2008年2月29日 星期五

2008年2月28日 星期四

Low-Dose Vasopressin in Septic Shock

Low-Dose Vasopressin No Better Than Norepinephrine in Septic Shock

Low-dose vasopressin does not provide a survival advantage over norepinephrine in refractory septic shock, according to a New England Journal of Medicine study.

Researchers studied almost 800 patients with septic shock unresponsive to initial fluid therapy and low-dose norepinephrine. Patients were randomized in a double-blind fashion either to low-dose vasopressin (0.01-0.03 U/min) or to norepinephrine (5-15 μg/min). All patients could continue to receive open-label catecholamine vasopressors as well.

There was no advantage to either regimen at 28 or 90 days after first infusions with regard to survival, rates of organ dysfunction, or rates of serious adverse events.

An editorialist writes: "Although adding vasopressin ... appears to produce similar mortality rates [as norepinephrine] and is safe, there is no compelling advantage to using vasopressin rather than norepinephrine."


2008年2月27日 星期三

Nephrotic Syndrome

Nephrotic Syndrome and Hypercoagulability
The nephrotic syndrome can induce a hypercoagulable state. In one study of patients with the nephrotic syndrome, thromboembolic events occurred in 5% of children and 44% of adults. The mechanisms for hypercoagulability in the nephrotic syndrome include low levels of antithrombin III, due to increased renal clearance; low functional levels of protein S, due to decreased clearance of the C4-binding protein, which binds to protein S, and increased renal clearance of free protein S; increased plasma levels of factors V, VII, VIII, von Willebrand factor, and fibrinogen; and increased production of Lp(a) lipoprotein by the liver.

Teaching topics from the New England Journal of Medicine - Vol. 358, No. 9, February 28, 2008

Pulmonary Embolism

Thrombolytics for Pulmonary Embolism
Heparin is the standard treatment for large pulmonary embolism but in certain rare instances, thrombolytics are sometimes used. However, most studies suggest that thrombolytic therapy does not affect the risk of death (Cochrane Database Syst Rev, 2006), but it may improve right ventricular function in the first 3 days of treatment. However, this benefit needs to be weighed against a 3% risk of a clinically significant hemorrhage. Although such a risk is mainly seen in older patients, there have been a number of reports of serious hemorrhage in children. One of the discussants in this case, explains the fact that he only uses thrombolytics when the patient with a large pulmonary embolism is in shock.

Teaching topics from the New England Journal of Medicine - Vol. 358, No. 9, February 28, 2008

2008年2月20日 星期三

Cold Urticaria

背痛記得要做 Romberg test !

Spinal Stenosis: Symptoms
The most common symptom associated with lumbar spinal stenosis is neurogenic claudication — discomfort that radiates beyond the spinal area into the buttocks and frequently into the thigh and lower leg; it is exacerbated by lumbar extension and improves with lumbar flexion. Patients with symptomatic stenosis are generally comfortable when sitting and have worsening pain with prolonged walking.

Best Radiographic Tests for Spinal Stenosis
Either magnetic resonance imaging (MRI) or computed tomography (CT) may confirm the presence of spinal stenosis, since both modalities can detect the cardinal features of stenosis — reductions in the cross-sectional area of the central canal and neural foramina due to a combination of disk protrusion, redundancy and hypertrophy of facet joints, with accompanying osteophytes. Bony findings such as facet arthropathy can be seen more clearly with CT scans, whereas soft-tissue lesions involving ligaments and disks are better detected with MRI scans. Because CT myelography is invasive and requires intrathecal contrast material, MRI is generally preferred. CT myelography can be used for patients who are not candidates for MRI (e.g., because of clostrophobia or metallic implants) and in rare, specific clinical situations.

Morning Report Questions
Q: What is the Romberg maneuver and what might a positive test indicate?
A: The Romberg maneuver, in which the patient, with eyes closed, stands and is observed for imbalance, may reveal a wide-based gait and unsteadiness. These findings reflect involvement of proprioceptive fibers in the posterior columns. The finding of a wide-based gait among patients with back pain has greater than 90% specificity for lumbar spinal stenosis.

Teaching topics from the New England Journal of Medicine - Vol. 358, No. 8, February 21, 2008

2008年2月14日 星期四




2008年2月13日 星期三

小兒之 vital signs


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


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

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

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

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.