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Biomedical subjects

S M Finkelstein

Publications and source records attributed to S M Finkelstein.

At least 37 records · Page 2Linked to original sources
PubMed1992

First- and third-order models for determining arterial compliance.

BACKGROUND: Engineering models of the arterial vasculature have been used to describe vascular properties of resistance and compliance. These approaches have used either Fourier frequency analysis, based on transmission line equations, or time domain analysis of the circuit equations describing modified Windkessel models of the vasculature. DESIGN: A third-order, four-element modified Windkessel model can reproduce arterial pressure waveforms, including both exponential and oscillatory pressure decays observed during the diastolic portion of the cardiac cycle. METHOD: A method to determine both capacitive and oscillatory compliance of the arterial vasculature was developed, and the effect of these compliance properties on the blood pressure waveform was examined.

Arteries↗
PubMed1992

Abnormalities of vascular compliance in hypertension, aging and heart failure.

AIM: Diastolic arterial pulse wave analysis and a modified Windkessel model were used to evaluate the vascular response to hypertension, heart failure and aging. RESULTS: Compared to age-matched normal subjects, arterial compliance was reduced in patients with hypertension and heart failure, particularly in the vessels that contribute to resonances or oscillations in the pulse wave. In elderly subjects, the capacitive function of the arteries and compliance of the smaller arteries that contribute to oscillations were both reduced. CONCLUSION: These small-vessel structural or functional abnormalities may serve as a marker for disease and for the response to therapy.

Aging↗
PubMed1991

Reduced vascular compliance as a marker for essential hypertension.

In 38 patients with established essential hypertension and 32 age-matched normotensive control subjects proximal and distal arterial compliance were determined by computer-based assessment of the diastolic decay of a brachial arterial tracing and a modified Windkessel model of the circulation. In the hypertensive subjects compared to the normotensive subjects mean arterial pressure was 25% higher (P less than .001), systemic vascular resistance 23% higher (P less than .01), proximal compliance 19% lower (P less than .01), and distal compliance 72% lower (P less than .001). The reduction in distal compliance was highly age-dependent. In the youngest age range (45 to 54 years) little overlap appeared between hypertensive and normotensive groups, whereas in the oldest subjects studied (65 to 75 years) distal compliance was comparably low in the two groups. Thus, distal vascular compliance provides a sensitive and specific marker for the abnormal vasculature associated with hypertension and may be particularly useful in identifying the disease in young individuals with borderline blood pressure.

Aged↗
PubMed1989

Monitor: an expert system that validates and interprets time-dependent partial data based on a cystic fibrosis home monitoring program.

The use of health diaries to monitor patients with chronic diseases has often been complicated by difficulties encountered in data quality assurance and interpretation. An expert system, Monitor, has been developed to predict the health status of cystic fibrosis patients based on daily home measurements of pulse, respiratory rate, weight, inspired vital capacity, and a check list of symptoms of acute illness. This system ensures data reliability beyond what can be achieved in most current automatic error detection procedures by validating inputs against patient-specific expectations. Its explicit representation of the time dimension and the hierarchical structure of its knowledge base facilitate the abstraction of trends and relationships among the time-dependent data. Dynamically imposed expectations also lend flexibility to the interpretation process by allowing the processing of partial (incomplete) data. Monitor correctly classified 86 percent (three-category classification) and 94 percent (two-category classification) of 111 cases. This demonstrates that expert systems can be a feasible approach in building more robust diary monitoring systems.

Cystic Fibrosis↗
PubMed1988

A medical information relational database system (MIRDS).

A medical information relational database system (MIRDS) which is resident on a relational database machine and is accessed via microcomputers has been created for a pediatric pulmonary division of a research hospital. The power and flexibility of MIRDS has permitted the integration of clinical tasks, research interests, and laboratory functions. Procedures have been devised to assure data integrity, allow flexibility in data retrievals, produce standardized report formats, and permit data access for users with a wide range of query expertise. There are few impediments to the integration of additional clinical, research, and laboratory functions as the system evolves.

Child↗
PubMed1988

A rule for the early detection of chronic changes in cystic fibrosis patient status.

A statistical decision-making system has been developed which will predict the clinical status of a patient with cystic fibrosis based on daily self measurements obtained at home. The data for the study were collected from CF patients within 7-12 years of age. Thirty-two participants recorded four daily measurements (weight, vital capacity, breathing rate, and resting pulse) and one weekly measurement (height). In addition to the 4 daily measured values, the clinical status of each patient at his/her most recent previous clinic visit was used as a predictor variable. The measured values were used as the basis for the development of a discriminant rule. The goal of the rule was to determine whether each patient's clinical status was deteriorating, stable, or improving at the time of the most recent set of weekly measurements. Three types of analysis were performed: linear discriminant analysis, quadratic discriminant analysis, and nearest neighbor. Quadratic discriminant analysis provided the best discrimination due to the differences in the covariance matrices among the populations. The rule was able to correctly classify 77% of the 103 cases in the learning set. To further evaluate the rule, both a weighted classification percentage and weighted kappa statistic were calculated for the rule. Bootstrapping was used to predict the performance of the rule on the population with results of 77% correctly classified overall.

Body Weight↗
PubMed1988

Diabetes mellitus associated with cystic fibrosis.

The prevalence of overt diabetes mellitus and carbohydrate intolerance was studied in 448 patients with cystic fibrosis (CF). Insulin-dependent diabetes (IDDM) developed in 7.6% of patients (13 male and 21 female). Survival was significantly lower (P less than 0.01) in the IDDM-CF group, with fewer than 25% surviving to age 30 years, whereas nearly 60% of the nondiabetic CF population reached this age. A significant deterioration in CF clinical status, based on NIH score, became apparent 2 years before onset of overt IDDM (P less than 0.05 at 2 years prior, P less than 0.01 at IDDM diagnosis). Total glycosylated hemoglobin (HbA1) was significantly (P less than 0.001) higher for the total CF population (7.3% +/- 1.2%) than for the general non-CF population (6.5% +/- 0.7%), and in the IDDM-CF group (P less than 0.05) compared with normoglycemic CF control patients. Female patients had a higher mean HbA1 after 12 years of age than their male counterparts did (P less than 0.02). HBA1 did not predict the development of IDDM, but there was a weak inverse relationship between HbA1 and both NIH clinical score (r = -0.41, P less than 0.02) and standard pulmonary function tests (forced vital capacity, r = -0.25, P less than 0.01) in the general CF population. Therefore, impaired carbohydrate tolerance in CF is associated with progressive clinical deterioration.

Adolescent↗
PubMed1988

Arterial vascular compliance response to vasodilators by Fourier and pulse contour analysis.

Vasodilator drugs are widely used in the management of cardiovascular disease. They decrease systemic vascular resistance, but they also may influence vascular arterial compliance. This study evaluated the effects of three vasodilators--nitroprusside, nitroglycerin, and hydralazine--on vascular compliance using impedance parameters determined by pulse contour and Fourier analyses. The open chest study was performed on anesthetized dogs. Mean arterial pressure decreased by a minimum of 20% after vasodilator intervention. The decrease in systemic vascular resistance was significant (p less than 0.01) only after hydralazine treatment. Proximal compliance increased after administration of all drugs, but the increase was not statistically significant. Distal compliance determined by pulse contour analysis increased by 60 to 120% after all three drug treatments (p less than 0.05 for nitroprusside, p less than 0.02 for nitroglycerin and hydralazine). Characteristic impedance from Fourier analysis responded variably, and changes were not statistically significant. The sensitivity of changes in distal compliance as a marker for the vascular effect of these drugs suggests that it might be used as a more reliable guide than blood pressure or vascular resistance in monitoring clinical response to such intervention. The more traditional measure of characteristic impedance provides a vascular measurement that is less sensitive than distal compliance to the effects of these vasodilator drugs.

Animals↗
PubMed1988

A home-based pulmonary function monitor for cystic fibrosis.

As care for the chronically ill makes increasing demands upon our medical system, cost-effective methods for addressing those demands are being sought. The use of self-monitoring coupled with telecommunication of results to the health-care provider can be expected to provide a partial solution in the appropriate clinical setting. An electronic spirometer with telecommunication ability for use by cystic fibrosis patients in the home has been developed.

Analog-Digital Conversion↗
PubMed1988

Implementation of a home-based program for early detection of clinical deterioration in cystic fibrosis.

A statistical decision-making system, based on daily self measurements obtained at home, has been developed that will predict the clinical status of a patient with cystic fibrosis (CF). The data for the study were collected from patients randomly selected from those served by the University of Minnesota CF Center. Participants recorded four daily measurements (weight, vital capacity, breathing rate, and resting pulse) and one weekly measurement (height) and returned completed diaries to the coordinating center each week. The goal of the rule was to determine whether each patient's clinical status was deteriorating, remaining stable, or improving at the time of the most recent set of weekly measurements. This early detection and intervention criterion (EDIC) is being used in the clinical setting to aid in the management of patients with cystic fibrosis. The computer hardware and software, particularly the relational database, have provided an efficient basis for the continued use of EDIC.

Adolescent↗
PubMed1986

Feasibility and compliance studies of a home measurement monitoring program for cystic fibrosis.

A home measurement monitoring system has been developed for assessing progress and planning changes in care for patients with cystic fibrosis. Daily diary recording of specified measurements, quantitative symptom data, and free text are to be used for early detection of deteriorating trends before serious complications develop. Daily measurements made at home are lung capacity, body weight, breathing rate, and pulse. The program has been in place for the past two years, and has maintained a 75-80% consistent diary response rate among the 111 patients initially committed to the program. Measurements are easy to perform, equipment design is simple and rugged, and data handling routines designed for the program using the INSIGHT clinical data base system perform satisfactorily. Checking for data entry errors and validity checks of home measurements are a regular part of the data handling activity. Patient acceptance and long-term compliance in this program agrees very favorably with reports of other diary programs in chronic disease. Diary compliance was significantly greater among younger patients and those who lived long distances from the hospital. This study has demonstrated that home monitoring is a feasible program for patients with cystic fibrosis. It presents the possibility of detecting adverse health trends earlier than is now practical, so that patients can be treated before serious complications develop, thereby preventing the large fluctuations in health status that often accompany CF.

Adolescent↗
PubMed1985

Vascular hemodynamic impedance in congestive heart failure.

The objective of this study was to determine whether pulse-contour analysis could provide a measure of the differences in peripheral vascular state between patients with congestive heart failure (CHF) and healthy persons. Vascular hemodynamic impedance parameters were determined from brachial artery pressure waveforms recorded in 14 patients with CHF, aged 20 to 55 years (mean 36 +/- 12) and in 7 healthy control subjects, aged 22 to 55 years (mean 33 +/- 12). Cardiac output, heart sounds and electrocardiogram were also monitored. Cardiac output was 32% lower (p less than 0.01) and heart rate was 43% higher (p less than 0.001) in the CHF group than in the control group. The mean arterial pressure did not differ between groups. Systemic vascular resistance was 47% higher (p less than 0.05) and distal vascular compliance 73% lower (p less than 0.001) in the CHF group than in control group. Proximal vascular compliance was unchanged. These studies suggest that distal compliance assessed from pulse-contour analysis is a more sensitive and specific index than systemic vascular resistance to the vascular changes in CHF.

Adult↗