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2008年2月14日 星期四
2008年2月13日 星期三
2008年2月7日 星期四
Orthostatic Hypotension
A fall in the systolic blood pressure of at least 20 mm Hg or in the diastolic blood pressure of at least 10 mm Hg after 3 minutes of standing is diagnostic of orthostatic hypotension. The history and physical examination, as well as laboratory testing (complete blood count, electrolytes, blood glucose level, serum immunoelectrophoresis, vitamin B12 level, and a morning cortisol level) should be focused on ruling out non-neurologic causes (e.g., blood loss, dehydration, and cardiovascular or endocrine disorders) and determining whether other features of primary autonomic degenerative disorders (e.g., Shy–Drager syndrome, Parkinson's disease, or Lewy-body dementia) or autonomic peripheral neuropathies (e.g., diabetes, amyloidosis, or Sjögren's syndrome) are present. If the diagnosis remains unclear, additional testing, including autonomic testing and imaging studies, may be useful.
Drugs that Can Cause Orthostatic Hypotension
The recognition and removal (when possible) of reversible causes of orthostatic hypotension are important. Diuretics, antihypertensive agents, antianginal agents, α-adrenoreceptor antagonists for the treatment of benign prostatic hyperplasia, antiparkinsonism agents, and antidepressants are the most common offending agents.
Q: What are some nonpharmacologic treatments for orthostatic hypotension?
A: Nonpharmacologic treatments for orthostatic hypotension include wearing custom-fitted elastic stockings, or an abdominal binder, or both to reduce peripheral pooling in the lower limbs and splanchnic circulation, increasing fluids and salt intake, raising the head of the bed by 10 to 20 degrees, moving from a supine to a standing position gradually, particularly in the morning, and employing physical maneuvers including crossing the legs, stooping, squatting, and tensing the muscles of the leg, abdomen, or buttock or of the whole body to help maintain blood pressure during daily activities. Rapid ingestion (e.g., over a period of 3 to 4 minutes) of approximately 0.5 liter of tap water elicits a marked pressor response and improvement in symptoms in many, but not all, patients with autonomic failure. Midodrine [ProAmatine], a peripheral, selective, direct α1-adrenoreceptor agonist, is the only medication presently approved by the Food and Drug Administration for the treatment of orthostatic hypotension.
Q: How does standing cause a temporary reduction in blood pressure?
A: Standing results in pooling of 500 to 1000 ml of blood in the lower extremities and splanchnic circulation. There is a decrease in venous return to the heart and reduced ventricular filling, resulting in diminished cardiac output and blood pressure. These hemodynamic changes provoke a compensatory reflex response, initiated by the baroreceptors in the carotid sinus and aortic arch, that results in increased sympathetic outflow and decreased vagal-nerve activity.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
Drugs that Can Cause Orthostatic Hypotension
The recognition and removal (when possible) of reversible causes of orthostatic hypotension are important. Diuretics, antihypertensive agents, antianginal agents, α-adrenoreceptor antagonists for the treatment of benign prostatic hyperplasia, antiparkinsonism agents, and antidepressants are the most common offending agents.
Q: What are some nonpharmacologic treatments for orthostatic hypotension?
A: Nonpharmacologic treatments for orthostatic hypotension include wearing custom-fitted elastic stockings, or an abdominal binder, or both to reduce peripheral pooling in the lower limbs and splanchnic circulation, increasing fluids and salt intake, raising the head of the bed by 10 to 20 degrees, moving from a supine to a standing position gradually, particularly in the morning, and employing physical maneuvers including crossing the legs, stooping, squatting, and tensing the muscles of the leg, abdomen, or buttock or of the whole body to help maintain blood pressure during daily activities. Rapid ingestion (e.g., over a period of 3 to 4 minutes) of approximately 0.5 liter of tap water elicits a marked pressor response and improvement in symptoms in many, but not all, patients with autonomic failure. Midodrine [ProAmatine], a peripheral, selective, direct α1-adrenoreceptor agonist, is the only medication presently approved by the Food and Drug Administration for the treatment of orthostatic hypotension.
Q: How does standing cause a temporary reduction in blood pressure?
A: Standing results in pooling of 500 to 1000 ml of blood in the lower extremities and splanchnic circulation. There is a decrease in venous return to the heart and reduced ventricular filling, resulting in diminished cardiac output and blood pressure. These hemodynamic changes provoke a compensatory reflex response, initiated by the baroreceptors in the carotid sinus and aortic arch, that results in increased sympathetic outflow and decreased vagal-nerve activity.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
咳超過2個月...
Q: What is the differential diagnosis for a cough that lasts longer than 8 weeks?
A: A key feature when evaluating a patient with cough is symptom duration. Acute cough lasts less than 3 weeks and is usually caused by respiratory tract infection. Cough lasting longer than 8 weeks is considered chronic and is most often due to postnasal drip, asthma, or gastroesophageal reflux disease.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
A: A key feature when evaluating a patient with cough is symptom duration. Acute cough lasts less than 3 weeks and is usually caused by respiratory tract infection. Cough lasting longer than 8 weeks is considered chronic and is most often due to postnasal drip, asthma, or gastroesophageal reflux disease.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
Waxing and waning pulmonary nodules
Q: What conditions could cause waxing and waning pulmonary nodules?
A: Waxing and waning pulmonary nodules can occur with several conditions. Sarcoidosis is one possible diagnosis in a patient who also has hilar and mediastinal adenopathy. Patients with rheumatoid arthritis can also have cavitary nodules that relapse and remit in concert with systemic disease activity. Other conditions to consider include Wegener's granulomatosis and chronic thromboembolic disease.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
A: Waxing and waning pulmonary nodules can occur with several conditions. Sarcoidosis is one possible diagnosis in a patient who also has hilar and mediastinal adenopathy. Patients with rheumatoid arthritis can also have cavitary nodules that relapse and remit in concert with systemic disease activity. Other conditions to consider include Wegener's granulomatosis and chronic thromboembolic disease.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
咳血之 DDx
Hemoptysis can be caused by diseases of the airways, particularly bronchitis or bronchiectasis. Other causes include bronchogenic carcinoma, metastatic cancer or bronchial carcinoid. Kaposi's sarcoma involving the airways may cause hemoptysis in patients infected with HIV. Hemoptysis can also arise from the lung parenchyma. Autoimmune diseases (such as SLE, mixed connective tissue diseases, etc.), cocaine inhalation, and infections (including tuberculosis, bacterial pneumonia, and lung abscess), as well as pulmonary embolism, pulmonary arteriovenous malformation, mitral stenosis, severe left heart failure, and Wegener's granulomatosis should also be included in the differential diagnosis of hemoptysis.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 6, February 7, 2008
2008年2月5日 星期二
D-dimer and CRP
D-Dimer and Inflammatory Markers Are Associated with Short-Term Mortality
But these findings must be replicated before they can be used clinically.
Thrombosis and inflammation are involved in the pathogenesis of acute cardiovascular events, but whether markers of these processes can predict short-term harm is unknown. Researchers studied the association between such markers and mortality in a prospective cohort of 377 patients with peripheral arterial disease. During 4 years of follow-up, 76 patients (20%) died; 31 died of cardiovascular disease.
Higher levels of D-dimer, C-reactive protein, and serum amyloid A were each associated significantly with higher all-cause mortality within 1 year, and from 1 to 2 years, but not 2 to 3 years after measurement, in survival analyses adjusted for age, sex, race, cardiovascular diseases, cancer, diabetes, smoking, and ankle-brachial index. A similar pattern was observed for cardiovascular mortality (except that D-dimer remained a significant predictor at 2 to 3 years).
Comment: Biomarkers such as those studied in this cohort have not been particularly useful for predicting long-term mortality because they have not added much information beyond that provided by more easily measured traditional risk factors. But if these findings are confirmed in other samples, these biomarkers could have use for predicting short-term outcomes.
— Richard Saitz, MD, MPH, FACP, FASAM
Published in Journal Watch General Medicine February 5, 2008
Citation(s): Vidula H et al. Biomarkers of inflammation and thrombosis as predictors of near-term mortality in patients with peripheral arterial disease: A cohort study. Ann Intern Med 2008 Jan 15; 148:85.
But these findings must be replicated before they can be used clinically.
Thrombosis and inflammation are involved in the pathogenesis of acute cardiovascular events, but whether markers of these processes can predict short-term harm is unknown. Researchers studied the association between such markers and mortality in a prospective cohort of 377 patients with peripheral arterial disease. During 4 years of follow-up, 76 patients (20%) died; 31 died of cardiovascular disease.
Higher levels of D-dimer, C-reactive protein, and serum amyloid A were each associated significantly with higher all-cause mortality within 1 year, and from 1 to 2 years, but not 2 to 3 years after measurement, in survival analyses adjusted for age, sex, race, cardiovascular diseases, cancer, diabetes, smoking, and ankle-brachial index. A similar pattern was observed for cardiovascular mortality (except that D-dimer remained a significant predictor at 2 to 3 years).
Comment: Biomarkers such as those studied in this cohort have not been particularly useful for predicting long-term mortality because they have not added much information beyond that provided by more easily measured traditional risk factors. But if these findings are confirmed in other samples, these biomarkers could have use for predicting short-term outcomes.
— Richard Saitz, MD, MPH, FACP, FASAM
Published in Journal Watch General Medicine February 5, 2008
Citation(s): Vidula H et al. Biomarkers of inflammation and thrombosis as predictors of near-term mortality in patients with peripheral arterial disease: A cohort study. Ann Intern Med 2008 Jan 15; 148:85.
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