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Biomedical subjects

Y Nose

Publications and source records attributed to Y Nose.

323 records · Page 18Linked to original sources

Double chamber ventricular assist device with a roller screw linear actuator driven by left and right latissimus dorsi muscles.

A double chamber ventricular assist device (VAD) with a roller screw linear muscle actuator (RSLMA) driven by the left and right latissimus dorsi muscles was developed. The inflow port of each chamber was connected to form the compound inflow port, and the outflow ports were connected to form the compound outflow port. The advantages of this system include 1) the contraction of each muscle contributes to ejection from each ventricle into the common outflow port, thus doubling the net outflow; 2) through proper adjustment of muscle length, the preload to each muscle can be optimized to yield the maximum muscle force; 3) muscle can be stimulated at a lower rate to reduce fatigue and to optimize muscle performance; and 4) the compliance chamber needed in the implantable VAD system is not required with this system. In vitro evaluation in the mock loop with the human arm actuating the RSLMA revealed that the double chamber VAD can provide pump flows of 2-4 L/min against an afterload of 100 mmHg at a stimulation rate of 35-50 beats per minute. The power requirement for each muscle ranged from 2.5 to 3 W at a muscle stroke length of 4 cm. These results verify that the double chamber VAD with the RSLMA driven by the left and right latissimus dorsi muscles can meet the design requirements of a muscle driven VAD to assist the left heart.

Bioelectric Energy Sources↗

Long-term prognosis and prognostic factors of liver cirrhosis in the 1980s.

The prognosis of 174 patients with cirrhosis during the 1980s (1981-89) was analysed. The estimated survival rates were 87.3% in 3 years and 68.5% in 5 years. During the follow-up period, 58 patients died: 20 of hepatocellular carcinoma (37.7%); 11 of hepatic failure (20.8%); eight of gastrointestinal bleeding (15.1%); and 14 of other causes (26.4%). Multivariate analysis revealed that serum albumin, indocyanine green retention rate at 15 min and white blood cell count were significantly associated with prognosis. The results were also compared to our previous study covering the 1970s (1971-80). The estimated survival rate was significantly improved compared to that during the 1970s (54.3% in 5 years, P < 0.001). In the 1980s, hepatic failure mortality significantly decreased (P < 0.01), and non-liver-related mortality significantly increased (P < 0.05). In summary, the prognosis of cirrhosis has improved in recent years, and changes of death cause and prognostic factors were observed. It was concluded that to evaluate the severity and prognosis of cirrhosis, new indices and appropriate classification were necessary.

Adult↗

Computer analysis of left ventricular pressure-volume relationships by echocardiography.

Programs were developed for the analysis of left ventricular pressure-volume relationships in clinical situations. Regression lines of end-systolic points on the pressure-volume plane were obtained from nine patients. Correlation coefficients between end-systolic pressure and volume were high. The indices calculated may be useful for diagnosis and research of left ventricular function.

Blood Pressure↗

An on-line system for electrocardiogram interpretation using the Bonner program.

An on-line system for electrocardiogram (ECG) interpretation using the Bonner program has been developed. The system consists of a telephone network, a process computer, a host computer, a computer interface and an electrocardiograph equipped with transmitting options. The signal acquisition program offered by IBM was modified so as to be equipped with the following functions: The technician can distinguish whether the process computer is ready or not, even if he is working in an examination room which is distant from the computer room. The data received by the process computer is transferred to the host computer in real time. In cases where the host computer is unable to receive the data, the process computer restarts transmission quickly after the host computer recovers the function of receiving. The host computer interprets transferred data in real-time by the Bonner program. The interpretation report is printed in real time on a remote printer. As the result of these modifications, a series of data processing operations may be executed without intermediary operators. The printed interpretation report begins to appear about ten seconds after completion of transmission.

Electrocardiography↗

A patient follow-up system for stomach cancer.

The concept of PASK (Patient follow-up System of Kyushu University Hospital) has been innovated in order to manage clinical data of patients in the hospital-wide scope over long periods of time by using computers. PASK represents a collection of subsystems, each tuned to a specific disease. For the initial implementation, the subsystem for stomach cancer (STOMAC) was constructed according to the Cancer Center of Kyushu University Hospital project. STOMAC began to work in October 1984 and has proved effective. Using STOMAC, doctors in a clinical section can easily access patient data gained in another section. Besides providing a data reference function, STOMAC automatically gives alarms for abnormalities in clinical examination results, anti-tumor drug dosage, visitation cycles of patients, etc. The database and STOMAC programs are strongly standardized and easily applicable to another specific disease.

Aftercare↗

An electrocardiogram database incorporated into the hospital information system.

A database system was developed for storing and retrieving electrocardiogram (ECG) interpretations made by the Bonner program. One ECG record consists of the patient identification information, measurement matrix, and interpretive statements made by the program and by the reviewing cardiologist. The logical structure of the database is 3-level hierarchy. An ECG record is automatically inserted into the database when an ECG signal is analysed by the program. Stored ECG records can easily be retrieved using any parameter and qualifier for review, research and education. The physician can gather statistics on the parameters and qualifiers of the extracted ECG records using statistical program packages (BDMP, SCSS) and a decision support system (AS). Since the database management system is DL/I, the newly developed system can be transferred to various computers, and the relationships between the ECG findings and clinical records stored in the DL/I form can easily be studied.

Database Management Systems↗

A Holter-tape analyzer employing circuits for calculation of correlation coefficients.

An analyzer for ventricular premature contraction (VPC) arrhythmias was developed. At 60 times real time, the analyzer processes the Holter tape in which the long-term ambulatory electrocardiogram was recorded. Template matching algorithm using Pearson product-moment correlation coefficient is employed. A microprocessor controls the analyzer. Circuits for calculation of correlation coefficients were developed to support insufficient computing speed of the microprocessor. Evaluation study shows that the sensitivity for detecting the normal QRS complexes and the VPCs were 98.9% and 99.4%, and that the specificity for these were 97.5% and 98.4%. Algorithm for high-speed calculation of correlation coefficients is also considered.

Cardiac Complexes, Premature↗

A beat-to-beat calculator for the diastolic pressure time index and the tension time index.

We have developed a beat-to-beat calculator which can calculate in real-time the ratio of the diastolic pressure time index (DPTI), and the tension time index (TTI) as an index of the myocardial oxygen supply/demand balance. Physicians set up presumed value for the left ventricular endodiastolic pressure, a search area for the dicrotic notch, a threshold for the onset of the up-slope and the corresponding value of the calibration signal on the digital switches of the calculator. Next, the arterial pressure analog signal is input into the calculator. The calculator searches automatically for both the onset of the up-slope and the dicrotic notch. The arterial pressure curve is displayed beat-to-beat with the recognized onset and the dicrotic notch on the CRT to be confirmed by physicians. When physicians do not agree with the automatic recognition they can fit the automatic recognition to the observation. If the recognition of the onset is inadequate, the threshold can be re-adjusted to trigger the onset. If recognition of the dicrotic notch is inadequate, the physician can adjust the search-area. Therefore, physicians who operate the calculator can rely on the calculated DPTI/TTI. This calculator can continuously monitor the myocardial oxygen supply/demand balance in patients with acute myocardial infarction or just after open-heart surgery.

Blood Pressure↗

Quantitation of myocardial dyssynergy in closed-chest dogs by two-dimensional echocardiography.

Myocardial infarction was produced in 29 anaesthetized mongrel dogs by a closed-chest coronary occlusion technique. A two-dimensional echocardiographic examination (2-D echo) was carried out just before occlusion and again 48 h after occlusion. Many cross-sectional images were recorded by a video-tape recorder. The applied site of the probe was fixed in an intercostal space and the direction of the ultrasonic beam was tilted stepwise from the basis to the apex. The animals were sacrificed at 49 hours after occlusion. The hearts were removed, quick frozen, sliced into radiating sections and stained with nitroblue tetrazolium (NBT). The outline of dyssynergy, including dyskinesis, akinesis or extreme hypokinesis, was traced with a tablet digitizer by two specialists. The three-dimensional image of dyssynergy in the left ventricular wall was reconstructed by a computer in spherical co-ordinates and assumed to be made of numerous triangular pyramids. The volume of dyssynergy was calculated quantitatively as the sum of volumes of these numerous triangular pyramids. The volume of dyssynergy seen in 2-D echo correlated well over a wide range with the volume of infarction determined by NBT staining.

Animals↗

A method for early detection of abnormal trends in serial clinical examination results over time.

In this paper we describe a method for the early detection of changing health conditions which may eventually lead to serious disease. The method makes use of health screening test results accumulated for individuals and can be applied to those who have taken at least four health examinations. The degree of abnormality is calculated using a logistic regression equation. The variables defining the equation are selected by factor analysis and a stepwise variable selection method based on the likelihood ratio criterion. Statistical estimates include linear regression coefficients, isotonic regression probabilities and their standard deviations. These are used to represent trends in health screening results over time. The method is illustrated using a sample of 308 persons with gastric cancer and 3002 healthy persons. Cross-validations were also performed.

Adult↗

A personal computer network system for equitable allocation of cadaver organs.

We developed a personal computer network system for the equitable allocation of cadaveric organs. This network consists of a host computer (IBM PS55 model 5570 T) and various kinds of personal computers manufactured by many different computer makers in Japan. The merits of our personal computer network include lower cost and an easy access to the host computer from all the centres participating in this network while using their own favourite personal computers. Among the programs made for allocating cadaveric organs, we present in this paper the program for livers. This program was developed with a modified version of the logic developed by Starzl et al. The grade modification for the United Network for Organ Sharing (UNOS) in the United States was used as the basis for classification of medical urgency. Our program weighed the factors of medical urgency, compatibility of blood group and waiting time. Distance factors were omitted because of the smaller area of the network compared to that of UNOS. This computer network would be linked to other computer networks in creating a national organ procurement and transplant network in Japan, in order to help them to catch up with other advanced transplant countries. Such an equal and objective computer system should allow organ transplantation to become more widely accepted.

Computer Communication Networks↗

Interactive statistical analysis system for clinical investigators.

We have developed an interactive statistical analysis system (ISAS-Q) with which clinical investigators with little experience in computers and programming can easily perform statistical analyses. ISAS-Q can perform most of the frequently used statistical methods, including multivariate analysis, in an interactive mode. Furthermore, ISAS-Q has self-consistent and extensive help functions.

Data Interpretation, Statistical↗

Effect of graded coronary stenosis on regional myocardial blood flow and left ventricular function.

Dogs with 70% stenosis of the left circumflex coronary artery showed a reduction of myocardial blood flow with a minimal impairment of left ventricular wall motion. Eighty to ninety percent stenosis produced a marked reduction of flow and wall motion, and ST elevation close to 100% occlusion, but delayed antegrade run-off was found. The effectiveness of collaterals to protect against left ventricular dysfunction was supported.

Animals↗

A unique, efficient, implantable, electromechanical, total artificial heart.

A completely implantable, one piece electromechanical total artificial heart (TAH) intended for permanent human use was developed. It consisted of left and right conically shaped pusher-plate blood pumps sandwiching a thin centerpiece with a compact, efficient electromechanical actuator. The actuator consisted of a direct current brushless motor; a planetary roller screw fit the space between the two conically shaped pusher-plates. The rotational motion of the motor was converted to the rectilinear motion of the rollerscrew to displace the left and right pusher-plates in the left master alternate mode. The diameter of the assembled TAH was 97 mm, with a central thickness of 82 mm. The overall weight was 620 g, with a displaced volume of 510 ml. The pump provided flows of 3-8 L/min with a preload of 1-15 mmHg against an afterload of 100 mmHg. The net efficiency ranged from 15% to 18%. This model showed good fit in the pericardial space of heart transplant recipients (body weight, 77 kg).

Cardiac Output↗

Hospital construction materials: poor shielding capacity with respect to signals transmitted by mobile telephones.

Electromagnetic interference (EMI) with electronic medical equipment by the handsets of mobile telephones is a well documented problem in hospitals. To gain information about how to build an EMI-free hospital and how to make rooms safe for mobile telephone handset use in the hospital building the authors measured the shielding capacities of a concrete wall, concrete blocks, a steel door, and steel-surfaced partition panels. The shielding capacities of these materials were 2-7 dB for the concrete wall, 6-8 dB for the concrete blocks, 19-27 dB for the steel door, and 20-37 dB for the steel-surfaced partition panels. These results indicate that care should be taken to shield electronic equipment from signals coming from neighboring rooms and from those under and above any patient room in which such equipment is in use. Electricity-conductive paint, electricity-conductive wallpaper, and electricity-conductive cloth are examples of inexpensive materials that can increase shielding capacity.

Construction Materials↗