870 The Journal of Emergency Medicine

BY COMPUTED TOMOGRAPHY. Clancy TV, Ragoz- zino MW, Ramshaw D, et al. AM J Surg. 1993;166:680-5.

In this study, 492 patients who had received computed tomography (CT) scan over a 4-year period were reviewed retrospectively for the purpose of determining whether rou- tine use of CT scan without oral contrast leads to signifi- cant diagnostic error. The institution involved generally does not use contrast with their abdominal CT scans in trauma patients; thus, 484 (98.4%) of these patients re- ceived no contrast.

Only 1 patient in this study who had a CT scan interpre- ted as negative later required surgery. This was for a perfo- rated, ischemic cecum 24 h after admission. It was felt that oral contrast would not have helped with the diagnosis. In addition, 4 patients managed surgically with positive noncontrast CT scans had additional diagnoses made dur- ing surgery, and 5. patients with positive noncontrast CT scans managed conservatively later required surgery. How- ever, in none of these cases was it felt that oral contrast was or would have been useful in better establishing the diagnosis. Overall, the sensitivity of noncontrast CT scan was 98.4%, and the specificity was 99.8%.

The authors concluded that omission of oral contrast did not represent a disadvantage to patients with blunt abdominal trauma and avoided potential delays and risks.

[Scott J. Jones, MD]

Editor’s Comment: This is an absurd conclusion given the fact that only 1.6% of the study patients received oral contrast. With the increasing use of seat belts and the mor- bidity of a missed bowel injury, the use of oral contrast is mandatory.

0 SURGICAL HAZARDS POSED BY MARINE AND FRESHWATER ANIMALS IN FLORIDA. Howard RJ, Burgess GH. Am J Surg. 1993;166:563-7.

In a review of various registries for the state of Florida, some of the most common sources of injury and illness from marine life are discussed. Shark bites number lo-15 per year in Florida, but only 30 patients have died since 1882. Although causing greater damage, larger sharks are less likely to bite than smaller ones. Attacks tend to occur inside the first sandbar or at steep drop-offs, at times when bathers are most numerous, and in murky or turbid waters where sharks may mistake humans for other prey. Most attacks are “bump and runs” where, again, the shark mis- takes a human for a natural prey, bites, and then releases.

Other animals can cause significant tissue injury, but death is quite rare. Alligators can kill humans, although only 129 attacks and 7 deaths have been reported in Florida since 1947.

The common oyster is responsible for more serious ill- ness and injury than all other aquatic animals combined. This is due to their ability to concentrate marine bacteria, especially Vibrio. Ingestion may simply result in gastroen- teritis, but it can lead to soft-tissue infection, sepsis, and death. A similar scenario can unfold from external injuries caused by marine life. Of 103 patients with Vibrio infec-

tions between 1979 and 1991, 31 developed soft-tissue in- fections, 49 sepsis, and 23 both. While patients with liver disease are particularly susceptible to these infections due to altered iron metabolism, all patients are at risk, and therefore antibiotics are strongly recommended for all ma- rine injuries or ingestions. [Scott J. Jones, MD]

Editor’s Comment: It is hard to visualize that the risk from an oyster is greater than the risk from a Great White,

q IMPLEMENTATION OF THE OTTAWA ANKLE RULES. Stiell IG, McKnight RD, Greenberg GH, et al. JAMA. 271( 11):827-32.

The Ottawa Ankle Rules were developed to assist physi- cians in reducing unnecessary ankle and foot radiography. The initial study deriving the rules and a prospective valida- tion have been published previously. In this phase of the project, the impact of implementation of the rules into clinical practice was investigated. The study was a nonran- domized, controlled trial with before-and-after compari- sons of radiography utilization at an intervention hospital where the Ankle Rules were applied and at a control hospi- tal where no changes in usual practice were made. Of those examined, 2,342 adult patients with acute ankle injuries were included from the two hospitals. At the study hospi- tal, there were relative reductions of 28% and 14% in ankle and foot radiography, respectively. The control institution had relative increases in ankle and foot radiography of 2% and 13%. At the intervention hospital, nonfracture patients who did not undergo radiography spent signifi- cantly less time in the emergency department and had lower total charges than those patients who had radiographs completed. Nonperformance of radiography in nonfrac- ture patients did not have a significant adverse effect on patient satisfaction. Based on radiograph results and tele- phone follow-up, the Ottawa rules resulted in a sensitivity of 1 .O for detecting ankle and midfoot fractures.

[Marc David Taub, MD]

Editor’s Comment: This is an important study that may help reduce unnecessary radiation therapy of extremities.

0 QUANTITATIVE PLASMA D-DIMER LEVELS AMONG PATIENTS UNDERGOING PULMONARY ANGIOGRAPW FOR SUSPECTED PULMONARY EMBOLISM. Goldhaber SZ, Simons GR, Elliott G, et al. JAMA. 1993;270:2819-28.

This study was designed to test the hypothesis that a low D-dimer level has a high negative predictive value for pulmonary embolism (PE) among patients undergoing di- agnostic pulmonary angiography. D-dimer is a specific degradatory product released into the circulation by endog- enous fibrinolysis of cross-linked fibrin clot. The develop- ment of a blood test like D-dimer for helping to determine the likelihood of PE could potentially conserve health care resources.