Spine Immobilization for Penetrating Trauma Can Be Harmful
Patients who underwent immobilization were twice as likely to die as those who did not.
Despite a lack of supportive evidence for the practice, prehospital providers often apply spine immobilization to patients who have penetrating trauma to the head, neck, or torso without neurological symptoms or deficit. These authors retrospectively assessed the effect of prehospital spine immobilization on mortality in patients with penetrating trauma using data from the American College of Surgeons National Trauma Data Bank between 2001 and 2004.
Of 45,284 patients (median age, 29), 4.3% received cervical collars, spinal backboards, or both. The overall mortality rate was 8.1%. Multiple logistic regression analysis that controlled for confounders, including Injury Severity Score and Revised Trauma Score, showed that immobilized patients had significantly increased mortality (odds ratio, 2.06); this finding held true in subgroups of patients with gunshot wounds (OR, 2.12), hypotension (OR, 2.42), and gunshot wounds and hypotension (OR, 3.19). Complete data on in-hospital procedures were available for about 31,000 patients. Only 30 patients (0.1%) underwent operative spine stabilizing procedures for incomplete spinal-cord injury. The number needed to treat with spine immobilization to potentially benefit 1 patient was 1032. The number needed to harm with spine immobilization to potentially contribute to 1 death was 66.
Comment:
Increasing evidence indicates that limited intervention at the scene allows trauma patients to receive definitive care at a trauma center more rapidly. This study indicates that prehospital spine immobilization is associated with increased mortality in patients with penetrating trauma. Trying to assign cause and effect in a retrospective study is risky, but possibly increased scene time or interference with later care (e.g., intubation, radiography, examination of the patient's back) contribute to worse outcomes. Spine immobilization might be applied more wisely to patients with altered mental status, spine tenderness, or sensorimotor dysfunction.
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John A. Marx, MD, FAAEM
Published in Journal Watch Emergency Medicine January 29, 2010
Citation(s): Haut ER et al. Spine immobilization in penetrating trauma: More harm than good? J Trauma 2010 Jan; 68:115.
2010年1月29日 星期五
2010年1月22日 星期五
CT Radiation Exposure and Cancer
Radiation from CT scans might cause 2% of future cancers.
An estimated 72 million computed tomography (CT) scans were performed in the U.S. in 2007. Two research groups assessed radiation dose from CT scans and future cancer risk.
Smith-Bindman and colleagues studied CT scans performed at four hospitals (private and public, large and small) in San Francisco in 2008. For each of 11 types of CT studies, the researchers estimated the effective dose of radiation, which takes into account "the amount of radiation to the exposed organs and each organ's sensitivity to developing cancer from radiation exposure."
The effective dose varied widely both within and between institutions for each type of CT study. The median effective dose was 2 millisieverts (mSv) for a noncontrast head CT scan and 31 mSv for an abdomen-pelvis study. For comparison, the effective dose is 0.065 mSv from posteroanterior and lateral chest radiography and 0.42 mSv from conventional mammography.
The authors estimated that a coronary angiogram delivers radiation to the breast equivalent to 15 mammograms and to the lung equivalent to 711 chest x-rays. The lag time between exposure and cancer development makes exposure potentially riskier for younger than older patients; the authors estimated that 1 in every 270 women who undergo coronary CT angiography at age 40 will develop cancer.
Berrington de Gonzalez and colleagues used a national database to estimate age-specific cancer risks from CT studies performed in the U.S. in 2007. CT scans performed during the last 5 years of life or after a diagnosis of cancer were excluded from the analysis. Thirty percent of CT scans were performed on patients aged 35 to 54. The authors predict that 2% (29,000) of future cancers will be caused by CT scans performed in 2007, and they estimate a cancer mortality rate of 50%.
Comment:
An editorialist terms these numbers "eye opening" and calls for dose standardization, patient education, and test ordering guidelines. A recent government report shows an eightfold difference in test ordering across states, with no detectable mortality benefit from higher rates of testing. One approach to limiting radiation exposure is to display patients' historical cumulative radiation dose in electronic order entry systems. It is time for someone to shout "stop."
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J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine January 22, 2010
Citation(s): Smith-Bindman R et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 2009 Dec 14/28; 169:2078.
An estimated 72 million computed tomography (CT) scans were performed in the U.S. in 2007. Two research groups assessed radiation dose from CT scans and future cancer risk.
Smith-Bindman and colleagues studied CT scans performed at four hospitals (private and public, large and small) in San Francisco in 2008. For each of 11 types of CT studies, the researchers estimated the effective dose of radiation, which takes into account "the amount of radiation to the exposed organs and each organ's sensitivity to developing cancer from radiation exposure."
The effective dose varied widely both within and between institutions for each type of CT study. The median effective dose was 2 millisieverts (mSv) for a noncontrast head CT scan and 31 mSv for an abdomen-pelvis study. For comparison, the effective dose is 0.065 mSv from posteroanterior and lateral chest radiography and 0.42 mSv from conventional mammography.
The authors estimated that a coronary angiogram delivers radiation to the breast equivalent to 15 mammograms and to the lung equivalent to 711 chest x-rays. The lag time between exposure and cancer development makes exposure potentially riskier for younger than older patients; the authors estimated that 1 in every 270 women who undergo coronary CT angiography at age 40 will develop cancer.
Berrington de Gonzalez and colleagues used a national database to estimate age-specific cancer risks from CT studies performed in the U.S. in 2007. CT scans performed during the last 5 years of life or after a diagnosis of cancer were excluded from the analysis. Thirty percent of CT scans were performed on patients aged 35 to 54. The authors predict that 2% (29,000) of future cancers will be caused by CT scans performed in 2007, and they estimate a cancer mortality rate of 50%.
Comment:
An editorialist terms these numbers "eye opening" and calls for dose standardization, patient education, and test ordering guidelines. A recent government report shows an eightfold difference in test ordering across states, with no detectable mortality benefit from higher rates of testing. One approach to limiting radiation exposure is to display patients' historical cumulative radiation dose in electronic order entry systems. It is time for someone to shout "stop."
—
J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine January 22, 2010
Citation(s): Smith-Bindman R et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 2009 Dec 14/28; 169:2078.
2010年1月21日 星期四
Heart Failure
Which patients with heart failure should be treated with angiotensin-converting–enzyme (ACE) inhibitors?
ACE inhibitors are the first-line therapy for patients with systolic heart failure; therapy should be initiated promptly after diagnosis and continued indefinitely. ACE inhibitors increase the ejection fraction modestly and reduce ventricular size, symptoms, hospitalization, and overall mortality. ACE inhibitors also reduce the risk of myocardial infarction.
When should spironolactone be used in patients with heart failure?
In a large, placebo-controlled, randomized trial in which patients received spironolactone in addition to a diuretic, digoxin, and an ACE inhibitor, a reduction in symptoms and in hospital admissions, and a 30% reduction in mortality, were seen among patients with severe systolic heart failure (NYHA class III or IV). Therefore, the addition of an aldosterone antagonist should be considered for any patient who remains in NYHA class III or IV, despite treatment with a diuretic, an ACE inhibitor (or angiotensin-receptor blocker [ARB]), and a beta-blocker.
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Teaching topics from the New England Journal of Medicine - Vol. 362, No. 3, January 21, 2010
ACE inhibitors are the first-line therapy for patients with systolic heart failure; therapy should be initiated promptly after diagnosis and continued indefinitely. ACE inhibitors increase the ejection fraction modestly and reduce ventricular size, symptoms, hospitalization, and overall mortality. ACE inhibitors also reduce the risk of myocardial infarction.
When should spironolactone be used in patients with heart failure?
In a large, placebo-controlled, randomized trial in which patients received spironolactone in addition to a diuretic, digoxin, and an ACE inhibitor, a reduction in symptoms and in hospital admissions, and a 30% reduction in mortality, were seen among patients with severe systolic heart failure (NYHA class III or IV). Therefore, the addition of an aldosterone antagonist should be considered for any patient who remains in NYHA class III or IV, despite treatment with a diuretic, an ACE inhibitor (or angiotensin-receptor blocker [ARB]), and a beta-blocker.
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Teaching topics from the New England Journal of Medicine - Vol. 362, No. 3, January 21, 2010
What is Takotsubo cardiomyopathy?
Takotsubo cardiomyopathy
Also known as transient left ventricular apical ballooning syndrome or stress cardiomyopathy. One of the hallmarks of this syndrome is that the apical ballooning is transient, typically resolving in days to weeks. Takotsubo cardiomyopathy typically arises in the context of acute emotional or physical stress. It often resembles an acute coronary syndrome. The pathognomic findings are ballooning (dilatation and akinesis) of the left ventricular apex, with compensatory hyperkinesis of the basal walls of the left ventricle. Coronary angiography reveals no obstructive coronary-artery lesions; in addition, the distribution of left ventricular dysfunction often extends beyond the distribution of a single coronary artery.
Also known as transient left ventricular apical ballooning syndrome or stress cardiomyopathy. One of the hallmarks of this syndrome is that the apical ballooning is transient, typically resolving in days to weeks. Takotsubo cardiomyopathy typically arises in the context of acute emotional or physical stress. It often resembles an acute coronary syndrome. The pathognomic findings are ballooning (dilatation and akinesis) of the left ventricular apex, with compensatory hyperkinesis of the basal walls of the left ventricle. Coronary angiography reveals no obstructive coronary-artery lesions; in addition, the distribution of left ventricular dysfunction often extends beyond the distribution of a single coronary artery.
2010年1月16日 星期六
Fusobacterium necrophorum
A New Culprit for Pharyngitis in Adolescents
A gram-negative anaerobe that causes Lemierre syndrome has become a common cause of pharyngitis.
Guideline recommendations for the management of pharyngitis vary from doing nothing, to treating patients with positive test results (rapid or culture), to treating empirically. Current guidelines focus on infections with group A streptococcus, because, although the disease is self-limiting, it can cause substantial complications, most notably rheumatic fever (JW Pediatr Adolesc Med Apr 1 2009).
A recent surge in complicated cases of pharyngitis, particularly in adolescents, prompted more-elaborate microbiological testing. DNA analysis revealed that the gram-negative anaerobe, Fusobacterium necrophorum, is as common as group A strep in this age group. An estimated 1 in 400 cases of F. necrophorum pharyngitis progresses to complications, including abscess, septicemia with septic pulmonary emboli, and Lemierre syndrome, which is a septic thrombophlebitis of the internal jugular vein. In case series of patients with F. necrophorum pharyngitis, death — an almost unknown complication of group A strep pharyngitis — has been reported in 2% to 5% of patients, along with a substantial morbidity rate of 10%.
The organism is not sensitive to macrolides, which are recommended for suspected strep pharyngitis in penicillin-allergic patients. Penicillin or a cephalosporin remains the first treatment choice for adolescents and young adults with pharyngitis, and the addition of clindamycin is indicated for those with evidence of sepsis or neck swelling. Clindamycin should be the primary treatment in penicillin-allergic patients.
Comment:
The differential diagnosis of pharyngitis in adolescents and young adults includes group A strep, mononucleosis, and acute HIV infection and should now also include F. necrophorum, both at initial presentation and in cases that have not resolved in the usual 5-day interval from onset. Any clinical indicator of bacteremia indicates the need for admission (at least to an observation unit), blood cultures, and antibiotic coverage for F. necrophorum pending culture results.
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J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine January 15, 2010
Citation(s): Centor RM. Expand the pharyngitis paradigm for adolescents and young adults. Ann Intern Med 2009 Dec 1; 151:812.
A gram-negative anaerobe that causes Lemierre syndrome has become a common cause of pharyngitis.
Guideline recommendations for the management of pharyngitis vary from doing nothing, to treating patients with positive test results (rapid or culture), to treating empirically. Current guidelines focus on infections with group A streptococcus, because, although the disease is self-limiting, it can cause substantial complications, most notably rheumatic fever (JW Pediatr Adolesc Med Apr 1 2009).
A recent surge in complicated cases of pharyngitis, particularly in adolescents, prompted more-elaborate microbiological testing. DNA analysis revealed that the gram-negative anaerobe, Fusobacterium necrophorum, is as common as group A strep in this age group. An estimated 1 in 400 cases of F. necrophorum pharyngitis progresses to complications, including abscess, septicemia with septic pulmonary emboli, and Lemierre syndrome, which is a septic thrombophlebitis of the internal jugular vein. In case series of patients with F. necrophorum pharyngitis, death — an almost unknown complication of group A strep pharyngitis — has been reported in 2% to 5% of patients, along with a substantial morbidity rate of 10%.
The organism is not sensitive to macrolides, which are recommended for suspected strep pharyngitis in penicillin-allergic patients. Penicillin or a cephalosporin remains the first treatment choice for adolescents and young adults with pharyngitis, and the addition of clindamycin is indicated for those with evidence of sepsis or neck swelling. Clindamycin should be the primary treatment in penicillin-allergic patients.
Comment:
The differential diagnosis of pharyngitis in adolescents and young adults includes group A strep, mononucleosis, and acute HIV infection and should now also include F. necrophorum, both at initial presentation and in cases that have not resolved in the usual 5-day interval from onset. Any clinical indicator of bacteremia indicates the need for admission (at least to an observation unit), blood cultures, and antibiotic coverage for F. necrophorum pending culture results.
—
J. Stephen Bohan, MD, MS, FACP, FACEP
Published in Journal Watch Emergency Medicine January 15, 2010
Citation(s): Centor RM. Expand the pharyngitis paradigm for adolescents and young adults. Ann Intern Med 2009 Dec 1; 151:812.
2010年1月12日 星期二
Cyanide antidotes
Cyanide antidotes：nitrites and sodium thiosulfate之作用機轉
- The nitrites oxidize some of the hemoglobin's iron from the ferrous state to the ferric state, converting the hemoglobin into methemoglobin. (Treatment with nitrites is not innocuous as methemoglobin cannot carry oxygen, and methemoglobinemia needs to be treated in turn with methylene blue).
- Cyanide preferentially bonds to methemoglobin rather than the cytochrome oxidase, converting methemoglobin into cyanmethemoglobin.
- In the last step, the intravenous sodium thiosulfate converts the cyanmethemoglobin to thiocyanate, sulfite, and hemoglobin. The thiocyanate is excreted.
2010年1月6日 星期三
孕婦H1N1流感重症的特徵
Severe influenza during pregnancy: which trimester?
In this large series of pregnant and postpartum patients who were hospitalized with or died from 2009 H1N1 influenza, 95% of the pregnant patients were infected in the second or third trimester. The fact that eight of the cases of influenza in this study involved a postpartum onset of symptoms, with severe disease and death in some of these cases, highlights the continued high risk immediately after pregnancy.
Should pregnant women receive the H1N1 influenza vaccine?
Pregnant women are a top-priority group for immunization against 2009 H1N1 influenza. Since the 2009 H1N1 monovalent vaccine is manufactured according to the same processes that are used for the seasonal influenza vaccine, its safety profile among pregnant women is expected to be similar to that of the seasonal influenza vaccine, which has consistently been shown to be safe during pregnancy. Preliminary results from a trial of 2009 H1N1 monovalent vaccine have shown a robust immune response in pregnant women, similar to the response in nonpregnant adults, and no safety concerns have been identified. Maternal vaccination may also provide a benefit to the newborn infant, with a decreased risk of respiratory infections related to influenza in both the mother and infant during the first 6 months after delivery.
How should pregnant women with H1N1 influenza infection be treated?
Regardless of the results of rapid antigen tests, women with suspected or confirmed influenza who are pregnant or who have delivered within the previous 2 weeks should receive aggressive antiviral treatment and undergo close monitoring. The Centers for Disease Control and Prevention (CDC) recommends prompt antiviral treatment of pregnant women with suspected or confirmed 2009 H1N1 influenza, ideally within 48 hours after symptom onset.
What underlying condition most commonly predisposed pregnant women to complications from H1N1 influenza infection?
A total of 32 of the 93 pregnant women for whom data were available (34%), 2 of the 8 postpartum women (25%), and 82 of the 137 nonpregnant women (60%) had underlying conditions besides pregnancy that placed them at increased risk for complications from influenza; the most common condition was asthma, affecting 16% of pregnant women and 28% of nonpregnant women.
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http://content.nejm.org/cgi/content/abstract/362/1/27?query=BUL
In this large series of pregnant and postpartum patients who were hospitalized with or died from 2009 H1N1 influenza, 95% of the pregnant patients were infected in the second or third trimester. The fact that eight of the cases of influenza in this study involved a postpartum onset of symptoms, with severe disease and death in some of these cases, highlights the continued high risk immediately after pregnancy.
Should pregnant women receive the H1N1 influenza vaccine?
Pregnant women are a top-priority group for immunization against 2009 H1N1 influenza. Since the 2009 H1N1 monovalent vaccine is manufactured according to the same processes that are used for the seasonal influenza vaccine, its safety profile among pregnant women is expected to be similar to that of the seasonal influenza vaccine, which has consistently been shown to be safe during pregnancy. Preliminary results from a trial of 2009 H1N1 monovalent vaccine have shown a robust immune response in pregnant women, similar to the response in nonpregnant adults, and no safety concerns have been identified. Maternal vaccination may also provide a benefit to the newborn infant, with a decreased risk of respiratory infections related to influenza in both the mother and infant during the first 6 months after delivery.
How should pregnant women with H1N1 influenza infection be treated?
Regardless of the results of rapid antigen tests, women with suspected or confirmed influenza who are pregnant or who have delivered within the previous 2 weeks should receive aggressive antiviral treatment and undergo close monitoring. The Centers for Disease Control and Prevention (CDC) recommends prompt antiviral treatment of pregnant women with suspected or confirmed 2009 H1N1 influenza, ideally within 48 hours after symptom onset.
What underlying condition most commonly predisposed pregnant women to complications from H1N1 influenza infection?
A total of 32 of the 93 pregnant women for whom data were available (34%), 2 of the 8 postpartum women (25%), and 82 of the 137 nonpregnant women (60%) had underlying conditions besides pregnancy that placed them at increased risk for complications from influenza; the most common condition was asthma, affecting 16% of pregnant women and 28% of nonpregnant women.
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http://content.nejm.org/cgi/content/abstract/362/1/27?query=BUL
尿毒症病患使用EPO的風險
Should patients with CKD receive erythropoiesis-stimulating agents?
The use of erythropoiesis-stimulating agents results in a reduced need for blood transfusions among patients with advanced CKD and has also been associated with a reduction in left ventricular hypertrophy. However, there is increasing evidence that erythropoiesis-stimulating agents should be used cautiously.
In clinical trials higher hemoglobin levels have led to an increased risk of death, stroke cardiovascular events, and hospitalization for congestive heart failure. Though treated patients in the TREAT study needed fewer transfusions and had a modest reduction in fatigue they had no benefit in other quality-of-life measures.
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New England Journal of Medicine - Vol. 362, No. 1, January 7, 2010
The use of erythropoiesis-stimulating agents results in a reduced need for blood transfusions among patients with advanced CKD and has also been associated with a reduction in left ventricular hypertrophy. However, there is increasing evidence that erythropoiesis-stimulating agents should be used cautiously.
In clinical trials higher hemoglobin levels have led to an increased risk of death, stroke cardiovascular events, and hospitalization for congestive heart failure. Though treated patients in the TREAT study needed fewer transfusions and had a modest reduction in fatigue they had no benefit in other quality-of-life measures.
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New England Journal of Medicine - Vol. 362, No. 1, January 7, 2010
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