Search PubMed⌕ Search

Biomedical subjects

P D Cameron

Publications and source records attributed to P D Cameron.

13 recordsLinked to original sources
PubMed1992

Herpes simplex virus encephalitis: problems in diagnosis.

Six children aged 13 days to nine years with herpes simplex encephalitis (HSE) are presented. Institution of appropriate antiviral treatment was later than six days in three cases; original diagnosis in these cases were post-traumatic epilepsy, bacterial meningitis and febrile convulsion. Initially pyrexia was absent in two cases and cranial CT was normal in two cases. Encephalitic changes were observed on the EEGs of five children. Diagnosis was confirmed by paired serological titres, brain biopsy, vesicle culture and CSF titres. The outcome for all six children was poor. HSE should always be considered in children presenting with focal seizures, even when apyrexial and with normal CT findings. In such situations, saving CSF for antibody titres or antigen identification should be routine practice. Treatment with acyclovir is justified before precise virological diagnosis has been established.

Adolescent↗
PubMed1990

Sialic acid storage disease.

A baby girl with coarse facial features, hepatosplenomegaly, and developmental delay had raised free sialic acid concentrations in her urine and cultured fibroblasts. She died aged 13 months. Sialic acid is an important constituent of many glycoproteins and glycolipids; impaired release from the lysosome may be the underlying biochemical defect.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1987

Quantification of thoracic volumes by three-dimensional imaging.

End-expiratory thoracic cavity volume (Vthx) was measured in eight volunteers lying supine by three-dimensional X-ray computed tomography using the Dynamic Spatial Reconstructor. Untrapped end-expiratory pulmonary gas volume at functional residual capacity (FRC) was determined by nitrogen clearance. Both measurements were done before and after induction of anesthesia-paralysis. After induction of anesthesia-paralysis, Vthx and FRC were consistently and significantly (P less than 0.01) reduced by 0.28 +/- 0.22 (SD) and 0.59 +/- 0.24 liter, respectively. The reduction of FRC was larger than the reduction of Vthx (delta Vthx) in six of the eight subjects, a finding suggesting that intrathoracic fluid (blood) plus trapped gas volume (Vtt) increased. Changes in Vthx were partitioned into volume changes from the thoracic rib cage (delta Vrc) and from shape and/or position changes of the diaphragm (delta Vdi). delta Vrc contributed significantly (0.17 +/- 0.15 liter, P less than 0.02) to delta Vthx, whereas delta Vdi contributed only in four of the eight subjects. We conclude that delta Vrc, delta Vdi, and delta Vtt contribute to the reduction of FRC after induction of anesthesia-paralysis in humans; the relative contribution of them varies among subjects.

Adult↗
PubMed1986

Pharmacokinetics of ranitidine in critically ill patients.

The plasma pharmacokinetics of ranitidine (50 mg i.v.) have been studied in 17 critically ill patients in an intensive care unit. Measurements of gastric aspirate pH were also made in 16 of these patients. Ranitidine therapy was part of the patients' normal drug regimen. Ranitidine plasma concentration was measured by high performance liquid chromatography and appropriate polyexponential equations were fitted to concentration-time data to enable calculation of relevant pharmacokinetic parameters. Values of the volume of the initial dilution space (median = 89 ml kg-1) and volume of distribution at steady state (median = 1.54 l kg-1) were about 60% of corresponding mean literature values for healthy controls. Plasma clearance (median = 4.22 ml min-1 kg-1) and terminal half-life (median = 4.7 h) were about 2-3 fold less and 2-3 fold greater, respectively, than values for healthy controls. There was wide interpatient variation in all the pharmacokinetic parameters. Renal impairment was considered to be largely responsible for the low plasma clearance. Gastric aspirate pH was measured at 0, 1 and 7 h after ranitidine administration and 58% of samples were found to be above pH 4. Four patients had gastric pH values which were consistently below pH 4 despite average trough plasma ranitidine concentrations equal to or greater than those required for a 50% suppression of gastric acid secretion in normal volunteers.

Adult↗
PubMed1986

Newer modes of mechanical ventilatory support.

Recent modes of ventilatory support aim to facilitate weaning and minimise the physiological disadvantages of intermittent positive pressure ventilation (IPPV). Intermittent mandatory ventilation (IMV) allows the patient to breathe spontaneously in between ventilator breaths. Mandatory minute volume ventilation (MMV) ensures that the patient always receives a preset minute volume, made up of both spontaneous and ventilator breaths. Pressure supported (assisted) respiration is augmentation of a spontaneous breath up to a preset pressure level, and is different from 'triggering', which is a patient-initiated ventilator breath. Other modes or refinements of IPPV include high frequency ventilation, expiratory retard, differential lung ventilation, inversed ratio ventilation, 'sighs', varied inspiratory flow waveforms and extracorporeal membrane oxygenation. While these techniques have useful applications in selective situations, IPPV remains the mainstay of managing respiratory failure for most patients.

Humans↗
PubMed1985

A comparison of continuous flush devices.

Six different makes of continuous flush device were compared for reliability of flow rate and ease of use. All of the devices tested were considered suitable for flushing of vascular pressure monitoring catheters. However, flow rates were considered too variable for control of drug infusions or flushing of intracranial pressure monitoring systems.

Blood Pressure Determination↗
PubMed1984

Effect of long-term continuous infusion of alfathesin on clinical biochemical and haematological parameters.

Clinical biochemical and haematological parameters during long-term continuous infusion of alfathesin were studied in twelve neurosurgical patients who did not have multiple organ failure. Significant changes which were possibly caused by alfathesin were an alteration of blood film morphology, an elevation of plasma triglyceride and a reduction in plasma high-density lipids.

Adult↗
PubMed1984

Pressure infusors: variability in delivered infusion pressure.

A pressure infusor was used to apply external pressures of 300, 250, 200, and 150 mm Hg to 500-ml plastic bags of saline. At constant applied pressure, 50-ml aliquots of saline were periodically withdrawn. The delivered pressures were less than the applied pressures, and the difference increased as the volume of saline within the bag decreased. This inherent pressure difference should be considered when the system is used with a continuous flush device.

Catheterization↗
PubMed1983

A multiple-purpose automatic pressure regulator.

The Gairdner Hospital Automatic Pressure Regulator was developed to deliver a constant pre-set gas pressure for the continuous inflation of infusion pump cuffs or pneumatic tourniquets. It has been found to be economical, safe, reliable and easy to use. The device facilitates both continuous flushing of catheters and rapid intravenous infusions especially during emergency situations. It may also be used in other clinical situations where a continuous gas supply at a pre-set constant pressure is required.

Air Pressure↗