Lit Bits: March 27, 2007

From the recent medical literature...

1. Chest Compression Without Mouth-to-Mouth Beats CPR for Cardiac Arrest

Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observational study. Lancet 2007; 369:920-926.

Chest compression without mouth-to-mouth ventilation is more effective than standard CPR when used by bystanders -- who may be fearful of catching disease -- on victims of out-of-hospital cardiac arrest, according to a study in Lancet.

Paramedics noted the resuscitation techniques employed by bystanders in about 4000 cardiac arrests. Compared with standard CPR, cardiac-only resuscitation was associated with greater likelihood of favorable neurologic outcome (6% vs. 4%) at 30 days, including among patients who received resuscitation starting within 4 minutes of collapse. In no subgroup was there any evidence of benefit from the addition of mouth-to-mouth ventilation.

An editorialist writes that both assisted ventilations and chest compressions should still be used for respiratory arrests such as in drowning and drug overdose, "but the guidelines should promptly be changed to chest-compression-alone for witnessed unexpected sudden collapse (a condition that is, in all probability, cardiac arrest)."

The accompanying editorial added some helpful insight: Ewy JA. Cardiac arrest—guideline changes urgently needed. Lancet 2007; 369 (9565):882-884.

Cardiopulmonary resuscitation is traditionally defined as chest compression and ventilation. The need for chest compressions is unquestionable, but the need or advisability of intermittent ventilation for out-of-hospital non-respiratory primary cardiac arrest has been very controversial. The article by the SOS-KANTO study group in today's Lancet is of the utmost importance because it provides evidence in human beings that chest compression without ventilation is preferable for out-of-hospital cardiac arrest. This finding is an important piece of evidence that should lead to a prompt interim revision of the guidelines for out-of-hospital cardiac arrest. Eliminating the need for mouth-to-mouth ventilation will dramatically increase the occurrence of bystander-initiated resuscitation efforts and will increase survival.

A major problem with most studies of out-of-hospital cardiac arrest is that most patients studied have absolutely no chance of surviving. Therefore a better approach to resuscitation is almost impossible to show. Nevertheless, many studies have identified a subgroup of patients with the greatest chance for survival: those who have a witnessed cardiac arrest and a shockable rhythm when the emergency team arrives. Within this important subgroup in the SOS-KANTO study, 22% of those who received bystander-initiated chest-compression alone had a favourable neurological outcome, as compared to 10% of those who received 2000 AHA and ILCOR guideline-recommended chest compressions and mouth-to-mouth breathing.

From their inception, the standards and guidelines for a bystander's response to out-of-hospital cardiac arrest have always emphasised the imperative of mouth-to-mouth ventilation, paradoxically called “rescue breathing.” While mouth-to-mouth ventilation may “rescue” an individual with respiratory arrest, this approach actually decreases the likelihood of a “rescue” in a much larger group of patients—those with a primary cardiac arrest.

Mouth-to-mouth ventilation for primary cardiac arrest is detrimental for several reasons. First, this requirement greatly decreases bystander-initiated resuscitation efforts, an important determinant of survival from out-of-hospital cardiac arrest. Second, studies have long reported that survival is better in individuals with cardiac arrest who receive chest compression only than it is in those in whom no bystander rescue efforts were started until the actual or simulated arrival of emergency personnel. Third, mouth-to mouth ventilations by single bystanders requires inordinately long interruptions of essential chest compressions. Fourth, during cardiac arrest, mouth-to-mouth or positive-pressure ventilation increases intrathoracic pressures, thereby reducing venous return to the chest. Therefore positive-pressure ventilation reduces the already marginal coronary and cerebral blood flow during cardiac arrest and resuscitation. This situation is made worse when forceful ventilation is given while the chest is being compressed.

Fifth, with sudden unexpected primary cardiac arrest, ventilations are initially neither necessary nor logical, for with the onset of ventricular-fibrillation-induced arrest, the pulmonary veins, the left heart, and the entire arterial system are filled with oxygenated blood and the recommended ventilations do not increase arterial saturation—they only further delay the onset of critical chest compressions. Sixth, mouth-to-mouth ventilation is not necessary in a significant number of victims of witnessed cardiac arrest because they initially gasp, and if chest compressions are started early and continued, many of these patients will continue to gasp and thereby provide physiological ventilation (eg, that with decreasing intrathoracic pressures that facilitates venous return to the chest). Seventh, survival from experimentally induced cardiac arrest is better with higher coronary perfusion pressures produced by forceful chest compressions. Eighth, in non-paralysed animals in cardiac arrest, survival is dramatically better with chest-compression-only resuscitation than with ventilations plus chest compressions, when chest compressions were interrupted for a realistic 16 s to provide the two mouth-to-mouth breaths between each set of 15 chest compressions. The SOS KANTO study has now shown this result in human beings.

2. Weekend Admission for Acute MI Associated With Higher Mortality

from Heartwire — a professional news service of WebMD. Michael O'Riordan. March 15, 2007 (New Brunswick, NJ) – Patients with MI who come to the hospital on weekends are less likely to survive than patients who are admitted to the hospital during the week, a new study has shown [1]. Likely mediating this higher rate of mortality, say investigators, is the additional finding that admission on the weekend is associated with lower use of invasive cardiac procedures.

Publishing their findings in the March 15, 2007 issue of the New England Journal of Medicine, lead author Dr William Kostis (Robert Wood Johnson Medical School, Piscataway, NJ) and colleagues write that this higher rate of mortality represents 9 to 10 additional deaths per 1000 admissions per year and has important implications for clinical care.

"The increase in mortality, which may persist for more than a year, could account for several thousand deaths annually in the United States," write the authors. "More appropriate hospital staffing or regionalization of the care of patients with acute myocardial infarction may prevent some of these deaths."

In an editorial accompanying the published study, Drs Donald Redelmeier and Chaim Bell (University of Toronto, ON) note that while clinicians strive to provide care to patients every day of week, doing so is difficult, partly because many who work in hospitals are not always compensated for taking the weekend shift [2]. Even casual observations of the hospital parking lot on a Saturday suggest that the intensity of care on the weekend does not match the care provided on other days of the week, they write.

"The shortfall of weekend medical care is important because the consequences of adverse events cannot always be offset by working harder on subsequent days," write Redelmeier and Bell. "If the patient dies on the weekend, no heroics on Monday will suffice."

Fewer procedures and higher mortality

Kostis and colleagues note that hospital staffing is typically reduced on weekends, both in terms of the number of clinicians and the available expertise on site. While the difference in staffing might result in different outcomes for patients with acute conditions--management of acute MI, specifically, requires urgent diagnostic and therapeutic procedures--findings from previous studies have been inconsistent.

To compare mortality rates among patients admitted with MI on weekends and those admitted during the week, investigators obtained data from the Myocardial Infarction Data Acquisition System (MIDAS), a database that contains clinical data on patients discharged with an acute MI diagnosis from nonfederal hospitals in New Jersey as well as information on the use of invasive cardiac procedures such as catheterization, PCI, or CABG. The study included 231 164 patients admitted to New Jersey hospitals between 1987 and 2002 with acute MI as the primary reason for admission.

Mortality 30 days after admission was also significantly higher for patients admitted on a weekend than for those admitted during the week. This difference became significant the day after admission and persisted until one year. Mortality on the weekend remained significantly higher after adjustment for clinical characteristics, but became nonsignificant after the additional adjustment for invasive cardiac procedures, the investigators report.

"Overall," the authors conclude, "our study suggests that a hospital workweek of Monday through Friday is not optimal for the care of patients with acute myocardial infarction."

In an audio supplement to the published study, Dr Thomas Lee (Partners Health Care System, Boston, MA), one of the associate editors of the journal, said that most hospitals would reduce overhead costs if labs could run full time, but staff shortages preclude hospitals from operating 24 hours per day, seven days per week [3]. While aware there are falloffs in how aggressive physicians are with patients having an MI on the weekend, Lee said he was surprised at how many fewer angioplasties were performed on the weekend.

"When people are not in the hospital, and they are further away, the threshold for calling somebody in is very different," commented Lee. "On the weekend, at night, waking up your colleagues, calling them, it's very inconvenient, and doctors will use a different threshold [for calling the cath lab team in]. The result is that fewer procedures are performed. A lot of times it doesn't make a difference if you wait and do those procedures on Monday, but myocardial infarction is one diagnosis where it does make a real difference."

According to editorialists Redelmeier and Bell, an awareness of the shortfalls in weekend hospital care has implications for patients. If patients feel unwell during the week, they should not wait until the weekend to see whether they feel better. Second, if unsure how sick they might be, they should contact their doctor before the end of workweek. And finally, if hit by a medical emergency on the weekend, they should still proceed to the emergency department, as they are still far safer there than at home.

To offset the disparity in weekend care, Lee said his hospital attempts to schedule physicians who live close to the hospital for on-call service. In addition, the emergency department is able to directly activate the cath lab team without having to first call a cardiologist.

"We run the risk that the cath lab team might come in and find that it wasn't a myocardial infarction at all, but we feel it's a small price to pay for reducing the delay," said Lee. If such solutions do not work, Lee said some hospitals might have very little choice but to pay to operate the cath lab at night and on weekends or else live with the notion that they are providing second-rate care.

[1.] Kostis WJ, Demissie K, Marcella SW et al. Weekend versus weekday admission and mortality from myocardial infarction. N Engl J Med 2007; 356:1099-1109.
[2.] Redelmeier DA, Bell CM. Weekend worriers. N Engl J Med 2007; 356:1164-1165.
[3.] Interview with Thomas Lee on increased mortality with weekend hospital admissions. Supplement to: Kostis WJ et al. Weekend versus weekday admission and mortality from myocardial infarction. N Engl J Med 2007; 356:1099-1109.

3. Fasting and ED Procedural Sedation and Analgesia: A Consensus-Based Clinical Practice Advisory

Green SM, et al. Ann Emerg Med 2007;49: 454-461.

Background
In an ongoing effort to optimize patient safety during procedural sedation and analgesia, emergency physicians query patients about the timing and nature of recent oral intake and use this information to estimate the risk of pulmonary aspiration and to plan sedation depth and timing accordingly. However, emergency physicians have no specific guidelines addressing this requisite task. Procedural sedation and analgesia guidelines from the American College of Emergency Physicians state: “Recent food intake is not a contraindication for administering procedural sedation and analgesia, but should be considered in choosing the timing and target level of sedation.” Corresponding guidelines from the American Academy of Pediatrics and American Society of Anesthesiologists (ASA) are no more specific.

Importance
A consequence of the inherent ambiguity in how to apply preprocedural fasting information is wide practice variation. At one end of the spectrum are emergency physicians who administer procedural sedation and analgesia “without regard to oral intake,” whereas at the opposite end are emergency physicians who have adopted fasting guidelines crafted for elective operative anesthesia. Although the former approach seems unacceptably cavalier, given that aspiration can result in significant morbidity and even mortality, the latter approach denies a substantial number of emergency department (ED) patients the clear benefits of timely sedation. The emergency medicine community would benefit from a clearer consensus for assessment of the risks and benefits of procedural sedation and analgesia in the nonfasted ED patient.

The ideal mechanism to assist in standardizing practice would be the development and dissemination of an evidence-based clinical practice guideline. However, because aspiration is an extremely rare event (in both procedural sedation and analgesia and operative anesthesia), research evaluating its risk factors and potential preventive interventions is prohibitively difficult. Therefore, large retrospective anesthesia studies from decades ago will likely remain the primary evidence for preprocedural risk stratification into the foreseeable future, and practice guidelines will of necessity remain consensus-based.

Goals
Given the compelling need for specific recommendations to address presedation fasting in the ED, we created an emergency medicine–specific clinical practice advisory. Recognizing the limitations of the published evidence, we augmented the advisory with expert consensus, a technique that, while imperfect, represented the only feasible option for this topic.

Full text (free!): http://www.annemergmed.com/article/PIIS0196064406021378/fulltext

4. External Validation of the San Francisco Syncope Rule…Not as Accurate as We Thought, and Not Quite Ready for Prime-time

Sun BC, et al (including Jerry Hoffman). Ann Emerg Med 2007;49:420-427.

Background and Importance
Syncope, defined as a transient loss of consciousness, may herald life-threatening events. As a result, patients presenting with syncope to emergency departments (EDs) are frequently hospitalized. Syncope accounts for 1% to 3% of all ED visits and hospital admissions from the ED. Unfortunately, current admission practices result in marginal diagnostic and therapeutic benefit and consume enormous health care resources. Between 39% and 50% of admitted patients are discharged without an explanation for syncope, and syncope-related admissions in the United States account for $2.4 billion in annual health care costs.

The San Francisco Syncope Rule is an instrument designed to identify patients with syncope or near-syncope who are at low risk of a short-term, serious clinical event. Low-risk patients can potentially be discharged for an outpatient evaluation of syncope. The San Francisco Syncope Rule predictors include an abnormal ECG result, complaint of shortness of breath, hematocrit level less than 30%, systolic blood pressure less than 90 mm Hg, and a history of congestive heart failure.

In a derivation study, outcomes included any predefined clinical events within 7 days; the San Francisco Syncope Rule demonstrated 96% sensitivity (95% confidence interval [CI] 92% to 100%) and 62% specificity (95% CI 58% to 66%). In a validation study, outcomes included 30-day predefined events that were diagnosed after the ED visit; the San Francisco Syncope Rule demonstrated 98% sensitivity (95% CI 89% to 100%) and 56% specificity (95% CI 52% to 60%). These studies suggest that application of the San Francisco Syncope Rule may safely decrease syncope-related admissions by 7% to 10%.

Goals of This Investigation
The published San Francisco Syncope Rule derivation and validation studies have been performed at the same institution. Our goal was to evaluate the accuracy of the San Francisco Syncope Rule to identify “low-risk” patients in an independent, prospective validation sample. The primary outcome included all 7-day serious clinical events. The secondary outcome included 7-day serious clinical events that were diagnosed only after the index ED visit. Analysis of the secondary outcome is important because there is little clinical utility in “predicting” serious conditions that are evident at the ED evaluation.

Abstract
Methods
Patients who presented to a single academic emergency department (ED) between 8 am and 10 pm with syncope or near-syncope were prospectively enrolled. Treating physicians recorded the presence or absence of all San Francisco Syncope Rule risk factors. Patients were contacted by telephone at 14 days for a structured interview. A 3-physician panel, blinded to the San Francisco Syncope Rule score, reviewed ED medical records, hospital records, and telephone interview forms to identify predefined serious clinical events. The primary outcome was the ability of the San Francisco Syncope Rule to predict any 7-day serious clinical event. A secondary outcome was the ability of the San Francisco Syncope Rule to predict 7-day serious clinical events that were not identified during the initial ED evaluation.

Results
Of 592 eligible patients, 477 (81%) provided informed consent. Direct telephone contact or admission/outpatient records were successfully obtained for 463 (97%) patients. There were 56 (12%) patients who had a serious 7-day clinical event, including 16 (3%) who received a diagnosis after the initial ED evaluation. Sensitivity and specificity of the San Francisco Syncope Rule for the primary outcome were 89% (95% confidence interval [CI] 81% to 97%) and 42% (95% CI 37% to 48%), respectively, and 69% (95% CI 46% to 92%) and 42% (95% CI 37% to 48%), respectively, for the secondary outcome. Estimates of sensitivity were minimally affected by missing data and most optimistic assumptions for missing follow-up information.

Conclusion
In this external validation cohort, the San Francisco Syncope Rule had a lower sensitivity and specificity than in previous reports.

How this might change clinical practice: These results suggest that the San Francisco Syncope Rule requires further external validation before being adopted into general ED use.

5. Exercise: Working Out the Memory as Well as the Muscles

By ERIC NAGOURNEY. New York Times, March 20, 2007. Exercise, researchers have found over the years, appears to help people fight the natural memory loss that comes with aging.

Now a new study suggests a possible explanation for why this is so. The report, which appears online in The Proceedings of the National Academy of Sciences, says working out may stimulate the growth of neurons in a part of the brain associated with memory loss.

The researchers, led by Dr. Scott A. Small, an associate professor of neurology at the Columbia University Medical Center, looked at changes in the brains of volunteers who worked out on exercise equipment.

The researchers were trying to confirm the findings of earlier research they did involving mice. When the mice exercised, blood flow increased to a part of the brain called the hippocampus, and more specifically to the dentate gyrate. In post-mortems, the researchers found evidence of neuron growth in the dentate gyrate.

The research could not be replicated in people for reasons practical — who would volunteer? — and ethical, to say nothing of legal.

But using 11 volunteers, an M.R.I. machine and equipment like treadmills, the researchers were able to see whether blood flow increased to the same part of the brain in humans as it had in mice. It did, suggesting that working out may help produce neurons in a part of the hippocampus that loses them disproportionately as people age.

The researchers also found that as the volunteers went through a three-month exercise period, their scores on memory tests went up. “Our study does suggest that it’s probably aerobic exercise that’s inducing this effect,” Dr. Small said.

6. Pulmonary embolism risk assessment screening tools: the interrater reliability of their criteria

Nordenholz KE, et al. Amer J Emerg Med. 2007;25:285-290.

Background
Diagnostic evaluation for suspected pulmonary embolism (PE) is challenging. Dimerized plasmin fragment D (D-dimer) assays are increasingly used but have been validated only in “low-risk” patients. The accurate interpretation and application of risk assessment criteria are critical to the appropriate use of D-dimer. We sought to determine the interrater agreement of attending and third-year resident emergency medicine physicians in the specific elements of the Canadian and the Charlotte risk stratification tools and their clinical application.

Methods
We prospectively enrolled a convenience sample of patients presenting to an urban university emergency department with suspected PE. Standardized data collection sheets were used by an attending physician and a third-year resident physician to determine the presence or absence of risk factors included in published PE prediction instruments. Each physician was blinded to the other's results and the patients' D-dimer result. Interrater agreement was measured using κ statistics (with 95% confidence intervals).

Results
Two hundred seventy-one patients were screened. The κ scores for each risk criterion were as follows: previous deep vein thrombosis, 0.90 (95% confidence interval, 0.83-0.97); malignancy, 0.87 (0.76-0.97); deep vein thrombosis symptoms, 0.54 (0.39-0.70); immobilization, 0.41 (0.26-0.57); unexplained hypoxia, 0.58 (0.42-0.74); tachycardia, 0.94 (0.89-0.98); hemoptysis, 0.76 (0.51-1.0); and PE more likely than another diagnosis, 0.50 (0.36-0.64).

Conclusions
Interrater agreement was only fair for several important risk criteria. Small differences in determining pretest probability can lead to significant variability in risk assessment and how, or whether, the diagnosis of PE is evaluated. This study raises questions about the reliability and applicability of published PE screening criteria in clinical settings.

7. RCT of Two IV Morphine Dosages (0.10 mg/kg and 0.15 mg/kg) in ED Patients With Moderate to Severe Acute Pain

Birnbaum A, et al. Ann Emerg Med 2007;49:445-453.

Editor’s Capsule Summary
What is already known on this topic: A morphine dose of 0.10 mg/kg is inadequate to control acute severe pain in many adults who present to the emergency department (ED).

What question this study addressed: Is 0.15 mg/kg of morphine more effective than and as safe as 0.10 mg/kg?

What this study adds to our knowledge: The higher morphine dose was only marginally more effective than the lower dose and equally safe.

How this might change clinical practice: This study demonstrates that even a high (0.15 mg/kg) loading dose of morphine does not consistently relieve severe pain in ED adults, supporting the idea of individualized titration to effect.

Study objective
We compare pain relief and safety of morphine 0.10 mg/kg with 0.15 mg/kg in adult emergency department (ED) patients with acute pain.

Methods
This was a randomized double-blind placebo-controlled trial of intravenous morphine 0.10 mg/kg versus 0.15 mg/kg, (delivered in 2 divided doses) in adult ED patients with acute pain requiring opioid analgesia. Assessment was made at baseline, 30 minutes, and 60 minutes with a validated verbal numeric rating scale. Pain reduction and satisfaction scores were measured at 30 and 60 minutes. The primary outcome measure was the between-group difference in mean before-after change in numeric rating scale from baseline to 60 minutes.

Results
Two hundred eighty patients were enrolled. Between-group difference in numeric rating scale improvement from baseline to 60 minutes was 0.8 (95% confidence interval 0.1 to 1.5), favoring the 0.15 mg/kg group. Pain relief scores and adverse events were similar in the 2 groups.

Conclusion
Although 0.15 mg/kg of morphine is safe and provides statistically superior analgesia compared with a dose of morphine at 0.10 mg/kg, this difference in pain reduction did not reach the threshold of greater than 1.3 numeric rating scale units required to declare the higher dose of morphine clinically superior.

8. Prolonged Strenuous Activity May Cause Increase in Troponin Levels

NEW YORK (Reuters Health) Mar 08 - Troponin levels may increase significantly in marathon runners, even reaching levels diagnostic for acute myocardial infarction, according to results of a study involving participants in the 2002 Boston Marathon.

Dr. Elizabeth B. Fortescue and her colleagues, based at Children's Hospital Boston, recruited 482 runners a day or two before the marathon. As the authors note in the Annals of Emergency Medicine for February, the cohort was heterogeneous in terms of experience, age, and fitness.

The subjects completed questionnaires prior to the race, including demographics and medical history. Immediately after completing the 26.2-mile course, subjects provided a blood sample and answered questions about symptoms during the race.

Overall, 68% of runners had some degree of post-race troponin level increase, ranging from 0.02 to 0.74 ng/mL for troponin T and 0.05 to 4.17 ng/mL for troponin I.

Dr. Fortescue's team defined significantly elevated troponin T as at least 0.075 ng/mL, and elevated troponin I as at least 0.50 ng/mL, based on reference values diagnostic for myocardial infarction. Fifty-five of the runners (11%) had troponin levels in this range.

Eight subjects had never before participated in a marathon, and their risk of elevated serum troponin was 3-fold higher than for experienced runners. Age less than 30 years and female gender were also associated with elevated troponin levels.

Pre-race questionnaires completed by the subjects showed that 28 had significant histories of heart or circulatory problems, including one myocardial infarction, one heart valve replacement surgery, 20 with exertional chest pain and 24 with hypertension. However, cardiovascular history had no effect on troponin increases, and elevated troponin levels were not associated with palpitations or chest pain experienced during the race. "Further work is needed," say the researchers, "to determine the clinical significance of these findings."

Ann Emerg Med 2007;49:137-143.

9. Ambulance Diversion: How to Decrease It

In March was released Report One of the California ED Diversion Project. This project is supported by the California HealthCare Foundation, based in Oakland, California. This report concludes the initial research and reporting phase of the project.

The purpose of this project is to measure and publicly report the extent of ambulance diversion in California by EMS region and hospital, identify best practices to minimize diversion, and help to implement these best practices in regions that have been less successful at reducing ambulance diversion.

Ambulance diversion is a major issue in California. Statewide, hospital EDs were closed to ambulances 11.0 percent of the time during 2005. Four EMS regions had the most diversion hours, they were diverting 22.6 percent of the time. This equates to one out of every five ambulance patients being potentially transported to an alternate hospital during 2005. EMS diversion impacts patient care resources and drives potential continuity issues as the patient’s physician may not have hospital privileges at the alternate receiving hospital and that hospital probably does not have the patient’s medical records. Diverting at one ED may also artificially create diversion at neighboring EDs. Additional ambulance unit hours and other EMS costs are realized due to longer transport times. EMS diversion also increases the overall cost of healthcare when patients cannot be transported to hospitals within their health plans.

For more information: http://www.abarisgroup.com/index.cfm?area=projects

10. Can’t get the LP? Two Studies suggest an Ultrasound might Help

A. The use of ultrasound to identify pertinent landmarks for lumbar puncture. Stiffler KA, et al. Amer J Emerg Med 2007;25:331-335.

Objective
This study was conducted to assess the ultrasound's (US's) ability to identify pertinent landmarks for lumbar puncture (LP) in patients of various body mass indices (BMIs) and establish spatial relationships of pertinent LP landmarks across BMIs.

Methods
In this institutional review board–approved cross-sectional study, we calculated the BMIs of eligible patients and then categorized them as normal (BMI less than 25), overweight (BMI 24.9-30), or obese (BMI 30 or greater). We recorded the difficulty in palpating traditional LP landmarks. Identification and measurement of the spatial relationships of the sacrum; spinous processes of lumbar vertebrae L3, L4, and L5; ligamentum flavum; and the spinal canal by US was attempted.

Results
Successful identification of pertinent structures (L4-L5 spinous processes and the spinal canal) occurred in 100% of patients with normal BMI, 95% of those who were overweight, and 74% of those who were obese (P = .011). Difficulty in palpating landmarks was noted in 5% of patients with normal BMI, 33% of those who were overweight, and 68% of those who were obese (P less than .0001). In subjects with difficult-to-palpate landmarks, US identified pertinent structures in 16 of 21 (76%; 95% confidence interval, 53-92). The average distance from skin to ligamentum flavum was 44 mm in those with normal BMI, 51 mm in those who were overweight, and 64 mm in those who were obese (P less than .00001); measurements between spinous processes did not vary by BMI. Overall, there was a moderate correlation (0.62) between BMI and the distance from skin to ligamentum flavum.

Conclusion
The usefulness of US in identifying structures for LP is inversely related to BMI. Even with this limitation, US is still able to identify obese patients' pertinent landmarks almost 75% of the time. In addition, US may be helpful in identifying pertinent structures for LP in those patients with difficult-to-palpate landmarks. In patients who were obese with structures not palpable by hand or identifiable by US, other modalities should be considered.

B. Emergency physicians can easily obtain ultrasound images of anatomical landmarks relevant to lumbar puncture. Ferre RM, et al. Amer J Emerg Med 2007;25:291-296.

Introduction
Although ultrasound has been used in administering epidural anesthesia, it is unknown if emergency physicians (EPs) can obtain ultrasound images useful for lumbar puncture.

Objective
The objective of the study was to determine EPs' ability to apply a standardized ultrasound technique for visualizing landmarks surrounding the dural space.

Methods
Two EPs sought to identify relevant anatomy in emergency patients. Visualization time for 5 anatomical structures (spinous processes or laminae, ligamentum flavum, dura mater, epidural space, subarachnoid space), body mass index, and perception of landmark palpation difficulty were recorded.

Results
Seventy-six subjects were enrolled. Soft tissue and bony anatomical structures were identified in all subjects. Mean body mass index was 31.4 ± 9.8 (95% confidence interval, 29.1-33.6). High-quality images were obtained in less than 1 minute in 153 (87.9%) scans and in less than 5 minutes in 174 (100%) scans. Mean acquisition time was 57.19 seconds; SD, 68.14 seconds; range, 10 to 300 seconds.

Conclusion
In this cohort, EPs were able to rapidly obtain high-quality ultrasound images relevant to lumbar puncture.

11. Just what is a TIA? And how long can it last?

A reappraisal of the definition and pathophysiology of the transient ischemic attack

Hadjiev DI, et al. Med Sci Monit, 2007; 13(3): RA50-53.

Summary:

Recent data on the pathophysiology of brain ischemia obtained by neuroimaging methods and the new concept of transient ischemic attack (TIA) emergency have called for a redefinition of TIA. According to the new definition proposed by the TIA Working Group, TIA is a brief episode of neurological dysfunction caused by focal brain or retinal ischemia with clinical symptoms typically lasting less than one hour and without evidence of acute brain infarction.

This new definition leads to a discussion on the duration of the neurological dysfunction and the availability of appropriate neuroimaging for all patients. It has been reported that the diffusion-weighted imaging abnormalities could be seen in TIA patients with durations of the neurological symptoms of less than 30 minutes, but they were not detected in 29% of patients with transient deficit lasting as much as 6 to 24 hours. Persisting perfusion abnormalities in TIA patients are also observed. Therefore, a cutoff period of any duration of TIA is inaccurate. From the pathophysiological viewpoint, TIA may be considered an ischemic penumbra of varied duration, which could proceed to cerebral infarction or reduce to benign oligemia. TIA, characterized as an ischemic penumbra, presents an ideal target for rapid reperfusion and neuroprotection. Follow-up perfusion imaging can guide and individualize its treatment.

Full-text (free): http://www.medscimonit.com/pub/vol_13/no_3/8683.pdf

12. Alzheimer Disease Toll Rising

More than 5 million people in the U.S. now live with Alzheimer disease and by mid-century, with the aging of the population, that number could reach as high as 16 million, warns a report released Tuesday by the Alzheimer's Association. Based on previously published estimates and new extrapolations, the report says:

-- Alzheimer disease was the seventh leading cause of death in 2004.

-- While mortality rates for heart disease, stroke, and breast and prostate cancer all declined between 2000 and 2004, the death rate from Alzheimer rose 33%.

-- In 2005, Medicare spent $91 billion on beneficiaries with Alzheimer disease or other dementias. That cost is projected to increase to $160 billion in 2010 and $189 billion in 2015.

Alzheimer’s Association report: http://www.alz.org/national/documents/Report_2007FactsAndFigures.pdf

13. Firefighting Duties Pose Substantial Cardiovascular Risk

The sudden stress of firefighting poses a significant risk for cardiovascular death, according to an 11-year study published in the March 22 issue of New England Journal of Medicine.

Using a national database, the authors estimated time typically spent in different firefighter duties, then estimated expected cardiovascular deaths during each. They measured actual cardiovascular deaths in firefighting centers serving communities of various sizes.

Although fire suppression accounted for only between 1% and 5% of firefighters' professional time, a third of all deaths from coronary artery disease in this population occurred during this activity -- 10 to 100 times as high as the risk associated with nonemergency duties. The risk was also increased during alarm response and return and physical training.

Editorialists conclude that in this population "modifiable risk factors, whether or not they are related to occupation, should be aggressively addressed."

NEJM report: http://content.nejm.org/cgi/reprint/356/12/1207.pdf

14. New Recommendations for Evaluating and Treating Adult Bacterial Meningitis

Laurie Barclay, MD. March 22, 2007 — A review of diagnostic and therapeutic practices for evaluating and treating adult bacterial meningitis in primary and emergency care settings is published in the March issue of Lancet Infectious Diseases.

"Despite the existence of antibiotic therapies against acute bacterial meningitis, patients with the disease continue to suffer significant morbidity and mortality in both high and low-income countries," write Michael T. Fitch, MD, PhD, from the Wake Forest University School of Medicine in Winston-Salem, North Carolina, and colleagues. "Dilemmas exist for emergency medicine and primary-care providers who need to accurately diagnose patients with bacterial meningitis and then rapidly administer antibiotics and adjunctive therapies for this life-threatening disease. Physical examination may not perform well enough to accurately identify patients with meningitis, and traditionally described lumbar puncture results for viral and bacterial disease cannot always predict bacterial meningitis."

The authors review current treatment guidelines for adults with suspected bacterial meningitis in the context of findings from recent studies. To increase awareness of guidelines for antibiotics and adjunctive steroids among clinicians who prescribe the initial doses of antibiotics in an emergency setting, the authors present an overview and discussion of key diagnostic and therapeutic decisions in the emergency evaluation and treatment of adults with suspected bacterial meningitis.

Although the initial steps in evaluation typically focus on history and physical examination, the available literature suggests that much of this evaluation may not accurately identify meningitis. The authors review the basis for decision making regarding neuroimaging before lumbar puncture, the interpretation of lumbar puncture results, and the empiric treatment of presumptive bacterial meningitis with antibiotics together with adjunctive systemic steroids.

To assist clinicians in their approach to patient care for this potentially life-threatening infection, the authors present a previously published algorithm for the treatment of patients with suspected community-acquired bacterial meningitis. Although signs and symptoms alone provide insufficient information to diagnose meningitis, one meta-analysis suggests that the absence of fever, neck stiffness, and altered mental status effectively eliminates meningitis as a likely diagnosis with a sensitivity of 99% to 100%.

In another study, at least 1 of 4 key elements (headache, fever, neck stiffness, and alterations in mental status) was present in 99% of patients, suggesting that aspects of history and physical examination can be used to heighten suspicion of meningitis even if they cannot alone rule out the diagnosis.

Most adults with bacterial meningitis do not present with prominent skin findings such as the rash typical of meningococcus infection (only 11% of cases in a large retrospective series and only 26% of cases in a prospective study). Kernig's sign, Brudzinski's sign, and meningismus also lack adequate sensitivity to be used in isolation to diagnose or exclude a potentially life-threatening disease.

Although increased intracranial pressure may result in brain herniation following lumbar puncture, several studies have shown no clinical changes in patients who had lumbar puncture to diagnose meningitis. In the opinion of the authors, it is reasonable to proceed with lumbar puncture without a computed tomographic (CT) scan if the patient does not have any of the following: new-onset seizures, an immunocompromised state, signs that are suspicious for space-occupying lesions (papilloedema or focal neurologic signs excluding cranial nerve palsy), or moderate-to-severe impairment of consciousness.

Cerebrospinal fluid findings may not accurately differentiate viral from bacterial meningitis. White blood cell count (cells per microliter) is typically 1000 to 10,000 (range, less than 100 to greater than 10,000) with bacterial and less than 300 (range less than 100 to 1000) with viral meningitis. Neutrophils are typically more than 80% vs less than 20%; protein levels elevated vs normal; and glucose levels reduced vs normal, respectively. However, these general predictions do not always hold true. The authors therefore recommend prospective studies to evaluate the diagnostic accuracy of signs, symptoms, and cerebrospinal fluid results in patients with suspected bacterial meningitis.

Some studies suggest worsening patient outcome with increased delays between presentation and antibiotic administration. Early antibiotic treatment in the emergency department may improve survival compared with delayed antibiotic treatment until after hospital admission.

"Although some guidelines attempt to propose an arbitrary time-based goal for antibiotic administration, others feel that a specific time point has not yet been identified as essential, but instead focus on level of disease severity and antibiotic administration as soon as possible once the diagnosis is considered," the authors write. "Until prospective data are available to support this practice, we suggest rapid administration of antibiotic therapy in the emergency department.... It is important to remember that the recommendations for CT scan include the caveat that patients who undergo CT first should have blood cultures and antibiotics started before ordering the CT scan."

Practice guidelines and expert opinions recommend broad spectrum coverage pending bacterial identification. The choice of initial antibiotic must be based on the most common bacteria causing the disease, according to the patient's age, clinical setting, and local patterns of antimicrobial susceptibility.

Empirical coverage with a third-generation cephalosporin (cefotaxime or ceftriaxone) at appropriate doses for meningitis is recommended, based on a broad spectrum of activity and excellent penetration into the cerebrospinal fluid when the meninges are inflamed. Because of the increasing prevalence of multidrug-resistant Streptococcus pneumoniae in many parts of the world (as high as 35% in parts of the United States), most experts recommend adding vancomycin to initial empirical therapy in adult patients. Patients older than 50 years should have ampicillin added for additional coverage of Listeria monocytogenes, which is more common in this age group.

This review recommends giving adult patients with suspected bacterial meningitis dexamethasone, 10 mg intravenously, with the first dose of antibiotics in the emergency department.

"The intense inflammatory response to bacterial infection within the enclosed spaces of the brain and spinal cord is thought to lead to significant morbidity and mortality despite effective antibiotic therapy," the authors conclude. "Therefore, pharmacological attempts to modulate this inflammatory response may be an essential component of a successful strategy to treat this life-threatening disease, and dexamethasone is the only currently accepted adjunctive therapy for the treatment of patients with bacterial meningitis that has proven clinical efficacy."

Lancet Infect Dis. 2007;7:191-200.

15. Can ED staff accurately estimate the weight of adult patients?

Kahn CA, et al. Amer J Emerg Med. 2007;25:307-312.

Purpose: The purpose of the study was to determine the accuracy of adult weight estimates by emergency department personnel.

Basic procedures: This was a prospective, nonrandomized, observational study in a university tertiary referral center. All patient care staff and all adult patients were eligible. Patients were weighed at the bedside, then staff were asked individually for estimates. Data were analyzed using SPSS general linear modeling procedures (SPSS, Chicago, IL) to obtain a generalized analysis of variance.

Main findings: Eighty-seven staff provided 957 estimates on 241 patients. Providers were within 5% of true weight on 33% of estimates (95% confidence interval [CI], 28-38). In our a priori subgroups, a significant difference was noted only for body mass index (BMI); percentages of correct estimates were 16% (95% CI, 0-33; n = 33) for BMI less than 18.5; 38% (95% CI, 33-43; n = 654) for BMI between 18.5 and 30; and 23% (95% CI, 17-30; n = 270) for BMI beyond 30 (P less than .001).

Principal conclusions: Emergency department personnel provided accurate weights in only 33% of estimates. Estimates became significantly less accurate in underweight and obese patients (defined by BMI).

16. Interrater Reliability of 3 Simplified Neurologic Scales Applied to Adults presenting to the ED with ALOC

Gill M, et al. Ann Emerg Med 2007;49:403-407.

Background
Patients presenting to the emergency department (ED) with altered levels of consciousness of traumatic and nontraumatic cause require careful assessment and continuous monitoring. Historically, a variety of neurologic scales has been used to monitor these patients, including the Glasgow Coma Scale (GCS), Advanced Trauma Life Support AVPU (Alert, responds to Verbal stimuli, responds to Painful stimuli, Unresponsive) scale, ACDU (Alert, Confused, Drowsy, Unresponsive) scale, and Swedish Reaction Level Scale. With the exception of the GCS, most of these have never undergone prospective assessment to ensure reliability and validity but have rather been adapted for use either because of institutional preference or ease of application. The GCS has recently been found to exhibit only moderate interrater reliability when tested in the ED setting in patients with altered levels of consciousness from traumatic and nontraumatic causes.

Editor’s Capsule Summary
What is already known on this topic: In an earlier derivation study, the Simplified Motor Scale (SMS), an easily remembered 3-point scale (2=obeys commands, 1=localizes pain, 0=withdraws to pain or less response), appeared to predict outcome after head injury as well as the Glasgow Coma Scale (GCS) and each of its 3 components (eye, verbal, motor).

What question this study addressed: How does the reliability (reproducibility) of the SMS compare to the GCS, the GCS’s 3 components, and 2 additional 4-point scales in the assessment of patients with altered levels of consciousness from all causes, ie, traumatic and nontraumatic?

What this study adds to our knowledge: The SMS, when examined with multiple measures of concordance and correlation in 120 emergency department patients with altered level of consciousness, appears to be more reproducible than the 6 other scales to which it was compared.

How this might change clinical practice: The SMS shows promise in the assessment of patients with altered levels of consciousness from all causes but cannot be recommended for use in clinical practice until its predictive validity has been demonstrated and its reproducibility independently replicated.

Study objective
The Simplified Motor Score was recently found to exhibit equal test performance to the Glasgow Coma Scale (GCS) when predicting 4 clinically important trauma outcomes. The present study tests the interrater reliability of the Simplified Motor Scale, the GCS and its components, and 2 other simplified neurologic scales when applied to patients presenting to the emergency department with altered levels of consciousness from any cause.

Methods
In this prospective observational study, emergency physicians independently assigned the GCS, Simplified Motor Scale, and 2 4-point scales—AVPU (Alert, responds to Verbal stimuli, responds to Painful stimuli, Unresponsive) and ACDU (Alert, Confused, Drowsy, Unresponsive)—to qualifying adult subjects. Two physicians filled out prospective data forms within 5 minutes of each other while remaining blinded to each other’s assessments. Data were pooled and analyzed for interrater reliability of all scales using simple agreement, unweighted κ, Spearman’s ρ, and Kendall’s τ-b.

Results
One hundred twenty-six subjects were enrolled, with 6 later excluded. Percentage agreements were 83% for the Simplified Motor Scale, 58% for the ACDU scale, 57% for the AVPU scale, and 42% for the Total GCS. The κ values were 0.70 for the Simplified Motor Scale, 0.43 for ACDU, 0.41 for AVPU, and 0.32 for the Total GCS. The Simplified Motor Scale also had the highest Spearman’s ρ (.85) and second highest Kendall’s τ-b (0.81).

Conclusion
The Simplified Motor Scale has the best interrater reliability for the assessment of altered level of consciousness of traumatic and nontraumatic cause among the scales tested.

17. Discordance between serum creatinine and creatinine clearance for identification of ED patients with abdominal pain at risk for contrast-induced nephropathy

Band RA, et al. Amer J Emerg Med. 2007;25:268-272.

Study Objective
Despite creatinine clearance (CrCl) being a better estimate of renal function, serum creatinine (Cr) is more commonly used to screen for renal insufficiency in patients scheduled for an enhanced abdominal computed tomography (CT) in an attempt to reduce the likelihood of contrast-induced nephropathy (CIN). Our objective was to determine the incidence of renal insufficiency (a CrCl less than 60 mL/min) among patients who have serum Cr below 1.5 mg/dL (the most commonly accepted Cr cutoff for the administration of intravenous contrast). This study was conducted in a population of emergency department patients with acute abdominal pain being considered for CT scan.

Methods
We performed post hoc analysis of a prospective cross-sectional study that enrolled nongravid adults with acute nontraumatic abdominal pain. Patients on dialysis were excluded. The data that we collected included demographics, history, duration/description of pain, patient reported weight, laboratory data, imaging studies, and final diagnosis. Creatinine clearance values (less than or greater than 60 mL/min) were compared to Cr values of 1.0, 1.2, 1.5, and 1.8 mg/dL to determine the percentage of patients at risk for nephropathy after contrast injection at each Cr cutoff. Descriptive statistics were used with 95% confidence intervals (CIs).

Results
Seven hundred sixty-five patients were enrolled; 59% (451/765) had an abdominal CT scan. Of 108 patients with CrCl less than 60 mL/min, 59 patients had a Cr less than 1.8 mg/dL (55%; 95% CI, 45%-64%); 43 had a Cr less than 1.5 mg/dL, the most commonly accepted Cr cutoff for contrast administration (40%; 95% CI, 31%-50%); 21 patients had a Cr less than 1.2 mg/dL (19%; 95% CI, 12%-28%); and 10 had a Cr less than 1.0 mg/dL (9%; 95% CI, 5%-16%).

Conclusion
The most commonly used Cr cutoff (1.5 mg/dL) for contrast administration fails to identify 40% of the patients at risk for CIN. Future studies should address whether using CrCl rather than serum Cr decreases the incidence of contrast-induced nephropathy

18. Emergency Physicians Urged to Act Locally to Solve Overcrowding

Karen Dente, MD. March 16, 2007 (Las Vegas) — The release of the Institute of Medicine (IOM) report in June 2006 on the future of emergency care in the United States health system increased awareness of overcrowding many emergency departments (EDs) and trauma centers across the country — a concern long known to many EM physicians working at the frontlines of emergency patient care.

Experts at the 13th annual meeting of the American Academy of Emergency Medicine (AAEM) discussed the implications of the IOM report for the community emergency physician. The overload of EDs across the country adversely affects all patients by delaying emergency care.

Brent Asplin, MD, MPH, a member of the IOM's subcommittee for hospital-based emergency care, told session attendees that the committee "pinned the responsibility clearly on the hospital CEOs" but that "it's our job as emergency physicians to get CEOs involved to improve the flow of patients."

Dr. Asplin, who is also emergency department head at Emergency Medicine Regions Hospital in St. Paul, Minnesota, and associate professor and vice chair of the department of emergency medicine at the University of Minnesota Medical School in Minneapolis, strongly urged ED physicians to voice any problems with overcrowding directly to their local hospital administrators.

According to the IOM report, between 1993 and 2003, ED visits in the United States grew 26% to 114 million annually, while the number of EDs decreased by 400 and the number of operating hospital beds decreased by almost 200,000 per year during that same period.

"The biggest take-home message for community emergency physicians is to end the practice of boarding inpatients in the ED," said Dr. Asplin. Delayed boarding of patients who are not immediately sent to an inpatient unit and who require further work-up and monitoring crowd the ED, taking up beds that should be reserved for patients requiring urgent care.

"One way to alleviate the crowding is to divert the patients to observation units," Robert Glatter, MD, FAAEM, attending emergency physician at Lenox Hill Hospital in New York City, told Medscape. "We have to recognize the fact that keeping the patients in the ED for a long work-up delays the next patient getting in the door, often by 3 to 4 hours."

AAEM 13th Annual Scientific Assembly: Plenary Session Lecture. Presented March 12, 2007.

19. FDA Clears Rapid Test for Viral Meningitis

The FDA this month cleared a rapid test that can determine the presence of viral meningitis in just 2.5 hours. The test employs gene isolation and amplification technology to detect Enteroviruses -- which cause roughly 90% of viral meningitis cases -- in cerebrospinal fluid. In a multisite study of 255 patients, the test had a positive predictive value of 96% and a negative predictive value of 97%.

Because it can help quickly distinguish between viral and bacterial meningitis, the test could help reduce the unnecessary use of antibiotics, the FDA said.

FDA Press Release: http://www.fda.gov/bbs/topics/NEWS/2007/NEW01588.html

20. PCI Fails to Provide Additional Benefit in Stable Patients on Optimal Medical Therapy

PCI does not lower the rates of myocardial infarction or death in patients with stable coronary artery disease who receive optimal medical treatment, a large trial concluded.

The study, released early online by NEJM, randomized nearly 2300 patients either to PCI with optimal medical therapy (intensive pharmacologic treatment plus lifestyle intervention) or to optimal medical therapy alone. After a median follow-up of almost 5 years, 19% in the PCI group died or had MIs, compared with 18.5% who received medical therapy alone.

PCI patients were more likely to be free of angina after 1 and 3 years, but there was no significant difference after 5 years. One-third of patients in the medical therapy group ultimately required revascularization, while 21% in the PCI group needed additional revascularization.

An editorialist concludes: "Patients whose condition is clinically unstable, who have left main coronary artery disease, or in whom medical therapy has failed to control symptoms remain candidates for revascularization, but PCI should not play a major role as part of a secondary prevention strategy."

NEJM abstract: http://content.nejm.org/cgi/content/abstract/NEJMoa070829v1

21. Jazz and the ‘Art’ of Medicine: Improvisation in the Medical Encounter

Haidet P. Ann Family Med 2007; 5:164-169.

Excerpt
Communication is central to human experience. It provides the vehicle through which we share ideas, coordinate actions, and build social structures. In medicine, important care processes such as information sharing and decision making occur in the context of patient-physician communication. A large and growing body of research shows that high-quality communication results in fewer medical errors, lower rates of litigation, and a variety of favorable social, psychological, and biological outcomes.

Improvisation is an important aspect of patient-physician communication. The medical encounter, like most encounters involving communication, is typically unscripted and constructed "in the moment." Although physicians often follow biomedical patterns of inquiry, a patient-centered care ideal calls for adjustments to and departures from these patterns in response to concerns and perspectives voiced by the patient. In other words, physicians often need to improvise when they encounter patients’ unique illness narratives. Improvisation guides a physician’s process of making moment-to-moment communicative decisions (eg, what to say next, how to structure particular questions, which threads to follow, when to interrupt and when to let the patient keep going). Stephen Nachmanovitch, PhD, a violinist and scholar on creativity and the spiritual underpinnings of art, described a tension between biomedical training and patients’ novel contexts as he discussed the importance of improvisation in medicine:

"In real medicine you view the person as unique—in a sense you drop your training. You are immersed in the case itself, letting your view of it develop in context. You certainly use your training; you refer to it, understand it, ground yourself in it, but you don’t allow your training to blind you to the actual person who is sitting in front of you. In this way, you pass beyond competence to presence. To do anything artistically, you have to acquire technique, but you create through your technique and not with it."

Full-text (free): http://www.annfammed.org/cgi/content/full/5/2/164