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Biomedical subjects

G J Kost

Publications and source records attributed to G J Kost.

At least 55 records · Page 3Linked to original sources
PubMed1990

New whole-blood testing for laboratory support of critical care at cardiac transplant centers and US hospitals.

Whole-blood analytical techniques include ion-specific, substrate-specific, amperometric, and impedance electrodes. These allow direct measurement of critical analytes simultaneously in whole blood without centrifugation, resulting in a response time of 2 to 5 minutes. Cardiac transplantation centers rely heavily on whole-blood instruments to provide rapid response tests essential for cardiovascular management. A survey of 81 blood gas laboratories in 25 cardiac transplantation centers and 73 blood gas laboratories in 36 general hospitals showed an increase in testing for potassium, free calcium, and glucose by blood gas laboratories since 1982 and extensive use of satellite laboratories near areas serving critically ill patients. The following three recent developments are improving the availability of laboratory results: (1) direct whole-blood measurement is gaining acceptance, (2) instrumentation designed specifically for rapid critical care profiling is being used extensively, and (3) testing is moving closer to patients. These trends suggest a significant change in laboratory support of critical care in the United States.

Blood Chemical Analysis↗
PubMed1989

New NMR probe designs for neonatal, immature and adult heart research. With a brief review.

We present three new radiofrequency probes for nuclear magnetic resonance (NMR) research with perfused rabbit hearts at different maturational ages. The objective of the double-tunable, cylindrical-window probe design was to achieve a highly homogeneous magnetic field throughout the 16, 25 or 30 mm diameter usable volume for consistency of comparison of measurements obtained from neonate, immature and adult rabbit hearts, respectively. This probe design tunes to 23-Sodium for rapid shimming and then, to 31-Phosphorus for measurements of pH and high energy phosphate metabolites. All three probes yielded excellent signal-to-noise ratios and radiofrequency operating characteristics. We introduce these new probes here in the context of a brief review of other state-of-the-art designs for in vitro and in vivo cardiovascular research.

Animals↗
PubMed1988

Indications for measurement of total carbon dioxide in arterial blood.

There is increasing evidence of variability in pK1', the practical dissociation coefficient used in the Henderson-Hasselbalch equation to calculate arterial bicarbonate from measurements of arterial pH and pco2. The case presented here illustrates not only potential technical artifacts in arterial blood sampling, which can confuse, but also irreconcilable differences in the values of calculated arterial bicarbonate vs measured arterial and venous total carbon dioxide (carbon dioxide content). Measurements of total carbon dioxide in arterial blood will resolve such conflicts, particularly for acutely ill patients, and will reflect the correct bicarbonate measurements for use in therapeutic decisions.

Acid-Base Imbalance↗
PubMed1987

A microcomputer-based system for processing 31-phosphorus nuclear magnetic resonance spectra from studies of cardiac metabolism in immature hearts.

We designed an interactive microcomputer-based digital data processing system for analysis of 31-phosphorus nuclear magnetic resonance (31P-NMR) spectra from studies of cardiac metabolism in immature and neonatal hearts. This system included a digitizing tablet (Kurta Series Two), a microcomputer (IBM PC XT) and a graphics plotter (Hewlett-Packard 7470A) used in conjunction with a Nicolet 1280 NMR signal processing computer. We obtained 31P spectra from isolated perfused rabbit hearts with a Nicolet NT-200 4.7 Tesla superconducting NMR spectrometer operated in the pulsed Fourier transform mode. The small size of the hearts resulted in increased noise in spectra and demanded comparison of methods used to quantitate changes in inorganic phosphorus, phosphocreatine and ATP during ischemic stress. We performed microcomputer operations and interfacing functions with a software package written in BASIC. This system simplified documentation, data filing and statistical data processing. Our microcomputer system displayed and made hard copies of digitized spectra and results of analyses. Errors in data entry were rectified directly with this program. Consistent data reduction improved the precision of the physiological results and reduced the influence of noise on 31P spectra from neonatal hearts weighing about 0.5 g. The system flexibility extends its application to NMR spectra analysis for other in vivo organ systems, and signal processing in other biological research.

Animals↗
PubMed1986

Monitoring of ionized calcium during human hepatic transplantation. Critical values and their relevance to cardiac and hemodynamic management.

During human hepatic transplantation, ionized calcium (ICa) measured in whole blood with an ion-selective electrode varied greatly from ICa predicted from total calcium (TCa), protein, albumin, and pH, by means of recently published nomograms. Measurement of ICa was necessary because the interaction of citrate in transfused blood and calcium chloride (administered to offset citrate binding) caused large variations in TCa. During hepatic transplantation, ICa and electrolyte measurements were obtained at approximately 15-minute intervals or more frequently if indicated by changing cardiac status. In one patient, hemodynamic instability was accompanied by a large decrease in ICa, which then was followed by cardiac arrest aggravated by myocardial depression from inadequate ICa. Cardiovascular phenomena associated with ionized hypocalcemia suggest that the critical value for ICa should be no more than 0.4 mmol/L (1.6 mg/dL) below the reference range mean. The authors propose critical limits for ICa and discuss their significance in clinical management of tetany, hypotension, arrythmias, and cardiac arrest.

Adolescent↗
PubMed1986

Application of Program Evaluation and Review Technic (PERT) to laboratory research and development planning.

Software for the personal computer dramatically changes the ease with which managers of research and development can use network planning to guide projects to completion in the academic medical center setting. A case study of the use of the Critical Path Method (CPM) and Project Evaluation and Review Technic (PERT) in planning and implementing transcutaneous pCO2 monitoring by a department of laboratory medicine illustrates the utility and efficiency of these network planning technics. By means of iterative PERT analyses, the project was kept on track, despite an overly optimistic estimate of the completion date initially and intense demand by clinicians for use of the new monitoring technic in the management of premature infants with respiratory disease. Additionally, the iterative management approach improved project participants' expertise in estimating and meeting deadlines. Network planning is fully adaptable to the IBM PC or an equivalent microcomputer. This article summarizes several excellent project management software packages that have become available recently.

Carbon Dioxide↗
PubMed1986

Management by objectives for the academic medical center.

Management by Objectives (MBO) is results-oriented, participatory management, which is appropriate for the current era of keen competition for resources. MBO was installed in the author's institution in clinical laboratory divisions meeting prerequisites and fit the system to the local management environment. The results were decidedly positive. Benefits included improved communication, organizational clarity, planning for deadlines, motivation of participants, work load distribution, and productivity. Projects were easier to visualize, track, and coordinate. A natural review cycle of three to four months evolved, with general review twice a year. MBO worked best with one- to two-year-long projects involving problem solving and innovation. The author expects maturity of his MBO application within three years. He recommends MBO for other academic medical center laboratories, provided executive management commits the necessary time and resources to install MBO carefully as a relatively loose, locally administered form of management philosophy, rather than management technology.

Academic Medical Centers↗
PubMed1984

Surface pH of the medial gastrocnemius and soleus muscles during hemorrhagic shock and ischemia.

Surface pH (SpH) responses of muscles of different fiber type composition were determined in sodium pentobarbital-anesthetized rabbits by comparison of the medical gastrocnemius (MG) and soleus (S) muscles. With hemorrhagic shock, S SpH decreased to 7.24 +/- 0.04 (mean +/- SD, P much less than 0.001) and MG SpH to 7.05 +/- 0.13 (P much less than 0.001). The mean of paired difference in SpH decrease (PDD) was 0.20 +/- 0.14 (P less than 0.002). With 1 hour of arterial ischemia, S SpH increased 0.02 +/- 0.03 (P less than 0.06) initially; overall, it decreased 0.17 +/- 0.07 (P much less than 0.001) to 7.24 +/- 0.09. The MG SpH decreased 0.49 +/- 0.24 (P much less than 0.001) to 6.90 +/- 0.23. The mean PDD was 0.32 +/- 0.22 (P less than 0.001). With 2 hours of arterial ischemia, S SpH increased 0.03 +/- 0.04 (P less than 0.05) initially; overall, it decreased 0.46 +/- 0.18 (P much less than 0.001) to 6.95 +/- 0.17. The MG SpH decreased 0.74 +/- 0.23 (P much less than 0.001) to 6.66 +/- 0.23. The mean PDD was 0.28 +/- 0.14 (P less than 0.001). Four of the 10 MG responses in the 2-hour arterial ischemia group were irreversible. SpH responses correlated with fiber type compositions. Initial increases in S SpH demonstrate that SpH does not invariably decrease during ischemia (as formerly assumed) and represent a potentially false negative clinical response. The large decrease in MG SpH shows that a highly glycolytic muscle will give the most sensitive indicator of reduced perfusion. Assessment of reperfusion may be problematic because of irreversible changes in SpH after prolonged ischemia. Conversely, SpH measurements may help identify regions of irreversibly damaged skeletal muscle, particularly those with mainly glycolytic fibers.

Animals↗
PubMed1983

Theory of network planning for laboratory research and development.

Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT) are quantitative network planning strategies that facilitate management of projects with many interrelated activities. They determine the minimum time necessary to complete a project and identify which activities are critical to achieving the minimum. PERT also incorporates probabilistic estimates of activity durations. This statistical approach is useful when planning a project entailing some uncertainty and allows one to calculate chances of finishing on time. CPM and PERT encourage participation of all key personnel in the planning process, effective fit between project variables and organizational structure, and optimization of resource allocation. Availability of several levels of sophistication make network planning flexible enough to be applied easily in laboratory research and development. Iterative refinement of network plans and time estimates in progressive steps of involvement with clinical colleagues augments the effectiveness of these technics in hospital settings.

Laboratories↗
PubMed1983

Monitoring of transcutaneous carbon dioxide tension.

The authors studied the analytic and clinical characteristics of transcutaneous carbon dioxide monitoring in acutely ill NICU infants. Most infants were premature. The authors used both developmental and commercially available equipment. Monitoring was performed at temperature settings of 44 degrees C. With commercially available equipment, it was found that the least-squares linear regression relationship (r = 0.86, Sy.x = 12.9 torr, n = 100 patients) between transcutaneous PCO2 (y) and arterial PCO2 (x) was: y = -2.8 + (1.86)(x) (in torr). Calibration drift was unacceptably large in about 10% of the 500 monitoring sessions performed. Therefore, the authors conclude that transcutaneous PCO2 monitoring is most appropriate for following short-term trends in PCO2 over a period of one to three hours. Continuous transcutaneous PCO2 monitoring was most useful clinically after extubation when the objectives were careful observation for changes in PCO2 and prevention of reintubation.

Acidosis, Respiratory↗
PubMed1983

Surface pH responses of muscles of different fiber-type composition to catecholamines.

Catecholamines were infused intravenously for 45 min into pentobarbital sodium-anesthetized rabbits. Physiologically low-dose epinephrine (0.125 microgram . min-1 . kg-1) decreased medial gastrocnemius (MG) surface pH (SpH) 0.16 +/- 0.03 (SD) (P less than 0.001) to a low of 7.25 +/- 0.11 and soleus (S) SpH 0.09 +/- 0.04 (P less than 0.01) to a low of 7.33 +/- 0.08 without changing blood pressure significantly. Surface temperature measurements suggested a statistically insignificant small increase in local blood flow in both muscles. With 1.25 microgram . min-1 . kg-1 epinephrine, MG SpH decreased 0.22 +/- 0.05 (P less than 0.001) to a low of 7.17 +/- 0.06 and S SpH decreased 0.10 +/- 0.05 (P less than 0.02) to a low of 7.26 +/- 0.04. The MG SpH decrease exceeded the S SpH decrease in each experiment for both epinephrine infusion levels, and the incremental difference was significantly greater (P less than 0.02) with the higher dose, demonstrating a dose-response effect more pronounced for glycolytic compared with oxidative fibers. Norepinephrine infusions of 1.25 and 2.5 micrograms . min-1 . kg-1 did not change SpH of either muscle significantly, despite increases in blood pressure of 10 +/- 3 (P less than 0.002) and 19 +/- 10 mmHg (P less than 0.02), respectively.

Animals↗
PubMed1983

Transcutaneous carbon dioxide for short-term monitoring of neonates.

We studied transcutaneous pCO2 monitoring in 70 neonates, most of them premature with respiratory distress syndrome. Measurements were at 44 degrees C. Calibration drift was large in some instances. Least squares linear regression analyses of transcutaneous pCO2 (y) vs arterial pCO2 (x) in kilopascals showed, for all observations (n = 516), for one observation randomly selected from each patient (n = 70), and for the first observation from each patient (n = 70): y = -0.28 + 1.80x, y = 0.01 + 1.74x, and y = 0.73 + 1.63x, respectively. Regression lines for individual patients with 14 or more observations each were not coincident (F = 2.80, p less than 0.002). Transcutaneous pCO2 monitoring was most useful clinically as a means of following short-term trends in arterial pCO2 continuously during extubation and afterward when avoiding re-intubation. In view of the potential for error associated with drift, we recommend that intervals between calibrations be limited to about 3 h.

Blood Gas Analysis↗
PubMed1982

Muscle surface pH: measurement technique and responses to acidosis and alkalosis.

The technique of muscle surface pH measurement used clinically was refined for application in animal experimentation. Guidelines for electrode utilization were developed, and sources of error were investigated. In pentobarbital sodium-anesthetized rabbits, during steady-state conditions, the surface pH of the medial gastrocnemius [7.39 +/- 0.05 (SD)] was equal to that of the soleus, and both were lower than femoral venous outflow pH (7.42 +/- 0.04, P less than 0.001), which was lower than arterial pH (7.46 +/- 0.05, P less than 0.001). With acid-base infusions, the same relationship found during steady-state control conditions (arterial greater than venous outflow greater than muscle surface pH) was observed despite large fluctuations in blood pH. Only during forced hypoventilation, when CO2 transiently moved into muscle, did the relationship reverse. In all experiments, muscle surface pH followed venous outflow pH more closely than it followed arterial pH, the soleus more rapidly than the medial gastrocnemius. Results were consistent with the physiological characteristics of the two muscles and demonstrated that muscle surface pH reflects the local pH of the interstitial compartment under the site of electrode placement.

Acidosis↗