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Biomedical subjects

B Tiplady

Publications and source records attributed to B Tiplady.

At least 19 recordsLinked to original sources
PubMed2003

A comparison of target-controlled therapy with patient-controlled administration of propofol combined with midazolam for sedation during dental surgery.

Forty anxious day case patients undergoing extraction of third molar teeth under local anaesthesia with sedation, were studied in a randomised double-blind controlled trial. A target-controlled infusion of propofol was compared with patient-controlled propofol for sedation, combined with a small dose of midazolam to improve amnesia. The objectives of the study were to measure the total dose of propofol used by the two groups and assess recovery and patient satisfaction. The mean dose of propofol used in the patient-controlled sedation group was significantly less than the target-controlled group (p < 0.00007). Five patients became over-sedated in the target-controlled group compared with none in the patient-controlled group. Only one of the three tests of performance showed that the target-controlled patients were more sedated. Patient satisfaction was high in both groups despite a greater recollection of events in the patient-controlled group.

Adult↗
PubMed2003

Assessment of postsurgical recovery after discharge using a pen computer diary.

We assessed patients after their return home following gynaecological surgery, using a daily electronic diary. Thirty-two females aged 27-77 years took part. After a hospital stay of 1-6 days (mean 2.3), they were given a pen-based electronic diary and asked to record symptoms and other data over one month. They also completed a questionnaire at the end of the study. Substantial effects on quality and duration of sleep, pain during both the night and day, interference with daily activities, energy, and ability to concentrate were recorded, mostly during the first week of treatment. Symptoms reported in the final questionnaire correlated significantly with diary data. Most patients found the electronic diary easy to use, and none found it difficult. Daily electronic diaries are an acceptable method of obtaining better information on the extent and duration of symptoms and other difficulties after discharge following surgery.

Activities of Daily Living↗
PubMed2003

Errors in performance testing: a comparison of ethanol and temazepam.

Both ethanol and benzodiazepines impair psychomotor function. Previous work has suggested that ethanol may have a greater effect on errors while benzodiazepines may cause greater slowing, but this has not been tested in a direct comparison. We assessed the effects of ethanol, at blood concentrations of approximately 80-100 mg/100 ml, compared to two doses of temazepam (20 mg and 30 mg) on psychomotor speed and accuracy and on long-term memory. Sixteen healthy volunteers (eight male, aged 20-25 years) took part in a four-period, placebo-controlled cross-over study. Performance was evaluated using analysis of covariance (critical significance level, p = 0.05) comparing the areas under the response-time curves. Performance on a psychomotor maze showed an almost complete dissociation, with ethanol leading to a substantial and significant increase in errors with little effect on speed, while temazepam slowed performance with no significant change in accuracy. Other tasks showed a similar pattern, but the dissociation was less complete. Handwriting size was substantially increased by ethanol, but not by temazepam. Information processing capacity and long-term memory formation were reduced by a similar amount both for ethanol and 30 mg temazepam. The faster, more error-prone, behaviour on ethanol than with a similarly impairing dose of temazepam has clear implications for the relative potential of the two drugs to contribute to accidents. The results are also important in understanding the differential effects of drugs with different mechanisms of action on human performance.

Adult↗
PubMed2002

Effect of ethanol on psychomotor performance and on risk taking behaviour.

Ethanol may increase the willingness to take risks, but this issue remains controversial. We used a risk-taking paradigm in which volunteers answered a series of general knowledge questions with numerical answers and were asked to judge the length of a line that would just fit into a given gap. A maximum score was given for an exactly correct answer. For answers that were less than the correct value, the score was reduced gradually to zero, while answers even slightly over the correct value were penalized considerably. Total points were rewarded by cash payments, so volunteers were taking real risks when making their responses. Performance was assessed in a two-period, double-blind crossover study, comparing ethanol (0.7 g/kg) with placebo in 20 female volunteers aged 19-20 years. Tests were carried out before and at 45 min after dosing. Mean (SD) ethanol blood alcohol concentrations were 65 (10.5) mg/100 ml. Ethanol impaired the skill/ability measure of the length estimation test (SD of difference between length of line and gap), which increased from 5.9 to 6.6 (p < 0.05), indicating a reduced accuracy of estimation. The risk measures in both tasks were not significantly affected. The skill/ability measure in the general knowledge task was not significantly affected. Other performance tests showed that ethanol produced the expected impairment of both speed and accuracy. These results suggest that risk-taking is not increased by ethanol at doses approaching the UK legal limit for driving.

Adult↗
PubMed2001

Validity and sensitivity of a pen computer battery of performance tests.

This study compared administration of performance tests and visual analogue scales (VAS) using a newly developed pen computer (PenC) battery with established tests using either pencil-and-paper (PP) or conventional computer. The performance of 47 subjects (23 male, age 18-45 years, weight 51-112 kg) was compared on the two systems after a dose of ethanol (0.8 g/kg up to a maximum of 60 g for males, 50 g for females) or placebo in a double-blind two-period randomized crossover study. Mean (SD) blood ethanol concentrations (breathalyser) were 94.5 mg/100 ml (21.9) at the start of the test battery (30 min post-drink) and 80.2 (13.0) at the end of the battery (75 min post-drink). Ethanol effects were found in all tests, with most outcome measures showing significant slowing or loss of accuracy. Results from the Rapid Visual Information Processing, Sentence Verification and Continuous Attention tasks show that the ethanol-placebo difference and the statistical significance of this difference are in close correspondence for the two modes of administration. The pen computer versions of these tasks may therefore be used as direct replacements for the previous versions. Digit-Symbol and maze tasks did not correspond so closely both showing differences in the speed-accuracy trade-off between the two modes. These tests, however, are sensitive to the effects of ethanol, and may be useful in their own right. Principal component analysis suggested that VAS may be grouped into two factors: (1) 'functional integrity', including measures of alertness and perceived proficiency, and (2) 'mood', including happiness and sociability. Factor 1 showed substantial effects of ethanol, while factor 2 was unchanged. There was close agreement between the results from PP and PenC for both factors as well as for the Sober-Drunk scale, which showed the expected effects of ethanol. Thus pen computer VAS perform in a similar way to the PP versions.

Adolescent↗
PubMed1999

Single dose pharmacodynamics of thioridazine and remoxipride in healthy younger and older volunteers.

Phenothiazines are widely used in older patients, but little experimental work has been carried out in this age group. Two groups of healthy volunteers, a younger group (Y: six males and six females, aged 20-42 years) and an older group (O: six males and eight females, aged 65-77 years) took part in a randomized double-blind three-period crossover study in which they received by mouth single doses of thioridazine (Y: 50 mg; O: 25 mg) remoxipride (Y: 100 mg; O: 50 mg) or placebo. Measures of central nervous system (CNS) and haemodynamic function were carried out before drug administration and at 1.5-h intervals up to 9 h post-dose, and blood samples were collected over a 24-h period. No significant differences in dose-corrected pharmacokinetic variables were found between the two groups. There was evidence of marked CNS depressant effects of thioridazine from both objective and subjective measures. The effects for remoxipride were similar, though generally less marked. After allowance was made for dose, there was little indication of any difference in degree of CNS depression between the two age groups. Haemodynamic measures showed orthostatic reductions in blood pressure with thioridazine which were particularly marked in the older group, who also showed lower compensatory increases in pulse rate. These results indicate potential problems with orthostatic hypotension with thioridazine in older patients. CNS depression may also be a problem, especially in patients with compromised cholinergic function.

Adult↗
PubMed1998

Psychomotor performance: investigating the dose-response relationship for caffeine and theophylline in elderly volunteers.

OBJECTIVE: The aim of the study was to investigate the dose-response relationship for psychomotor performance, caffeine and theophylline in healthy elderly volunteers. METHODS: In a randomized, double-blind, placebo-controlled, six-period cross-over study we compared the effect of three doses of theophylline (predicted peak concentrations of 3, 6 mg. 1(-1) and 12 mg . 1(-1), two doses of caffeine (predicted peak concentrations of 4.5 mg. 1(-1) and 9 mg. 1 (-1) and placebo on ten healthy elderly volunteers. Psychomotor performance was measured using a continuous attention task, symbol digit substitution test and choice reaction time. Subjective effects were assessed using visual analogue scales. Following drug administration, subjects received the test battery at 30-min intervals, up to 150 min. Maximum and mean effects from baseline on each variable were included in the analysis. RESULTS: Significant improvement on the continuous attention task was seen at the lowest concentration of caffeine and theophylline used, while at higher concentrations there was a non-significant trend towards placebo scores. There was little effect of either drug on the subjective effects measured by visual analogue scales. CONCLUSION: Caffeine and theophylline increase psychomotor performance measures of attention at low plasma concentrations in healthy elderly volunteers. This effect is not increased by higher drug concentrations and there is trend towards a return to placebo scores. The lack of effect of both caffeine and theophylline on subjective measures is consistent with previous studies of caffeine in the elderly.

Aged↗
PubMed1998

Validity and sensitivity of visual analogue scales in young and older healthy subjects.

BACKGROUND: Previous findings from studies on the acute effects of drugs indicate that older subjects report less change on visual analogue scales than do younger subjects, when the observed drug effects on objective performance measures are as great or greater. AIM: To validate the use of visual analogue scales independently of internal perceptions. SUBJECTS AND METHODS: 50 younger and 50 older subjects rated attributes of four animals--tortoise, crow, tiger and wasp--on a series of 10 cm lines. The attributes rated included physical qualities (size, noise) and psychological aspects (danger). RESULTS: Ratings were generally similar for the two groups, although older subjects tended to rate slightly greater differences between animals, but the variability was also slightly greater. Thus the mean difference between tiger and wasp for size was 60.1 (SD 15.6) in the younger group and 68.8 (SD 18.4) in the older group. CONCLUSIONS: These results support the validity of the use of visual analogue scales in both groups. Explanations for the previously observed discrepancy may need to be sought in terms of an effect of age on the perception of internal changes rather than on any difference in the use of the scales.

Adult↗
PubMed1998

Computer anxiety: a comparison of pen-based personal digital assistants, conventional computer and paper assessment of mood and performance.

The recent growth of pen-based devices, such as the Personal Digital Assistant (PDA), offer mobility and a more natural interface than that of a conventional computer. The feasibility and application of the PDA for mood and cognitive assessment were investigated by examining possible interactions of individual characteristics and administration medium. Previous studies have provided evidence that individual characteristics of 'computer anxiety' and 'private self-consciousness' divergently covaried with mood scores measured by computer and paper methods. To investigate the relationship between individual characteristics and medium effects, 136 paid participants were allocated to and completed mood assessment tasks and a short battery of cognitive tasks by either the computer, PDA or the paper method. Self-ratings of mood measured by these three modalities covaried divergently with measures of computer anxiety and private self-consciousness. In addition, computer anxiety covaried with reaction time on the visual search task obtained on computers, but there was no such relationship when measured by a PDA. These results show that computer anxiety can affect the results of assessments of cognitive function as well as of mood ratings, and suggest that pen-based systems may have advantages over conventional computers in this respect.

Adolescent↗
PubMed1995

Electronic quality of life questionnaires: a comparison of pen-based electronic questionnaires with conventional paper in a gastrointestinal study.

The use of pen-based electronic questionnaires and conventional paper questionnaires was compared in a randomized crossover study. Forty-six patients, aged 17-81 years, suffering from gastro-intestinal disorders, initially filled in a paper quality of life questionnaire for familiarization purposes, then on two subsequent visits completed electronic and paper questionnaires in randomized order. At the last visit they completed a preference survey. The results showed a high degree of acceptability of the electronic questionnaire, with 57% of patient preferring electronic and 13% preferring paper, while the remaining 30% expressed no preference. Neither age, gender nor familiarity with technology showed any marked association with patients' preferences. All patients found both paper and electronic questionnaires easy to use. Data were more complete on the electronic questionnaire (100%) than on the paper (99.1%). Data handling procedures were greatly simplified. These results show that major benefits in completeness of data, speed of data flow, and data handling workload can be obtained from the use of pen-based electronic questionnaires.

Adolescent↗
PubMed1995

Effects of nitrous oxide on psychological performance. A dose-response study using inhalation of concentrations up to 15%.

In this six-period randomised double-blind study, 12 healthy volunteers inhaled mixtures of nitrous oxide at concentrations of 0% (placebo); 3%, 5%, 7%, 10%, and 15% in oxygen. Each concentration was inhaled for 55 min, each period being on a separate day. The order of treatments was randomised using a Latin-Square design. The effects of nitrous oxide were assessed using a battery of performance tests which included measures of attention, psychomotor function, memory and cognition. Mood was assessed using visual analogue scales. Measures of attention and psychomotor performance showed impairment at 15% nitrous oxide, and subjective measures showed sedation at this dose. The Buschke Selective Reminding Task showed impairment to long-term recall at all doses of nitrous oxide compared to placebo, while short-term recall was impaired only at 15%. These results suggest that consolidation of memory may be particularly sensitive to disruption as a result of CNS depression.

Administration, Inhalation↗
PubMed1994

A dose-response study of the effects of inhaled nitrous oxide on psychological performance and mood.

In this five-period randomised double-blind crossover study, 12 healthy volunteers inhaled mixtures of nitrous oxide at concentrations of 0% (placebo); 5%, 10%; 20% and 40% in oxygen. Each concentration was inhaled for about 1 h, each period being on a separate day. The effects of nitrous oxide were measured using a comprehensive battery of performance tests including measures of attention, psychomotor function, memory and cognition. Mood was assessed with visual analogue scales. All tests except critical flicker fusion showed substantial effects at the highest does (40%). No measure showed evidence of change at the lowest concentration (5%). Several measures showed significant impairment at 10%, viz: digit-symbol substitution, choice reaction time (latency and total), tapping, and continuous attention. Subjects felt dizzy and muzzy on nitrous oxide, but no significant effect was seen on the Alert-Drowsy VAS. The dose-response profiles of the various tests showed substantial differences. Thus tapping was virtually linear, while choice reaction motor time and body sway showed steeply accelerating impairment with increasing dose. These results indicate that comparisons of profiles of drug-induced change must take into account the variable effects of dose before interpretations in terms of specific drug effects can be made.

Administration, Inhalation↗
PubMed1992

Effects of nitrous oxide on psychological performance.

Thirty healthy volunteers took part in this double-blind crossover study comparing 15 percent nitrous oxide in oxygen with 100 percent oxygen. They received each treatment for 45 minutes, in counter-balanced order, with no break between treatments. Central nervous system (CNS) effects of nitrous oxide were assessed by a battery of performance tests and by the Visual Analog Scales. The Digit-symbol Substitution Test showed significant slowing with nitrous oxide as did Symbol-digit Substitution and Sentence Verification. Subjects rated themselves as more drowsy, dizzy, abnormal, drunk, and muzzy on nitrous oxide than on oxygen. Significant carryover effects were seen only for the Alert-Drowsy scale at 2.5 minutes after the start of treatment, and not at any later time point. These results show that the onset and offset of the CNS effects of 15 percent nitrous oxide are sufficiently rapid to permit the study of two treatment periods within a single experimental session.

Adult↗
PubMed1991

Effects of remoxipride on measures of psychological performance in healthy volunteers.

The acute psychomotor effects after oral doses of 30, 60 and 120 mg remoxipride, a new selective D2 receptor blocker, and placebo were investigated in a double-blind crossover study in 11 healthy male volunteers. Two out of the first three subjects given 120 mg remoxipride experienced marked akathisia, and therefore no subsequent subjects were given this dose. There were no other clearly drug-related adverse effects reported below 120 mg, although restlessness was reported at 60 mg. Remoxipride was associated with increases in error scores on a continuous attention task and on auditory vigilance, and with a reduction in critical flicker frequency, suggesting a decrease in arousal level. There were no significant changes in psychomotor measures such as choice reaction time, decision making time, or body sway. Subjective assessments using visual analogue scales showed a slight dose-related increase in drowsiness, while the calm-excited scale showed a small change in the excited direction with 30 mg only. The peak effects were at 4-6 h after drug intake, which was later than expected from previous pharmacokinetic data. These results indicate that remoxipride may have a slight depressant effect in the dose-range used. The pattern of changes is consistent with current theories on the role of dopamine in attention and arousal, and with the effects of other neuroleptics. It differs, however, from tranquilisers such as the benzodiazepines, which show a more global pattern of effects.

Adult↗
PubMed1991

Effects of i.v. lignocaine on psychological performance and subjective state in healthy volunteers.

In order to assess the effects of different doses of lignocaine on performance, nine healthy volunteers aged 21-34 yr received i.v. infusions of saline, low and high dose lignocaine (mean plasma concentrations 0.92 and 1.78 micrograms ml-1, respectively) in a double-blind randomized order. The Digit-Symbol Substitution Test (DSST) and Visual Analogue Scales (VAS) were performed repeatedly and a battery of performance tests once. The median (lower, upper quartile) number of correct responses for the DSST during the infusion period was: placebo 69 (67, 77); low 74 (71, 80); high 66 (61, 75) (P less than 0.001, General Linear Models; all pairwise comparisons P less than 0.05). None of the measures in the full battery showed any significant changes. VAS showed that subjects felt more interested (P less than 0.05), drowsy (P less than 0.01), dizzy, tense, abnormal, drunk and muzzy (P less than 0.001) with lignocaine than with placebo. These results confirm that lignocaine can produce acute performance effects (both improvements and impairments). Subjects were clearly aware of the presence of lignocaine, suggesting that subjective reports may be a useful indicator of its CNS effects.

Adult↗
PubMed1991

A comparison of the central nervous system effects of caffeine and theophylline in elderly subjects.

1. The effects of oral administration of 250 mg caffeine or theophylline and placebo on subjective ratings and psychological test performance were studied in a double-blind crossover experiment in 20 healthy elderly subjects. 2. Performance on the continuous attention task showed a significant improvement compared with placebo with both active treatments. Performance with caffeine was significantly better than with theophylline. Mean error index scores (normalised AUCs) were: placebo--0.130; caffeine--0.083; theophylline--0.093. No other objective measure shows significant treatment effects. 3. Subjective ratings showed that subjects felt significantly more alert on caffeine than on either theophylline or placebo. Subjects also rated themselves as more energetic and interested on caffeine than on placebo. 4. Plasma concentrations of caffeine were lower than those of theophylline (mean 5.76 and 8.72 mg l-1 respectively at 2 h post-drug. 5. These results suggest that caffeine is a more potent CNS stimulant than theophylline.

Aged↗
PubMed1990

A study of the psychometric effects of chlormethiazole in healthy young and elderly subjects.

The pharmacokinetics and effects of chlormethiazole (91 mg intravenously together with 356 mg orally) on psychomotor performance were studied in 10 young (mean age 29 years) and 10 older (mean age 66.2 years) volunteers using an open design. Chlormethiazole affected psychomotor function and decreased subjective arousal in both age groups. The peak effect was found at approximately 30 min, i.e. at the end of the infusion, and performance returned to normal by 3 h. There was no evidence of increased sensitivity of the older subjects to the psychomotor or subjective effects of chlormethiazole. The incidence and type of reported symptoms was also similar in the two age groups. The volume of distribution of chlormethiazole was greater in the old than in the young subjects as was the elimination half-life after intravenous administration. Other pharmacokinetic variables showed no significant differences between young and old subjects.

Administration, Oral↗