Comparative incidence of cardiovascular changes during venous air embolism as detected by transesophageal echocardiography alone or in combination with end tidal carbon dioxide tension monitoring.

The objective of our study was to compare the incidences of cardiovascular disturbance during venous air embolism (VAE) episodes detected using transesophageal echocardiography (TEE) and end tidal carbon dioxide (ETCO(2)) tension monitoring. We retrospectively analyzed the anesthesia records of patients who underwent posterior fossa surgery while in the sitting position and who were simultaneously monitored using both TEE and ETCO(2) tension monitoring. Data on the occurrence of VAE and the cardiovascular changes associated with it were recorded. Patients were divided into the ETCO(2)-positive group (both TEE and ETCO(2) tension monitoring indicated VAE) and the ETCO(2)-negative group (TEE alone indicated VAE, no significant drop in ETCO(2)). No instances of cardiovascular disturbance were detected in the ETCO(2)-negative group, whereas the incidences of tachycardia and hypotension were 20% and 30%, respectively, in the ETCO(2)-positive group. None of the episodes of VAE detected by TEE (without a fall in ETCO(2)) were clinically significant. We conclude that ETCO(2) monitoring is sensitive enough to detect hemodynamically significant VAE episodes.

Scheduled prophylactic ondansetron administration did not improve its antiemetic efficacy after intracranial tumour resection surgery in children.

BACKGROUND AND OBJECTIVE: Postoperative nausea and vomiting after craniotomy may increase intracranial pressure and morbidity in children. This prospective, randomized, placebo-controlled and double-blinded study was designed to evaluate the antiemetic efficacy of prophylactic ondansetron after intracranial tumour resections in children. METHODS: Ninety children were divided into three groups and received saline (Group 1), ondansetron 150 microg kg-1 intravenously at dural closure (Group 2) or two doses of ondansetron 150 microg kg-1 intravenously, the second dose repeated after 6 h (Group 3). Episodes of nausea, emesis and side-effects were noted for 24 h postoperatively. RESULTS: Overall 24 h incidence of postoperative nausea and vomiting was not significantly different among the three groups (9 (37.5%) in Group 1 vs. 7 (27%) in Group 2 and 8 (32%) in Group 3, P = 0.73). No difference in rescue antiemetic treatment or postoperative nausea and vomiting at specific time intervals (0-6 and 6-24 h postoperative period) was seen among the three groups. No significant side-effects were noted in any of the three groups. CONCLUSIONS: Ondansetron, in this study of 90 children, was not very effective in preventing nausea and vomiting after neurosurgical operations.

Effect of orientation of a standard polyvinyl chloride tracheal tube on success rates during awake flexible fibreoptic intubation.

We conducted a randomised study in 70 patients to assess the effect of orientation of a standard polyvinyl chloride tracheal tube on the ease of railroading the tube during awake fiberoptic orotracheal intubation. Conventional orientation of the tube (with the bevel of the tube directed to the patient's left) was compared with orientation of the tube with the bevel facing posteriorly. The success rate of intubation at the first attempt was higher with the bevel oriented posteriorly (35/35; 100%) than with the conventional orientation (21/35; 60%; p = 0.0001), and the intubating time was shorter (median (range) 7 (5-11) s and 11 (5-60) s, respectively; p = 0.0001). We recommend that the tracheal tube should be aligned in this manner when railroading it over the fibrescope during awake fibreoptic orotracheal intubation.

Lidocaine infiltration of the scalp does not completely abolish increased intraocular pressure due to skull pin insertion.

Insertion of skull pins results in haemodynamic perturbations, which can be blunted by local anaesthetic infiltration of the pin sites. No study has assessed the effects on intraocular pressure. General anaesthesia was induced in 71 patients undergoing cervical spine surgery with attachment of Gardner Wells tongs to the skull. Skull pins were attached five minutes after induction following either saline (group I, 35 patients) or lidocaine (group II, 36 patients) infiltration of scalp. Intraocular pressure, mean arterial pressure and heart rate were recorded before (baseline), immediately after, and 60 s following pin insertion and analysed statistically. Insertion of pins increased intraocular pressure in both groups (from 8.4+/-2.7 to 14.2+/-3.0 mmHg in group I, and from 8.8+/-2.3 to 12.7+/-2.7 mmHg in group II, P < 0.001), which persisted even at 60 s but the increase was significantly greater in group I. Insertion of pins significantly increased blood pressure in group I only. We conclude that lidocaine infiltration at the skull pin sites for Gardner Wells tong attachment fails to completely abolish increased intraocular pressure.

Can propofol precipitate pancreatitis in patients with Cushing's syndrome?

We encountered two cases of acute pancreatitis in patients with Cushing's disease following transnasal transsphenoidal hypophysectomy. In both cases propofol was used in bolus doses, and is thought to be the probable factor for its development. Since elevated cortisol levels in Cushing's disease poses a threat for pancreatitis, there is a possibility that patients with Cushing's disease might be more prone to acute pancreatitis following propofol administration. Anaesthesiologists and physicians dealing with the management of Cushing's disease need to be aware of this possibility.

Anaesthetic management of Osler-Weber-Rendu syndrome with coexisting congenital methaemoglobinaemia.

A 9-year-old cyanosed child suffering from Osler-Weber-Rendu syndrome with bilateral pulmonary arteriovenous malformations (PAVMs) was posted for cerebral angiography under general anaesthesia. Careful preanaesthetic evaluation led to the diagnosis of coexisting congenital methaemoglobinaemia. There is no previous report of Osler-Weber-Rendu syndrome coexisting with congenital methaemoglobinaemia. This report emphasizes that a second contributory cause of cyanosis must be suspected and meticulously looked for if the symptomatology in a patient cannot be explained by a single established diagnosis. Positive-pressure ventilation was associated with reduction in arterial oxygenation despite an increasing inspired oxygen concentration, which returned to preanaesthetic levels only after extubation and resumption of spontaneous respiration.

Comparative incidence of venous air embolism and associated hypotension in adults and children operated for neurosurgery in the sitting position.

BACKGROUND AND OBJECTIVE: Venous air embolism is a constant threat during neurosurgery performed in the sitting position. No large prospective study has compared the incidence of venous air embolism and associated hypotension between adults and children. METHODS: Four hundred and thirty patients (334 adults, 96 children) scheduled to undergo planned posterior fossa surgery in the sitting position (between January 1989 to December 1994) were studied with end-tidal carbon dioxide monitoring. Intraoperatively, a sudden and sustained decrease in end-tidal carbon dioxide tension of >0.7 kPa was presumed to be due to venous air embolism. Management during the episode was on the established guidelines. Hypotension (decrease in systolic arterial pressure of 20% or more from the previous level) was treated with crystalloids and/or a vasopressor. RESULTS: Capnometry detected a 28% incidence rate of air embolism in adults (93/334) and a 22% incidence rate in children (21/96) (P = 0.29). In both groups, the highest incidence rate of embolism took place during muscle handling (44% of adults versus 38% of children, P = 0.8). Embolic episodes were accompanied by hypotension in 37% of adults (34/93) and in 33% of children (7/21) (P = 0.98). To restore arterial pressure to pre-embolic levels, 53% of adults (18/34) and 43% of children (3/7) were administered vasopressors (P = 0.94). There was no intraoperative mortality. The surgical procedure on one adult was abandoned because of persistent hypotension following the embolic episode. CONCLUSION: The incidence of venous air embolism and consequent hypotension is similar in adults and children.