2010年3月26日 星期五

【EBM】App 做 CT 不必打顯影劑


Study objective
We seek to determine the diagnostic test characteristics of noncontrast computed tomography(CT) for appendicitis in the adult emergency department (ED) population.
We conducted a search of MEDLINE, EMBASE, the Cochrane Library, and the bibliographies of previous systematic reviews. Included studies assessed the diagnostic accuracy of noncontrast CT for acute appendicitis in adults by using the final diagnosis at surgery or follow-up at a minimum of 2 weeks as the reference standard. Studies were included only if the CT was completed using a multislice helical scanner. Two authors independently conducted the relevance screen of titles and abstracts, selected studies for the final inclusion, extracted data, and assessed study quality. Consensus was reached by conference, and any disagreements were adjudicated by a third reviewer. Unenhanced CT test performance was assessed with summary
receiver operating characteristic curve analysis, with independently pooled sensitivity and specificity values across studies.
The search yielded 1,258 publications; 7 studies met the inclusion criteria and provided a sample of 1,060 patients. The included studies were of high methodological quality with respect to appropriate patient spectrum and reference standard. Our pooled estimates for sensitivity and specificity were 92.7% (95% confidence interval 89.5% to 95.0%) and 96.1% (95% confidence interval 94.2% to 97.5%), respectively; the positive likelihood ratio=24 and the negative likelihood ratio=0.08.
We found the diagnostic accuracy of noncontrast CT for the diagnosis of acute appendicitis in the adult population to be adequate for clinical decision making in the ED setting.

Annals of emergency medicine Volume 55, Issue 1, Pages 51-59.e1

2010年3月18日 星期四

Vertebral osteomyelitis

Vertebral osteomyelitis can be complicated by direct seeding in different compartments, resulting in paravertebral, epidural, or psoas abscesses. In one series, vertebral osteomyelitis was complicated by epidural abscess in 17% of cases, paravertebral abscess in 26%, and a disk-space abscess in 5%. One fourth of patients developed motor weakness or paralysis, with particularly high rates among patients with cervical spine osteomyelitis. Neurologic complications have been reported in 38% of patients with vertebral osteomyelitis. In an analysis of 14 case series, vertebral osteomyelitis was complicated by relapse in 8% of cases, and death in 6%.

What organisms are most frequently implicated in pyogenic vertebral osteomyelitis?
Staphylococcus aureus is the most common microorganism implicated in pyogenic vertebral osteomyelitis, followed by E. coli. Coagulase-negative staphylococci and Propionibacterium acnes cause almost exclusively exogenous osteomyelitis after spine surgery, particularly if fixation devices are used. However, in case of prolonged bacteremia (e.g., pacemaker-electrode associated infection), hematogenous vertebral osteomyelitis due to low-virulence microorganisms (e,g., coagulase-negative staphylococci) has been described.

What tests are highly sensitive for the diagnosis of vertebral osteomyelitis?
Increased CRP is highly sensitive for the diagnosis of osteomyelitis, reported in 100% of cases. CRP is the preferred marker of infection, at least in postoperative spinal wound infection. Increased blood leukocyte counts or a high percentage of neutrophils (above 80%) are insensitive for the diagnosis of osteomyelitis. In a systematic review of studies of vertebral osteomyelitis, positive blood cultures were reported in 58% (range across studies, 30 to 78%).

What diagnostic step is recommended if vertebral osteomyelitis is suspected by imaging procedures and blood cultures show no growth?
If vertebral osteomyelitis is suspected by imaging procedures and blood cultures do not show growth, biopsy is generally warranted. Biopsy should be performed regardless of whether or not blood cultures are negative if polymicrobial osteomyelitis is suspected (e.g., intraabdominal sepsis). If the patient has a paravertebral, epidural, or psoas abscess, CT-guided drainage (with stain and culture of the specimen) may make bone biopsy unnecessary. Culture of a biopsy specimen, either CT-guided or open, has a higher overall yield than blood cultures (77%, range across studies 47 to 100%). Bone samples should be cultured for aerobic and anaerobic bacteria and for fungi. In patients with a suggestive history (e.g., stay in endemic region, subacute presentation), cultures should also be performed for mycobacteria and brucella species. In addition, analysis by histopathology is useful, because the presence of leukocytes in the specimens distinguishes infection from contamination.

2010年3月12日 星期五

EtCO2 已是 standard of care?

Does Capnography Add Benefit During Emergency Department Propofol Sedation?
All patients who became hypoxemic demonstrated respiratory depression by capnography before developing hypoxemia.

Capnography has been used as a real-time adjunct to procedural sedation monitoring in intensive care units and operating rooms for decades, yet it is not commonly used in the emergency department (ED) for this purpose. These authors determined whether adding capnography to standard monitoring (pulse oximetry, pulse rate, and blood pressure) during ED procedural sedation decreases the incidence of hypoxic events. In a prospective trial, 132 consecutive adults undergoing propofol sedation with standard monitoring and capnography at a single tertiary-care hospital ED were randomized to a study group, in which treating physicians could view the capnography monitoring screen, or to a control group, in which physicians could not view the screen.

Procedural sedation was initiated with a bolus of 1 mg/kg of propofol, followed by additional boluses of 0.5 mg/kg. All patients received opioids (0.5 µg/kg of fentanyl or 0.05 mg/kg of morphine) at least 30 minutes before administration of propofol. Hypoxia was defined as a pulse oximetry oxygen saturation (SpO2) level <93%.>/= 50 mm Hg, an ETCO2 absolute increase or decrease from baseline of >/= 10%, or loss of the waveform for >/= 15 seconds.

Patient characteristics were similar in the two groups. The rate of capnography-detected respiratory depression was similar between groups, but hypoxia was more frequent in the control group (42% vs. 25%). Capnographic evidence of respiratory depression was 100% sensitive for predicting hypoxia. Overall, 64% of patients with capnographic evidence of respiratory depression developed hypoxia.

This study and myriad others from the anesthesia and intensive care literature provide convincing evidence that capnography is extremely useful for detecting respiratory depression and preventing hypoxia in patients undergoing procedural sedation. Its use should be standard for emergency department patients receiving deep procedural sedation.

Richard D. Zane, MD, FAAEM
Published in Journal Watch Emergency Medicine March 12, 2010
Citation(s): Deitch K et al. Does end tidal CO2 monitoring during emergency department procedural sedation and analgesia with propofol decrease the incidence of hypoxic events? A randomized, controlled trial. Ann Emerg Med 2010 Mar; 55:258.

2010年3月10日 星期三

commotio cordis

Ventricular fibrillation and sudden death triggered by a blunt, nonpenetrating, and often innocent-appearing unintentional blow to the chest without damage to the ribs, sternum, or heart (and in the absence of underlying cardiovascular disease) constitute an event known as commotio cordis.

When does commotio cordis occur?
About 55% of occurrences of commotio cordis have been reported in young competitive athletes (mostly those between 11 and 20 years of age) participating in a variety of organized amateur sports — typically baseball, softball, ice hockey, football, or lacrosse — who receive a blow to the chest that is usually (but not always) delivered by a projectile that is used to play the game.

How should suspected commotio cordis be treated?
A public health strategy that incorporates a plan for making automated external defibrillators (AEDs) widely available is likely to result in the survival of more young people in the event of commotio cordis. Indeed, AEDs have also effectively terminated ventricular fibrillation in animal models of commotio cordis. However, even under optimal conditions, an AED can fail to restore the heart to normal rhythm after commotio cordis. Both clinical studies and experimental studies suggest that precordial thumps are unreliable in terminating ventricular fibrillation caused by chest blows.

What location of a blow can precipitate commotio cordis?
To precipitate commotio cordis, the blow must be directly over the heart, particularly at or near the center of the cardiac silhouette. Precordial bruises representing the imprint of a blow are frequently evident in victims. There is no evidence in humans or in experimental models that blows sustained outside the precordium (e.g., the back, the flank, or the right side of the chest) cause sudden death.

At what part of the cardiac electrophysiological cycle must the blow occur?
The blow must occur within a narrow window of 10 to 20 msec on the upstroke of the T wave, just before its peak (accounting for only 1% of the cardiac cycle) — that is, the blow must occur during an electrically vulnerable period, when inhomogeneous dispersion of repolarization is greatest, creating a susceptible myocardial substrate for provoked ventricular fibrillation.

Teaching topics from the New England Journal of Medicine
Vol. 362, No.10, March 11, 2010

2010年3月6日 星期六


Conventional Cardiopulmonary Resuscitation Is Better Than Compression-Only CPR for Children with Noncardiac Causes of Arrest
Among patients aged 1–17 years with primary cardiac arrest, conventional CPR and compression-only CPR similarly improved outcomes over no bystander CPR, but for children with noncardiac causes of arrest, conventional CPR was better.

Compression-only cardiopulmonary resuscitation (CPR) has been shown to be as effective as conventional CPR for adults, in whom most arrests are of primary cardiac origin (JW Emerg Med Mar 30 2007), but is compression-only CPR useful for children, who are much more likely to arrest from respiratory causes? Researchers in Japan analyzed data from a nationwide, prospective observational database for 5170 children (age, 17 years) with out-of-hospital cardiac arrest (71% noncardiac etiology, 29% cardiac etiology). Bystander CPR was provided to 47% of children; 30% received conventional CPR, and 17% received chest compressions only without rescue breathing.

The primary endpoint was favorable neurological outcome (defined as Glasgow-Pittsburgh cerebral performance category 1 or 2) 1 month after arrest. Multiple logistic regression analysis revealed that favorable neurological outcome was significantly more likely for children who received bystander CPR than for those who did not (4.5% vs. 1.9%), for patients aged 1–17 years than for infants younger than 1 year (4.1% vs. 1.7%), for those with ventricular fibrillation as the initial rhythm than for those with other rhythms (20.6% vs. 2.3%), and for those with witnessed arrest (by family or others) than for those with unwitnessed arrest (6.7% and 10.3%, respectively, vs. 1.3%). In children aged 1–17 years, rates of favorable neurological outcome were significantly higher with conventional CPR than with compression-only CPR among patients with noncardiac causes of arrest (7.2% vs. 1.6%), but rates did not differ by type of CPR among patients with cardiac causes of arrest. Neurological outcomes were poor in infants (age, <1 year), regardless of type of CPR or etiology of arrest.

Bystander CPR, particularly for witnessed arrest, greatly improves meaningful survival in adults and children. Compression-only CPR is a reasonable alternative for adults and might increase the likelihood that CPR is performed. However, children's arrests are usually from noncardiac causes, and conventional CPR clearly is superior to compression-only CPR in such cases. For a bystander, determining a cardiac versus a noncardiac cause for an arrest is almost impossible, so the recommendation is clear: Conventional CPR for children up to age 17!

Kristi L. Koenig, MD, FACEP
Published in Journal Watch Emergency Medicine March 2, 2010

Kitamura T et al. Conventional and chest-compression-only cardiopulmonary resuscitation by bystanders for children who have out-of-hospital cardiac arrests: A prospective, nationwide, population-based cohort study. Lancet 2010 Mar 3; [e-pub ahead of print]. (http://dx.doi.org/10.1016/S0140-6736(10)60064-5)
López-Herce J and Álvarez AC. Bystander CPR for paediatric out-of-hospital cardiac arrest. Lancet 2010 Mar 3; [e-pub ahead of print]. (http://dx.doi.org/10.1016/S0140-6736(10)60316-9)


Dopamine vs. Norepinephrine in Treatment of Shock
A large randomized trial shows no difference in death rates with the two agents overall but significantly higher mortality with dopamine among patients with cardiogenic shock.

When fluid therapy is not successful in reversing a shock state, adrenergic agents are used, most commonly dopamine or norepinephrine. These agents differ in their modes of action, as they affect -adrenergic and β-adrenergic receptors differently. Observational studies have shown higher death rates with dopamine than with norepinephrine in patients with shock; the few randomized trials to date have been too small to provide meaningful data.

In the current multicenter European study, 1679 adult patients with shock (signs of tissue hypoperfusion and systolic blood pressure <100 mm Hg or mean arterial pressure <70 mm Hg) that persisted after treatment with "adequate" fluids (at least 1000 mL of crystalloids or 500 mL of colloids) were randomized to receive dopamine or norepinephrine. Patients who had already received vasopressors for more than 4 hours were excluded. Treating physicians were blinded to drug assignment. Patients with hypovolemic shock, cardiogenic shock, and septic shock were included. The primary endpoint was the rate of death at 28 days. Secondary endpoints included time to hemodynamic stability and incidence of adverse events, such as serious arrhythmias and myocardial necrosis.

Rates of death at 28 days and times to hemodynamic stability did not differ significantly between the dopamine and norepinephrine groups. However, significantly more patients in the dopamine group than in the norepinephrine group experienced arrhythmias (24% vs. 12%). A predefined subgroup analysis according to type of shock showed that among 280 patients with cardiogenic shock, the death rate at 28 days was significantly higher in dopamine recipients than in norepinephrine recipients. An editorialist notes the relatively low amount of fluids considered by the investigators to be adequate to gauge response before starting vasopressors.
Comment: The authors "strongly challenge" the current American College of Cardiology–American Heart Association guidelines that recommend dopamine as a first-line agent for cardiogenic shock. In such cases, norepinephrine seems to be the prudent choice. No evidence supports one agent over the other for different forms of shock.

J. Stephen Bohan, MD, MS, FACP, FACEP

2010年3月5日 星期五

Gastroesophageal varices

Gastroesophageal varices are present in almost half of patients with cirrhosis at the time of diagnosis, with the highest rate among patients with Child–Turcotte–Pugh class B or C disease. The 1-year rate of recurrent variceal hemorrhage is approximately 60%. The 6-week mortality with each episode of variceal hemorrhage is approximately 15 to 20%.

How should acute variceal hemorrhage be treated in patients with compensated cirrhosis?
Patients who have Child class A or B disease or who have an hepatic venous pressure gradient (HVPG) of less than 20 mm Hg have a low or intermediate risk and should receive standard therapy — specifically, the combination of a vasoconstrictor (terlipressin, somatostatin, or analogues, administered from the time of admission and maintained for 2 to 5 days) and endoscopic therapy (preferably endoscopic variceal ligation, performed at diagnostic endoscopy less than 12 hours after admission), together with short-term prophylactic antibiotics (either norfloxacin or ceftriaxone). Placement of a transjugular intrahepatic portosystemic shunt is currently considered a salvage therapy for the 10 to 20% of patients in whom standard medical therapy fails. What treatments should be used to prevent recurrent variceal hemorrhage?
Given the high recurrence rate, patients who survive an acute variceal hemorrhage should receive therapy to prevent recurrence before they are discharged from the hospital. Combination pharmacologic therapy (nonselective beta-blockers such as propranolol or nadolol plus nitrates) or combination endoscopic variceal ligation plus drug therapy are warranted because of the high risk of recurrence, even though the side effects will be greater than those with single-agent therapy (recommended for primary prophylaxis).

Should patients with cirrhosis but without varices be treated with non-selective beta-blockers for primary prophylaxis?
A: Patients without gastroesophageal varices or with gastroesophageal varices that have never bled are at relatively low risk for bleeding and death; therefore, therapies for these patients should be the least invasive. In patients without varices, treatment with nonselective beta-blockers is not recommended because they do not prevent the development of varices and are associated with side effects.

In patients with cirrhosis without varices, which one of the following measurements is the best method to stratify risk?
A: In patients without varices and in those with variceal hemorrhage, measurement of portal pressure with the use of the HVPG is the best method to stratify risk. Portal hypertension is present when the HVPG is greater than 5 mm Hg, but it is considered clinically significant when the HVPG is greater than 10 mm Hg, because in patients without varices, this pressure is the strongest predictor of the development of varices, clinical decompensation, and hepatocellular carcinoma. The HVPG is obtained by means of catheterization of a hepatic vein with a balloon catheter through a jugular or femoral vein.

Teaching topics from the New England Journal of Medicine - Vol. 362, No. 9, March 4, 2010