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Biomedical subjects

D Thorne

Publications and source records attributed to D Thorne.

14 recordsLinked to original sources
PubMed2003

Oculomotor impairment during chronic partial sleep deprivation.

OBJECTIVE: The effects of chronic partial sleep (sleep deprivation) and extended sleep (sleep augmentation) followed by recovery sleep on oculomotor function were evaluated in normal subjects to explore the usefulness of oculomotor assessment for alertness monitoring in fitness-for-duty testing. METHODS: Sixty-six commercial drivers (24-62 years, 50m/16f) participated in a 15 day study composed of 3 training days with 8h time in bed per night, 7 experimental days with subjects randomly assigned to either 3, 5, 7, or 9h time in bed, and 3 recovery nights with 8h time in bed. Data from 57 subjects were used. Saccadic velocity (SV), initial pupil diameter (IPD), latency to pupil constriction (CL), and amplitude of pupil constriction (CA) were assessed and correlated with the sleep latency test (SLT), the Stanford sleepiness scale (SSS), and simulated driving performance. RESULTS: Regression analyses showed that SV slowed significantly in the 3 and 5h groups, IPD decreased significantly in the 9h group, and CL increased significantly in the 3h group. SLT and SSS significantly correlated with SV, IPD, CL, and driving accidents for the 3h group, and with CL for the 5h group. Analyses also showed a significant negative correlation between decreasing SV and increasing driving accidents in the 3h group and a significant negative correlation between IPD and driving accidents for the 7h group. CONCLUSIONS: The results demonstrate a sensitivity primarily of SV to sleepiness, and a correlation of SV and IPD to impaired simulated driving performance, providing evidence for the potential utility of oculomotor indicators in the detection of excessive sleepiness and deterioration of complex motor performance with chronic partial sleep restriction. SIGNIFICANCE: This paper shows a relationship between sleep deprivation and oculomotor measures, and suggests a potential utility for oculometrics in assessing operational performance readiness under sleep restricted conditions.

Accidents, Traffic↗
PubMed2001

Intermediate care. Homeward bound.

Establishing a community acute and rehabilitation team for stroke patients has reduced the length of acute inpatient stay from 23 to eight days, without adversely affecting outcomes. The numbers of GPs referring directly to the community stroke team exceeded expectations (37 per cent of all referrals), avoiding accident and emergency admissions. Establishing good inter-agency agreements was crucial to the success of the project.

Continuity of Patient Care↗
PubMed2000

Neural basis of alertness and cognitive performance impairments during sleepiness. I. Effects of 24 h of sleep deprivation on waking human regional brain activity.

The negative effects of sleep deprivation on alertness and cognitive performance suggest decreases in brain activity and function, primarily in the thalamus, a subcortical structure involved in alertness and attention, and in the prefrontal cortex, a region subserving alertness, attention, and higher-order cognitive processes. To test this hypothesis, 17 normal subjects were scanned for quantifiable brain activity changes during 85 h of sleep deprivation using positron emission tomography (PET) and (18)Fluorine-2-deoxyglucose ((18)FDG), a marker for regional cerebral metabolic rate for glucose (CMRglu) and neuronal synaptic activity. Subjects were scanned prior to and at 24-h intervals during the sleep deprivation period, for a total of four scans per subject. During each 30 min (18)FDG uptake, subjects performed a sleep deprivation-sensitive Serial Addition/Subtraction task. Polysomnographic monitoring confirmed that subjects were awake. Twenty-four hours of sleep deprivation, reported here, resulted in a significant decrease in global CMRglu, and significant decreases in absolute regional CMRglu in several cortical and subcortical structures. No areas of the brain evidenced a significant increase in absolute regional CMRglu. Significant decreases in relative regional CMRglu, reflecting regional brain reductions greater than the global decrease, occurred predominantly in the thalamus and prefrontal and posterior parietal cortices. Alertness and cognitive performance declined in association with these brain deactivations. This study provides evidence that short-term sleep deprivation produces global decreases in brain activity, with larger reductions in activity in the distributed cortico-thalamic network mediating attention and higher-order cognitive processes, and is complementary to studies demonstrating deactivation of these cortical regions during NREM and REM sleep.

Adult↗
PubMed1999

A comparison of subcutaneous morphine and fentanyl in hospice cancer patients.

This study compares subcutaneous (s.c.) morphine and fentanyl with respect to pain control and side effects using a 6-day randomized, double-blind, cross-over design. Results were obtained from 23 patients (12 males and 11 females: mean age of 70.5 years) who could tolerate morphine. Thirteen patients were randomized to receive morphine for the first 3 days followed by fentanyl; 10 received fentanyl first followed by morphine. There were no significant differences in the scores for pain between the two drugs, suggesting that fentanyl is equally efficacious and the conversion ratio of morphine 10 mg: fentanyl 150 micrograms is appropriate. Patients had more frequent bowel movements during days 4-6 while on the fentanyl arm [t-test, df (22), P = 0.015]. Other measures for nausea, delirium, and cognitive function showed no differences between the two drugs. This study highlights the need to further assess the role of various opioids in hospice patients, and emphasizes the requirement for sensitive and simple cognitive tests in this population.

Aged↗
PubMed1996

Reusing disposables: same old story--more characters added.

In recent years health care professionals have become increasingly concerned with the economic issues of patient care. One of the most controversial issues is the practice of reprocessing items labeled "single use." Professionals in varied health care settings have different priorities to consider on the basis of their clinical responsibilities. This article explores resterilization and reuse considerations, including the use of manufacturers' written guidelines; legal and ethical issues of patient rights; health care providers' responsibilities with regard to informed consents, clinical trials, and testing of reprocessed items; and performing cost comparisons of reused versus single-use items, in both hospital and free-standing health care facilities.

Cost Control↗
PubMed1996

Dextromoramide pharmacokinetics following sublingual administration.

The extent of absorption and other pharmacokinetic parameters of dextromoramide following sublingual administration were assessed in five patients receiving chronic opioid analgesia. The use of the standard 5 mg tablet formulation was associated with negligible absorption in two patients, a prolonged time to peak concentration in the other three and substantial variability in clearance. The study concluded that the standard tablet formulation cannot be recommended for sublingual use where reliable, rapid onset analgesia is required.

Absorption↗
PubMed1995

Effective dose to patients due to fluoroscopic screening in barium meal examinations: comparison between free and restricted X-ray beams.

Four complete barium meal (BM) fluoroscopic examinations were digitised as sequences of 160 x 128 pixel, 8 bit images, at a rate of about 100 per min using a computer frame-grabber system and were recorded on disk for processing. The images were latter replayed and, using a suitable program, were superimposed in a new picture so that anatomic details coincided. At the same time, two more pictures were created by summing the radiation fields corresponding to the images grabbed, one with open diaphragms at 26 x 22 cm field size and one with simulated closed diaphragms at 7 x 11 cm. The average effective dose rate delivered to the patient during fluoroscopic screening was calculated for a hermaphrodite mathematical phantom and was found to be 0.21 mSv/min and 0.005 mSv/min, respectively, if either technique had been used exclusively. The average effective dose delivered to the patients with the actual techniques used in the 4 BM examinations recorded was 0.394 mSv. Data from these examinations was extrapolated to a sample group of 122 BM examinations, performed during a 9-week period, for which total exposure duration was known. The average effective dose calculated for fluoroscopy was shown to be negligible, particularly if only the 'closed' diaphragm technique was used, when compared to the estimated average effective dose of about 8.6 mSv delivered by the radiographs made during each examination.

Barium Sulfate↗
PubMed1995

The effects of L-dihydroxyphenylalanine on alertness and mood in alpha-methyl-para-tyrosine-treated healthy humans. Further evidence for the role of catecholamines in arousal and anxiety.

Treatment with alpha-methyl-para-tyrosine (AMPT), a catecholamine synthesis inhibitor, has been shown to produce pronounced increases in sleepiness and mild increases in negative mood and anxiety when administered to healthy male adults. The present study was conducted to ascertain whether these effects of AMPT are secondary to decreases in brain catecholamines or whether they represent nonspecific drug effects. Forty-one healthy males were randomized to one of four treatment groups. (1) Treatment with AMPT alone (AMPT/placebo); (2) treatment with AMPT plus L-dopa/carbidopa (AMPT plus L-dopa/carbidopa); (3) treatment with L-dopa/carbidopa alone (placebo plus L-dopa/carbidopa); or (4) treatment with placebo alone (placebo plus placebo). Repeated measures of alertness, mood, and anxiety were obtained over a three-day period of drug treatment and following drug discontinuation. As before, AMPT treatment led to increased sleepines. In addition, AMPT treatment led to decreased calmness, increased tension and anger, and a trend for increased depression. Replacement of catecholamine stores with L-dopa reversed the effects of AMPT and was associated with a more rapid recovery from AMPT's effects. These findings indicate that AMPT's effects on alertness and anxiety are catecholamine-specific. Further, they provide additional evidence that catecholamines are involved in the regulation of normal states of arousal, and they are consistent with the view that brain catecholaminergic dysregulation is involved in pathological anxiety states.

Adult↗
PubMed1993

Caffeine reversal of sleep deprivation effects on alertness and mood.

This study assessed the ability of high doses of caffeine to reverse changes in alertness and mood produced by prolonged sleep deprivation. Fifty healthy, nonsmoking males between the ages of 18 and 32 served as volunteers. Following 49 h without sleep, caffeine (0, 150, 300, or 600 mg/70 kg, PO) was administered in a double-blind fashion. Measures of alertness were obtained with sleep onset tests, the Stanford Sleepiness Scale (SSS), and Visual Analog Scales (VAS). Sleep deprivation decreased onset to sleep from a rested average of 19.9 min to 7 min. Following the highest dose of caffeine tested, sleep onset averaged just over 10 min; sleep onset for the placebo group averaged 5 min. Scores on the SSS increased from a rested mean of 1.6-4.8 after sleep deprivation. Caffeine reduced this score to near rested values. Caffeine reversed sleep deprivation-induced changes in three subscales of the POMS (vigor, fatigue, and confusion) and produced values close to fully rested conditions on several VAS. Serum caffeine concentrations peaked 90 min after ingestion and remained elevated for 12 h. This study showed that caffeine was able to produce significant alerting and long-lasting beneficial mood effects in individuals deprived of sleep for 48 h.

Adolescent↗
PubMed1989

The effects of d-amphetamine on arousal, cognition, and mood after prolonged total sleep deprivation.

Thirty-six normal male subjects underwent total sleep deprivation for 48 hours, were then administered either placebo, 5, 10, or 20 mg of d-amphetamine, and sleep deprived for an additional 12 hours. Sleep deprivation produced a significant reduction in sleep latency, as well as marked decrements in cognitive performance and self-ratings reflecting vigor and fatigue. Amphetamine reversed these effects in a dose-related way but the pattern and persistence of the reversal varied across measures. After 20 mg, sleep latency normalized for several hours, but then declined. Behavioral effects tended to follow the pattern of sleep latency. On cognitive tasks, 20 mg produced a sustained return to normal performance in an attentional arithmetic task and a gradual improvement in a verbal reasoning task. The partial temporal dissociation among sleep latency, behavioral, and cognitive effects suggests that varying doses of amphetamine may have time-related differential neurochemical effects or that various dimensions of arousal and alertness may be differentially sensitive to amphetamine.

Adult↗