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J C Westengard

Publications and source records attributed to J C Westengard.

14 recordsLinked to original sources
PubMed1994

Band neutrophil counts are unnecessary for the diagnosis of infection in patients with normal total leukocyte counts.

The authors have assessed the clinical value of an "accurate" band count as a correlate to infection in 33 patients with a culture proven bacterial infection and a normal total leukocyte count. Thirty hematologically normal outpatients, presumably with no infections, were selected for the control group. Manual 500 cell differentials were performed on each subject in both groups. The absolute and percent band count, the absolute and percent total neutrophil count, and the presence of neutrophils more immature than bands were analyzed for their ability to identify the patients with an infection. The presence of neutrophils more immature than bands and the absolute neutrophil count are the two values that best separated the infected patients from the outpatients, even though the selected patients had a normal total leukocyte count. The band count had minimal value for identifying infected patients. Other studies were reviewed regarding the utility of band counts. The authors conclude that manual band counts are unnecessary because when accompanied by a clinical assessment of the patient, automated instruments accurately provide the appropriate hematologic data that may aid in the diagnosis of infection.

Bacterial Infections↗
PubMed1994

Population variability in the effect of aspirin on platelet function. Implications for clinical trials and therapy.

Little or nothing is known about how the inhibitory effect of aspirin on platelets distributes in the general population. We describe a simple whole-blood assay for the extent of aspirin-induced inhibition of platelet aggregation and its application to 31 aspirin-treated subjects. Platelet inhibition to two or more 325-mg aspirin tablets was measured using a newly developed method in 31 healthy, young adults. These subjects showed a wide range of variation in their response to aspirin, which in subsequent studies was found to be stable over time. The effect persisted even when the steps of gut absorption and liver metabolism were bypassed. We conclude that the response of platelets to aspirin varies to the extent that a significant proportion of the population may be nonresponsive and that this variability may be intrinsic to platelets and/or their blood environment.

Adolescent↗
PubMed1993

Calibration and validation for erythrocyte sedimentation tests. Role of the International Committee on Standardization in Hematology reference procedure.

The Westergren erythrocyte sedimentation rate (ESR) has been used for many years without any formal procedure for method validation or for quality assurance. In 1988, the International Committee on Standardization in Hematology (ICSH) (Leuven, Belgium) described an ESR validation procedure as well as a method for producing ESR reference material (ICSH reference method) in the laboratory where it is to be used. The ICSH proposal was tested in our laboratory during a consecutive period of 36 months. In this article, a new mathematical relationship between the ICSH recommendation and the Westergren method is developed, which can be easily used for method validation and/or quality assurance. A table has been made that establishes 95% action limits for Westergren ESRs based on ICSH reference ESRs from 5 through 105 mm/h. The table, derived from 36 months of data, has been tested against two new data sets and used to validate two commercial ESR methods. Analysis of outliers was performed with special attention to the mixing of whole blood samples with sodium citrate necessary for the Westergren ESR. This mixing process is best performed in a large-bore test tube as opposed to the use of the Westergren ESR tube as an aliquoting and mixing device.

Blood Sedimentation↗
PubMed1992

Effects of angiographic needle size and subsequent catheter insertion on arterial walls. An in vitro experiment in human cadavers.

RATIONALE AND OBJECTIVES: It is widely believed that down-sizing catheters, and possibly needles, will decrease damage to the entry vessel in the performance of angiography. The purposes of this in vitro experiment are to determine if smaller needles produce less arterial wall damage than larger needles and to assess the influence of subsequent catheter insertion. METHODS: Each iliac artery pair from 35 fresh human cadavers was punctured three times with an 18-g needle and three times with a 21-g needle, for a total of 210 punctures. In two of each set of three, a 5- or 7-F dilator was passed. One hundred ninety-eight puncture tracts were usable and examined microscopically. They were graded on a scale of 1 to 3 in each of four categories: size of tract, margin irregularity, approximation of edges, and shape of tract. RESULTS: Chi-square analysis of the grading scores showed a significant shift of cases into lower damage grades when the smaller gauge needle was used for initial punctures (P < .0005). The subsequent insertion of a dilator, however, imposed further damage, such that the initial differences due to needle gauge were obliterated (P > .2). CONCLUSION: These data indicate that a 21-g needle produces less arterial wall damage than an 18-g needle, but that any safety conferred by the smaller needle is eliminated by the subsequent insertion of a 5- or 7-F catheter.

Adolescent↗
PubMed1991

Guide wire traversal test: retrospective study of results with fibrinolytic therapy.

The validity of the guide wire traversal test as a predictor of the outcome of selective fibrinolytic infusion therapy was investigated. A retrospective analysis of 51 consecutive urokinase infusions at the authors' institution revealed that the initial attempt at guide wire traversal of clotted vessels was successful in 36 patients and unsuccessful in 15. In those 15 patients in whom the initial guide wire traversal was unsuccessful, urokinase was infused proximal to the occlusion for 2-8 hours. In 10 of these 15 vessels, either guide wire traversal (n = 7) or complete lysis with only proximal infusion (n = 3) was then achieved. Final results for this group of 15 patients were similar to those found in the group of 36 patients in whom initial attempts at guide wire traversal were successful (chi 2 contingency analysis, P greater than .8). There were no statistically significant differences between these two groups with regard to ages of the grafts, duration of vessel occlusion prior to treatment, infusion times, or patient gender composition. These data indicate that failure to traverse a clotted vessel with a guide wire does not preclude successful urokinase fibrinolytic therapy in a substantial percentage of patients.

Aged↗
PubMed1991

Heparin supplementation of nonionic contrast agents.

Diatrizoate has been widely used clinically for many years and has been effective in inhibiting clot formation in catheters and syringes. The authors attempted to determine the amount of heparin required to raise the anticoagulant potency of ioversol, iohexol, or iopamidol to that of diatrizoate. The anticoagulant potency of ioxaglate was also examined. One hundred eighty glass syringes containing unmodified diatrizoate, unmodified ioxaglate, or a nonionic contrast agent mixed with incremental amounts of heparin were contaminated with venous blood from 10 healthy volunteers. The syringes were then repeatedly disturbed to simulate the frequent handling that occurs during an angiographic procedure. The weights of the clots in the syringes at 30 minutes were plotted against heparin levels and indicated that, for the average sample studied, the "diatrizoate-equivalent" heparin level for ioversol, iohexol, or iopamidol was less than 1.5 U (USP) of heparin per milliliter. An additional margin of anticoagulation is probably desirable. The 97.5 percentile of the distribution of the diatrizoate equivalents in the population was estimated to require a heparin dose of 3.5 U/mL.

Anticoagulants↗
PubMed1991

Use of angiographic needles with or without stylets: pathologic assessment of vessel walls after puncture.

There is controversy as to whether angiographic needles without stylets produce more arterial damage than those with stylets. Iliac arteries from 15 fresh human cadavers were punctured 56 times with either an 18-gauge angiographic needle with a stylet or one without a stylet (28 punctures with each needle type). These puncture sites were serially sectioned and examined microscopically. Each needle tract was evaluated for margin irregularity, shape of puncture, and approximation of edges. No statistically significant differences in arterial wall changes were found. The authors' data suggest that the choice of beveled needle use in angiography can probably be made on a basis other than concern for differences in vessel wall damage secondary to the presence or absence of a stylet.

Angiography↗
PubMed1989

Efficacy of tests used to monitor rheumatoid arthritis.

The relative efficacy of clinical and laboratory tests used to monitor disease activity in rheumatoid arthritis was determined by consensus analysis in a study of 21 patients treated for 6 months. Erythrocyte sedimentation rate (ESR), which is influenced by the anaemia of chronic disease and by variation in the blood concentration of acute-phase proteins, was the most effective single test. ESR was a better guide to disease severity than measurement of plasma viscosity, serum C-reactive protein, and serum orosomucoid--tests that reflect the blood concentration of acute-phase proteins only. Clinical tests performed poorly unless combined with laboratory data in a numerical index. Consensus analysis can be used to assess the efficacy of clinical and laboratory tests and to identify redundant tests.

Adult↗
PubMed1989

Does tube diameter influence the packed cell volume?

The relationship between observed PCV and PCV tube diameter was investigated and it was found that the PCV decreased as the PCV tube diameter decreased. An equation which predicted the PCV as a function of the PCV tube radius was derived from the hypothesis that red blood cells in contact with the glass wall were partially dehydrated during high-speed centrifugation and that the amount of dehydration was related to the type of glass. PCV determinations were made on five patient blood samples using eight tubes of varying diameters, four made of soda-lime glass and four made of borosilicate glass. The predictions of the equation correlated well with the experimental results. Twice as much dehydration was observed in the soda-lime tubes as in the borosilicate, thus confirming both parts of the hypothesis. Independent confirmation of the hypothesis was obtained by counting the number of spheroechinocytes in the bottom of the PCV tube. There were twice as many in the soda-lime as in the borosilicate glass tubes. We conclude that dehydration errors must be considered along with trapped plasma errors when attempting to perform a reference PCV determination.

Centrifugation↗
PubMed1988

A technique for estimating the probability of clots in blood/contrast agent mixtures.

Blood that contaminates the contrast agent syringe during angiography may clot and is thus a potential source of emboli. The older, high-osmolality agents prevent clotting. Newer, low-osmolality agents, while possessing other advantages, are less effective in this regard. The time over which such mixtures do not contain clot can be determined by allowing gross clotting to take place, modeling the process mathematically and determining the clot-free time from the model. Blood-contaminated Omnipaque-300 (Winthrop-Breon, New York, NY) (iohexol), Isovue-300 (E.R. Squibb and Sons, New Brunswick, NJ) (iopamidol), Hexabrix (Mallinckrodt, St. Louis, MO) (ioxaglate sodium meglumine), Renografin-76 (E.R. Squibb and Sons, New Brunswick, NJ) (diatrizoate sodium meglumine), and saline were studied in glass and plastic syringes (80 samples of each agent). After deliberate blood contamination, Renografin and Hexabrix showed no clots during the 90-minute study period. There was, however, a 1.3% chance of clotting in Omnipaque (range 0.4%-4.0%) and a 1.9% chance of clotting in Isovue (range 0.6%-5.5%) at 5 minutes after contamination of these contrast agents in plastic syringes. The chance of clotting in glass containers was significantly greater. We conclude that Hexabrix is a substantially stronger anticoagulant than Omnipaque and Isovue. Furthermore, it appears that this method will allow determination of clotting risks for other combinations of contrast agent and container.

Angiography↗
PubMed1986

Ranking of laboratory tests by consensus analysis.

A new analytical technique (consensus analysis) was devised to assess the performance of laboratory tests that are commonly used to monitor the acute and chronic phases of inflammatory disease. On thirty-one tests carried out monthly for 7 months in seventeen patients with rheumatoid arthritis, the consensus analysis procedure ranked plasma viscosity and erythrocyte sedimentation rate in a tie for first place. Measurement of the acute-phase serum protein orosomucoid ranked third. Consensus analysis has the potential to reduce laboratory costs by identifying the most useful tests; it also promises to be helpful in the design of new laboratory tests that are more sensitive and specific.

Adult↗
PubMed1984

Platelet involvement in the activated coagulation time of heparinized blood.

The activated coagulation time (ACT), commonly used during cardiopulmonary bypass (CPB), is assumed to measure only differences in heparin levels. Studies were undertaken to determine whether platelet activation/inhibition might also influence the test. When either the platelet inhibitor prostacyclin or the platelet activator adenosine diphosphate (ADP) was added to healthy donor blood containing 2 IU of heparin per ml, there was significant prolongation of the ACT (prostacyclin: mean prolongation, 60.6%; ADP: mean prolongation, 52.3%). In blood taken from the extracorporeal circuit of ten CPB cases, the prolongation with the platelet inhibitor carbacyclin, a prostacyclin analogue, was infinite. It is concluded that the ACT as used during CPB must be interpreted as a measure of both platelet procoagulant activity and heparin activity. Furthermore, this dual sensitivity, while fortuitous, is probably advantageous; patients with hyporeactive platelets will automatically receive less heparin.

Adenosine Diphosphate↗