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Biomedical subjects

R D Jones

Publications and source records attributed to R D Jones.

At least 109 records · Page 6Linked to original sources
PubMed1994

A comparison of three induction agents in paediatric anaesthesia--cardiovascular effects and recovery.

We studied 30 children undergoing circumcision randomly allocated to receive either thiopentone 4 mg.kg-1, propofol 2.5 mg.kg-1 or midazolam 0.5 mg.kg-1 (n = 10) IV over 30 seconds at induction of anaesthesia. Blood pressure and pulse rate during the first 15 minutes of induction were recorded by a Finapres 2300e and a Cardiocap CM-104, and changes from preinduction baseline compared between the three induction agents and the two recording instruments. Postoperatively, blood levels of the induction agents were measured and recovery from anaesthesia was assessed by clinical criteria, mood and sedation scores and psychomotor performance. The Cardiocap data revealed no statistically significant haemodynamic differences between the three induction agents. Finapres data demonstrated that propofol caused a greater decrease in mean arterial pressure when compared to thiopentone at one minute (P = 0.01) and the MAP remained significantly lower than midazolam at five minutes (P = 0.02), illustrating an advantage of continuous over intermittent non-invasive blood pressure monitoring. The midazolam group took longer to identify themselves compared to both the propofol (P = 0.005) and the thiopentone groups (P = 0.02), but there was no difference in the groups in time to eye-opening. Psychomotor performance on awakening was significantly worse in the midazolam group compared to the propofol (P < 0.03) and thiopentone groups (P < 0.02). Most children had recovered to 80% of their best, practised, unmedicated, preoperative performance four hours after awakening, irrespective of the induction agent administered. Drug blood levels correlated weakly with both methods of psychomotor assessment (r > or = 0.6). Of the three induction agents, thiopentone caused the least haemodynamic perturbation on induction, and anaesthesia induced with midazolam caused the greatest psychomotor impairment on awakening. Within one hour patients in all drug groups were equally awake, co-operative and co-ordinated.

Affect↗
PubMed1994

Effects of atropine in the beagle dog measured by quantitative electroencephalography and regional cortical analysis.

A treatment-by-subjects design was used to identify and characterize quantitative electroencephalography (qEEG) changes, at rest and under stimulus conditions, in Beagle dogs given 3 dose levels of atropine sulfate. In general, total power, absolute delta and theta amplitudes increased, while relative beta contribution and spectral frequency 90 decreased, as increased levels of atropine were administered. Regional analysis of this qEEG dataset suggests cortical mapping and contour plot imaging can be done in the dog. Through statistical analysis and visual evaluation of regional patterns may be more acceptable for interpretation in regulatory toxicology studies until normative databases are developed.

Analysis of Variance↗
PubMed1994

The effect of premedication on oxygen saturation during the post-premedication period in 20 Chinese children undergoing elective surgery.

Peri-operative continuous pulse oximetric data were studied in healthy Chinese children randomly allocated to receive either pethidine 1 mg kg-1 and atropine 0.02 mg kg-1 intramuscularly 90 min prior to surgery (n = 10), or midazolam 0.5 mg kg-1 and atropine 0.02 mg kg-1 orally, 120 min before surgery (n = 10). Data were collected during the night before surgery, after premedication and for 8 h post-operatively. The pulse oximeter (Nellcor N-200E) output was retrospectively evaluated using Satmaster, a computer programme which permits storage, retrieval, signal evaluation and compilation of oximetric data. There was no significant difference in the frequency, duration, or magnitude ofdesaturation episodes recorded during the post-premedication period compared to the desaturation episodes which occurred in the same child during normal sleep, on the night before surgery. Furthermore, there was no significant difference in the desaturation data between the two premedicant regimens. No child recorded a genuine desaturation less than 80% for longer than 15 s at any time during the study. Neither regimen significantly depressed saturation in otherwise healthy children presenting for minor surgical procedures.

Atropine↗
PubMed1994

A patient's experience of a new post-operative patient-controlled analgesic technique.

A patient underwent major spinal surgery, twice within a 3 week period. On the first occasion his post-operative pain was managed by conventional morphine patient-controlled analgesia (PCA). After the second procedure his pain was managed by a patient-controlled computer-assisted titration of alfentanil. This provided the opportunity to compare the efficacy of these two drug regimens in the same subject. The results showed comparable quality of analgesia and sedation and similar effects on respiration. However, the patient expressed a preference for morphine PCA.

Alfentanil↗
PubMed1993

Simultaneous determination of flumazenil, midazolam and metabolites in human biological fluids by liquid chromatography.

A simple procedure for the simultaneous determination of flumazenil, midazolam, 1-hydroxymethylmidazolam and 4-hydroxymidazolam in plasma or urine in surgical patients is described. The assay involves a preliminary extraction of the drugs, metabolites and internal standard (flurazepam) from biological fluid into an organic solvent mixture (dichloromethane-diethyl ether, 40:60 v/v). The extract was evaporated to dryness at 40 degrees C under a gentle stream of nitrogen. The residue was re-dissolved in distilled methanol (80 microliters) and a 30-microliters aliquot was injected via an automatic sampler into the liquid chromatograph and eluted with the mobile phase (32% acetonitrile in 0.004 M sodium hydrogenphosphate buffer containing 1 ml of triethylamine and adjusted to pH 7.2) at a flow-rate of 1.5 ml/min on a 30-microns C8 precolumn linked to a 4-microns Nova-pak C18 cartridge column (100 mm x 8 mm I.D.) at ambient temperature (25 degrees C). The eluate was detected at 220 nm.

Child↗
PubMed1993

Relationship between arterial thrombosis and neutralization of a polyethylene ionomer.

The influence of three levels of sodium neutralization of an ethylene/methacrylic acid copolymer on in vivo blood compatibility was studied in a canine arterial model. Effects due to sample fabrication methods (thermal pressing versus solution casting) were also monitored. Sodium content, sodium release, hydrogen dissociation, and localization of anionic groups were noted. Polymer surface energy, surface morphology, water uptake, and thermal properties were characterized. Material characterization and in vivo implantation disclose the following: 1) Thermal pressing generated oxidation degradation products that decreased in vivo blood compatibility. Solution-cast samples adhered and activated fewer blood elements. 2) Platelets and leukocytes were sensitive to differences in shear rate in the carotid and femoral arteries, with the femoral site tending toward higher shear, more platelet deposition and fewer leukocytes. 3) The surface properties of the polyethylene control, 0% Na, and 50% Na samples tended to be similar. These properties were different from the 100% Na sample. The 100% Na ionomer was more hydrophilic, had a higher polar component for its surface energy, and was unique in exhibiting discrete ionic clusters 1-10 microns in diameter on its surface. 4) These differences were manifested in vivo by platelet activation and thrombus development on the polyethylene, 0% Na, and 50% Na implants, while the 100% Na implant surfaces were predominantly covered by singly adherent, unactivated platelets. 5) It is proposed that the improvement in biocompatibility for the 100% Na ionomer is due to the cluster development in the neutralized methacrylic component and that either directly, or through appropriate protein adsorption and/or conformational adjustment to the cluster regions, platelets are not activated and do not initiate the coagulation mechanism.

Absorption↗
PubMed1993

Multifocal synchronous osteosarcoma: the Scottish Bone Tumour Registry experience.

We report 3 cases of multifocal synchronous osteosarcoma constituting 1% of osteosarcoma cases in the Scottish Bone Tumour Registry over 30 years. All were children and had a median age of 10 years. They all presented with multiple bony lesions in the absence of demonstrable pulmonary metastases. Treatment was with palliative radiotherapy in two and combination chemotherapy and radiotherapy in the most recent case. Survival was poor in all cases, with a median of 7 months. A proposal is made for genetic studies in future cases to help elucidate the origin of these tumours. The multicentric and metastatic hypotheses are discussed.

Adolescent↗
PubMed1993

Identification of metoclopramide metabolites in the urine of cattle by gas chromatography-mass spectrometry and high-performance liquid chromatography-photodiode array detection.

The urinary metabolites of metoclopramide (4-amino-5-chloro-N-[2-diethylaminoethyl]-2-methoxybenzamide) were identified in cows. The drug was administered intravenously, voided urine was collected, and individual urine extracts were analysed by gas chromatography-mass spectrometry and high-performance liquid chromatography-photodiode array detection. The parent compound and one major metabolite (4-amino-5-chloro-N-[2-(ethylamino)ethyl]-2-methoxybenzamide) were common to all individuals. In addition to the parent and major metabolite, a second, minor metabolite was identified in two cows as 4-amino-5-chloro-N-[2-(diethylamino)ethyl]-2-hydroxybenzamide. The identity of the minor metabolite was confirmed by comparison with a standard synthesized by a new method. Metabolite identification and characterization in food animal species allows the design of safety and environmental impact studies and relative metabolite ratios between dose treatment groups.

Animals↗
PubMed1993

Pharmacokinetics of flumazenil and midazolam.

We have studied simultaneously the pharmacokinetics of flumazenil and midazolam in 12 healthy Chinese children, aged 5-9 yr, undergoing circumcision. Two hours before operation each patient received midazolam 0.5 mg kg-1 orally for premedication and 0.5 mg kg-1 i.v. during induction. Six minutes after cessation of anaesthesia, a bolus of flumazenil 10 micrograms kg-1 was given i.v., followed by an infusion of flumazenil at 5 micrograms kg-1 min-1 which was maintained until the child could identify himself. Midazolam data were consistent with a three-compartment model with a mean (SD) elimination half-life of 107 (30) min, total body clearance of 15.4 (3.2) ml min-1 kg-1 and apparent volume of distribution at steady state of 1.9 (0.6) litre kg-1. Flumazenil data were best interpreted by a monoexponential function, with a mean terminal elimination half-life of 35.3 (13.8) min, a total plasma clearance of 20.6 (6.9) ml min-1 kg-1 and apparent volume of distribution at steady state of 1.0 (0.2) litre kg-1. No unchanged midazolam was detected in the 24-h urine sample, but 5.8-13.8% of the flumazenil dose was recovered unchanged. At the time of self identification, 4.5 (1.4) min after flumazenil administration, the mean plasma concentrations of midazolam and flumazenil were 163.1 (43.7) and 29.9 (16.1) ng ml-1, respectively.

Child↗
PubMed1993

A multistage system to detect epileptiform activity in the EEG.

A PC-based system has been developed to automatically detect epileptiform activity in sixteen-channel bipolar EEG's. The system consists of three stages: data collection, feature extraction, and event detection. The feature extractor employs a mimetic approach to detect candidate epileptiform transients on individual channels, while an expert system is used to detect focal and nonfocal multichannel epileptiform events. Considerable use of spatial and temporal contextual information present in the EEG aids both in the detection of epileptiform events and in the rejection of artifacts and background activity as events. Classification of events as definite or probable overcomes, to some extent, the problem of maintaining high detection rates while eliminating false detections. So far, the system has only been evaluated on development data but, although this does not provide a true measure of performance, the results are nevertheless impressive. Data from 11 patients, totaling 180 minutes of sixteen-channel bipolar EEG's, have been analyzed. A total of 45-71% (average 58%) of epileptiform events reported by the human expert in any EEG were detected as definite with no false detections (i.e., 100% selectivity) and 60-100% (average 80%) as either definite or probable but at the expense of up to nine false detections per hour. Importantly, the highest detection rates were achieved on EEG's containing little epileptiform activity and no false detections were made on normal EEG's.

Adolescent↗
PubMed1993

The Finapres 2300e finger cuff. The influence of cuff application on the accuracy of blood pressure measurement.

Blood pressure measurements associated with malapplication of a finger cuff were compared with contemporaneous intra-arterial pressure data in seven volunteers to determine the influence of cuff application on the accuracy of the Finapres 2300e. Systolic readings in all cuff positions differed from arterial line data by more than the recommended standard and tight and loose cuff applications under and over-read respectively, in all subjects. The results show the Finapres to be sensitive to small degrees of finger cuff malapplication which contribute to the bias on direct arterial comparison and limit the reliability of the instrument in clinical practice.

Adult↗
PubMed1993

Changes in the radiation treatment of cancer of the anus in Glasgow.

The survival and complication rate of two groups of patients with carcinoma of anus were compared. The first group of 20 patients were treated between 1974 and 1983 by double plane implantation using radium or equivalent caesium needles and supplementary external beam radiotherapy to groin nodes if present. The second group of 26 patients were treated between 1984 and 1990 by external beam radiotherapy followed by a jig implant using afterloading iridium needles. 5-year survival was superior in the second group (73% vs. 40%) with a lower incidence of radiation-induced complications.

Adenocarcinoma↗
PubMed1992

Nonsteroidal anti-inflammatory drug toxicosis in dogs and cats: 240 cases (1989-1990)

A search of medical records at the Georgia Animal Poison Information Center over a 19-month period revealed 240 cases of dog and cat exposure to nonsteroidal anti-inflammatory drugs (NSAID). The most common NSAID consumed were ibuprofen, acetaminophen, aspirin, and indomethacin. The most common clinical signs of toxicosis were vomiting and diarrhea, CNS depression, and circulatory manifestations. Pets are at risk from NSAID toxicosis through administration by the owners or accidental consumption of improperly stored drugs.

Accidents↗
PubMed1992

Impairment of high-contrast visual acuity in Parkinson's disease.

Several studies have shown that the visual system is affected in Parkinson's disease (PD) with reduced contrast sensitivity, low-contrast acuity, and flicker sensitivity, as well as altered electroretinograms (ERGs) and pattern visual evoked potentials (VEPs). Apparently, however, no study has yet specifically determined whether visual acuity to high-contrast stimuli is impaired in PD. Visual acuity was measured in a group of 16 patients with PD, both on and off drugs (for 24 h), and 16 age- and sex-matched normal control subjects. Acuity was impaired in the PD group both on standard Snellen chart and on a screen in a computerized test of visual resolution. The degree of impairment was 24 and 25%, respectively, in the two tests. The PD patients had marginally better acuity on both tests while receiving drugs, but the differences were not significant. The difference between the two groups was consistent with impaired resolution and could not be accounted for by any perceptual dysfunction that may also have been present in the PD group. Conversely, however, impaired acuity may be implicated in studies that have reported mild deficits of visuospatial/visuoperceptual function in PD. Reduced acuity appears to be a subtle sequela of dopaminergic deficiency in the visual system.

Adult↗
PubMed1992

The upgraded Finapres 2300e. A clinical evaluation of a continuous noninvasive blood pressure monitor.

Measurements from the upgraded Finapres 2300e continuous noninvasive blood pressure monitor, the Finapres 2300 and Colin oscillometric noninvasive blood pressure monitor were compared with invasive arterial line blood pressure readings. Fifteen young Chinese patients undergoing elective spinal surgery of more than 2 h duration had contemporaneous blood pressure measurements digitally recorded every minute. Data were analysed using methods described by Bland and Altman to assess agreement of noninvasive devices with an arterial line. Results showed that although the Finapres 2300e was significantly more accurate than the Finapres 2300 and Colin noninvasive blood pressure monitors it could not be recommended as a substitute for continuous arterial line blood pressure monitoring. Both Finapres devices demonstrated reductions in accuracy related to time (drift) and over-read diastolic and mean pressures by 5-8 mmHg throughout the range of mean arterial line pressures (bias). The Colin was consistently less accurate than the Finapress monitors and performed worst at low mean arterial line pressures.

Adolescent↗
PubMed1992

An evaluation of prolonged oximetric data acquisition.

Data derived from pulse oximetry has inherent limitations, one of which is artifactual desaturation caused by patient movement. Perioperative patterns of oxygen desaturation were studied for a mean duration of 67 hours in eight young patients following corrective spinal surgery. Pulse oximetry data were relayed to a computer using Satmaster, a program which permits storage, retrieval, signal evaluation and statistical analysis of oximetry data. Desaturation episodes were mild, of short duration and their infrequent occurrence was not increased during intravenous morphine infusion. Retrospective identification of contemporaneous artifactual changes in signal amplitude permitted the removal of artifactual desaturations from our statistical data analysis. This decreased the average time desaturated from 5.4% (220 minutes) to 4.2% (162 minutes) of the monitored period representing a 25% reduction in absolute incidence and a 35% reduction in episodic incidence of desaturation. Acquired data should be validated and inferences drawn from non-validated data must be assessed with caution.

Adolescent↗