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Emergency Medicine News:
doi: 10.1097/01.EEM.0000361691.26519.75
Living with the LLSA

Acute Heart Failure Syndromes, CT Radiation, and Radiological Casualties

Lovato, Luis M. MD

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Author Credentials and Financial Disclosure:

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Dr. Lovato is an Associate Professor of Medicine at the David Geffen School of Medicine at the University of California at Los Angeles, the Director of Critical Care for the Department of Emergency Medicine at Olive View-UCLA Medical Center, and the LLSA Workshop Co-Director for the Olive View-UCLA National Conference on Advances in Emergency Medicine.

All faculty and staff in a position to control the content of this CME activity have disclosed that they have no financial relationships with, or financial interests in, any commercial companies pertaining to this educational activity.

Learning Objectives: After reading this article, the physician should be able to:

1. Summarize the recommendations of the American College of Emergency Physicians for the emergent treatment of acute heart failure syndrome.

2. Describe the oncogenic effects of ionizing radiation and the need to balance the benefits of computerized tomography (CT) against the oncogenic risk to public health.

3. Define the principles of managing radiological casualties.

Release Date: October 2009

Article from the 2009 LLSA Reading List

Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department with Acute Heart Failure Syndromes.

Silvers SM, et al

Ann Emerg Med

2007;49(5):627

This article discusses the limitations of widely used but poorly defined terminology such as pulmonary edema and congestive heart failure. The authors ultimately endorse the term “acute heart failure syndrome” defined by the International Working Group on Acute Heart Failure Syndromes as the “gradual or rapid deterioration in heart failure signs and symptoms resulting in the need for urgent therapy.” (Circulation 2005;112[25]:3958.)

As with other clinical policies from the American College of Emergency Physicians, articles from the literature are initially assessed for quality and strength of evidence. Selected articles are subsequently used to answer key clinical questions, with the final strength of each recommendation based on the pooled body of evidence.

Level C recommendations are the weakest, and are based on evidence that is preliminary, inconclusive, or conflicting, or in the absence of literature, from panel consensus. According to this clinical policy on acute heart failure syndromes, these are Level C recommendations:

▪ The use of bi-level positive airway pressure (BiPAP) for managing acute heart failure syndrome and respiratory distress.

▪ Avoid the use of nesiritide for first-line therapy in the ED management of acute heart failure syndrome.Level B recommendations are based on evidence that is of moderate clinical certainty or strong consensus evidence. According to this clinical policy, these are Level B guidelines for acute heart failure syndrome in the ED:

▪ The use of continuous positive airway pressure (CPAP) for managing acute heart failure syndrome and respiratory distress.

▪ The use of a single basic natriuretic peptide (BNP) measurement to improve the diagnostic accuracy of heart failure syndrome. BNP is especially helpful to rule out acute heart failure syndrome when below a well-defined threshold.

▪ The use of nitrates alone or with furosemide in managing patients with acute heart failure syndrome.

▪ The use of angiotensin-converting enzyme inhibitors (ACEI) with acute heart failure syndrome.

Finally, Level A recommendations are based on evidence that is of high clinical certainty or overwhelming consensus evidence. According to this clinical policy, there were no Level A recommendations for managing acute heart failure syndrome.

After reading this article, you may want to reconsider your approach to diagnosing and managing acute heart failure syndrome in the ED. If so, it may be prudent to prioritize any changes to your practice based on the recommendation's level of strength.

Article from the 2009 LLSA Reading List

Computed Tomography-An Increasing Source of Radiation Exposure

Brenner DJ, Hall EJ

N Engl J Med

2007;357(22):2277

Advances in radiology have revolutionized the practice of medicine, bringing universal access to health care in this country. Now even the uninsured can get a screening CT or 4D ultrasound at the local strip mall. But this ubiquitous use of technology comes at a price. This article examines the increasing risk of radiation exposure from the use and overuse of CT in the medical field.

Simply stated, ionizing radiation is oncogenic. The direct and indirect effects of radiation cause DNA damage that can result in cancer over time. Cells undergoing mitosis at the time of radiation exposure are most susceptible to DNA damage and subsequent malignant transformation.

The oncogenic risks of radiation are amplified in younger patients because their cells have higher mitotic rates than adults, and for the same amount of delivered radiation, they receive higher organ doses due to their smaller body mass. Children also have more life-years ahead of them to manifest any malignancy arising from radiation-damaged DNA.

Real-world radiation exposure from a typical CT study is often much higher than commonly cited radiation estimates. An estimate of radiation received from a single abdominal CT often doesn't include the additional radiation from pelvic imaging, fine cuts through the pancreas, or the fact that a scan is done twice, before and after contrast is administered.

Based on estimates of death from cancer induced in low-dose radiation survivors from Japan (<50 mSv) and another large cohort of nuclear industry workers exposed to radiation (average of 20 mSv), the risk of inducing cancer death in a single individual from a real-world CT study (30 to 90 mSv) is extremely small. This small risk applied in mass scale to a large population receiving CT studies, however, undoubtedly means that in some patients, a CT scan will actually cause their cancer. In fact, the article estimates that at the time of publication, up to two percent of all cancers in the United States may be attributed to radiation from CT studies.

The use of CT is expected to rise steadily. Most of these CTs will represent the appropriate use of medical technology to improve patient outcomes. Unfortunately, a growing number of these scans will be unnecessary. Barriers to sharing the medical record, blind implementation of poorly written clinical policy, and plain old defensive medicine can all lead to unnecessary CT. Bad decision-making by well-intentioned physicians also can be blamed. In one study, introducing ELISA D-dimer to an academic ED resulted in a 35 percent increase in rule-out PE imaging with no increase in PE diagnosis. (Acad Emerg Med 2006;13[5]:519.) In addition, following the recent trend of the pharmaceutical industry, direct marketing to patients is sure to result in the increased use of unproven CT technology as patients insist on receiving their virtual colonoscopies, CT cardiac screens, and peace-of-mind whole body scans.

This article summarizes three key interventions that can potentially reduce the risk of cancer caused by CT: using exposure controls on the latest generation scanners, using alternative imaging (MRI, ultrasonography), and perhaps the one you can control the most, simply reducing the amount of CTs you order.

Article from the 2008 LLSA Reading List

Medical Treatment of Radiological Casualties: Current Concepts

Koenig KL, et al

Ann Emerg Med

2005;45(6):643

Most emergency physicians have never treated a radiological casualty. With the exception of military personnel or those enrolled in a special course, most have never had any formal training on the subject. This article offers a comprehensive review of evaluating and managing a patient exposed to radiation, and it reviews possible scenarios of mass radiation exposure. Accidental exposure may come from the medical field, conventional industry, or the nuclear industry. Possible types of intentional exposure include nuclear detonation, a radiological dispersion device, or the public placement of unshielded radioactive material in a high-traffic area such as a stadium or subway station.

The effects on the body depend on the whole body exposure (WBE) dose measured in Grays (Gy). At lower doses, most affected cells will recover although they will be at risk for future malignant transformation. At higher doses, cells simply die, with symptomatic effects determined by the number and function of affected cells. Cells with high turnover rates such as marrow or GI mucosa are the most quickly affected.

A reliable early manifestation of the acute radiation syndrome is vomiting. Mild exposures (1 to 2 Gy) induce vomiting hours after exposure, while vomiting may occur in less than 10 minutes with lethal doses (> 8 Gy). Headache, diarrhea, weakness, fever, hair loss, and hypotension can all be part of the acute radiation syndrome, with rate of onset depending on severity of exposure. Death from mild exposures is rare, but death from very severe exposures (6 to 8 Gy) can occur within days.

In many cases, the exposure event is very clear and the WBE dose of radiation can be accurately predicted. In other cases, especially when the exposure is not immediately apparent, the amount of radiation exposure can be unclear. In these cases, the minimal lymphocyte count within 48 hours of exposure can be used to approximate the absorbed dose of radiation. More accurate estimates can be made with additional clinical data such as time to onset of vomiting and serial lymphocyte counts using the Armed Forces Research Institute Biodosimetry Assessment Tool, which is available online. (www.afrri.usuhs.mil/outreach/biodostools.htm)

Localized radiation exposure occurs after handling radioactive items without proper shielding. Radiation burns are similar to thermal burns, but instead of being immediately apparent, they may not manifest for hours to days after the exposure. Survival is usually good because the WBE dose in these cases is often not severe.

As with all serious injury, first aid, resuscitation, and stabilization are very important. With the radiological casualty, decontamination and containment also are critical to prevent further exposure to the victim, other patients, rescue workers, and hospital personnel. As with chemical exposures, removal of clothing, copious water rinsing, gentle soap and water brushing, and proper wound dressings are key to decontamination and containment.

The article concludes with a detailed discussion of three categories of medical countermeasures, many of which are still under investigation. Radioprotectants prevent cellular damage, radiomitigators accelerate cellular repair, and radionuclide eliminators reduce continued exposure. Depending on the source radionuclide, specific therapies may be indicated to minimize internal contamination.

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About the LLSA

As part of its continuous certification program, the American Board of Emergency Medicine has developed the Lifelong Learning and Self-Assessment (LLSA) program to promote continuous education of diplomates. Each year, beginning in 2004, 16 to 20 articles are chosen based on the Emergency Medicine Model. A list of these articles can be found on the ABEM web site, www.abem.org.

ABEM is not authorized to confer CME credit for the successful completion of the LLSA test, but it has no objection to physicians participating in such activities. EMN's CME activity, Living with the LLSA, is not affiliated with ABEM's LLSA program, and reading this article and completing the quiz does not count toward ABEM certification. Rather, participants may earn 1 CME credit from the Lippincott Continuing Medical Education Institute, Inc., for each completed EMN quiz.

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CME Participation Instructions

To earn CME credit, you must read the article in Emergency Medicine News, and complete the quiz, answering at least 80 percent of the questions correctly. Mail the completed quiz with your check for $10 payable to the Lippincott Continuing Medical Education Institute, Inc., 530 Walnut Street, 8th Floor East, Philadelphia, PA 19106. Only the first entry will be considered for credit, and must be received by Lippincott Continuing Medical Education Institute, Inc., by October 31, 2010. Acknowledgement will be sent to you within six to eight weeks of participation.

Lippincott Continuing Medical Education Institute, Inc., is accredited by the Accreditation Council for Continuing Medical Education to provide medical education to physicians. Lippincott Continuing Medical Education Institute, Inc., designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit.™ Physicians should only claim credit commensurate with the extent of their participation in the activities.

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