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Quantitative plasma D-dimer levels among patients undergoing pulmonary angiography for suspected pulmonary embolism
870
The Journal
TOMOGRAPHY. Clancy TV, Ragozzino 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 routine use of CT scan without oral contrast leads to significant 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 received no contrast. Only 1 patient in this study who had a CT scan interpreted as negative later required surgery. This was for a perforated, 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 during surgery, and 5. patients with positive noncontrast CT scans managed conservatively later required surgery. However, 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 morbidity of a missed bowel injury, the use of oral contrast is mandatory. BY COMPUTED
0 SURGICAL FRESHWATER
HAZARDS ANIMALS
POSED BY MARINE AND 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 lesslikely 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 mistakes 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 illness 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 gastroenteritis, 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-
of Emergency
Medicine
tions between 1979 and 1991, 31 developed soft-tissue infections, 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 marine 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 assistphysicians in reducing unnecessary ankle and foot radiography. The initial study deriving the rules and a prospective validation 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 nonrandomized, controlled trial with before-and-after comparisons of radiography utilization at an intervention hospital where the Ankle Rules were applied and at a control hospital 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 hospital, 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 significantly lesstime in the emergency department and had lower total charges than those patients who had radiographs completed. Nonperformance of radiography in nonfracture patients did not have a significant adverse effect on patient satisfaction. Based on radiograph results and telephone follow-up, the Ottawa rules resulted in a sensitivity of 1.Ofor 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 diagnostic pulmonary angiography. D-dimer is a specific degradatory product released into the circulation by endogenous fibrinolysis of cross-linked fibrin clot. The development of a blood test like D-dimer for helping to determine the likelihood of PE could potentially conserve health care resources.
Abstracts
This was a blinded comparison of quantitative plasma D-dimer levels (measured using monoclonal antibody assay) with pulmonary angiographic results from 173 patients with suspected acute PE. The authors of this study found plasma D-dimer levels less than 500 rig/ml to be strongly predictive of a normal pulmonary angiogram (negative predictive value 91.4%). While acknowledging flaws in their study, the authors concluded that plasma D-dimer levels hold promise as a useful diagnostic tool. [Thomas Caffrey , MD 1 Editor’s Comment: D-dimer results when combined with O2 or CO2 gradient calculations may prove to enhance the negative predictive value of the test and be a useful screen for PE.
0 USE OF ALVEOLAR-ARTERIAL OXYGEN GRADIENT IN THE DIAGNOSIS OF PULMONARY EMBOLISM. McFarlane MJ, Imperiale TF. Am J Med. 1994;96: 57-62. The diagnostic value of a normal alveolar-arterial oxygen (A-a) gradient for excluding the diagnosis of pulmonary embolism (PE) was examined. All patients who underwent ventilation/perfusion (V/Q) scanning at Cleveland MetroHealth Medical Center in 1988-1989 and in 1987 and 1990 were retrospectively reviewed as derivation and validation sets, respectively. Patients below age 20 or receiving supplemental oxygen were excluded. The derivation set included 873 patients. Of these, 540 had valid room air arterial blood gas (ABG) measurements. One hundred nine patients were discharged with the diagnosis of PE. Seventy-two patients were identified as having normal A-a gradients. Five of the 72 patients were in the PE group, but 4 of these were noted to have a previous history of PE or deep venous thrombosis (DVT). The validation set included 805 patients. Four hundred eighty-seven patients had valid ABG measurements. Seventy-five patients were discharged with the diagnosis of PE. One patient was identified as having a PE and normal A-a gradient without a history of PE or DVT. The authors suggest the combination of a normal A-a gradient, low clinical suspicion of PE, and a patient lacking the history of a prior PE or DVT should provide sufficient evidence to exclude the diagnosis of PE. [John Papavasiliou, MD] Editor’s Comment: Given the fact that V/Q scanning was the gold standard in this study, the conclusion is not justified, but a normal A-a gradient may be useful to place a low-risk patient in an even lower risk category.
Cl RUPTURED ABDOMINAL AORTIC ANEURYSM: THE INTERNIST AS DIAGNOSTICIAN. Lederle FA, Parenti CM, Chute EP. Am J Med. 1994;96:163-7. A ruptured abdominal aortic aneurysm (AAA) is a diagnosis that requires early identification to reduce the mor-
871
bidity and the mortality associated with this diagnosis. This paper examines the hospital course of ruptured kAA that presented to internists during a 7 %-year period at a large academic medical center. The methods included examining the charts of all patients identified as having a ruptured AAA. The paper clarifies that the medical center does not accept surgical emergencies and that most evaluations are performed by internists. Twenty-three patients were found to be managed by internists. Eighteen of these patients were seen in the emergency department where 10 were ultimately diagnosed. The remaining 8 patients were transferred to the inpatient medicine service. Only 3 patients had a systolic pressure below 90 mmHg upon presentation. In the 14 casesthat were initially missed, only 6 had evidence on the chart that a symptomatic AAA was considered but not felt to be the cause of the symptoms. The mean AAA size was 7.6 cm. The diagnosis was not made in 5 patients until they became hemodynamically unstable. Five diagnoses were made postmortem. Eight of the ruptured AAA also had surgical consults that initially missed the diagnosis. The authors discussthat the chart review demonstrated a lack of awareness of the syndromes associated with a contained ruptured AAA and a symptomatic unruptured AAA. The characteristics associated with the former were thought by the physicians caring for the patients to be evidence against the diagnosis. Another factor was the failure to palpate a large AAA in an undistended abdomen. [Saralyn R. Williams, MD] Editor’s Comment: The majority of these patients presented with abdominal or back pain, and these symptoms were ascribed most often to urinary tract or spinal disease.
0 OUTPATIENT MANAGEMENT WITHOUT ANTIBIOTICS OR FEVER IN SELECTED INFANTS. Baker MD, Bell LM, Avner JR. NEJM. 1993;329:1437-41. A 5-year prospective controlled study was designed to determine if strict screening criteria could safely be used to identify febrile 1 to 2-month-old infants at low risk for serious infection who could safely be cared for as outpatients without antibiotics. The study group consisted of 747 consecutive infants, ages 29 to 56 d, with rectal temperatures greater than 38.2% If no evidence of serious bacterial infection was found on a complete examination, infants with normal laboratory values were placed into either outpatient care without antibiotics or inpatient observation without antibiotics. The outpatient group was re-examined at 24 and 48 h. Laboratory screening criteria for serious bacterial infection included a white blood cell count greater than 15,000 per cubic millimeter, spun urine with greater than 10 white cells per high-powered field or more than a few bacteria, cerebral spinal fluid with greater than 8 white cells per cubic millimeter or a positive gram stain, or an infiltrate on chest radiography. Two hundred eighty-seven infants (28.4%) had no evidence of serious bacterial infection. One hundred thirty-nine (18.6%) were assigned to
The Journal
TOMOGRAPHY. Clancy TV, Ragozzino 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 routine use of CT scan without oral contrast leads to significant 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 received no contrast. Only 1 patient in this study who had a CT scan interpreted as negative later required surgery. This was for a perforated, 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 during surgery, and 5. patients with positive noncontrast CT scans managed conservatively later required surgery. However, 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 morbidity of a missed bowel injury, the use of oral contrast is mandatory. BY COMPUTED
0 SURGICAL FRESHWATER
HAZARDS ANIMALS
POSED BY MARINE AND 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 lesslikely 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 mistakes 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 illness 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 gastroenteritis, 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-
of Emergency
Medicine
tions between 1979 and 1991, 31 developed soft-tissue infections, 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 marine 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 assistphysicians in reducing unnecessary ankle and foot radiography. The initial study deriving the rules and a prospective validation 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 nonrandomized, controlled trial with before-and-after comparisons of radiography utilization at an intervention hospital where the Ankle Rules were applied and at a control hospital 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 hospital, 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 significantly lesstime in the emergency department and had lower total charges than those patients who had radiographs completed. Nonperformance of radiography in nonfracture patients did not have a significant adverse effect on patient satisfaction. Based on radiograph results and telephone follow-up, the Ottawa rules resulted in a sensitivity of 1.Ofor 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 diagnostic pulmonary angiography. D-dimer is a specific degradatory product released into the circulation by endogenous fibrinolysis of cross-linked fibrin clot. The development of a blood test like D-dimer for helping to determine the likelihood of PE could potentially conserve health care resources.
Abstracts
This was a blinded comparison of quantitative plasma D-dimer levels (measured using monoclonal antibody assay) with pulmonary angiographic results from 173 patients with suspected acute PE. The authors of this study found plasma D-dimer levels less than 500 rig/ml to be strongly predictive of a normal pulmonary angiogram (negative predictive value 91.4%). While acknowledging flaws in their study, the authors concluded that plasma D-dimer levels hold promise as a useful diagnostic tool. [Thomas Caffrey , MD 1 Editor’s Comment: D-dimer results when combined with O2 or CO2 gradient calculations may prove to enhance the negative predictive value of the test and be a useful screen for PE.
0 USE OF ALVEOLAR-ARTERIAL OXYGEN GRADIENT IN THE DIAGNOSIS OF PULMONARY EMBOLISM. McFarlane MJ, Imperiale TF. Am J Med. 1994;96: 57-62. The diagnostic value of a normal alveolar-arterial oxygen (A-a) gradient for excluding the diagnosis of pulmonary embolism (PE) was examined. All patients who underwent ventilation/perfusion (V/Q) scanning at Cleveland MetroHealth Medical Center in 1988-1989 and in 1987 and 1990 were retrospectively reviewed as derivation and validation sets, respectively. Patients below age 20 or receiving supplemental oxygen were excluded. The derivation set included 873 patients. Of these, 540 had valid room air arterial blood gas (ABG) measurements. One hundred nine patients were discharged with the diagnosis of PE. Seventy-two patients were identified as having normal A-a gradients. Five of the 72 patients were in the PE group, but 4 of these were noted to have a previous history of PE or deep venous thrombosis (DVT). The validation set included 805 patients. Four hundred eighty-seven patients had valid ABG measurements. Seventy-five patients were discharged with the diagnosis of PE. One patient was identified as having a PE and normal A-a gradient without a history of PE or DVT. The authors suggest the combination of a normal A-a gradient, low clinical suspicion of PE, and a patient lacking the history of a prior PE or DVT should provide sufficient evidence to exclude the diagnosis of PE. [John Papavasiliou, MD] Editor’s Comment: Given the fact that V/Q scanning was the gold standard in this study, the conclusion is not justified, but a normal A-a gradient may be useful to place a low-risk patient in an even lower risk category.
Cl RUPTURED ABDOMINAL AORTIC ANEURYSM: THE INTERNIST AS DIAGNOSTICIAN. Lederle FA, Parenti CM, Chute EP. Am J Med. 1994;96:163-7. A ruptured abdominal aortic aneurysm (AAA) is a diagnosis that requires early identification to reduce the mor-
871
bidity and the mortality associated with this diagnosis. This paper examines the hospital course of ruptured kAA that presented to internists during a 7 %-year period at a large academic medical center. The methods included examining the charts of all patients identified as having a ruptured AAA. The paper clarifies that the medical center does not accept surgical emergencies and that most evaluations are performed by internists. Twenty-three patients were found to be managed by internists. Eighteen of these patients were seen in the emergency department where 10 were ultimately diagnosed. The remaining 8 patients were transferred to the inpatient medicine service. Only 3 patients had a systolic pressure below 90 mmHg upon presentation. In the 14 casesthat were initially missed, only 6 had evidence on the chart that a symptomatic AAA was considered but not felt to be the cause of the symptoms. The mean AAA size was 7.6 cm. The diagnosis was not made in 5 patients until they became hemodynamically unstable. Five diagnoses were made postmortem. Eight of the ruptured AAA also had surgical consults that initially missed the diagnosis. The authors discussthat the chart review demonstrated a lack of awareness of the syndromes associated with a contained ruptured AAA and a symptomatic unruptured AAA. The characteristics associated with the former were thought by the physicians caring for the patients to be evidence against the diagnosis. Another factor was the failure to palpate a large AAA in an undistended abdomen. [Saralyn R. Williams, MD] Editor’s Comment: The majority of these patients presented with abdominal or back pain, and these symptoms were ascribed most often to urinary tract or spinal disease.
0 OUTPATIENT MANAGEMENT WITHOUT ANTIBIOTICS OR FEVER IN SELECTED INFANTS. Baker MD, Bell LM, Avner JR. NEJM. 1993;329:1437-41. A 5-year prospective controlled study was designed to determine if strict screening criteria could safely be used to identify febrile 1 to 2-month-old infants at low risk for serious infection who could safely be cared for as outpatients without antibiotics. The study group consisted of 747 consecutive infants, ages 29 to 56 d, with rectal temperatures greater than 38.2% If no evidence of serious bacterial infection was found on a complete examination, infants with normal laboratory values were placed into either outpatient care without antibiotics or inpatient observation without antibiotics. The outpatient group was re-examined at 24 and 48 h. Laboratory screening criteria for serious bacterial infection included a white blood cell count greater than 15,000 per cubic millimeter, spun urine with greater than 10 white cells per high-powered field or more than a few bacteria, cerebral spinal fluid with greater than 8 white cells per cubic millimeter or a positive gram stain, or an infiltrate on chest radiography. Two hundred eighty-seven infants (28.4%) had no evidence of serious bacterial infection. One hundred thirty-nine (18.6%) were assigned to