgement. Conners' parent-teacher ratings, objective tests of attention, standard perceptualmotor tests and subtests from the Wechsler Intelligence Scale for Children (WISC), were used as response variables. The children were tested before and after four weeks on the elimination diet, after a tartrazine and placebo challenge, and, finally, after a four-week washout period on the diet. Results showed a statistically significant improvement in the mothers' ratings of the children's behaviour after the first four weeks of the diet. The improvement was maintained in a combined analysis of the initial four-week diet period and four-week washout period. This result was not substantiated by the statistical analysis of the results from objective tests. The rating scales and objective tests for the full sample did not show a statistically significant deterioration in the children's behaviour when they were challenged under double-blind test conditions with the Yellow Dye No. 5, tartrazine, and the tests were conducted the day after a two-week challenge period. A comparison of mother ratings of behaviour during challenge and placebo double-blind trial and in the 24 hours preceding tests, in a subgroup of the children who, while on the diet, showed a 25% reduction of symptoms on the Conner's rating scale, indicated a significant challenge effect (P less than 0.025), with mothers reporting more symptoms during the challenge period. Dietary infringements with suspected trigger substances occurred throughout the trial.

The diagnosis and treatment of functional disorders of the biliary tract.

An approach to the diagnosis and treatment of patients with presumed functional disorders of the biliary tract (biliary dyskinesia) is described. The current diagnostic criteria are pain compatible with biliary pain in the absence of gallstones and other organic gastrointestinal disease, or other disorders which might produce abdominal pain, together with reproduction of the patient's symptoms by cholecystokinin, or morphine, or both. Other diagnostic methods are described together with their limitations. The results of operation in 38 of 45 patients seen in this Unit during the past six years are presented. The results were poor in 20% of patients, but two-thirds of the group have had good results in the short term.

Transmural redistribution of myocardial blood flow during isoflurane anesthesia and its effects on regional myocardial function in a canine model of fixed coronary stenosis.

BACKGROUND: The effects of isoflurane on the transmural distribution of myocardial blood flow distal to an acute critical coronary stenosis and the relationship between the changes in regional blood flow and function were studied to determine whether isoflurane can produce a transmural "steal" phenomenon and to assess the role of this phenomenon in producing changes in regional myocardial function. METHODS: After production of acute critical coronary stenosis under baseline chloralose and fentanyl anesthesia, the animals were exposed to increasing end-tidal concentrations of isoflurane (0.7%, 1.4%, and 2.1%) without control of the hemodynamic parameters. At 2.1% isoflurane, the blood pressure then was restored to the baseline level by administration of phenylephrine. Changes in the following parameters were assessed: global contractility (measured by changes in pressure with time), regional myocardial function (assessed by systolic wall thickening and measured by sonomicrometers), transmural distribution of myocardial perfusion (measured by the radioactive microsphere method), and regional oxygen consumption and extraction. RESULTS: Distal to the critical stenosis, a transmural redistribution of myocardial blood flow (endocardial-epicardial ratio < 1) occurred with all concentrations of isoflurane. With higher concentrations (1.4% and 2.1%), a significant decrease in subendocardial blood flow occurred only in the presence of hemodynamic changes and was restored by phenylephrine. In this area, changes in regional myocardial function correlated most strongly with changes in subendocardial perfusion (y = -0.17 + 1.70x -0.58x2, r2 = 0.90). In the stenotic region, oxygen extraction remained stable, but oxygen consumption decreased in parallel with reductions in regional myocardial function. In the normal region, oxygen consumption did not change, but oxygen extraction decreased with increasing isoflurane concentrations. CONCLUSIONS: These results show that isoflurane is a coronary vasodilator able to induce a transmural redistribution of myocardial blood flow distal to an acute critical coronary stenosis. A true transmural steal, however, was not produced reliably in the absence of hemodynamic changes, suggesting that isoflurane either is only a moderate vasodilator, or that the decrease in subendocardial blood flow is offset by the negative inotropic action of the drug. When regional myocardial dysfunction distal to a severe coronary stenosis occurs, this correlates with decreasing subendocardial blood flow during isoflurane anesthesia, suggesting ischemia as the cause.

Effects of the volatile anesthetic agents on sinus node function and atrioventricular conduction in dogs: a comparison with chloralose anesthesia.

The effects of equipotent concentrations (1.5 times minimum alveolar concentration) of the inhalational agents halothane, enflurane, and isoflurane on sinus node function, and atrioventricular (A-V) conduction and refractoriness were compared with chloralose anesthesia in 49 mongrel dogs. Sinus node function was assessed using corrected sinus node recovery time. Atrial-His and His-ventricular conduction times were measured at paced heart rates of 150, 180, and 200 beats/min, and A-V refractoriness was assessed by Wenckebach periodicity. There was no evidence that sinus node function was impaired by any of the inhalational agents. Enflurane anesthesia was associated with a significant prolongation of atrial-His conduction at paced heart rates of 180 and 200 beats/min when compared to chloralose anesthesia and the other two inhalational agents (P < .001). Atrioventricular refractoriness was impaired by enflurane (P < .001) and halothane (P < .05), but not isoflurane, when compared with chloralose anesthesia. Ventricular-His conduction was not altered by any of the agents. The authors conclude that enflurane is associated with a greater impairment of A-V conduction and refractoriness than halothane or isoflurane, and that these changes are related to the anesthetic agent and not the anesthetic state.

Effect of P6 acupressure on postoperative vomiting in children undergoing outpatient strabismus correction.

A prospective, double-blind study was conducted to compare the effect of pressure at the P6 (Neikuan) point with placebo as an antiemetic in children. Sixty-six patients, ages 3-12 yr, undergoing outpatient surgery for correction of strabismus, were allocated randomly to receive either bilateral P6 acupressure or placebo during the perioperative period. The study was designed to detect a 50% difference in the incidence of postoperative vomiting between the two groups, with a 90% power of achieving a statistically significant result at the 5% level (two-tailed). The incidence of postoperative vomiting for the placebo group was 58% before discharge from hospital, 73% at home and 82% in the first 24 h after surgery. The corresponding results for the acupressure group were 58% before discharge, 71% at home and 94% in the first 24 h. These differences were not significant; P6 acupressure did not reduce the incidence of postoperative vomiting in children undergoing strabismus surgery.

Comparison of the analgesic and emetic properties of ketorolac and morphine for paediatric outpatient strabismus surgery.

In a prospective, double-blind, randomized study, we have compared i.v. ketorolac and morphine in paediatric outpatients undergoing strabismus surgery. Forty-two ASA I or II children, aged 2-12 yr, were allocated randomly to receive either ketorolac 0.75 mg kg-1 i.v. or morphine 0.1 mg kg-1 i.v. and metoclopramide 0.15 mg kg-1. Anaesthesia was induced with propofol and maintained with propofol and nitrous oxide. Pain was assessed at 15-min intervals until discharge, and the incidence of nausea and vomiting was recorded for the first 24 h. There was no difference in pain behaviour scores or recovery times. The incidence of nausea and vomiting during the first 24 h was 19% in the ketorolac group and 71% in the morphine group (P < 0.001). We concluded that ketorolac was an effective analgesic for this type of surgery and that it was associated with less postoperative emesis than morphine and metoclopramide.

Propofol infusion and the incidence of emesis in pediatric outpatient strabismus surgery.

A prospective, randomized, double-blind study was conducted to examine the effect of a propofol infusion on the incidence of postoperative emesis in children undergoing outpatient strabismus surgery. Seventy-eight children, aged 3-12 yr, were allocated randomly to receive either nitrous oxide and halothane or nitrous oxide and a propofol infusion for the maintenance of anesthesia. The overall incidence of vomiting during the first 24 h was 64% in those receiving halothane and 41% in those receiving the propofol infusion; this difference was statistically significant (P < 0.05). In children who received no opioids postoperatively, the incidence of vomiting in the first 24 h was 71% in the halothane group and 24% in the propofol group; this difference was also significant (P = 0.001). We conclude that propofol was effective in reducing the incidence of postoperative emesis in pediatric outpatient strabismus surgery.