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Biomedical subjects

S D Nielsen

Publications and source records attributed to S D Nielsen.

35 records · Page 2Linked to original sources
PubMed1995

Prevalence of alcohol problems among adult somatic in-patients in Naples.

The aim of this cross-sectional study was to determine the prevalence of alcohol problems among adult somatic in-patients in urban hospitals of Naples. The patients were screened with a structured questionnaire regarding life style. After discharge, the patient records were examined and the hospital discharge diagnoses were registered. A patient was considered having an alcohol problem if one or more of the following criteria were fulfilled: (1) a Michigan Alcoholism Screening Test score at or above five; (2) a self-reported daily consumption for at least 2 years of at least 60 g of ethanol for males and 36 g for females; (3) an alcohol-related discharge diagnosis. The prevalence of patients with alcohol problems was significantly (P < 0.01) higher among male (43.8%, 95% confidence limits, 37.6-50.2%) than among female patients (14.8%, 95% confidence limits, 9.6-21.4%). There were no significant differences among the different types of somatic departments regarding the prevalence of alcohol problems when gender was considered. Patients with alcohol problems differed significantly from those without alcohol problems regarding a number of variables: the former drank significantly more alcohol, smoked for more years, and had a higher prevalence of alcohol problems in the family. It is concluded that alcohol problems among in-patients are as prevalent in Naples as in other industrialized countries, that it is often not registered among discharge diagnoses, and that the problems are more prevalent in males than in females, irrespective of the type of department.

Adolescent↗
PubMed1994

The validity of the Michigan Alcoholism Screening Test (MAST).

This review examines the validity of the Michigan Alcoholism Screening Test (MAST) as a screening instrument for alcohol problems. Studies that compare the MAST-questionnaire with other defined diagnostic criteria of alcohol problems were retrieved through MEDLINE and a cross-bibliographic check. A total of 20 validity studies were included. The studies varied considerably regarding the prevalence of alcohol problems, the diagnostic criteria, and the examined patient categories. The MAST compared with other diagnostic criteria of alcohol problems gave validity measures with the following span: predictive positive value (PVpos) 0.24-0.96, predictive negative value (PVneg) 0.78- approximately 1, sensitivity 0.36- approximately 1, and specificity 0.36-0.96. It appears that the PVneg are high. Except from one study, the sensitivities (0.57- approximately 1) are also high. The PVpos and the specificities show substantial variations. The variables that seem to have the largest influence on the PVpos seem to be the prevalence of alcohol problems, the diagnostic method against which the MAST-questionnaire is validated, and the populations on which the MAST is applied. The MAST should in the future be validated against internationally accepted diagnostic methods on populations with representative prevalences of alcohol problems.

Alcoholism↗
PubMed1994

Prevalence of alcohol problems among adult somatic in-patients of a Copenhagen hospital.

The adult patients of somatic departments of a Copenhagen hospital were screened on a randomly selected day during a 14 day period by interviewers who examined them using a structured questionnaire regarding life-style. A patient was considered having an alcohol problem if one or more of the following criteria was fulfilled: (1) a self-reported daily alcohol consumption for at least 2 years of at least 60 g of ethanol in men and 36 g in women, (2) a Michigan Alcoholism Screening Test (MAST) score of or above 5, (3) an alcohol-related discharge diagnosis. In total, 692 patients fulfilled the entry criteria, but 181 patients (26.2%) had to be excluded owing to predefined exclusion criteria (terminal illness, dementia, etc.), and 74 patients (14.5%) refused to participate. Among the 437 interviewed patients, 125 patients (28.6%; 95%-confidence limits 24.4-33.1%) fulfilled one or more of the diagnostic criteria for an alcohol problem. Only 14 patients (3.2%; 95%-confidence limits 1.8-5.3%) had an alcohol-related discharge diagnosis. The prevalence of patients with alcohol problems was significantly (P < 0.05) higher among male patients (82 of 171 men (48.0%; 95%-confidence limits 40.3-55.7%)) than among female patients (43 of 266 women (16.2%; 95%-confidence limits 12.0-21.2%)). The prevalence of patients with alcohol problems was 32.4% (95%-confidence limits 25.5-39.8%) in internal medicine departments, 28.5% (95%-confidence limits 21.3-36.6%) in surgical departments, and of female patients 22.2% (95%-confidence limits 13.7-32.8%) in the department of gynaecology and obstetrics.

Adolescent↗
PubMed1992

Physician's information about alcohol problems at hospitalisation of alcohol misusers.

Information was gathered on recognition and treatment of alcohol problems in the primary and secondary health sectors, the latter represented by a department of hepatology. The general practitioner finds in most cases (18/26, 69%) that it is relevant to advise about a patient's alcohol misuse on admission forms when the patient previously has been discharged from another department with this diagnosis. However, if the patient has not previously been hospitalised due to alcohol misuse, information on the diagnosis is only rarely (30/114, 26%) available. This difference is highly significant (P = 0.0001). The case-recording hospital physician at admission recognises 73% of alcohol misusers who are admitted with a non-alcohol-related diagnosis. When the patient had been evaluated by both the admitting physician and the case-recording hospital physician, information on the alcohol problem occurred significantly less often in female compared to male patients (75% vs. 94%; P < 0.002). Only 42 of 208 (20%) of alcohol misusers were under treatment with thiamine/B-vitamins and/or disulfiram before admission. There was a significant difference (P < 0.003) as to whether the patient was treated when the general practitioner wrote alcohol misuse on the admission form and when he did not (37% vs. 10%). At admission, treatment was begun in 54%, and by the discharge 78% were under treatment. Further quality assurance in the diagnosis and treatment of patients with alcohol problems is needed.

Adult↗
PubMed1988

In vitro development of automatic control for the actively filled electrohydraulic heart.

The in vitro development of automatic control of the actively filled, alternately pumped, volumetrically coupled, electrohydraulic total artificial heart was the goal of this investigation. Control features under study were (a) cardiac output (CO) response to preload; (b) CO relationship to mean aortic pressure (AoP); and (c) control of balanced ventricular outputs. A modified pulmonic valve to increase backflow was used as a balancing mechanism. Hydraulic fluid pressure transducers monitored diastolic pressures, and microprocessor control of motor speed maintained in a mild suction to yield filling rate dependent on atrial pressure. Results indicated a rise in CO from 5 to 9 L/min, with a change in mean right atrial pressure (RAP) from 0 to 7 mm Hg. No significant difference in CO was found as AoP was varied from 80 to 120 mm Hg with a maximum variation of +/- 0.5 L/min on CO and +/- 1 mm Hg on RAP. Balance was maintained for bronchial flows up to 50% with mean left atrial pressure never exceeding 15 mm Hg. An alternately pumped electrohydraulic heart was automatically controlled to respond sensitively to preload changes. Afterload changes did not alter the CO response curve. Automatically controlled, balanced ventricular outputs were maintained.

Algorithms↗
PubMed1986

The artificial heart: pursuit of a noninvasive method for determining atrial pressures.

The use of conventional open-port catheters in total artificial heart (TAH) research shortens the survival time of recipients owing to sepsis and embolism caused from the catheters. Valuable data are lost when an open-port catheter clots off, and transducer position must be keyed to the level of the atria for accuracy. The need for an accurate, easily obtainable, noninvasive method for measuring atrial pressure is of obvious value. Such a method has been developed in vitro using a device that measures the stroke volume of a pneumatic ventricle. The stroke volume is obtained by quantifying the amount of air exiting a pneumatic TAH in diastole. Using this information ventricular filling rates can be calculated by the stroke volume measurement device, and these rates are correlated to measured atrial pressures. There is no need to continually adjust transducer levels in relation to the atria with this system. The data show an average percentage error of 2.4 of full scale (25 mm Hg) or 0.6 mm Hg. The method of measurement is accurate, without limitations on driving parameters. The information is available without any additional prosthetic fabrication or surgical intervention than that already needed for basic TAH implantation. This method of measuring atrial pressures now needs to be proved effective in vivo.

Heart Atria↗
PubMed1985

Management of a malfunctioning left ventricle in an artificial heart.

Artificial heart research is carried out in the United States, Europe, Japan, Argentina and the Soviet Union, and prolonged survival has been achieved in animals, which has increased the interest of the media and public in this field. Although recent advances are promising, device malfunction remains an obstacle to overcome in most laboratories. Relying on noninvasive monitoring techniques we were able to diagnose and correct artificial heart malfunction safely using surgical techniques employed during the heart implantation.

Animals↗
PubMed1984

A cardiac output monitor and diagnostic unit for pneumatically driven artificial hearts.

The pneumatic artificial heart uses a flexible diaphragm to separate blood from air. The air space behind the diaphragm is connected to the atmosphere during diastole. Blood entering the heart during diastole displaces an equal volume of air into the atmosphere. A pneumotachograph is used to sense this flow of air. Integration of the airflow signal with respect to time yields the volume of air displaced during diastole, which is equal to the volume of blood entering the heart over the same period. This measured filling volume is equal to the cardiac output when averaged over a number of cardiac cycles. Allowance is made for regurgitant losses owing to the prosthetic heart valves. The output of the pneumotachograph is independent of absolute pressure, and so the device may also be used during the systolic (air compression) phase of the cardiac cycle. Analysis of the display of the airflow curves during diastole and systole has great diagnostic value. This device is accurate, easy to calibrate, stable, noninvasive, and does not require modification of any existing air-driven artificial hearts.

Air↗
PubMed1981

Are the Jarvik artificial ventricles limited by inflow resistance?

The pneumatic total artificial heart has been assumed to be inflow limited. Mock circulation studies on the Jarvik-5 and Jarvik-7 artificial ventricles seemed to support this assumption because a Starling's response comparable to the natural heart was not achieved. Unfortunately, mock circulation studies do not separate the effects of valvular regurgitation from inflow resistance. By using a simple filling tank, filling times were determined for the Jarvik ventricles that were a function of inflow resistance alone. Theoretical maximum cardiac outputs based on these inflow resistance-dependent filling times were then calculated. For filling pressures around 5 mmHg and under modest diastolic vacuum of 5 cm H2O, the Jarvik ventricles yield a theoretical cardiac output as good as the natural heart's. Thus, inflow resistance is not a limiting factor and valvular regurgitation is left as the most likely cause of a less than optimal Starling's response on mock circulation and in vivo.

Cardiac Output↗
PubMed1981

A seven-month survival of a calf with an artificial heart designed for human use.

A Jarvik-7 type of pneumatic artificial heart, which was specifically designed to fit the anatomy and hemodynamic requirements of human patients, was implanted in a calf in an experiment to test the hemodynamic performance of the artificial heart. The experiment lasted for 221 days, longer than any animal had ever lived without its natural heart, despite the fact that the calf increased its body weight to 171 kg. The calf showed typical signs of low cardiac output before its death, but the direct cause of death was intestinal bleeding. At autopsy, it was discovered that the low cardiac output was due to severe pannus around the left inflow valve, as diagnosed earlier by changes in the pneumatic pressure wave form.

Animals↗
PubMed1979

Intra-aortic balloon pumping device for infants.

The miniature components of an intra-aortic balloon pumping system (IABP) have been successfully developed in this laboratory and have been effectively tested both in vitro and in 32 in vivo experiments using small animals weighing 3.5--18 kg. It is reasonable to assume that IABP can be successfully employed for clinical use in infants and small children.

Animals↗
PubMedDate not supplied

The role of cardiac valves in artificial heart performance.

The criteria for the design, selection of materials, and fabrication of a total artificial heart have evolved over several years. As these criteria have become more sophisticated and exact, they have optimized the performance of all components within the system. A pump with sufficient volume and pressure output that fits in the available anatomic space was a primary objective. Concomitantly, a nonthrombogenic, durable material that was nondegradable in body fluids was being developed. The most easily managed energy source selected to date has been pulsed, compressed air programmed for gentle but effective systole and diastole. The evolution of good cardiac valves has been of major importance to the artificial heart effort. The historical development of the artificial heart has often centered around existing prosthetic valves which are currently an integral component of the complete system. A detailed analysis of the performance of the total artificial heart clearly identifies the role of the cardiac valve.

Animals↗