- Email: [email protected]
Pneumothoraces on abdominal CT in pediatric blunt trauma patients
RESEARCH
FORUM
ABSTRACTS
Study objective: To examine specific antibiotic prescriptions and differences according to patient age in ED patients with common colds, upper respiratory tract infections (URI), and bronchitis. Methods: Data were obtained from the 1996 National Hospital Ambulatory Medical Care Survey (NHAMC) of 21,902 ED visits and 450 emergency service areas. A standardized patient record with patient, visit, and provider characteristics was used. Exclusion criteria included asthma, emphysema, and chronic bronchitis. Statistical analysis included X2 and mufiivariate logistic regression for independence of association. Results: Overall, there was a difference in antibiotic prescription rates for pediatric (<18 years) patients (27% had antibiotics prescribed) versus adult (40%; P<.05). Adults were further stratified from I8 to 45 years (41% had antibiotics prescribed), 46 to 64 years (40%), and >65 years (34%; P<.01 for trend with age). Of the antibiotics prescribed, patients with colds or URIs usually received amino-penicillins, whereas bronchitis patients received macrolides. Conclusion: (1) Antibiotics are often prescribed inappropriately for patients with viral URIs. (2) Pediamc and elderly patients are less likely to receive antibiotics for these conditions. (3) There are differences in the types of medications given for each of these conditions. (4) Further study of the reasons for these prescribing patterns and the impact on antibiotic resistance is warranted.
163
Leukocyte Esterase as a Marker of the Presence of Fecal Leukocytes
Grillo A/Christiana Care Health Systems, Newark, DE Stud)- objective: The presence of fecal leukocytes (FL) aids in the diagnosis of invasire bacterial diarrhea. This study compares microscopic examination of stool for FL with leukocyte esterase (LE) reactivity from urine dipsticks exposed to stool. Methods: Blood and stool samples were obtained for analysis. The blood was serially diluted with saline, then mixed with stool. All specimens were stained with methylene blue and microscopically examined for FL. Each specimen was exposed to the LE tab of a standard urine dipstick. The dipsticks were moistened with saline before the addition of the specimen. Statistical analysis was done using McNemar's exact test. Results: FL were present up to and including the 1:16 dilution, whereas LE were present up to and including the 1:32 dilution. Further dilutions were negative for each test. These data are summarized in the Table. The probability that the difference between the 2 groups was due solely to chance was greater than 75% (P= 75). Conclusion: LE may represent a quick, surrogate, bedside test for the presence of FL. This study pro*ides the foundation for larger, clinical trials.
Presence of FL compared with that of LE reactivity Stool Blood Only Only 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: Dilution (Control) (Conl]rol) 1 2 4 8 10 16 32 64 100 1,000 10~00100,000
64
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+ +
+ + + + + + + + + +
+ +
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Validation of a Computer Model for the Determination of Aortic Compliance Curves
Summers RL. Mizelle LH, Jones AE, Montani JP/University of Mississippi Medical Center, Jackson, MS Stud),' objective: A reduction in aortic compliance (AC) is known to be a marker for atherosclerosis and coronary artery disease. However, specific AC measurements are dependent on the patient's current hemodynamic state, thus making evaluations and comparisons difficult. An individual's AC is best defined as a series of complex cur"es using computer models that incorporate the effects of reflexes, pressure, and the mechanical state of the arte W. Methods: A computer model of the aorta based on physiologic principles was constructed using object-oriented simulation software to define subject-specific AC curves using clinically determined hemodynamic profiles. To validate the method, the actual AC was measured in chronically instrumented conscious dogs over a vatting range of hemod)mamic states and compared with those values predicted by the computer-sim-
OCTOBER 1999, PART 2
65
Pneumothoraces on Abdominal CT in Pediatric Blunt Trauma Patients Holmes JF, Brant WE. Bogren HG. London KL. Kuppermann N/University of California-Davis School of Medicine. Sacramento. CA Stud)" objective: To compare abdominal computed tomography (CT) with plain chest radiography (CXR) for the detection of pneumothoraces in pediatric blunt trauma patients. Methods: We conducted a prospective observational cohort stud)' of pediatric (<16 years old) blunt trauma patients undergoing both abdominal CT and CXR in the emergency department of a Level 1 trauma center over a 28.5-month period. All abdominal CTs were interpreted by a single faculty radiologist. The CXRs of all patients with pneumothoraces detected on CT scan. as well as a random sample of CXRs in patients without pneumothoraces on abdominal CT (ratio: 4 normals per pneumothorax), were re~aewed by a second facuhy radiologist Both radiologists were masked to all clinical data and the objective of the study. All patients were followed through their hospital courses to document therapy and outcome. Results: Five-hundred fifty children under,vent abdominal CT and were enrolled. Nineteen patients (3%) were found to have pneumothoraces on CT. Of these 19 patients, 8 (42%, 95% confidence interval 2090 to 67%) had pneumorhoraces identified on initial CXR and all 8 underwent tube thoracostomy. In the remaining 11 patients with pneumothoraces visualized only on abdominal CT, 1 patient (9%, 95% confidence inter"al 0 to 42%) underwent tube thoracostomy. None of the 10 patients with pneumothoraces detected only on CT and who were managed without tube thoracostomy (including 2 patients who underwent positive-pressure ventilation) had complications from their pneumothoraces. No patient had pneumothorax solely on CXR. Conclusion: Of pediamc blunt trauma patients with pneumothoraces identified on abdominal CT, less than half have pneumothorax identified on CXR Patients with pneumothoraces identified solely on abdominal CT, however, rarely require tube thoracostomy
66
Table, abstract 163.
FL(+) LE(+-.)
ulated cur"es using a paired t test (P<.05). The study was approved by the institutional animal care committee. Results: The computer model generated AC curves consistent with those t)q?ically observed expenmentally. In 7 dogs studied, there was no sigraficant difference in the extrapolated values of AC deterrmned from the simulated curves and those observed in the indixldual animals at 2 widely different levels of heart rote, stroke volume, and arterial pressure. Conclusion: A computer model that accurately predicts AC over a wide range of hemodynamic states was validated using parameters invasively measured in dogs. This model and method may be clinically useful in defining patient-specific AC curves under a variety of hemod)~amlc conditions.
34:4
ANNALS OF EMERGENCY MEDICINE
Observation Improves CT Scan Utilization in Abdominal Pain Evaluation for Appendicitis Graft L, Mahadevan M, Russell J/New Britain General Hospital, New Britain, CT Stud)" objective: Observation improves computed romography (CT) scan utilization without worsening its diagnostic performance in identifying acute appendicitis in abdominal pain patients Methods: This ',,,'as a threshold for testing analysis of the value of obser"ation combining 2 retrospective obser"ational cohort studies. One was at 11 acute care hospitals examining consecutive patients who had an appendectomy for possible acute appendicitis (n= 1,045). Use of imaging was identified. The second was at 1 acute care hospital examining dunng 1 year all consecutive acute appendicitis (n= 105, 44 under,vent observation before surgeD'), all consecutive emergency department obset-,'ation unit patients (n=252), and a sample of consecutive ED abdominal pain patients without acute disease (n=100) Clinical findings were abstracted on all patients to calculate Alvarado appendicitis score and probability of disease. Results: In the first study, 916 patients had appendicitis and 110 patients had a negative laparotomy Dunng that same period at those hospital EDs, there were an estimated 20.044 abdominal pare patients evaluated who did not have appendicitis. CT scans were performed on 131 (14%) of 916 appendicitLs patients wuh 89% seusitix'ity. In the second stud)', there were 2,401 abdominal pain patients evaluated in the ED. At a threshold 5 Alvarado appendicitis score (15.4% pretest probability of disease) to test patients with CT scan, the use of observation improved sensitix'lty (76.3% to 80.6%), improved specificity (89.5% to 90%), and decreased CT scan usage from 3,265 (15.6%) of 20,960 patients to 2,753 (13.1%) of 20,960 patients, P<.001. Conclusion: Observation lowers the utiltzation of CT scan imaging without worsening its diagnostic performance in identifymg acute appendicitis in abdominal pain patients.
S 43
FORUM
ABSTRACTS
Study objective: To examine specific antibiotic prescriptions and differences according to patient age in ED patients with common colds, upper respiratory tract infections (URI), and bronchitis. Methods: Data were obtained from the 1996 National Hospital Ambulatory Medical Care Survey (NHAMC) of 21,902 ED visits and 450 emergency service areas. A standardized patient record with patient, visit, and provider characteristics was used. Exclusion criteria included asthma, emphysema, and chronic bronchitis. Statistical analysis included X2 and mufiivariate logistic regression for independence of association. Results: Overall, there was a difference in antibiotic prescription rates for pediatric (<18 years) patients (27% had antibiotics prescribed) versus adult (40%; P<.05). Adults were further stratified from I8 to 45 years (41% had antibiotics prescribed), 46 to 64 years (40%), and >65 years (34%; P<.01 for trend with age). Of the antibiotics prescribed, patients with colds or URIs usually received amino-penicillins, whereas bronchitis patients received macrolides. Conclusion: (1) Antibiotics are often prescribed inappropriately for patients with viral URIs. (2) Pediamc and elderly patients are less likely to receive antibiotics for these conditions. (3) There are differences in the types of medications given for each of these conditions. (4) Further study of the reasons for these prescribing patterns and the impact on antibiotic resistance is warranted.
163
Leukocyte Esterase as a Marker of the Presence of Fecal Leukocytes
Grillo A/Christiana Care Health Systems, Newark, DE Stud)- objective: The presence of fecal leukocytes (FL) aids in the diagnosis of invasire bacterial diarrhea. This study compares microscopic examination of stool for FL with leukocyte esterase (LE) reactivity from urine dipsticks exposed to stool. Methods: Blood and stool samples were obtained for analysis. The blood was serially diluted with saline, then mixed with stool. All specimens were stained with methylene blue and microscopically examined for FL. Each specimen was exposed to the LE tab of a standard urine dipstick. The dipsticks were moistened with saline before the addition of the specimen. Statistical analysis was done using McNemar's exact test. Results: FL were present up to and including the 1:16 dilution, whereas LE were present up to and including the 1:32 dilution. Further dilutions were negative for each test. These data are summarized in the Table. The probability that the difference between the 2 groups was due solely to chance was greater than 75% (P= 75). Conclusion: LE may represent a quick, surrogate, bedside test for the presence of FL. This study pro*ides the foundation for larger, clinical trials.
Presence of FL compared with that of LE reactivity Stool Blood Only Only 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: Dilution (Control) (Conl]rol) 1 2 4 8 10 16 32 64 100 1,000 10~00100,000
64
-
+ +
+ + + + + + + + + +
+ +
. . +
.
.
.
. -
-
Validation of a Computer Model for the Determination of Aortic Compliance Curves
Summers RL. Mizelle LH, Jones AE, Montani JP/University of Mississippi Medical Center, Jackson, MS Stud),' objective: A reduction in aortic compliance (AC) is known to be a marker for atherosclerosis and coronary artery disease. However, specific AC measurements are dependent on the patient's current hemodynamic state, thus making evaluations and comparisons difficult. An individual's AC is best defined as a series of complex cur"es using computer models that incorporate the effects of reflexes, pressure, and the mechanical state of the arte W. Methods: A computer model of the aorta based on physiologic principles was constructed using object-oriented simulation software to define subject-specific AC curves using clinically determined hemodynamic profiles. To validate the method, the actual AC was measured in chronically instrumented conscious dogs over a vatting range of hemod)mamic states and compared with those values predicted by the computer-sim-
OCTOBER 1999, PART 2
65
Pneumothoraces on Abdominal CT in Pediatric Blunt Trauma Patients Holmes JF, Brant WE. Bogren HG. London KL. Kuppermann N/University of California-Davis School of Medicine. Sacramento. CA Stud)" objective: To compare abdominal computed tomography (CT) with plain chest radiography (CXR) for the detection of pneumothoraces in pediatric blunt trauma patients. Methods: We conducted a prospective observational cohort stud)' of pediatric (<16 years old) blunt trauma patients undergoing both abdominal CT and CXR in the emergency department of a Level 1 trauma center over a 28.5-month period. All abdominal CTs were interpreted by a single faculty radiologist. The CXRs of all patients with pneumothoraces detected on CT scan. as well as a random sample of CXRs in patients without pneumothoraces on abdominal CT (ratio: 4 normals per pneumothorax), were re~aewed by a second facuhy radiologist Both radiologists were masked to all clinical data and the objective of the study. All patients were followed through their hospital courses to document therapy and outcome. Results: Five-hundred fifty children under,vent abdominal CT and were enrolled. Nineteen patients (3%) were found to have pneumothoraces on CT. Of these 19 patients, 8 (42%, 95% confidence interval 2090 to 67%) had pneumorhoraces identified on initial CXR and all 8 underwent tube thoracostomy. In the remaining 11 patients with pneumothoraces visualized only on abdominal CT, 1 patient (9%, 95% confidence inter"al 0 to 42%) underwent tube thoracostomy. None of the 10 patients with pneumothoraces detected only on CT and who were managed without tube thoracostomy (including 2 patients who underwent positive-pressure ventilation) had complications from their pneumothoraces. No patient had pneumothorax solely on CXR. Conclusion: Of pediamc blunt trauma patients with pneumothoraces identified on abdominal CT, less than half have pneumothorax identified on CXR Patients with pneumothoraces identified solely on abdominal CT, however, rarely require tube thoracostomy
66
Table, abstract 163.
FL(+) LE(+-.)
ulated cur"es using a paired t test (P<.05). The study was approved by the institutional animal care committee. Results: The computer model generated AC curves consistent with those t)q?ically observed expenmentally. In 7 dogs studied, there was no sigraficant difference in the extrapolated values of AC deterrmned from the simulated curves and those observed in the indixldual animals at 2 widely different levels of heart rote, stroke volume, and arterial pressure. Conclusion: A computer model that accurately predicts AC over a wide range of hemodynamic states was validated using parameters invasively measured in dogs. This model and method may be clinically useful in defining patient-specific AC curves under a variety of hemod)~amlc conditions.
34:4
ANNALS OF EMERGENCY MEDICINE
Observation Improves CT Scan Utilization in Abdominal Pain Evaluation for Appendicitis Graft L, Mahadevan M, Russell J/New Britain General Hospital, New Britain, CT Stud)" objective: Observation improves computed romography (CT) scan utilization without worsening its diagnostic performance in identifying acute appendicitis in abdominal pain patients Methods: This ',,,'as a threshold for testing analysis of the value of obser"ation combining 2 retrospective obser"ational cohort studies. One was at 11 acute care hospitals examining consecutive patients who had an appendectomy for possible acute appendicitis (n= 1,045). Use of imaging was identified. The second was at 1 acute care hospital examining dunng 1 year all consecutive acute appendicitis (n= 105, 44 under,vent observation before surgeD'), all consecutive emergency department obset-,'ation unit patients (n=252), and a sample of consecutive ED abdominal pain patients without acute disease (n=100) Clinical findings were abstracted on all patients to calculate Alvarado appendicitis score and probability of disease. Results: In the first study, 916 patients had appendicitis and 110 patients had a negative laparotomy Dunng that same period at those hospital EDs, there were an estimated 20.044 abdominal pare patients evaluated who did not have appendicitis. CT scans were performed on 131 (14%) of 916 appendicitLs patients wuh 89% seusitix'ity. In the second stud)', there were 2,401 abdominal pain patients evaluated in the ED. At a threshold 5 Alvarado appendicitis score (15.4% pretest probability of disease) to test patients with CT scan, the use of observation improved sensitix'lty (76.3% to 80.6%), improved specificity (89.5% to 90%), and decreased CT scan usage from 3,265 (15.6%) of 20,960 patients to 2,753 (13.1%) of 20,960 patients, P<.001. Conclusion: Observation lowers the utiltzation of CT scan imaging without worsening its diagnostic performance in identifymg acute appendicitis in abdominal pain patients.
S 43