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Saturday, March 9, 2013
சிறுவர்களும் உளச்சோர்வும்
Saturday, February 23, 2013
divide and rule policy of media
polio eradication
Tuesday, January 25, 2011
Saturday, December 18, 2010
artifiificial kidneycial kidney!!!!!?
One of the indian Boiscientists who is working in america has came out with artifial kidney which has been succesfly been tested with swine. andnow they are going in with monkeys will hopethe best for the best of renal patients
Thursday, July 22, 2010
Thursday, July 15, 2010
Eponymous signs of Aortic regurgitation
Austin Flint Murmur
Origin
In 1862, while Austin Flint was professor of medicine at the New Orleans School of Medicine in Louisiana and an attending at Charity Hospital, he reported two cases of aortic regurgitation that also demonstrated a “blubbering presystolic murmur,” which seemed characteristic of mitral stenosis However, normal mitral valves and apparatus were revealed at autopsy. Of interest, although his perspicacious observation led to his name being attached to the sign, Austin Flint himself was categorically opposed to eponyms. He wrote, “So long as signs are determined from fancied analogies, and named from these or after the person who describes them, there cannot but be obscurity and confusion”.
Description
The murmur typically begins in mid-diastole, often has a presystolic accentuation, and terminates at the end of diastole. It is low-pitched, with a rough and rumbling quality, and best heard at the apex. An Austin Flint murmur can be deemed present only in the setting of aortic regurgitation without coexisting mitral stenosis, since the latter can generate a similar murmur.
Pathophysiology
Austin Flint postulated that regurgitant blood flow in severe aortic regurgitation impinges on the leaflets of the mitral valve, leading to a functional stenosis. Diastolic inflow across this narrowed mitral valve orifice generates turbulence that is clinically appreciable as a mid- to late diastolic murmur. Later investigations have advanced a variety of other theories as causes for the murmur, including overlap of aortic regurgitation and mitral inflow jets, fluttering of mitral valve leaflets, and left ventricular endocardial vibrations due to the aortic regurgitation jet. However, a universally accepted explanation remains elusive.
Elicitation
The murmur is best heard on auscultation at the apex by using the bell of the stethoscope, with the patient in the left lateral position.
Evidence
The Austin Flint murmur was mentioned in each of the 11 textbooks , and all mentions were categorized as important (Studies of this sign have focused more on investigating its mechanism than documenting its existence or diagnostic accuracy. Twelve studies met our inclusion criteria (. Three reports, which dealt with patients who had both aortic regurgitation and mitral stenosis, were excluded from further analysis because an Austin Flint murmur cannot occur in the presence of mitral stenosis. The remaining 9 studies are detailed in . Only 2 involved more than 35 patients . In addition, selection bias was a significant methodologic flaw, since all studies included only patients with aortic regurgitation. Failure to blind examiners to the results of reference tests was a potential source of test review bias in 6 of 9 reports. Conversely, readers of the reference test were potentially aware of the index test results in 7 of 9 cases. Different reference standards were used to establish the diagnosis of aortic regurgitation, both across and within studies. Earlier studies frequently used phonocardiography as a reference standard, while later studies largely incorporated angiography or echocardiography.
There was extreme variation in the reported sensitivity of the studies from 25% to 100%. Limiting the analysis to patients with known severe aortic regurgitation yielded sensitivities ranging from 57% to 100%. Low sensitivity, ranging from 0% to 50%, was reported among patients with known mild to moderate disease. Although some researchers have reported specificity for the Austin Flint murmur, we have refrained from doing so. By definition, the murmur can occur only in the setting of aortic regurgitation; therefore, estimates of specificity are meaningless.
Corrigan Pulse
Origins
Sir Dominic Corrigan wrote the seminal paper on aortic regurgitation in 1832 while at the Jervis Street Hospital in Dublin, Ireland. Corrigan emphasized the visual nature of the pulse (sometimes referred to thereafter as a Corrigan sign), but the eponym has come to represent its tactile qualities. Common synonyms include “collapsing pulse” and “water-hammer pulse.”
Description
This sign is characterized by a rapidly swelling and falling arterial pulse that is typically appreciated by palpating the radial artery and accentuated by wrist elevation.
Pathophysiology
Numerous hypotheses have been advanced over the past century and a half. A recent investigation found that patients with aortic regurgitation had increased amplitude of the pulse, lower mean arterial pressure, and narrower pulse pressure than normal patients. The investigators concluded that these characteristics reflected an increase in the compliance of the arterial wall in patients with aortic regurgitation.
Elicitation
The examiner palpates the patient's radial artery while elevating the wrist. If the pulse clearly increases in amplitude, then the sign is present.
Evidence
The Corrigan pulse was mentioned in 11 textbooks; 10 of these mentions were categorized as important. Six studies met our inclusion criteria. One study was excluded because it used the presence of a collapsing pulse as an inclusion criterion. The remaining 5 studies are detailed in. All reports involved more than 35 patients yet suffered from selection bias. Three studies were prospective, and 1 used blinded examiners for both index and reference tests. Two studies used angiography as the gold standard, another used echocardiography, and a fourth used autopsy. One study did not report a reference standard.
Sensitivity ranged widely, from 38% to 95%. One study examined the impact of aortic regurgitation severity on sensitivity and found no significant effect. It should be noted that this report had a low prevalence of hemodynamically significant aortic regurgitation. The same study reported specificity, which was extremely low (16%) among 103 patients. Ranges for sensitivity, stratified by severity of aortic regurgitation, and specificity are presented in
Duroziez Sign
Origin
Paul Duroziez was a noted French physician with a special interest in the heart. In 1861, the same year he described the “double intermittent murmur” over the femoral arteries, he also wrote a classic treatise on pure mitral stenosis
Description
The sign denotes an intermittent to-and-fro femoral artery murmur (occurring in systole and diastole, respectively) generated by femoral artery compression.
Pathophysiology
Duroziez believed the systolic portion of the murmur was caused by forward flow into the lower extremity and that the diastolic segment was caused by aortic regurgitation toward the heart . Despite earlier controversy , subsequent investigations support this theory .
Elicitation
Duroziez auscultated the femoral artery while applying digital compression proximal and distal to the stethoscope . Blumgart and Ernstene replaced digital compression with cephalad and caudad tilting of the stethoscope. Luisada showed that the optimal compressive pressure needed to successfully evoke a Duroziez sign was about three quarters of the pulse pressure above the diastolic pressure.
Evidence
The sign was mentioned in 9 texts; 7 mentions were classified as important. Five reports met our inclusion criteria. Of these, 3 had sample sizes exceeding 35 patients. All studies suffered from selection bias. Two included patients without aortic regurgitation and all but 1 study were prospective. Examiners were blinded to reference test results in a single study Two studies did not specify a consistent reference standard Of the 3 remaining studies, 1 used autopsy and 2 used angiography
Sensitivity was highly variable, ranging from 33% to 81% Similar variations were seen in specificity, from 35% (based on 31 patients) to 100% (based on only 2 patients). We are unable to comment on the impact of aortic regurgitation severity on the Duroziez sign because data were inadequate. shows ranges for sensitivity, stratified by aortic regurgitation severity, and specificity.
Hill Sign
Origin
Sir Leonard Hill was an English physiologist. W. Holtzmann, one of his assistants, chanced to observe that lower-extremity blood pressures in patients with aortic regurgitation were consistently higher than pressures in the upper extremity. Hill and colleagues reported these findings in 1909 followed by a similar study of healthy young men in 1911 This sign is also known as the popliteal–brachial gradient.
Description
Hill and colleagues described a “marked” increase of systolic blood pressure in the lower extremity compared with the upper extremity in patients with aortic regurgitation, without specifying numerical criteria . Frank and coworkers subsequently proposed that the degree of regurgitation is correlated with the increase in the popliteal–brachial gradient above 20 mm Hg This criterion has been generally accepted and used in some later studies and textbook descriptions , as well as in this review.
Pathophysiology
Etiologic investigations have yielded conflicting results. From later studies, it is apparent that there is no true increase in intra-arterial lower-extremity blood pressures compared with the upper extremity in patients with aortic regurgitation The Hill sign, therefore, remains an unexplained artifact of indirect blood pressure measurement that is consistently more common and pronounced in patients with aortic regurgitation than in those without.
Elicitation
The blood pressure is manually obtained over the brachial and femoral arteries by using appropriately sized cuffs, with the patient in the recumbent position. The difference in systolic pressures denotes the gradient.
Evidence
The Hill sign was mentioned in four textbooks , and all mentions were classified as important (Seven reports met our inclusion criteria (Only 1 study had more than 35 patients Selection bias was uniformly present. With the exception of 1 study that blinded examiners, there was no evidence of blinding to index or reference test results. Five studies did not specify a reference standard A sixth study used more than one standard (angiography, phonocardiography) within the cohort , and the seventh study incorporated angiography . Reported sensitivity was extremely variable, ranging from 0% to 100% . There were 4 reports of specificity, ranging from 71% in 14 patients to 100% in 3 studies with 5, 23, and 24 patients, respectively
One study attempted to correlate indirectly measured popliteal–brachial blood pressure values with angiographic findings The investigators concluded that the degree of the popliteal–brachial gradient predicted severity of aortic regurgitation. For patients with more than mild aortic regurgitation, an increase in popliteal–brachial gradient above 20 mm Hg had a sensitivity of 89%. However, the sign did not distinguish between patients with mild aortic regurgitation and normal persons. This was confirmed by a later report, which found a sensitivity of 0% for the diagnosis of mild aortic regurgitation in 22 patients The threshold of 20 mm Hg was used to calculate the sensitivity and specificity estimates in and in
Discussion
Aortic regurgitation is a chronic valvular disorder that can lead to substantial morbidity and mortality The long-term prognosis of chronic aortic regurgitation is closely linked to the severity of regurgitation and the development of left ventricular dysfunction Asymptomatic patients with normal left ventricular function rarely warrant aortic valve replacement but may benefit from therapy with vasodilators, such as nifedipine Aortic valve replacement is usually considered for patients with severe aortic regurgitation accompanied by significant symptoms or onset of left ventricular dysfunction It is therefore vital to determine both the presence and severity of aortic regurgitation.
The history and physical examination are the first steps in this process. These assessments can guide the choice of ancillary tests, such as echocardiography, that may be necessary to reach a diagnostic conclusion with an acceptable degree of certainty. The key physical finding of aortic regurgitation is an early diastolic murmur. However, this murmur can be difficult to appreciate and has poor sensitivity In addition, murmur characteristics do not necessarily predict the severity of aortic regurgitation Therefore, consideration of additional physical findings may be valuable, and textbooks are replete with eponymous signs thought to be associated with chronic aortic regurgitation. On review of 11 prominent textbooks, we found 12 such eponymous signs. Although the textbooks generally supported them evidence was rarely cited. We therefore conducted a systematic review of the literature and found that only the Austin Flint murmur, the Corrigan pulse, and the signs of Duroziez and Hill had sufficient evidence to meet our criteria for detailed review.
The papers reviewed varied widely in methods, disease definitions, and reference standards. In particular, the use of different reference standards within the same study has been shown to result in a biased estimate of diagnostic accuracy Thus, the available data, particularly from older studies, may not accurately reflect the operating characteristics of these signs in aortic regurgitation.
Reported sensitivities for the four signs reviewed in detail were highly variable. As discussed previously, specificity was not considered for the Austin Flint murmur. The Corrigan pulse had extremely low specificity. The Duroziez sign also had low specificity in the one report of reasonable size Specificity of the Hill sign seems to be quite good but is based on four reports with small samples
Evidence regarding the impact of severity of aortic regurgitation on the manifestation of these signs is similarly sparse. Several studies included data on patients with varying severity of disease. However, only three studies specifically examined this question The first examined the Austin Flint murmur and found that sensitivity modestly increased with worsening severity of aortic regurgitation . The second studied the Corrigan pulse and found no association between increasing severity of aortic regurgitation and sensitivity. Finally, a detailed investigation of the Hill sign reported significant correlation between an increase in the popliteal–brachial gradient and worsening severity of regurgitation. All three studies used the currently accepted reference standards of echocardiography or angiography to determine the presence and severity of aortic regurgitation.
What do our findings mean? Thoughtful educators and clinicians should be mindful that, although textbooks support many of these eponymous signs, there is little evidence in the published literature. This may seem surprising given the longevity of these signs in textbooks and medical lore. However, variance between textbook recommendations and actual literature is not uncommon with respect to the clinical manifestations of disease, as highlighted in a recent editorial The reasons for this are multifactorial and include refinements in the accepted standards of medical evidence, changes in patient populations and disease characteristics, a shift from meticulous physical examination to a greater reliance on technology, and the difficulty of obtaining funding for research to perform primary studies focusing on the physical examination Therefore, the absence of evidence to support these signs does not mean that they are without merit. Instead, it attests to the need to rejuvenate the overall literature on the physical examination and attune it to the 21st century. Such an effort would be of value not only to the profession but also to patients because it could potentially reduce the need for expensive and time-consuming ancillary tests.
Our report has limitations. First, the textbooks reviewed to provide an estimate of the current popularity of the signs of aortic regurgitation were works prominent in the United States. Despite the broad international readerships of the works selected, texts that are influential in other parts of the world may have been excluded. Second, our qualitative estimate of textbook content may not accurately represent the attitudes of the medical profession at large. However, textbooks are widely used as fundamental reference sources for physical diagnosis and generally represent an accepted synthesis of expert opinion. Third, our literature review was confined to reports in English, leading to the potential omission of relevant reports in other languages. To minimize the effect of this possible bias, we also reviewed citations of non–English-language reports in our MEDLINE text word search and did not identify any of potential significance. Finally, although summary estimates of diagnostic accuracy for these signs would have been desirable, the heterogeneity among studies precluded such calculations.
Much like the attending physician in our clinical scenario, those who have long embraced time-honored components of the physical examination may be challenged to reexamine their place in contemporary teaching and practice. Such challenges should prompt neither a reflexive defense nor an apologetic retreat. Rather, they should inspire clinicians and educators who value the physical examination to redouble their efforts to update and improve the evidence so the physical examination can earn a more substantial place in current medical practice. If celebrated elements of the physical examination such as the eponymous signs of aortic regurgitation are to prosper in the clinical lexicon, they will need the support not only of tradition but also of science
Courtesy www.annals.org
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