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Biomedical subjects

T Simpson

Publications and source records attributed to T Simpson.

At least 19 recordsLinked to original sources
PubMed1996

Relationships among sleep dimensions and factors that impair sleep after cardiac surgery.

Factors associated with the attempted length, disturbance, effectiveness, and nap supplementation of sleep were analyzed in 97 patients recovering from cardiac surgery a few days before hospital discharge. Patients rated sleep for the prior night and factors that impaired their sleep after transfer from the critical care unit. The group averaged little sleep, with moderate disturbance and effectiveness and low nap supplementation. The disturbance, effectiveness, and attempted length of sleep were associated with an inability to perform their usual routine before sleep, inability to get comfortable, pain, noises, procedural care, and an unfamiliar bed. Patients encounter difficulties with sleep, even near discharge from the hospital. Interventions should be tested to mitigate specific factors that affect selected dimensions of sleep.

Adult↗
PubMed1996

Functional MRI of lateral occipitotemporal cortex during pursuit and motion perception.

We performed functional imaging with a conventional 1.5-T magnetic resonance scanner in 9 normal subjects. We used a gradient-echo technique to examine changes in signal between periods when subjects viewed a stationary black-and-white grating, a moving grating, and when they followed a moving spot. We located image pixels with significant differences between the viewing conditions. In 7 subjects, these occurred in the lateral occipitotemporal cortex, a region previously identified as a putative human homologue of the motion-sensitive middle temporal area (MT, or V5) of monkeys. Signal intensity was greater during pursuit of the moving dot than during viewing of the moving grating with the eyes still, despite the fact that the moving grating generated more retinal image motion. In contrast, signal intensity in striate cortex was least during pursuit of the moving dot. These findings suggest that the lateral occipitotemporal cortex has extraretinal signals during pursuit. Such signals may include attentional input, corollary eye movement information, or even a pursuit command. Extraretinal signals suggest that the lateral occipitotemporal cortex may contain a human homologue not only of MT but also of other components of the monkey V5 complex, such as the medial superior temporal area.

Adult↗
PubMed1996

Optical blur and the perception of global coherent motion in random dot cinematograms.

We evaluated the effect of +3.25 dioptres of optical blur on the discrimination of motion direction in random dot cinematograms. Dot displacement between frames varied from 2.1 to 63' of visual angle while the temporal interval was held constant. Optical blur worsened discrimination in three normal subjects at displacements below 16', but improved discrimination at displacements of 21' or more. In a second experiment, two subjects viewed equivalent velocity stimuli constructed with different combinations of temporal interval and spatial displacement. Results showed that the effect of blur was specific to displacement and not velocity. Furthermore, varying the dot density of the display showed that the effect of blur correlated with dot displacement and not the probability of dot mismatches. Since optical blur attenuates high spatial frequencies, this suggests that high spatial frequencies are important for motion perception when dot displacements are less than 16' to 21', but reduce motion perception at larger dot displacements. The use of random dot cinematograms in populations must take into account stimulus displacement and optical causes of reduced spatial acuity.

Contrast Sensitivity↗
PubMed1996

Role of endogenous renin-angiotensin system in c-fos activation and PKC-epsilon translocation in adult rat hearts.

Myocardial stretch and the renin-angiotensin system have been implicated in the development of cardiac hypertrophy through the activation of specific target genes. However, the relative importance of these putative hypertrophic stimuli has not been established in vivo. We used an isolated isovolumic heart preparation in which coronary perfusion pressure (CPP), left ventricular end-diastolic pressure, and pharmacological therapy can be independently manipulated to study this relationship. High CPP (140 cmH2O), which increased coronary flow (8.99 vs. 17.6 ml/min) and left ventricular systolic pressure (50 vs. 91 mmHg), increased steady state c-fos mRNA expression 2.3-fold (all P < 0.01 vs. low CPP). In contrast, increased left ventricular end-diastolic pressure (25 mmHg) and/or infusion of angiotensin II in the absence of increased CPP was not associated with an increase in c-fos mRNA expression. The change in c-fos gene expression seen with increased CPP was largely reversed by treatment with an angiotensin type 1 (AT1) receptor blocker. Hearts perfused at high CPP demonstrated increased translocation/activation of protein kinase C-epsilon relative to controls. None of the hearts studied were ischemic during perfusion. Thus, in the perfused adult rat heart, dynamic, but not static, stretch activates the early response gene, c-fos, and may involve the endogenous reninangiotensin system and protein kinase C.

Angiotensin II↗
PubMed1996

Patients' perceptions of environmental factors that disturb sleep after cardiac surgery.

BACKGROUND: Effective management of sleep disturbances after cardiac surgery requires insight into patients perceptions of which factors disturb sleep in the intensive care unit and after transfer from the intensive care unit. OBJECTIVE: To describe patients perceptions of environmental factors that disturbed sleep after cardiac surgery. SAMPLE: A convenience sample of 102 patients was surveyed in a 300-bed, acute-care teaching hospital. METHOD: Patients were interviewed several days before discharge from the hospital and rated the extent to which specific factors disturbed their sleep while in the intensive care unit and after transfer. RESULTS: The group mean for the extent of disturbance scores, averaged across all 35 environmental factors studied, was low during and after stay in the intensive care unit. However, selected items such as pain, and inability to get comfortable and perform a familiar nighttime routine, were moderately disturbing to many patients across phases of recovery. Patients varied widely in the number of factors, ranging from 0 to 33 factors, that disturbed sleep at least to some extent. Patients added factors that were not included in the original monitoring instrument. CONCLUSIONS: Patients attribute disturbed sleep to specific factors after cardiac surgery. The number of factors that disturb sleep varies among patients. Nurses can modify many of the factors that disturb sleep to promote an environment that will facilitate improved sleep, thereby enhancing the acute phase of recovery from cardiac surgery.

Aged↗
PubMed1996

Individual factors that influence sleep after cardiac surgery.

BACKGROUND: Up to 50% of patients who undergo cardiac surgery report problems with sleep after cardiac surgery. Knowledge about which individual factors are associated with sleep problems after cardiac surgery would help nurses identify patients who are at greater risk for sleep problems during hospitalization. OBJECTIVE: To compare patients perceptions of sleep before and during hospitalization for cardiac surgery and identify and analyze individual factors in relation to patients perceptions of sleep. METHOD: A sample of 102 patients who underwent elective or emergent cardiac surgery were studied at a 300-bed teaching hospital in the northwestern United States. A few days before their anticipated discharge from the hospital, consenting patients completed questions about their sleep before hospitalization and the night before their interview. RESULTS: Patients reported that they slept fewer hours in the hospital than at home. No differences were found in patients perceived depth and sufficiency of sleep, or refreshment before and after surgery. Patients who slept poorly at home did not report any worse sleep after surgery than patients who slept well at home. Women's perceptions about the sufficiency, refreshment, and quality of sleep were consistent before and after surgery, but no relationships were found among men's ratings. The length of sleep at home was positively related to the length of sleep after surgery in older patients. CONCLUSIONS: Sleep length is related to patients perceptions of sleep after cardiac surgery. Gender and age are also related to qualitative aspects of sleep before and after surgery and can be instrumental in an individualized assessment of sleep patterns anticipated after cardiac surgery.

Adult↗
PubMed1996

Implementation and evaluation of a liberalized visiting policy.

BACKGROUND: Visiting policies have been liberalized in ICUs, but the process and outcome of policy modifications have not been well described. OBJECTIVES: To describe the process by which nurses in one critical care unit modified visiting from a restricted to a liberalized (i.e., modified open) policy, and to evaluate the nurses' perceptions about visiting before and after the policy was liberalized. METHODS: A group of ICU/coronary care unit nurses met to discuss changes in their unit's visiting policy. Before the change was initiated, nurses (N = 36) in the unit were informally surveyed regarding their perceptions and attitudes about visiting. After a 3-month trial of liberalized visiting, in which visiting hours were increased at the discretion of the nursing staff, nurses (N = 32) were surveyed using a questionnaire about their beliefs, attitudes, level of satisfaction, and perceptions of their actual visiting policy. RESULTS: Nurses confirmed that the visiting policy had become liberalized, and they believed that liberalized visiting had positive effects on patients' emotional well-being. Nurses had more positive attitudes about the effects of liberalized visiting on families than on patients and unit function. Most nurses were satisfied with liberalized visiting. However, attitudes differed about how liberalized visiting affected patients' physiological responses or the unit function. CONCLUSIONS: Effective implementation of liberalized visiting depends on assessment of the following: nurses' beliefs, attitudes, and satisfaction about a change toward a more open visiting policy; staff involvement in determining the policy; and nurse manager and clinical nurse specialist support.

Attitude of Health Personnel↗
PubMed1995

Multiple sclerosis can cause visual processing deficits specific to texture-defined form.

We performed the following tests in 25 patients with multiple sclerosis (MS) and 25 age-matched control subjects: recognition of texture-defined (TD) letters; recognition of motion-defined (MD) letters; and recognition of luminance-defined (LD) letters of 96% and 11% contrasts. Six patients with normal visual acuity were abnormal on recognizing TD letters, of whom one gave normal results on all other tests. Eleven patients were abnormal on MD letter recognition, of whom four gave normal results on all other tests. Visual acuity for letters of 11% contrast were abnormally low in seven patients, of whom two gave normal results on all other tests. We conclude that the neural mechanisms underlying recognition of TD, MD, and low-contrast LD letters in subjects with normal visual acuity are sufficiently different that they can be differentially damaged by MS. Therefore, TD, MD, and LD letter tests provide complementary information. We suggest that the detection of TD letters can be disrupted by demyelination of long-range horizontal connections between orientation-tuned neurons in the striate cortex.

Adult↗
PubMed1993

Unreliability of platelet glucose-6-phosphatase for the diagnosis of glycogen storage disease type Ia.

The diagnosis of glycogen storage disease type Ia currently uses enzyme analysis of liver tissue. This requires liver biopsy in the at-risk neonate or fetus. Conflicting reports have appeared in the literature on the use of peripheral platelet glucose-6-phosphatase activity for the diagnosis of this disorder. We have applied a sensitive radiometric assay system to the measurement of glucose-6-phosphatase activity in peripheral platelets. Two families with affected members were analysed, revealing no differences in glucose-6-phosphatase activity as compared with control values. Platelet measurement of glucose-6-phosphatase does not appear to be useful for the diagnosis of glycogen storage disease type Ia.

Blood Platelets↗
PubMed1993

Visit preferences of middle-aged vs older critically ill patients.

OBJECTIVE: To differentiate between middle-aged and older adults' visiting preferences in critical care settings. DESIGN: Patients' preferences for visiting, perceptions of illness severity and extent of fatigue associated with visiting and an objective measurement of illness severity while in critical care were surveyed within 3 days after transfer from the critical care unit. SETTING: Interviews occurred on the transitional care units with patients who transferred from either the coronary care or surgical intensive care units in a large Northeast teaching hospital. PATIENTS: Fifty-three middle-aged (35 through 65 years) and 46 older (over 65 years) patients were surveyed (N = 99). RESULTS: Both middle-aged and older patients consistently wanted to limit the number of visitors to two or three persons per visit. Compared with middle-aged patients, a greater proportion of older patients preferred to limit visits to once a day and wanted the visit length to be unlimited. A greater proportion of older coronary care unit patients preferred to limit visits to two times a day than older surgical unit patients. CONCLUSIONS: Middle-aged and older patients differed in their preferences for visits, with sufficient variation in responses to warrant tailoring visits to the unique preferences of patients based on age and clinical setting.

Adult↗
PubMed1992

Surgical treatment of ductal carcinoma in situ of the breast. 10- to 20-year follow-up.

Between 1967 and 1977, 36 patients received treatment at the Virginia Mason Medical Center in Seattle, Wash, for ductal carcinoma in situ of the breast. Twenty-five patients had modified radical mastectomies, 10 had radical mastectomies, and one had a simple mastectomy. Twenty-seven patients have been followed up for at least 10 years and are without known recurrence (mean follow-up, 17.7 years; range, 8 to 24 years), eight patients died without known recurrence (mean follow-up, 10.6 years; range, 6 to 14 years), and one patient with a prior contralateral mastectomy for infiltrating cancer of the breast had a recurrence in the scalene nodes on the side of the infiltrating cancer and died of metastatic cancer. No patients with ductal carcinoma in situ had local recurrences in the ipsilateral breast or chest wall, and no patients developed cancers in the contralateral breast; one patient had axillary metastasis. Twenty-eight (78%) of 36 patients had multicentric ductal carcinoma in situ in their mastectomy specimens. Twenty-three (88%) of 26 patients with comedocarcinoma-type ductal carcinoma in situ had multicentric lesions. Conversely, patients with low-grade nuclear papillary ductal carcinoma in situ did not have multicentric lesions. Five (14%) of 36 patients had incidental microinvasion discovered in the mastectomy specimens; all had comedocarcinoma. In summary, our study of patients with ductal carcinoma in situ revealed that (1) mastectomy provided excellent local and systemic control; (2) cancer in the contralateral breast was infrequent; (3) axillary metastasis was rare; and (4) histologic features of tumors markedly affected the frequency of multicentricity and chance for microinvasion.

Breast Neoplasms↗
PubMed1992

Monocular acuity in the presence and absence of fusion.

Because little is known about monocular acuity during binocular fusion, acuity of the right eye was measured in binocularly normal subjects, with the fellow eye open or fully occluded. The target was flashed for 65 ms or presented sinusoidally for 1 s. Subjects had both eyes optimally focused, or the right eye defocused by +3.00 D. Monocular acuities were equivalent during fusion or occlusion when both eyes were optimally focused. Acuity of the defocused eye was reduced when the fellow eye was open compared to when it was occluded. Suppression of the blur, therefore, produced a measurable reduction in recognition thresholds. As monocular acuity was not measurably affected by the fellow eye when each eye was in focus, the finding that monocular vision is improved with the fellow eye occluded should be ascribed to something other than suppression or more sensitive spatial measures of the suppression should be obtained.

Humans↗
PubMed1992

The effects of epidural versus parenteral opioid analgesia on postoperative pain and pulmonary function in adults who have undergone thoracic and abdominal surgery: a critique of research.

Studies comparing epidural and parenteral opioid analgesia for patients experiencing thoracic or abdominal surgery are analyzed with respect to differences in postoperative pain and pulmonary function. Although most studies suggest that epidural analgesia is superior for postoperative pain relief, few clearly demonstrate an improvement in pulmonary function attributable to epidural analgesia. Recommendations for future research are proposed to improve the design, measurement, analysis, and reporting of studies. Research relevant to the nursing care of patients receiving epidural analgesia is suggested.

Abdomen↗
PubMed1991

The family as a source of support for the critically ill adult.

A conceptual framework of supportive family functions derived from a previous analysis of taped visits to coronary care unit (CCU) patients was used to analyze CCU and surgical intensive care unit (SICU) patients' recollections about visits. The framework of family functions was supported by the patients' recollections. However, CCU patients recall behaviors in a different order of frequency than previously described with visit transcript analysis. Both CCU and SICU patients frequently recall caring actions of the family and evaluated visits overall as helpful. Principles are proposed for nurses in assisting families and patients to cope with the critical illness episode and thus provide a supportive visiting environment for patients.

Adaptation, Psychological↗
PubMed1991

A comparison of hypertensive and nonhypertensive coronary care patients' cardiovascular responses to visitors.

Patients with and without hypertension in a coronary care unit (n = 24) were compared with respect to cardiovascular responses to both a family visit and an interview by an investigator. Variables for each of the four cardiovascular indicators (systolic blood pressure, diastolic blood pressure, heart rate, and premature ventricular contractions) included the value before, the highest value during, the lowest value during, and the value after each social interaction condition. The highest group means for systolic blood pressure and heart rate were significantly higher for patients with hypertension than for patients without hypertension under both the interview and visit conditions. Differences in cardiovascular responses were not significantly greater for family visits than for interviews for patients with hypertension compared with those without hypertension. Thus, although hypertensive patients had greater cardiovascular reactivity to both social interaction conditions than nonhypertensive patients in the coronary care unit, family visits were no more physiologically stressful than a comparative interaction condition.

Adult↗