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Biomedical subjects

R A Case

Publications and source records attributed to R A Case.

15 recordsLinked to original sources
PubMed1996

Diagnostic value of echocardiography in suspected endocarditis. An evaluation based on the pretest probability of disease.

BACKGROUND: We hypothesized that for the diagnosis of endocarditis, (1) transthoracic echocardiography (TTE) would be most valuable in patients with an intermediate clinical probability of the disease and (2) transesophageal echocardiography (TEE) would be most useful in patients with an intermediate probability when TTE either does not yield an adequate study or indicates an intermediate probability of endocarditis. We also sought to investigate the influence of echocardiographic results on antibiotic usage and its duration. METHODS AND RESULTS: TTE and TEE were performed in 105 consecutive patients with suspected endocarditis. Patients were classified as having either low, intermediate, or high probability of endocarditis on the basis of clinical criteria and separately on the basis of both TTE and TEE findings. TTE and TEE classified the majority (82% and 85%, respectively) of the 67 patients with a low clinical probability of endocarditis as having a low likelihood of the disease. Of the 14 patients with intermediate clinical probability, 12 had technically adequate TTE studies; 10 of these (83%) were classified as either high or low probability. All patients with intermediate clinical probability were classified as high or low probability by TEE. The majority of the 24 patients with high clinical probability were placed in the low-likelihood category by echocardiography (15 by TTE and 12 by TEE). There was concordance between TTE and TEE in 83% of all cases. TEE was useful for the diagnosis of endocarditis in patients with prosthetic valves and in those in whom TTE indicated an intermediate probability; these constituted < 20% of patients in our study. The course of antibiotic therapy was influenced only by the clinical profile and not by the echocardiographic results. CONCLUSIONS: Echocardiography should not be used to make a diagnosis of endocarditis in those with a low clinical probability of the disease. In those with an intermediate or high clinical probability, TTE should be the diagnostic procedure of choice. TEE for the diagnosis of endocarditis should be reserved only for patients who have prosthetic valves and in whom TTE is either technically inadequate or indicates an intermediate probability of endocarditis.

Adolescent↗
PubMed1996

Cohort analysis of mortality rates as an historical or narrative technique.

A history of cohort analysis has been given, and it has been pointed out that the bulk of the literature on the subject has dealt with concepts that assume either that graduation and possibly extrapolation are desirable, preferably in conformity with some formula expressing what is implicitly accepted as a "law of mortality", or that, whether or not a fixed pattern of mortality exists, the intensity of mortality risk is largely determined in early life. The view is advanced that either concept alone, is, or both concepts together are, inadequate and may lead to an improper assessment of the nature-nurture complex, since environment and therapeutic measures are constantly changing. The plea is made for the technique of cohort analysis to be used as a narrative or historical technique, and for a synthesis of knowledge derived from social history, medical history, and cohort analysis to be made to interpret the narrative. The effects of a changing rate on the mortality pattern as depicted by date-contour analysis and cohort analysis are outlined and the danger of basing biological theories on the mortality pattern revealed by date-contour analysis alone is indicated. This point is illustrated by reference to a recent theory that has been based on such an analysis.

Age Distribution↗
PubMed1994

Physiological assessment of coronary artery disease and myocardial viability in ischemic syndromes using adenosine echocardiography.

We hypothesized that it would be feasible and safe to use adenosine echocardiography to assess the physiological significance of coronary stenoses, detect ischemic myocardium, and assess myocardial viability in a high risk group of patients with coronary artery disease (CAD). Therefore, in 40 patients with either unstable angina, non-Q myocardial infarction, or myocardial infarction treated with thrombolytic therapy, we performed adenosine echocardiography (140 mug/kg per min for 5 mins with a 16 segment model for analysis) and compared the findings with quantitative planar thallium-201 scintigraphy, and (in 26 patients) coronary angiography. The technique was safe, and there were no serious complications. Adenosine resulted in a significant increase in heart rate and decrease in blood pressure. The sensitivity of adenosine echocardiography and thallium scintigraphy were 96% and 88%, respectively, for detecting greater than 75% stenosis. The change in echo score from baseline during adenosine infusion was significantly higher with more severe coronary disease (single vessel right coronary artery {RCA} or left circumflex {LCX} disease = 0.125 +/- 0.15, proximal left anterior descending coronary artery {LAD} disease = 0.23 +/- 0.15, RCA and LCX disease = 0.30 +/- 0.14, LAD and RCA and/or LCX disease = 0.62 +/- 0.13). Likewise, the echo score during adenosine infusion was significantly higher in patients with high risk thallium scans (low risk = 1.29 +/- 0.26, medium risk = 1.74 +/- 0.22, and high risk = 2.21 +/- 0.37). In 13 patients receiving thrombolytic therapy, adenosine echocardiography identified 12 with viable myocardium as defined by quantitative thallium criteria. Furthermore, the wall-motion response of the viable segment was indicative of the degree of stenosis of the artery subtending the segment. Regional function deteriorated in patients with high grade (95 +/- 2%) stenoses and improved in those with nonflow limiting stenoses (66 +/- 25%, P = 0.03). Therefore, we conclude that adenosine echocardiography can detect significant coronary stenoses, has a high degree of concordance with thallium in detecting cardiac perfusion abnormalities, and can assess myocardial viability following thrombolytic therapy.

Adenosine↗
PubMed1982

Quantitative estimates of beta-lactam residues in raw milk around a reference standard: collaborative study.

A collaborative study was conducted to determine the reliability of a Bacillus stearothermophilus disc assay method for differentiating various concentrations of penicillin in raw milk. Participating laboratories tested 10 different samples (including one negative) in blind duplicate. Triplicate standards were alternated with triplicate unknowns around the periphery of each of 5 different plates. Zone diameters were measured and the difference in zone size of pairs of adjacent standard and unknown samples were analyzed by a paired t-test. Penicillin concentrations 0.003 IU/mL different from the reference concentrations were consistently distinguishable at a 95% confidence level. Such discriminatory power was determined to be possible with as few as 3 plates (9 replicates) per unknown. The method has been adopted official first action.

Animals↗