Biomedical subjects

A D Kester

Publications and source records attributed to A D Kester.

77 records · Page 5Linked to original sources

PubMed1985

Left and right ventricular function in porcine Escherichia coli sepsis.

In anesthesized pigs, hemodynamic measurements and gated bloodpool scintigraphy were performed during and after infusion of live Escherichia coli (2 X 10(8)/kg). Ejection fractions (EF) as well as the relation between end-diastolic volumes (EDV) and stroke work (SW) were used to evaluate changes in left (LV) and right ventricular (RV) function. Porcine E. coli sepsis proved to be characterized by pulmonary vascular hypertension (PVH) and systemic arterial hypotension, accompanied by a reflex increase in heart rate. Systemic flow remained essentially unchanged. E. coli infusion resulted in pronounced and opposite changes in LV and RV preload. RVEDV increased initially and then returned to the value observed before E. coli infusion. LVEDV showed a continuous decrease during the observation of 3 hours. Alterations in LVSW and RVSW appeared to parallel the changes in LVEDV and RVEDV. No significant changes in LVEF and RVEF were found. It is concluded that porcine E. coli sepsis might be a suitable model for human sepsis complicated by PVH. In this animal model no clear signs of myocardial depression or evidence of right heart failure were observed.

Animals↗

PubMed1984

Role of peripheral pooling in porcine Escherichia coli sepsis.

In anesthesized pigs the effects of E. coli (2 X 10(8)/kg) on hemodynamics and red cell distribution were studied. After injection of 99m-Tc red cells (15 mCi), regional radioactivity was followed during 3 hours. Gated bloodpool studies were performed to measure end-diastolic volumes (EDV). Escherichia coli E. coli was infused in 14 pigs, while 7 animals served as controls. E. coli resulted in an early increase in pulmonary arterial pressure. Systemic arterial pressure decreased gradually, while cardiac output did not change significantly. The gated studies revealed that especially left ventricular end-diastolic volume (LVEDV) declined, to 50% of the basal value. Regional radioactivity did not change over lungs, liver and abdomen. Splenic activity declined markedly. Over the hindlimb a significant increase (29 +/- 8%) was observed. It is concluded that E. coli infusion in pigs induces a hemodynamic pattern similar to human sepsis. The decrease in LVEDV is probably related to peripheral pooling and a change in right ventricle (RV) performance.

Animals↗

PubMedDate not supplied

The granularity of medical narratives and its effect on the speed and completeness of information retrieval.

OBJECTIVE: Using electronic rather than paper-based record systems improves clinicians' information retrieval from patient narratives. However, few studies address how data should be organized for this purpose. Information retrieval from clinical narratives containing free text involves two steps: searching for a labeled segment and reading its content. The authors hypothesized that physicians can retrieve information better when clinical narratives are divided into many small, labeled segments ("high granularity"). DESIGN: The study tested the ability of 24 internists and 12 residents at a teaching hospital to retrieve information from an electronic medical record--in terms of speed and completeness--when using different granularities of clinical narratives. Participants solved, without time pressure, predefined problems concerning three voluminous, inpatient case records. To mitigate confounding factors, participants were randomly allocated to a sequence that was balanced by patient case and learning effect. RESULTS: Compared with retrieval from undivided notes, information retrieval from problem-partitioned notes was 22 percent faster (statistically significant), whereas retrieval from notes divided into organ systems was only 11 percent faster (not statistically significant). Subdividing segments beyond organ systems was 13 percent slower (statistically significant) than not subdividing. Granularity of medical narratives affected the speed but not the completeness of information retrieval. CONCLUSION: Dividing voluminous free-text clinical narratives into labeled segments makes patient-related information retrieval easier. However, too much subdivision slows retrieval. Study results suggest that a coarser granularity is required for optimal information retrieval than for structured data entry. Validation of these conclusions in real-life clinical practice is recommended.

Cross-Over Studies↗

PubMedDate not supplied

Meta-analysis of ROC curves.

The authors present a method to combine several independent studies of the same (continuous or semiquantitative) diagnostic test, where each study reports a complete ROC curve; a plot of the true-positive rate or sensitivity against the false-positive rate or one minus the specificity. The result of the analysis is a pooled ROC curve, with a confidence band, as opposed to earlier proposals that result in a pooled area under the ROC curve. The analysis is based on a two-parameter model for the ROC curve that can be estimated for each individual curve. The parameters are then pooled with a bivariate random-effects meta-analytic method, and a curve can be drawn from the pooled parameters. The authors propose to use a model that specifies a linear relation between the logistic transformations of sensitivity and one minus specificity. Specifically, they define V = In(sensitivity/(1 - sensitivity)) and U = In((1 - specificity)/specificity), and then D = V - U, S = V + U. The model is defined as D = alpha + betaS. The parameters alpha and beta are estimated using weighted linear regression with bootstrapping to get the standard errors, or using maximum likelihood. The authors show how the procedure works with continuous test data and with categorical test data.

Alcoholism↗

PubMedDate not supplied

Diagnostic value of signs and symptoms associated with peripheral arterial occlusive disease seen in general practice: a multivariable approach.

OBJECTIVES: To assess the diagnostic values of single and combined data from the history, physical examination, and medical record with regard to peripheral arterial occlusive disease (PAOD) in patients with leg complaints; to construct a multivariable model for the clinical diagnosis of PAOD by primary care physicians. SETTING: 18 general practice centers in The Netherlands. DESIGN: Cross-sectional comparison of signs, symptoms, and data from the medical record with the independently assessed ankle-brachial systolic pressure index (ABPI; cutoff point < 0.90); analysis: bivariate, multiple logistic regression (MLR). POPULATION: 2,455 individuals with leg complaints, aged 40.7-78.4 years; ABPI < 0.90 present in 9.2% of legs (11.7% of individuals). OUTCOME MEASURES: Clinical variables: sensitivity, specificity, positive and negative predictive values (PV+, PV-), diagnostic odds ratio (OR); models: likelihood ratio test, area under the receiver operating characteristic curve (AUC). RESULTS: Bivariate analysis: highest sensitivity: age more than 60 years (77.3%); highest specificity: wounds or sores on toes and foot (99.7%); highest PV+: typical intermittent claudication (IC) (45.0%) (abnormal foot pulses 41.3%); highest PV-: strong pulses of both foot arteries (97.7%). MRL: the best-performing model (AUC 0.89) consisted of ten clinical variables: gender (OR 1.5), age more than 60 (OR 2.2); IC (OR 3.5); palpation of the skin temperature of the feet (OR 2.5), palpation of both foot pulses [OR 16.4 (abnormal) and 7.0 (doubtful)], auscultation of the femoral artery (OR 3.5); previous diagnosis of IHD (OR 1.7) or diabetes (OR 1.6), history of smoking (OR 2.1), and elevated blood pressure (OR 1.5). The range of predicted probabilities was 0.4-98%. The Hosmer-Lemeshow goodness-of-fit test indicated good overall fit (p = 52). CONCLUSIONS: Palpation of both foot pulses is the key procedure for the clinical diagnosis of PAOD. Traditional clinical evaluation enables the general practitioner to exclude the diagnosis of PAOD in many individuals with a high degree of certainly, to establish the diagnosis in a small group of patients, and to define a limited group of patients where supplementary noninvasive testing is appropriate. The MLR model can be used as a diagnostic checklist and as a reference for the physician's clinical hypothesis.

Adult↗