Search PubMed⌕ Search

Biomedical subjects

R S Wilson

Publications and source records attributed to R S Wilson.

At least 109 records · Page 6Linked to original sources
PubMed1995

Epidemiology of injury in people with Alzheimer's disease.

BACKGROUND: Previous studies have suggested that the risk of injury is elevated among persons with dementia, but these studies have focused primarily on falls and fractures. This study characterizes all injuries incurred in a large sample of community-dwelling persons with a specific form of dementia, Alzheimer's disease (AD). SUBJECTS AND METHODS: The sample consisted of 281 community-dwelling persons diagnosed with AD according to NINCDS/ADRDA guidelines. Information regarding all injuries occurring within the previous 6 months was obtained through a structured interview of a caregiver. RESULTS: The rate of injuries was 58.4 per 100 persons per year. Although falling was the single most common mechanism by which injuries occurred, it accounted for only 43.8% of all injuries. Fractures accounted for 13.7% of injuries. Medical treatment was sought for 52.1% of the injuries. After adjustment for age and gender, the likelihood of injury was significantly associated with cognitive impairment and with ADL limitation, but the independent contribution of these two factors could not be assessed. CONCLUSIONS: The findings suggest that injuries are a significant problem in persons with AD.

Activities of Daily Living↗
PubMed1995

Cardiorespiratory effects of volume- and pressure-controlled ventilation at various I/E ratios in an acute lung injury model.

Numerous approaches to the provision of mechanical ventilation during acute lung injury are currently available. Of these, pressure control inverse ratio ventilation has been considered superior to volume control ventilation with PEEP with respect to improving gas exchange and minimizing cardiovascular compromise. However, no study systematically compares volume-controlled (VC) and pressure-controlled (PC) ventilation while maintaining mean airway pressure (MAP) constant at varying I/E ratios. We studied the effect of VC and PC with PEEP at normal (1:2) and inverse I/E ratios (2:1 and 4:1) on gas exchange, lung mechanics, and hemodynamics in a sheep lung injury model. Severe lung injury was induced in 12 sheep with bilateral lung lavages using normal saline; prelavage PO2 230 +/- 50 mm Hg, PEEP 5 cm H2O and postlavage, pretreatment PO2 70 +/- 20 mm Hg, PEEP 10 cm H2O, both at FIO2 0.50. MAP was kept constant throughout the study at 25 +/- 2 cm H2O while ventilating all animals with a VT of 10 ml/kg and a rate of 20/min by randomized application of VC and PC with I/E ratios of 1:2, 2:1, and 4:1. Despite liberal fluid administration, all ventilatory modes depressed cardiac output compared with preinjury values. However, gas exchange and hemodynamics did not differ among ventilation modes or I/E ratios.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Clinical and echocardiographic correlates of symptomatic tachydysrhythmias after noncardiac thoracic surgery.

BACKGROUND: Supraventricular tachydysrhythmias (SVTs) following thoracic surgery occur with significant frequency and may be associated with increased morbidity. Prospective data on the etiology and importance of these dysrhythmias are sparse. METHODS: In 100 patients undergoing pulmonary resection without history of atrial dysrhythmias or previous thoracic surgery, we examined the effects of predefined risk factors by history, pulmonary function, and echocardiography on the incidence of postoperative SVT. Serial echocardiograms were performed preoperatively, on postoperative day 1, and again between postoperative days 2 to 6 (median = 3) to evaluate cardiovascular function and to estimate right ventricular systolic pressure (RVSP) by the tricuspid regurgitation jet (TRJ) Doppler velocity method. RESULTS: Symptomatic postoperative SVT occurred in 18 (18%) of the 100 patients studied at a median of 3 days after surgery and was disabling in 12 of 18 (67%). Digoxin loading was ineffective in controlling the ventricular response in 16 of 17 episodes. In the patients developing SVT, postoperative echocardiography revealed significant elevation of TRJ Doppler velocity (2.7 +/- 0.6 m/s vs 2.3 +/- 0.6 m/s, p < 0.05) but not right atrial or ventricular enlargement or right atrial pressure increase when compared with patients without SVT. Independent correlates of SVT determined in a stepwise logistic regression included intraoperative blood loss > or = 1 L (p = 0.0001) and a postoperative TRJ Doppler velocity > or = 2.7 m/s (p < 0.05). Patients who developed SVT had a higher rate of intensive care unit admission (p < 0.004), a longer hospital stay (p < 0.02), and higher 30-day mortality (p < 0.02). CONCLUSIONS: These prospective data suggest that increased right heart pressure but not fluid overload or right heart enlargement predisposes to clinically significant SVT after pulmonary resection. SVT may be an important marker of poor cardiopulmonary reserve in patients who develop significant morbidity after thoracic surgery. Early interventions to reduce right heart pressure may decrease the incidence of postoperative SVT and potentially improve overall surgical outcomes.

Aged↗
PubMed1994

Superiority of aztreonam/clindamycin compared with gentamicin/clindamycin in patients with penetrating abdominal trauma.

There were 73 evaluable patients entered into a prospective, double-blinded trial comparing aztreonam/clindamycin (A/C) to gentamicin/clindamycin (G/C) for the prevention of infection after penetrating abdominal trauma. Aztreonam was administered at a dosage of 2 g every 8 hours and gentamicin at 5 mg/kg for the first 24 hours and then adjusted by serum monitoring to a peak of 6 to 8 micrograms/mL and a trough of less than 2 micrograms/mL; all patients received 900 mg of clindamycin every 8 hours. Patients with colon wounds received 4 days of antibiotics, and the remaining patients received a 24-hour course. Gunshot wounds occurred in 69% of patients: 74% of all patients had some hollow viscus injury, and 26% had only solid viscus injury. The groups were well matched according to abdominal trauma index, percentage with colon injury, and transfusion requirements. Failures occurred in eight patients (11%): two wound infections, five intra-abdominal infections, and one case of necrotizing fasciitis. Seven infections occurred in 36 (19%) G/C patients compared with 1 in 37 (3%) A/C patients (p < 0.03). The hospital stay was 12 +/- 11 days for G/C patients and 8 +/- 7 for A/C patients (p < 0.12). The superiority of the A/C regimen may be partially attributable to relative underdosing of gentamicin (approximately half of the patients had inadequate levels after 24 hours) combined with a favorable pharmacokinetic profile (significantly prolonged half-life) of aztreonam in this clinical setting.

Abdominal Injuries↗
PubMed1994

Intact text-specific implicit memory in patients with Alzheimer's disease.

The ability of patients with Alzheimer's disease (AD) to acquire and retain text-specific knowledge was investigated in a re-reading study. Patients and normal control Ss read 2 passages 3 times, each as quickly as possible, and answered recognition memory questions after the 3rd reading of each passage. The AD patients had poor explicit memory as evidenced by impaired recognition memory for the passages. In contrast, normal decreases in the times required for successive readings of each passage for AD patients indicated intact implicit memory for the passages. The absence of facilitation across passages indicated that the re-reading effect was text specific, suggesting that AD patients may retain the ability to form certain kinds of implicit new associations. Alternative accounts of the mechanism underlying text-specific priming, and of the nature of intact and impaired implicit memory in AD, are considered.

Aged↗
PubMed1994

Comparison of dementia criteria: sensitivity and specificity testing among African American patients.

We compared the sensitivity and specificity of recently proposed general dementia, vascular dementia, and Alzheimer's disease criteria using the DSM III-R as the 'gold standard' among 61 elderly African American patients. There were 10 patients with vascular dementia, 20 with Alzheimer's disease and 31 controls. Comparison of the sensitivity and specificity of the various criteria showed that with few exceptions, the results were similar. Additional studies of this kind among different populations, and among mild dementia patients, are needed to cross-validate the results.

Activities of Daily Living↗
PubMed1993

Comparison of thoracic and lumbar epidural infusions of bupivacaine and fentanyl for post-thoracotomy analgesia.

Epidural analgesia, via either a thoracic or lumbar route, is commonly used to provide postoperative analgesia following thoracotomy for pulmonary resection, but little data indicate which location is better in terms of postoperative analgesia, side effects, or associated complications. In this study, 45 patients, who were scheduled to have epidural analgesia and undergo a lateral thoracotomy, were randomized to receive either a thoracic or a lumbar catheter. Pain assessments and routine clinical data were recorded to determine if either thoracic or lumbar epidural catheters provided superior analgesia, fewer side effects, or fewer complications. This study found no statistical difference in pain relief or side effects between lumbar and thoracic epidural analgesia for post-thoracotomy pain. An increased infusion rate (6.4 +/- 1.9 v 5.1 +/- 1.4 mL/h, P = 0.02) was required in the lumbar group to achieve equivalent analgesic levels.

Adult↗
PubMed1993

Intimal sarcoma of the superior vena cava.

A case of superior vena cava syndrome caused by a primary intimal sarcoma of the superior vena cava is described. The known causes of superior vena caval obstruction are discussed, together with the difficulties in identifying the underlying lesion. The possibility of a primary superior vena caval neoplasm as a cause of superior vena caval obstruction should be considered in patients presenting with superior vena caval syndrome.

Cerebral Hemorrhage↗
PubMed1992

Clinical correlates of high signal lesions on magnetic resonance imaging in Alzheimer's disease.

The pathophysiology and clinical significance of high signal lesions, visualized on magnetic resonance imaging (MRI) in patients with Alzheimer's disease (AD), remain controversial. Since they are known to correlate with vascular disease and vascular risk factors, we reviewed the clinical correlates of periventricular high signal (PVH) and subcortical white matter lesions (WML) in a sample of 106 patients with probable AD, excluding persons with treated vascular risk factors or symptomatic cerebrovascular and cardiovascular disease. Grade 2 PVH were seen in 26 (25%) and scattered WML were identified in 29 (18%). PHV were associated with advancing age and gait disturbance. WML were associated with gait disturbance and incontinence. Neither radiologic finding was related to dementia severity. The findings suggest that these lesions are common in patients with AD even when those with evidence of cerebrovascular disease are excluded; their presence, therefore, should not preclude a diagnosis of AD. Additionally, the data suggest that HSL on MRI may be one of many risk factors associated with functional disability in persons with probable AD.

Aged↗
PubMed1992

Ideational fluency in Parkinson's disease.

Recent research on Parkinson's disease (PD) suggests that executive functions are impaired but that visuospatial functions may be spared. This dissociation has been attributed to dysfunction in ascending dopaminergic pathways affecting the prefrontal cortex. We investigated these ideas in a sample of intellectually intact patients with idiopathic, optimally treated PD (N = 20) and in spouse controls (N = 15); the groups were divided into young (age < 60) and old subgroups, each comparable on education, vocabulary level, and Mini-Mental State scores. Six tasks were selected from a set of factor-referenced cognitive tests to measure three abilities: (1) ideational fluency (ability to generate ideas), (2) flexibility of use (ability to shift mental set), and (3) spatial orientation (ability to perceive spatial patterns). PD patients were impaired only on the ideational fluency factor (p = .01). An age-related deficit was seen on the spatial factor (p < .05) with a trend on the flexibility factor (.05 < p < .10). No interactions were significant. The findings suggest that when age and verbal intelligence are controlled, PD patients show no deficit on purely spatial tasks; in contrast, patients seem less able to generate ideas though capable of shifting from one idea to another.

Brain Mapping↗
PubMed1992

Ondansetron does not affect alfentanil-induced ventilatory depression or sedation.

Ondansetron is a selective 5-hydroxytryptamine type 3 receptor antagonist effective as an antiemetic in patients experiencing post-operative or cancer chemotherapy-induced nausea and vomiting. Currently, no information is available regarding the interaction of ondansetron with opioids, although a serotonin antagonist might be expected to modify some opioid actions. This study was designed to measure the effects of ondansetron on alfentanil-induced ventilatory depression and sedation in healthy male volunteers. Ventilatory drive (measured as the end-tidal CO2 necessary to produce a minute ventilation of 15 l/min) was determined in 29 subjects using a modification of the Read rebreathing technique. Sedation was measured by asking the subjects to complete visual analog scales. Alfentanil was administered as a bolus (5 micrograms/kg) followed by a continuous infusion (0.25-0.75 micrograms.kg-1.min-1) for at least 90 min. Study medication (ondansetron 8 or 16 mg or vehicle placebo) was then administered in a randomized, double-blind manner, and the alfentanil was infused for an additional 15 min. Measurements of ventilatory drive and sedation were made at baseline, during alfentanil infusion, after study medication, and at 30-min intervals after alfentanil was discontinued. Alfentanil produced significant ventilatory depression (P less than 0.001) and sedation (P less than 0.001) in all three groups. Neither placebo nor ondansetron produced further change in the intensity of either alfentanil effect. After discontinuation of the opioid, both ventilatory depression and sedation decreased, and the rate of recovery was not significantly different between groups. The data indicate that alfentanil-induced sedation and ventilatory depression are not significantly affected by the subsequent administration of ondansetron.

Alfentanil↗
PubMed1991

Episodic and semantic memory in early versus late onset Alzheimer's disease.

The aim of this study was to replicate and extend previous work demonstrating selective impairment of semantic, but not episodic, memory in late versus early onset Alzheimer's disease (AD). Measures of episodic and semantic memory were administered to 12 pairs of patients; early (less than or equal to 62) and late (greater than or equal to 68) onset pairs were matched on dementia severity and education. As hypothesized, the groups did not differ on the three episodic memory measures but did on two of three semantic memory measures. In conjunction with prior research, these findings indicate that late onset AD is characterized by more profound impairment on measures of semantic processing.

Age Factors↗
PubMed1991

Maze learning in Alzheimer's disease.

Alzheimer's disease (AD) patients and normal elderly controls performed a block of 10 trials on a finger maze, followed by a 45-min period during which verbal learning measures were administered. Subjects then performed an additional 10 trials on the original maze, followed by 10 trials on a new maze. The AD patients and a subset of control subjects decreased mean completion time across Blocks 1 and 2, suggesting skill acquisition. Mean time on Block 3 was significantly less than mean time on Block 1, suggesting skill generalization. A subset of controls did not show the above pattern. The results of this study suggest that AD patients are able to acquire and generalize a cognitively mediated perceptual-motor skill.

Aged↗
PubMed1991

Nuisance parameters in the assessment of noncognitive manifestations of dementia.

Measures of noncognitive disturbances in dementia typically rely on ratings by informants. In this study, method variance in measures of affect, behavior, and functional competence was evaluated by comparing ratings from 2 types of informants (spouse vs. child) in patients with probable Alzheimer's disease. No differences were observed on 5 variables; for 2 measures of behavior disturbance and 1 measure of functional disability, ratings obtained from child informants were significantly higher than spouse ratings for patients at comparable levels of dementia severity. Although the effect of the rater dimension was relatively small and selective, the findings suggest the need for further research on potential sources of bias in the ratings of noncognitive features of the dementia syndrome.

Activities of Daily Living↗
PubMed1991

Predictors of behavioral disturbance in Alzheimer's disease.

The relationship of behavioral disturbances in Alzheimer's disease to disease severity, age at onset, and the presence of extrapyramidal signs was investigated in three studies. Five categories of behavior disturbance were ascertained through structured interview with the patient's primary caregiver: apathy, agitation, psychotic symptoms, disinhibition, and irritability. In Study 1, measures of disease severity accounted for 42% of the variance in the Apathy scale but less than 20% of the variance in the remaining scales. In Study 2, the presence of extrapyramidal signs was associated with increased Apathy and moderated the association between disease severity and the Psychotic Symptoms and Irritability scales. In Study 3, age at onset was associated with the Agitation scale and moderated the association between disease severity and the Apathy, Psychotic Symptoms, and Irritability scales. The findings are discussed in terms of the clinical heterogeneity within Alzheimer's disease, the possible biological bases of these behavioral disturbances, and the psychometric issues pertinent to their measurement.

Age Factors↗
PubMed1991

Hallucinations and associated factors in Alzheimer's disease.

In a consecutive sample of 230 community-dwelling patients with probable Alzheimer's disease, a structured interview yielded evidence of current hallucinations in 29.1% and misperceptions in another 11.3%. Visual and auditory modalities were similarly represented in apparent hallucinations. Hallucinations prior to the current monitoring period were rare among patients with misperceptions or with no perceptual abnormality. The probability of hallucinations was associated with the severity of cognitive dysfunction, the degree of other behavioral disturbances, and the presence of extrapyramidal signs. A logistic regression model predicting hallucinations based on these diverse clinical features accurately classified 87.0% of the sample.

Activities of Daily Living↗