Low-dose sufentanil and lidocaine supplementation of general anaesthesia

This randomized double-blind study compared the effects of: (1) saline infusion (C); (2) sufentanil alone (1.0 micrograms.kg-1) (S); and (3) low-dose sufentanil (0.5 micrograms.kg-1) in combination with lidocaine (1.5 mg.kg-1) (LS): on the cardiovascular responses to tracheal intubation and on postoperative ventilation as monitored by respiratory inductive plethysmography in day-care surgical procedures of approximately 60 min duration. Thirty healthy, unpremedicated patients were studied. Thiopentone requirements were reduced by 40 and 28 per cent in the S and LS groups respectively compared with control (P less than 0.001). Both treatments suppressed HR and BP responses (P less than 0.005) to intubation. Postoperatively, PaCO2 was elevated (P less than 0.05) in group S. Dose-related respiratory depression was observed. The incidence of postoperative apnoea was significantly higher in both S and LS groups than compared with control (P less than 0.05). However, only patients in group S showed higher apnoea index and mean apnoea duration over the initial 10-20 min after surgery compared with control (P less than 0.005). In addition, group S showed slower respiratory frequency and prolonged expiratory time (P less than 0.005). In conclusion, an induction dose of sufentanil (1 microgram.kg-1) used in balanced anaesthesia of less than 70 min duration was associated with significant respiratory depression, particularly during the initial 10-20 min after surgery, whereas low-dose sufentanil (0.5 micrograms.kg-1) with lidocaine (1.5 mg.kg-1) had minimal postoperative respiratory depression and comparable attenuation of pressor responses to intubation.     

Intraoperative anaphylaxis to latex

This case report describes intraoperative anaphylaxis occurring in a fourteen-year-old female with spina bifida in which latex surgical gloves were incriminated as the aetiologic agent. The patient was non-atopic but since eight years of age she had developed localized angioedema and urticarial skin reactions on exposure to rubber. She had previously undergone several uneventful surgical procedures. Forty-five minutes following induction of anaesthesia and during laparotomy for elective cholecystectomy she experienced sudden onset of increased airway pressure, oxygen desaturation, tachycardia, profound hypotension and erythema consistent with an anaphylactic reaction. Resuscitation with manual ventilation and oxygen, intravenous fluids and an epinephrine infusion was successful. Subsequent investigations for allergies demonstrated a strongly positive skin prick test and RAST to latex antigen, with negative results to anaesthetic agents, antibiotics and inhalant allergens. During two later operations prophylaxis consisting of diphenhydramine, ranitidine and hydrocortisone appeared to prevent further reactions. Latex should be considered as a cause of life-threatening intraoperative allergic reactions in patients with a history of rubber allergy or frequent exposure to latex products.     

Behavioral effects of MK-801 in the rat

Several experiments were conducted to study the effects of the noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, on learning and memory in the rat. Rats displayed impaired performance on several sensorimotor tests and appeared grossly intoxicated when treated IP with 0.2 mg/kg MK-801, but not when treated with lower doses (0.05 or 0.1 mg/kg). Postacquisition performance on two spatial learning tasks involving working memory protocols (reinforced alternation and radial arm maze) was impaired by MK-801 at intoxicating doses (0.2 mg/kg) but not at lower doses (0.05 or 0.1 mg/kg). Using a position habit reversal task, we found that rats could learn to reverse a position habit while under the influence of a nonintoxicating dose of MK-801 (0.1 mg/kg), but when tested on the following day performed as if they did not recall what they had learned. Thus, acute administration of a nonintoxicating dose of MK-801 disrupts the retention of new information learned under the influence of the drug but does not interfere with the performance of tasks that are well learned before the drug is administered. Whether the performance deficits on the spatial learning tasks observed only following intoxicating doses of MK-801 reflect an effect on memory is not clear.     

Intrapleural analgesia in a child with a mediastinal tumour

A case is presented of an eight-year-old child with a mediastinal tumour, who had developed acute renal failure following the institution of steroid therapy. Intrapleural analgesia was successfully used for the insertion of a peritoneal dialysis catheter so that the considerable risks of general anaesthesia were avoided. Subsequent dialysis allowed chemotherapy to commence and, as a result of the shrinkage in tumour size, general anaesthesia was administered safely two days later. The purpose of this report is to highlight the use of intrapleural analgesia in children as an alternative to general anaesthesia, when the latter is contraindicated. The mechanism of action of intra-pleural analgesia and the risks of anaesthesia in the presence of a mediastinal tumour are discussed.     

Monitoring during paediatric cardiac anaesthesia

Monitoring of paediatric anaesthesia has become increasingly more complex in recent years and this is particulary true of cardiac anaesthesia. The purpose of this review is to give a comprehensive update of published material related to both routine and specialized cardiac monitoring. Routine monitoring can be particularly affected by the alterations of cardiac rhythm, blood flow, cardiac output and oxygenation which result from the congenital heart abnormalities themselves, the type of surgery undertaken and the effects of cardiopulmonary bypass. The use of specialized monitoring is becoming more widespread, particularly in the areas of cerebral function, mixed venous oxygenation, cardiac output measurement and coagulation. In the last five years, with the development of smaller probes, a great deal has been published on transoesophageal echocardiography. The use of the current monitors of cerebral function still remains controversial despite the need for a monitor of adequate brain perfusion, reflecting the need for a great deal of further research in this area. This review will concentrate on particular areas which have seen the most profound changes and on monitoring that may form the standards of tomorrow. Finally, amongst all the technology, it should not be forgotten that the most important clinical monitor is the bedside clinical monitoring of the physicians themselves. Depuis quelques années, le monitorage de l’anesthésie pédiatrique devient déplus en plus complexe et tout particulièrement en anesthésie cardiaque. L’objectif de ce travail consiste à passer en revue la littérature actuelle qui traite du monitorage usuel et spécialisé. Le monitorage usuel peut être influencé par les modifications de la fréquence cardiaque, du courant sanguin, du débit cardiaque et de l’oxygénation provoqués par les anomalies cardiaques congénitales, du type de chirurgie et des retentissements de la circulation extracorporelle. L’utilisation du monitorage spécialisé est de plus en plus répandu et concerne particulièrement la circulation cérébrale, l’oxygénation du sang veineux mêlé, la mesure du débit cardiaque et la coagulation. Au cours des cinq dernières années, le développement de sondes plus petites a généré de nombreuses publications sur l’échocardiographie transoesophagienne. L’utilisation des moniteurs actuels de la fonction cérébrale demeure sujet à controverse bien qu ’un moniteur de perfusion cérébrale adéquat demeure toujours aussi essentiel, confirmant ainsi le besoin de recherches supplémentaires sur ce sujet. Ce survol se portera spécialement sur les champs d’activités qui ont connu les changements les plus profonds et sur le monitorage qui établira les standards du futur. Finalement, au milieu de cette technologie, il ne faut jamais oublier que le moniteur clinique le plus important se trouve au chevet du malade en la personne du médecin.     

Cerebral arteriovenous malformations in children

The treatment of cerebral arteriovenous malformations (AVM) or vascular anomalies are challenging neurosurgical procedures for an anaesthetist. Large AVMs are uncommon in children. Only 18% of AVMs become symptomatic before the age of 15 yr. This series reviews the experience at this institution during the period of 1982 to 1992. The symptoms at the time of presentation are varied and include haemorrhage (50%), seizures and hydrocephalus (36%) or congestive cardiac failure (18%). Symptoms of congestive heart failure predominate in the new-born whilst neurological symptoms, such as stroke, seizures or hydrocephalus occur more commonly in infants and older children. Approximately one third of AVMs in childhood present acutely. Radiological investigations, e.g., CT scan, MRI and cerebral angiography are essential to identify the precise location of the lesion. Therapeutic intervention in the acute presentation may involve craniotomy for evacuation of haematoma and treatment of increased intracranial pressure (ICP). Control of seizures and congestive heart failure may take priority and allow time to plan the elective procedures of embolization and surgical excision of the AVM. Operative intervention is hazardous and peroperative complications can be expected in more than 50% of patients. The morbidity and mortality associated with cerebral AVM are high, especially in infants who present in the neonatal period with congestive cardiac failure. The overall mortality in this series was 20%. Children presenting with intracranial arteriovenous malformations require a multidisciplinary approach. The successful management of anaesthesia either for embolization or surgical resection necessitates an understanding of the disciplines of paediatric and neuroanaesthesia. Special care and specific attention to detail may contribute to reduce the high morbidity and mortality encountered in these compromised children.     

A comparison of sevoflurane with halothane,enflurane, and isoflurane on bronchoconstriction caused by histamine

This study was conducted to assess the effect of sevoflurane on lung resistance and compliance, and its responsiveness to histamine. We studied eight dogs to compare the effect of sevoflurane, isoflurane, enflurane, and halothane on bronchoconstriction caused by histamine. Baseline values of pulmonary resistance (R_L) and dynamic pulmonary compliance (C_dyn) were measured prior to administration of histamine. Histamine (2, 4, and 8 μg · kg⁻¹) were administered iv, and the values of R_L and C_dyn at the time of peak effect were recorded. Under 1 or 2 MAC anaesthesia, sevoflurane as well as the other three anaesthetics had no bronchoactive effects. The four anaesthetics, including sevoflurane, demonstrated inhibitory effect on increases in R_L and decreases in C_dyn caused by histamine. At 1 MAC anaesthesia, % changes in R_L caused by 2, 4, or 8 μg · kg⁻¹ of histamine were 38 ± 11, 85 ± 21, or 132 ± 24% (mean ± SE) for halothane, and 65 ± 11, 132 ± 15, or 172 ± 19% for sevoflurane, respectively. Sevoflurane was less effective than halothane in preventing increases in R_L. In preventing decreases in C_dyn, sevoflurane was less effective than halothane only at 8 μg · kg⁻¹ of histamine under 1 and 2 MAC anaesthesia. There was no difference in attenuating effect on changes in R_L and C_dyn between sevoflurane and isoflurane or enflurane. We concluded that sevoflurane was less potent than halothane in attenuating changes in R_L and C_dyn in response to iv histamine. Cette étude a été réalisée dans le but d’évaluer les effets du sévoflurane sur la résistance et la compliance pulmonaires en réponse à l’histamine. Les effets du sévoflurane, de l’isoflurane, de l’enflurane et de l’halothane sur la bronchoconstriction induite par l’histamine sont comparés sur huit chiens. Avant l’administration d’histamine, on mesure les valeurs initiales de la résistance (R_L) et de la compliance dynamique (C_dyn) pulmonaires. L’histamine (2, 4, 8 μg · kg⁻¹) est administrée par la voie veineuse et les valeurs maximales de la R_L et de la C_dyn sont enregistrées. Les quatre anesthésiques, dont le sévoflurane inhibent l’augmentation de la R_L et la diminution de la C_dyn provoquées par l’histamine. A MAC 1 d’anesthésie, les pourcentages de changement de R_L produits par 2, 4, ou 8 μg · kg⁻¹ d’histamine sont respectivement de 38 ± 11, 85 ± 21, ou 132 ± 24% (moyenne + SD) pour l’halothane, et de 65 ± 11, 132 ± 15, ou 172 ± 19% pour le sévoflurane. Le sévoflurane est moins efficace que l’halothane pour prévenir les augmentations de R_L. Le sévoflurane est moins efficace pour prevenir la diminution de C_dyn mais seulement à 8 μg · kg⁻¹ d’histamine sous anesthésie à MAC 1 et 2. Le sévoflurane, l’halothane et l’isoflurane ne sont pas de différents pour amortir les changements de R_L et C_dyn. Nous concluons que le sévoflurane est moins puissant que l’halothane pour diminuer la réponse à l’histamine de la R_L et de la C_dyn.     

Anaesthetic management of an asthmatic child for appendicectomy

A 13-yr-old boy was scheduled for emergency appendicectomy because of abdominal pain. His preoperative medical history was complicated by a recent hospital admission for management of asthma. He had presented to hospital seven days earlier because of dyspnoea, tachypnoea and oxygen desaturation to 77% on room air. Following admission, he required intensive non-ventilatory management of his asthma, including intravenous salbutamol, methylprednisolone, and aminophylline, as well as use of an ipratroprium bromide inhaler and 100% oxygen by mask. He was discharged to the ward, and continued on prednisone (deltacortisone), beclomethasone inhaler, ipratroprium inhaler, and salbutamol inhaler. During his ICU stay, he complained of nonspecific abdominal pain, interpreted as gastro-oesophageal reflux. After four days, he was discharged to the ward. On his sixth hospital day, he began to experience right-sided lower abdominal pain and right shoulder pain. A surgeon was consulted, and the patient was found to have a very tender right lower quadrant with guarding and rebound pain. He was therefore scheduled for appendicectomy; antibiotic therapy with ampicillin, gentamicin, and metronidazole was initiated.     

Acute airway obstruction following placement of a subclavian Hickman catheter

The purpose of this case report is to describe the events, intervention, and aetiology which led to acute airway obstruction in an adult patient after the placement of a Hickman catheter. Airway obstruction secondary to superior vena cava obstruction occurred after placement of a subclavian vein Hickman catheter. This was felt to occur, in part, to a narrowed superior vena cava as evident by subclavian venography. It resulted in emergency oral tracheal intubation to relieve airway obstruction. Shortly after removal of the Hickman catheter, the signs of superior vena cava obstruction syndrome resolved and the patient was extubated without incidence. It is concluded that, although rare, the serious complication of acute airway obstruction can occur after placement of a Hickman catheter.