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Biomedical subjects

P S Baxter

Publications and source records attributed to P S Baxter.

At least 19 recordsLinked to original sources
PubMed2006

False diagnosis of papilloedema and idiopathic intracranial hypertension.

The diagnosis of idiopathic intracranial hypertension (IIH) relies heavily on the appearance of the optic disc. We report eighteen children referred to us over a 3 year period with disc swelling and suspected IIH. Following a tertiary ophthalmological review, papilloedema was excluded in ten with buried drusen, disc crowding, pseudopapilloedema, or misinterpretation of normal appearances. In these ten children, five had a mean opening pressure on lumbar puncture of 27.2 cm H2O, range 19-32, which was significantly lower than those with IIH (37.5 cm H2O, range 29-47; p<0.01). We conclude that diagnosis of IIH is difficult, and that more precisely defined criteria for assessment and diagnosis are needed.

Adolescent↗
PubMed2006

The significance of reduced respiratory chain enzyme activities: clinical, biochemical and radiological associations.

BACKGROUND: Mitochondrial diseases are an important group of neurometabolic disorders in children with varied clinical presentations and diagnosis that can be difficult to confirm. AIM: To report the significance of reduced respiratory chain enzyme (RCE) activity in muscle biopsy samples from children. METHODS: Retrospective odds ratio was used to compare clinical and biochemical features, DNA studies, neuroimaging, and muscle biopsies in 18 children with and 48 without reduced RCE activity. RESULTS: Children with reduced RCE activity were significantly more likely to have consanguineous parents, to present with acute encephalopathy and lactic acidaemia and/or within the first year of life; to have an axonal neuropathy, CSF lactate >4 mmol/l; and/or to have signal change in the basal ganglia. There were positive associations with a maternal family history of possible mitochondrial cytopathy; a presentation with failure to thrive and lactic acidaemia, ragged red fibres, reduced fibroblast fatty acid oxidation and with an abnormal allopurinol loading test. There was no association with ophthalmic abnormalities, deafness, epilepsy or myopathy. CONCLUSION: The association of these clinical, biochemical and radiological features with reduced RCE activity suggests a possible causative link.

Adolescent↗
PubMed2005

The "Lasso-o" tape: stretchability and observer variability in head circumference measurement.

Head circumference is an important clinical measurement in children. The stretchability of the Lasso-o tape and the intra- and inter-observer reproducibility of measurements using it were investigated. Old Lasso-o tapes stretch significantly. The intra-class coefficients were 0.999 for intra-observer and 0.979 for inter-observer measurements. Nonetheless in 9% of measurements inter-observer variability was over 1 cm.

Adolescent↗
PubMed2004

'Cerebral palsy' due to mitochondrial cytopathy.

Two children aged 10 and 13 years with initially static motor problems, diagnosed as cerebral palsy, were found to have respiratory chain defects after developing a progressive course and multisystem involvement. Mitochondrial cytopathies should be considered in the differential diagnosis of cerebral palsy.

Adolescent↗
PubMed2003

Focal neuropathy in children with critical illness.

Four children are described who developed focal lower limb nerve palsies following critical illness. Two had clinical and/or neurophysiological evidence of simultaneous generalised critical illness polyneuropathy. The diagnosis was delayed in three patients due to the presence of central motor abnormalities and slow motor recovery. Follow-up from seven months to three years showed minimal or no recovery. In three, a vasculitic skin infarct, compartment syndrome and focal myositis could have caused nerve compression. We suggest that in critical illness peripheral nerves have an increased susceptibility to damage by local pressure.

Adolescent↗
PubMed1999

Humidified gas prevents hypothermia induced by laparoscopic insufflation: a randomized controlled study in a pig model.

BACKGROUND: This experimental study evaluated whether humidification of warmed insufflated CO2 during laparoscopic procedures would resolve the problem of laparoscopy-induced hypothermia. METHODS: Changes in core temperature were quantified over a 3-h period of high-flow CO2 insufflation in a randomized, controlled trial of five pigs. Each animal was anesthetized and studied on three occasions under standardized conditions, acting as its own control by insufflation with no gas compared with insufflation by cool dry gas and heated humidified gas. RESULTS: Core temperatures after insufflation with heated humidified gas were no different from that of controls. After insufflation with cool dry gas, core temperature dropped by 1.8 degreesC, which was significantly more than the 0.6 degreesC drop experienced by control animals and those insufflated with heated humidified gas (p < 0.01). Calculations of the heat expended in evaporation of water were also performed. The temperature drop due to water evaporation alone in pigs insufflated with cool dry gas was calculated to be 1.5 degreesC. This compares favorably with the measured 1.2 degreesC temperature difference between these animals and the control group. CONCLUSIONS: The majority of heat lost during laparoscopic insufflation is due to water evaporation, and laparoscopic hypothermia may be prevented by using heated and humidified gas insufflation.

Analysis of Variance↗
PubMed1999

A randomized controlled trial assessing the benefit of humidified insufflation gas during laparoscopic surgery.

BACKGROUND: We conducted a randomized controlled trial during laparoscopic cholecystectomy to determine the extent of heat preservation and postoperative pain reduction using humidified carbon dioxide (CO2) gas insufflation instead of standard dry insufflation gas. METHODS: Forty consecutive patients were randomized. Twenty patients received humidified CO2, and 20 control patients received standard CO2 insufflation. A sample of 16 patients from each group was evaluated for postoperative pain levels. RESULTS: No adverse effects from the humidification of insufflated gas were observed. There was no significant difference in core body temperature between the two groups for this brief operation. Pain, as assessed by the Analogue Pain Score (APS) was significantly less for the group with humidified gas insufflation than for the control group at 6 h postoperatively as well as on the 1st, 2nd, and 3rd postoperative day and at follow-up 10 days after the operation. In the humidified group, the mean time to return to normal activities was significantly less-5.9 days, as compared to 10.9 days in the control group. CONCLUSIONS: The use of humidified insufflation gas reduces postoperative pain following laparoscopic cholecystectomy, but except for these relatively brief procedures, the heat-preserving effect of humidified gas insufflation is not significant.

Adult↗
PubMed1998

Overnight shunt pressure monitoring in children.

We audited the value of overnight shunt pressure monitoring in 17 children with symptoms of possible shunt dysfunction but no other supportive evidence. The shunt was accessed by a 25G butterfly connected to a disposable arterial pressure monitor positioned on the ipsilateral shoulder whose output was recorded continuously, while noting posture, sleep state and symptoms. Initially traces were analysed only for the portion spent both asleep and supine or prone. Six showed pressure peaks while asleep: of these four underwent shunt revision with remission of their symptoms and two resolved spontaneously, one with a simultaneous resolution of a peritoneal CSF collection, but the other had a recurrence of symptoms after six months. Two more subsequently shown to have blocked shunts had normal traces while asleep but abnormal pressure peaks when awake and upright. Two showed pressure troughs: one responded to insertion of an antisyphon device and one resolved spontaneously. Five had normal traces while asleep and awake: symptoms resolved in three and persisted in two in whom later prolonged extradural monitoring with a fibre-optic transducer was also normal. Studies failed in two. We conclude that prolonged overnight shunt pressure monitoring with this technique is useful in diagnosing shunt dysfunction and that abnormalities detected while awake and upright are as significant as those detected asleep and supine or prone.

Adolescent↗
PubMed1998

Electrochemically induced hepatic necrosis: the next step forward in patients with unresectable liver tumours?

BACKGROUND: The treatment of patients with unresectable liver tumours remains an unsolved clinical problem. Several methods of locoregional treatment have been developed. These methods rely mainly on direct thermal or chemical insults and consequently have their own inherent limitations in clinical usage. The 'ideal' treatment would combine the direct cytotoxic effects of chemical treatments with the relative predictability of thermal insults, without the associated complications. This study aims to investigate whether the direct chemical effect of electrolytic hepatic necrosis is associated with any heating effect, and if so, whether the temperature change is dose-dependent. METHODS: An electrolytic 'dose' sufficient to induce a localized zone of hepatic necrosis was delivered to the livers of rats and pigs via implanted platinum electrodes. RESULTS: The results showed that there was no significant temperature increase at low current levels (2-4 mA) in the rat liver. In the pig, there was a significant (P < 0.01) increase in temperature of 4.2 degrees C during electrolysis, when delivered at between 20 and 50 mA. However, such a small increase in temperature would have been insufficient to cause appreciable thermal necrosis. CONCLUSIONS: This study demonstrates that electrolysis-induced hepatic necrosis is produced without an increase in temperature; clearly cell death results from the direct effects of cytotoxic electrode products and an alteration of intracellular pH. Consequently, it is likely that as a method for ablating liver tumours, electrolysis should be associated with fewer complications than other forms of locoregional treatment.

Animals↗
PubMed1998

Effect of cisapride on gastroduodenal reflux and gall bladder motility in patients with gallstones.

The aim of this work was to assess the effect of 10 mg of cisapride twice daily for 1 week on symptoms, gastroduodenal reflux and gall bladder emptying in patients undergoing cholecystectomy. Seventy-seven patients, 29 male and 48 female, underwent a randomized, double-blind, placebo-controlled trial with a 1-week treatment period between studies before cholecystectomy. Fifty-one of these patients were suitable for gall bladder emptying ejection fraction analysis. Gastroduodenal reflux and gall bladder emptying were assessed using Milk 99Tcm DIDA scans. Cisapride did not significantly alter gastroduodenal reflux but gall bladder motility was altered after cisapride treatment (p < 0.05).

Adult↗
PubMed1997

The effect of laparoscopic cholecystectomy on gastroduodenal reflux.

BACKGROUND: The present study evaluates the effect of laparoscopic cholecystectomy on biliary reflux in patients with cholelithiasis. METHODS: All patients over 18 years of age awaiting elective cholecystectomy for gallstone disease in one of two teaching hospitals were contacted by telephone, and those who gave informed consent were entered in the study. A total of 66 patients (43 females and 23 males) underwent milk 99mTc DIDA scans. Elective laparoscopic cholecystectomy was perfomed after a median of 28.5 days (range: 8-588 days) and patients were re-investigated with a milk 99mTc DIDA scan at a median time of 50 days (range: 18-370 days) postoperatively. Scans were carried out in the Nuclear Medicine Department of the Royal Adelaide Hospital. RESULTS: All but two patients had a functioning gall-bladder on milk 99mTc N-2, 6-dimethylphenyl-carbamoylmethyl iminodiacetic acid scanning prior to cholecystectomy. One of these patients was found to have a gall-bladder carcinoma at cholecystectomy. Fifty-seven of the 66 patients had a successful laparoscopic cholecystectomy (nine open cholecystectomies). Nineteen patients experienced gastroduodenal reflux into the stomach prior to cholecystectomy and 23 patients experienced it postoperatively. There was no significant difference in gastroduodenal reflux in both the open and laparoscopic groups. CONCLUSION: The present study demonstrated that laparoscopic cholecystectomy did not significantly alter gastroduodenal reflux.

Adult↗
PubMed1997

Xp21 muscular dystrophy due to X chromosome inversion.

Two brothers with Duchenne muscular dystrophy have an inversion of the X chromosome, 46, Y, inv(X) (p11.2p21.2). Because their mother is an unaffected carrier of the inversion, this confirms that maternal passage of a structurally abnormal X chromosome can cause dystrophinopathy in males. Our experience suggests that as well as molecular genetic analysis, karyotyping can be useful in Xp21 muscular dystrophy.

Adult↗
PubMed1995

Vigabatrin monotherapy in resistant neonatal seizures.

Seizures in a term infant with Ohtahara syndrome, associated with polymicrogyria, and a pre-term neonate with similar clinical features, failed to respond to conventional anticonvulsants, but were controlled with vigabatrin monotherapy. Another infant with Aicardi syndrome improved with vigabatrin. Autopsy in the first infant showed no evidence of intramyelinic oedema. The developmental outcome in the two survivors was better than expected for their condition.

Agenesis of Corpus Callosum↗
PubMed1995

Attention-deficit hyperactivity disorder in children.

Attention-deficit hyperactivity disorder has been redefined in the classifications in the International Classification of Disease, 10th revision and Diagnostic and Statistical Manual of Mental Disorders, fourth edition. The definitions are more concordant than their predecessors and reemphasize the distinction between inattentiveness and hyperactivity. The causes and mechanisms are still uncertain, but dietary sugar or aspartame and thyroid dysfunction do not seem to be major factors. Specific subgroups, such as children with comorbid psychologic disorders, tic disorders, or mental handicap, seem to have different origins, natural history, prognoses, and responses to treatment, reflecting the heterogeneous nature of the disorder. Psychostimulant therapy has unquestioned short-term effects on behavior but less certain benefits on long-term psychosocial outcome or on academic performance.

Attention Deficit Disorder with Hyperactivity↗
PubMed1990

Bacterial reservoirs in cystic fibrosis.

To establish whether colonisation of the upper respiratory tract or bacterial contamination of inhaler devices or solutions predisposes to colonisation of the lower respiratory tract in patients with cystic fibrosis, bacterial isolates from groups of children who were positive (n = 13) or negative (n = 18) for Pseudomonas aeruginosa were studied. Cultures of swabs from inhaler devices, toothbrushes, and upper airways were compared with cough swabs or sputum cultures. No pathogens were obtained from inhaler equipment administering unit dose medications. Upper airway carriage of Staphylococcus aureus and Haemophilus influenzae was identified in both groups but correlated poorly with sputum isolates. P. aeruginosa was found only in the upper respiratory tract of children with established colonisation of the lower airways. No P aeruginosa isolates were obtained from the upper airways of the group with negative sputum, including one patient who became colonised by P aeruginosa during the study. Our results did not support the suggestion that colonisation of the upper respiratory tract by P aeruginosa predisposes to colonisation of the lower airways. Failure to isolate pathogenic organisms consistently from the upper airways in patients with positive sputum argues against a local epithelial factor predisposing to bacterial colonisation.

Adolescent↗