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.

Baculovirus expression and antigenic characterization of the capsid proteins of three Norwalk-like viruses.

Human caliciviruses (HuCVs) are antigenically diverse. The antigenic relationships among different HuCVs have been difficult to study because HuCVs cannot be passaged in the laboratory. In this study, we describe cloning, sequencing and expression of the viral capsid proteins of three HuCVs that were identified in outbreaks of acute gastroenteritis in Virginia in 1997-1998. Yields of the capsid proteins similar to previously expressed recombinant Norwalk virus were obtained using the baculovirus expression system. Recombinant VA97207 capsid protein (rVA97207) and rVA98387, but not rVA98115, formed virus-like particles (VLPs). All three recombinant capsid antigens detected seroresponses in patients involved in outbreaks of acute gastroenteritis associated with genetically homologous or related HuCVs. The antigenic relationships of the three strains were further characterized using hyperimmune antisera against the three capsid antigens as well as four previously characterized recombinant capsid antigens of Norwalk (rNV), Mexico (rMxV), Hawaii (rHV), and Grimsby viruses (rGrV). VA98387 shared 98% aa identity with GrV; rVA98387 was detected by antisera to GrV. VA98115 shared 87% aa identity with Desert Storm virus and 65% aa identity with prototype Norwalk virus (NV); rVA98115 reacted weakly with NV antisera. VA97207 shared 80% aa identity with Amsterdam and 75% aa identity with Leeds strains and rVA97207 was not detected by any of the heterologous antibodies. In conclusion, VA97207 and VA98115 may belong to CV antigenic types not previously expressed, while VA98387 is a GrV-like virus. Low levels of cross-reactive antibodies were detected between types. Further studies to characterize these antigens and to develop enzyme immune assays (EIAs) for these strains are in progress.

Prevalence and genetic diversity of human caliciviruses (HuCVs) in Mexican children.

Human caliciviruses (HuCVs) contain two genera: "Norwalk-like viruses" (NLVs) and "Sapporo-like viruses" (SLVs). The importance of the two genera as a cause of acute gastroenteritis of infants and children remains unknown. Beginning in 1989, a birth cohort of children in Mexico was enrolled and monitored for acute gastroenteritis. A subset of 115 diarrhea stool specimens from 76 children and 66 non-diarrhea stool specimens from 64 children was examined for HuCVs by RT-PCR by using a primer pair (p289/290) that detects both NLVs and SLVs. Twenty-two (19%) of the 115 diarrhea stool specimens and 5 (7%) of 66 non-diarrhea stool specimens produced RT-PCR products of expected size (319 bp for NLVs and 331 bp for SLVs). Twenty of the twenty-seven strains were cloned and sequenced. Pairwise sequence analysis showed that 9 (60%) and 6 (40%) of the 15 strains from the diarrhea stools were NLVs and SLVs, respectively. The same proportions of NLVs (60%) and SLVs (40%) were observed in the non-diarrhea stools. Strains in the NLV genus could be further divided into four clusters: Lordsdale, MxV, and HV and one potentially new cluster. Strains in the SLV genus could be divided into three clusters: Sapporo/82, Lon/92, and a potentially new cluster. Strains from the Lordsdale cluster were the most common among these children. The findings of both genera and multiple clusters of HuCVs co-circulating and the identification of new strains of HuCVs in the population justify the need for future studies of HuCVs in infants and children.

Diagnosis of human caliciviruses by use of enzyme immunoassays.

The application of molecular technologies, such as the expression of viral proteins in baculovirus, has provided a powerful approach to the diagnosis of human calicivirus (HuCV) infections. The baculovirus-expressed HuCV capsid protein self-assembles into virus-like particles, providing excellent reagents for immunologic assays, such as enzyme immunoassays (EIAs). Following the expression of the capsid protein of Norwalk virus, the capsid proteins of 8 other HuCV strains have been expressed in baculovirus. The unlimited supply of baculovirus-produced reagents for HuCVs allows these EIAs to be applied in large-scale clinical and epidemiological studies. Both the antigen and antibody-detection EIAs are highly sensitive. The antigen-detection EIAs are highly specific, but the antibody-detection EIAs are more broadly reactive. This article reviews baculovirus expression techniques used to produce HuCV capsid antigens, development of EIAs using these antigens, and application of these EIAs in studies of HuCV infection and illness.

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.

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.

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.

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.

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.

High-frequency jet ventilation improves cardiac function after the Fontan procedure.

Pulmonary vascular resistance is an important determinant of cardiac output after the Fontan procedure and is adversely affected by elevated mean airway pressure. High-frequency jet ventilation (HFJV) is an alternate form of mechanical ventilation which supports gas exchange at lower mean airway pressure. This study was performed to determine if HFJV could lower mean airway pressure and pulmonary vascular resistance and result in an increase in cardiac output after the Fontan procedure. We prospectively evaluated 13 patients ranging in age from 0.9 to 8.5 years (mean, 3.9 years) and in weight from 6.2 to 20.1 kg (mean, 13.9 kg). Right atrial, left atrial and pulmonary artery catheters were used to measure hemodynamic parameters. Cardiac index was measured by dye dilution technique, and pulmonary vascular resistance was calculated. The patients were stabilized on mechanical ventilation to achieve a PaCO2 = 30 +/- 5 mm Hg, and baseline hemodynamic and respiratory measurements were made. HFJV was begun at settings adjusted to achieve similar gas exchange. Respiratory and hemodynamic measurements were repeated after 30-60 minutes of HFJV. Mechanical ventilation was then resumed at baseline settings, and measurements were repeated 0.5-1 hour later. There was no significant change in gas exchange. HFJV resulted in a 50% reduction in mean airway pressure (9.2 +/- 0.2 cm H2O to 4.6 +/- 0.1 cm H2O, p less than 0.001), a 59% reduction in pulmonary vascular resistance (3.82 +/- 0.36 to 1.52 +/- 0.16 Woods units, p less than 0.001), and a 25% increase in cardiac index (2.32 +/- 0.12 l/min/m2 to 2.91 +/- 0.12 l/min/m2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.