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Biomedical subjects

M B Bongiovanni

Publications and source records attributed to M B Bongiovanni.

18 recordsLinked to original sources
PubMed2001

Mathematical modeling and computer simulation of erythrocytapheresis for SCD.

BACKGROUND: Erythrocytapheresis is used to prevent acute chest syndrome and stroke in patients with sickle cell disease (SCD). However, such regimens are associated with significant risks, such as iron overload and potential exposure to transfusion-transmitted infectious diseases. Computer modeling of erythrocytapheresis procedures may help optimize treatments and minimize risks. STUDY DESIGN AND METHODS: Mathematical models based upon material balance equations and patient-specific statistical analyses were developed to estimate HbS levels immediately after erythrocytapheresis and immediately before the next treatment. The equations were incorporated into a software application that was used to model the effects of various treatment values on four patients treated with 90 erythrocytapheresis procedures. RESULTS: Immediate postprocedure HbS values were accurately estimated with correlations between measured and calculated values ranging from R(2) = 0.83 to 0.96. Estimates of HbS just before the next treatment correlated well in three patients (R(2) = 0.71 to 0.83) but poorly in one (R(2) = 0.28 to 0.46). Varying the treatment values by computer simulation led to a wide variation in the number of RBC units and the net RBC volume transfused. CONCLUSION: Computer modeling of erythrocytapheresis can be used to optimize chronic treatment regimens for SCD patients and potentially to minimize the risks of overtransfusion.

Anemia, Sickle Cell↗
PubMed1997

Loss of red cells from the use of blood warmers during apheresis procedures.

In-line blood warmers increase the extracorporeal volume of apheresis procedures. A saline rinse of the blood warmer may be employed to minimize the loss of red blood cells (RBCs) from this extra volume. We measured the amount of RBCs remaining in three different brands of blood warmers at the end of a COBE Spectra rinseback to determine the clinical significance of blood warmer saline rinses. The volume of RBCs removed by a warmer rinse ranged from 15 to 24 ml per procedure and was statistically different among the three brands of warmers. The COBE warmer contained significantly less RBCs than either the Fenwal or Pharmaseal warmers. Patient hematocrit was not highly correlated with the residual RBC volume (r = 0.30). We estimate that 15-20 procedures are required before the equivalent of one unit of packed RBCs is lost to blood warmers. We conclude that the blood warmer saline rinse may be safely omitted for most patients.

Blood Component Removal↗
PubMed1989

Dot diagrams as source documents for evaluations of test performance.

Complete evaluations of test performance require data on many test results over many clinical states, not restricted to the traditional 2 X 2 table of two possible test results and two possible clinical states. Published reports on test performance often include dot diagrams, depicting many test results over many clinical states. From such dot diagrams, several methods may be used to obtain numerical data for quantitative evaluations of test performance. Dot diagrams, long used to depict multiple test results over multiple clinical states, can serve as source documents for quantitative evaluations of test performance.

Diagnosis, Computer-Assisted↗
PubMed1988

The dot plot. A starting point for evaluating test performance.

We suggest that evaluations of diagnostic tests start with dot plots that depict multiple test results over multiple clinical states. From this starting point we can calculate posttest probabilities for multiple clinical states at multiple test results. Also, we can project one subset of clinical states as "disease positive" and a second subset as "disease negative" to provide standard analyses such as likelihood ratios, relative operating characteristic curves, posttest/pretest probability plots, sensitivity, specificity, and predictive value. Finally, this starting point provides an excellent basis for comparing multiple studies of diagnostic performance. The advantages of dot plots are illustrated with data on serum ferritin levels over multiple clinical states.

Ferritins↗
PubMed1988

Evaluating diagnostic performance of clinical tests by spreadsheet modeling. Bayesian analysis using Ri/Cj ratio as a unifying concept.

We present a general spreadsheet model for evaluating diagnostic performance of clinical tests. Our model depicts test results as an r X c matrix, with r possible test results and c possible clinical states. Analysis of this matrix is based on the Ri/Cj ratio, calculated as a number of subjects having a specified result Ri within a given clinical state Cj, divided by total subjects within this clinical state. From this model, we can identify three special cases: (1) a 2 X c matrix, with two possible test results of T+ or T-, over c possible clinical states; (2) an r X 2 matrix, with r possible test results, over two possible clinical states of D+ or D-; and (3) a 2 X 2 matrix, with two possible test results over two possible clinical states. Application of the Ri/Cj ratio to the r X c matrix provides a useful approach to graphic analysis of multiple test results over multiple clinical states. The Ri/Cj ratio also provides a general approach to Bayesian analysis, in which likelihood ratio, relative operating characteristic analysis, sensitivity, and specificity represent special cases or special applications.

Bayes Theorem↗
PubMed1986

When is a diagnostic test result positive? Decision tree models based on net utility and threshold.

The question "When is a diagnostic test result positive?" can be addressed by clinical decision analysis. We developed two simple decision tree models for selecting appropriate cutoff levels: a net utility model and a threshold model. These models have been incorporated in a software program for desktop computers. We believe it is important for investigators to provide raw data on test performance, for three reasons. First, these data can be used in simple decision tree models to identify "appropriate" cutoff levels. Second, they can be used to evaluate empiric cutoff levels or decision rules. Third, they can be used to evaluate optimal cutoff levels for detailed decision trees depicting specific clinical problems.

Cost-Benefit Analysis↗
PubMed1986

A microcomputer program for critical evaluation of diagnostic tests.

We developed a microcomputer program that provides a Bayesian model of diagnostic performance and a simple decision tree model of clinical utility. We have used this program to review diagnostic performance and clinical utility for proposed new services at our 360-bed university hospital. We believe that significant benefits can be achieved if medical journals report complete data on test performance. First, this allows physicians to perform their own evaluations of diagnostic performance. Second, this allows physicians to evaluate clinical utility using either standard decision trees or decision trees that reflect specific clinical problems.

Bayes Theorem↗
PubMed1984

The complications of therapeutic plasma exchange.

We reviewed a series of 181 patients who were treated with therapeutic plasma exchange ( TPE ) a total of 1,389 times. Complications were associated with 22 (1.6%) of the procedures and involved 20 (11%) of the patients. Six of the complications were of a technical nature and did not affect the medical conditions of the patients. 8 patients developed the following serious medical problems: unexplained death during the post- TPE period, myocardial infarction, pulmonary embolus, loss of consciousness, myocardial ischemia, cerebral ischemia and chest pain. Although these problems were temporally associated with TPE none of them could be attributed to the TPE with certainty. The remaining eight medical complications were of a less serious nature.

Adolescent↗
PubMed1981

Evaluation of erythrocyte washing using the Haemonetics Model 102 Cell Washer.

The Haemonetics Model 102 Cell Washer was evaluated for efficiency of leukocyte removal and erythrocyte recovery. Groups of 25 units of blood were washed using five different protocols, including the methods recommended by the manufacturer. Mean erythrocyte recovery ranged from 83% to 91% and median residual leukocytes ranged from 1% to 4% for the five protocols. The mean erythrocyte recovery for units washed with 30 sec of increased pump speed was 95%, while it was 84% for units washed with 90 sec of increased pump speed (P less than 0.001). The median residual leukocytes was 1% for units washed after buffy coat removal and 4% for all other units (P less than 0.001). There was no other significant difference among the different protocols. These findings could not be explained on the basis of age of units, prewash erythrocyte mass, or prewash total leukocytes.

Blood Preservation↗
PubMedDate not supplied

Long-term plateletpheresis of a donor.

A 25-year-old woman underwent plateletpheresis 101 times over a 33-month period. The equivalent of 5.8 to 7.5 units of platelet concentrate was removed during each pheresis. Two machine-related complications occurred, resulting in the loss of one unit of blood and 150 milliliters of plasma. Other complications included a mild anemia consistent with iron deficiency. The donor's platelet count decreased but remained in the normal range. There were no significant changes in the serum proteins or immunoglobulins. Serum hepatic enzymes became elevated and were consistent with a mild, subclinical hepatitis. These returned toward normal during continued pheresis.

Adult↗
PubMedDate not supplied

Cytapheresis in a patient with Sezary syndrome.

A patient with Sezary syndrome underwent cytapheresis on the IBM 2997 cell separator. Four procedures were performed over a 12-day period. A total of 8.3 x 10(10) Sezary cells were removed. The patient's skin lesions and lymphadenopathy regressed. Transient thrombocytopenia occurred, requiring platelet transfusion. Although a significant number of platelets were removed by pheresis, this was not sufficient to explain the thrombocytopenia. The patient subsequently died of causes unrelated to the cytapheresis.

Cell Separation↗
PubMedDate not supplied

Rapid estimation of the glycerol concentration of frozen-thawed red cells prepared by the agglomeration technique.

The glycerol concentration of frozen-thawed red cells must be less than 2 percent to prevent hemolysis upon transfusion. Three methods were investigated for monitoring the glycerol concentration of frozen-thawed red cells prepared by the agglomeration technique. The supernatant osmolality and glycerol concentration were determined on 47 units of frozen-thawed red cells prepared by agglomeration, and were found to be linearly related (r = 0.83, p less than 0.001). The supernatant refractive index was determined on 29 of the same units. There also was a linear relationship between the refractive index and the glycerol concentration (r = 0.74, p less than 0.001). The relationships were different from those previously reported for red cells prepared by other methods. The simulated transfusion test was done on red cells from three units whose glycerol concentration had been artificially elevated. The simulated transfusion test was found to be sensitive to glycerol concentrations above 2 percent. All three of the methods evaluated can be used to estimate the glycerol concentration of frozen-thawed red cells prepared by the agglomeration technique.

Erythrocytes↗
PubMedDate not supplied

Parathyroid response during therapeutic plasma exchange.

Significant hypocalcemia is infrequently encountered during therapeutic plasma exchange. An increase in parathyroid hormone secretion during the procedure may be responsible for maintaining the calcium levels.

Adult↗