2008年3月29日 星期六
The "Taipei 101" sign
A 2-year-old boy presents with fever, a barking cough, and stridor. In the ED, he is agitated. His vital signs include a temperature of 102.3 F, and a heart rate of 120 beats/minute. Respiration is 28 breaths/minute, and oxygen saturation is 96%. He has mild nasal flaring and subcostal retraction.
Q-1: What is the characteristic finding on this radiograph?
Q-2: Is the radiograph necessary to make the diagnosis?
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Ans-1: Steeple sign, which is a narrowed subglottic air column.
Ans-2: Croup is a clinical diagnosis. X-ray and other laboratory studies are generally not necessary for diagnosis.
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Case History by Muhammed Waseem, MD
More similar cases could be found at:
http://www.accessemergencymedicine.com/
2008年3月27日 星期四
Framingham risk score
Q: What is the Framingham risk score and how does it predict cardiovascular risk?
A:
A:
- The Framingham score remains the most common way to predict cardiovascular risk.
- By assessment of clinical and laboratory values, including age, sex, total cholesterol level, high-density lipoprotein cholesterol level (HDL), smoking status, and systolic blood pressure, the 10-year risk of a cardiovascular event can be calculated with approximately 75% accuracy.
- In another study by Detrano and colleagues, participants who had a subsequent coronary event had significantly higher levels of coronary calcium, serum triglycerides, creatinine, and systolic blood pressure, lower levels of HDL, and a higher prevalence of diabetes and hypertension as compared with participants who did not have a coronary event.
Laplace's law
Q: What is Laplace's law and how does it relate to cardiac hypertrophy?
A:
A:
- Laplace's law is as follows: T = (P × R)/M where T is the tension in the walls, P is the pressure difference across the walls, R is the radius of the vessel and M is the thickness of the wall.
- In dilated cardiomyopathy, after prolonged increases in afterload (in the setting of hemodynamic stress such as hypertension), the heart becomes distended and the radius of the ventricle increases.
- To create the same pressure during ejection of the blood, much larger wall tension has to be developed by cardiac muscle and the ventricular wall thickens.
- The dilated hypertrophic heart requires more energy (and oxygen consumption) to pump the same amount of blood as compared to the heart of normal size.
- Dilated cardiomyopathy causes increases in the risks of ischemia and arrhythmias.
2008年3月18日 星期二
Trauma 之 c-spine survey
記得要照 adequate c-spine.
今天和哈醫師討論到 SICU 的 trauma 個案時，發現有些 case 的 c-spine 照得不好但卻沒有重照，恐怕會影響到 SICU 的 tertiary survey 及治療。
記得 c-spine x-光判讀的 A-B-C-S 順序：
A = Alignment + adequacy(從 skull base 到 T1 上半)，
B = Bony structures (找 fracture lines)，
C = Cartilages (含生長板及生長中心)，
S = Soft tissue (predental、prevertebral)。
More at....
http://er119test.blogspot.com/2007/08/c-spine-fractures-stable-or-not.html
http://er119.org/xoops_er119/er119uploads/c_spine_radiology.pdf
今天和哈醫師討論到 SICU 的 trauma 個案時，發現有些 case 的 c-spine 照得不好但卻沒有重照，恐怕會影響到 SICU 的 tertiary survey 及治療。
記得 c-spine x-光判讀的 A-B-C-S 順序：
A = Alignment + adequacy(從 skull base 到 T1 上半)，
B = Bony structures (找 fracture lines)，
C = Cartilages (含生長板及生長中心)，
S = Soft tissue (predental、prevertebral)。
More at....
http://er119test.blogspot.com/2007/08/c-spine-fractures-stable-or-not.html
http://er119.org/xoops_er119/er119uploads/c_spine_radiology.pdf
2008年3月14日 星期五
何時要驗 CSF lactate？
What Laboratory Testing May Be Helpful in Distinguishing Bacterial from Viral Meningitis?
Determination of Lactate Concentration
Measurement of CSF lactate concentration is not recommended for patients with suspected community-acquired bacterial meningitis (D-III)
However, measurement of CSF lactate concentrations was found to be superior to use of the ratio of CSF to blood glucose for the diagnosis of bacterial meningitis in postoperative neurosurgical patients, in which a CSF concentration of 4.0 mmol/ L (36 mg/dL) was used as a cutoff value for the diagnosis. The sensitivity was 88%, the specificity was 98%, the positive predictive value was 96%, and the negative predictive value was 94%. CSF lactate concentrations may be valuable in this subgroup of patients, in whom the usual CSF findings--elevated white blood cell (WBC) counts (total and differential), positive Gram stain results, diminished glucose concentrations, and elevated protein concentrations--are neither sensitive nor specific to reliably distinguish bacterial from a nonbacterial meningeal syndrome. Therefore, in the postoperative neurosurgical patient, initiation of empirical antimicrobial therapy should be considered if CSF lactate concentrations are > 4.0 mmol/L, pending results of additional studies (B-II).
http://www.guideline.gov/about/inclusion.aspx
Determination of Lactate Concentration
Measurement of CSF lactate concentration is not recommended for patients with suspected community-acquired bacterial meningitis (D-III)
However, measurement of CSF lactate concentrations was found to be superior to use of the ratio of CSF to blood glucose for the diagnosis of bacterial meningitis in postoperative neurosurgical patients, in which a CSF concentration of 4.0 mmol/ L (36 mg/dL) was used as a cutoff value for the diagnosis. The sensitivity was 88%, the specificity was 98%, the positive predictive value was 96%, and the negative predictive value was 94%. CSF lactate concentrations may be valuable in this subgroup of patients, in whom the usual CSF findings--elevated white blood cell (WBC) counts (total and differential), positive Gram stain results, diminished glucose concentrations, and elevated protein concentrations--are neither sensitive nor specific to reliably distinguish bacterial from a nonbacterial meningeal syndrome. Therefore, in the postoperative neurosurgical patient, initiation of empirical antimicrobial therapy should be considered if CSF lactate concentrations are > 4.0 mmol/L, pending results of additional studies (B-II).
http://www.guideline.gov/about/inclusion.aspx
2008年3月9日 星期日
2008年3月5日 星期三
腳比手 cyanosis 更嚴重
Patent ductus arteriosus (PDA), caused by failure of the embryologic ductus arteriosus to close after birth, represents 10% of cases of congenital heart disease. The most common symptoms include dyspnea, exercise intolerance, peripheral edema, and palpitations, although 25 to 40% of patients with a PDA are asymptomatic. With PDA, in contrast to many other shunts, continuous left-to-right shunting may occur because of the large resistance and the pressure gradient that normally exists between the systemic and pulmonary vascular beds. However, if left untreated, some patients may develop serious cardiac pathology — either elevated pulmonary artery pressure from the increased pulmonary blood flow due to the shunt, eventually leading to increased pulmonary vascular resistance and severe pulmonary hypertension or left heart volume overload due to the ductal shunt, eventually resulting in left-sided heart failure.
Morning Report Questions
Q: What is Eisenmenger's syndrome?
A: Eisenmenger's syndrome refers to right-to-left cardiac shunting with cyanosis. This syndrome develops as a serious consequence of patent ductus arteriosus when pulmonary systolic pressure equals or exceeds the aortic pressure, and a right-to-left shunt ensues.
Q: What type of cardiac anomaly might exist if a patient has cyanosis of the toenails and not the fingernails?
A: When the physiology of Eisenmenger's syndrome is due to patent ductus arteriosus (right-to-left shunting and cyanosis), the oxygen saturation in the descending aorta is reduced. As a result, physical examination may reveal increased cyanosis of the toenails as compared with the fingernails.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008
Morning Report Questions
Q: What is Eisenmenger's syndrome?
A: Eisenmenger's syndrome refers to right-to-left cardiac shunting with cyanosis. This syndrome develops as a serious consequence of patent ductus arteriosus when pulmonary systolic pressure equals or exceeds the aortic pressure, and a right-to-left shunt ensues.
Q: What type of cardiac anomaly might exist if a patient has cyanosis of the toenails and not the fingernails?
A: When the physiology of Eisenmenger's syndrome is due to patent ductus arteriosus (right-to-left shunting and cyanosis), the oxygen saturation in the descending aorta is reduced. As a result, physical examination may reveal increased cyanosis of the toenails as compared with the fingernails.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008
Urinary retention 的定義
Q: What are normal residual urine volumes?
A: What constitutes abnormal residual bladder urinary volumes is debated; however, residual volumes greater than 150 milliliters on two occasions are suggestive of urinary retention (which may result in “overflow” incontinence) and should prompt further evaluation for voiding dysfunction.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008
A: What constitutes abnormal residual bladder urinary volumes is debated; however, residual volumes greater than 150 milliliters on two occasions are suggestive of urinary retention (which may result in “overflow” incontinence) and should prompt further evaluation for voiding dysfunction.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008
DVT and Pulmonary Embolism
About 80% of patients who present with pulmonary embolism have evidence of deep venous thrombosis in their legs; if deep venous thrombosis is not detected in such patients, it is likely that the whole thrombus has already detached and embolized. Conversely, pulmonary embolism occurs in up to 50% of patients with proximal deep venous thrombosis.
D-Dimer Tests
Although a positive D-dimer test (which measures plasma levels of a specific derivative of cross-linked fibrin) indicates that venous thrombosis and pulmonary embolism are possible diagnoses, this test is nonspecific, since it may be positive in hospitalized patients with infection, cancer, trauma, and other inflammatory states and thus cannot inform decisions about treatment. When an ELISA-based D-dimer test is negative, deep venous thrombosis and pulmonary embolism are ruled out in patients with a low or moderate pretest probability, precluding the need for specific imaging studies.
Anticoagulation
The low-molecular-weight heparin and pentasaccharide preparations have advantages over unfractionated heparin, including greater bioavailability, more predictable dosing, subcutaneous delivery (usually without the need for monitoring), and a lower risk of heparin-induced thrombocytopenia.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008
D-Dimer Tests
Although a positive D-dimer test (which measures plasma levels of a specific derivative of cross-linked fibrin) indicates that venous thrombosis and pulmonary embolism are possible diagnoses, this test is nonspecific, since it may be positive in hospitalized patients with infection, cancer, trauma, and other inflammatory states and thus cannot inform decisions about treatment. When an ELISA-based D-dimer test is negative, deep venous thrombosis and pulmonary embolism are ruled out in patients with a low or moderate pretest probability, precluding the need for specific imaging studies.
Anticoagulation
The low-molecular-weight heparin and pentasaccharide preparations have advantages over unfractionated heparin, including greater bioavailability, more predictable dosing, subcutaneous delivery (usually without the need for monitoring), and a lower risk of heparin-induced thrombocytopenia.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008
2008年3月4日 星期二
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