Biomedical subjects

John A Brennan

Publications and source records attributed to John A Brennan.

6 recordsLinked to original sources

PubMed2005

An electronic chart prompt to decrease proprietary antibiotic prescription to self-pay patients.

OBJECTIVES: Emergency physicians unaware of patients' insurance status may prescribe expensive proprietary antibiotics for patients who cannot afford them. The objective of this study was to develop a clinical decision support system to display patient insurance status before prescription writing for outpatient conditions. METHODS: This was a 26-week "before-and-after" trial at an urban emergency department (ED) with 78,000 visits/year treating a medically underserved population. Sixty-one prescribers, including attending physicians, residents, and physician assistants, participated. All patients older than 18 years of age discharged from the ED receiving antibiotic prescriptions were eligible. The electronic ED chart is linked to prescription-writing software, which includes a menu of 74 antibiotics. The system was programmed so that when an emergency physician accessed the prescription menu, a prompt appeared displaying insurance status. Prescribers also received educational interventions. The main outcome measure was the percentage of prescribers who reduced their prescription writing of proprietary antibiotics to self-pay patients. Data were analyzed with cluster techniques using SPSS 10.0 (SPSS Inc., Chicago, IL). RESULTS: Of 594 prescriptions written for self-pay patients before prompt insertion, 158 (26.6%) were for proprietary antibiotics. After the intervention, self-pay patients received 564 antibiotic prescriptions, of which 117 (20.7%) were for proprietary drugs. Analyzed by prescriber, the reduction in the prescription rate for proprietary antibiotics was statistically significant (p = 0.03, chi(2) test). Patients with respiratory or urinary infections also had a statistically significant reduction in proprietary antibiotic prescription (p = 0.03). CONCLUSIONS: A clinical decision support system, integrated into a prescription-writing program, can decrease the prescription of proprietary antibiotics for self-pay patients in the ED.

Adult↗

PubMed2004

Heterogeneity of tensile strength and matrix metalloproteinase activity in the wall of abdominal aortic aneurysms.

PURPOSE: To measure the tensile strength of the aneurysm wall and the matrix metalloproteinase (MMP) activity in similar samples of aortic tissue. METHODS: Detailed mechanical testing was conducted on 124 standardized specimens of aneurysm wall harvested from 24 patients undergoing elective aneurysm repair. The intrasac pressure required to cause aneurysm rupture was calculated based upon the Law of Laplace. In addition, MMP-2 and 9 were assayed from these specimens. Sixty specimens of nonaneurysmal aorta from 6 cadaveric organ donors served as controls. Intrasubject and intersubject variations were analyzed. RESULTS: In the aneurysm specimens, the Young's modulus was 1.80x10(6) N/m(2), the load at break was 6.36 N, the strain at break was 0.30, the ultimate strength was 0.53x10(6) N/ m(2), and the MMP activity was 312 for MMP-2 and 460 for MMP-9. In the controls, the circumferential measurements were a Young's modulus of 1.82x10(6) N/m(2), a load at break of 5.43 N, strain at break of 0.29, ultimate strength of 0.61x10(6) N/m(2), and MMP activity of 395 for MMP-2 and 2019 for MMP-9. Longitudinal measurements in controls were a Young's modulus of 1.38x10(6) N/m(2), a load at break of 11.39 N, a strain at break of 0.33, and ultimate strength of 1.30x10(6) N/m(2). Intra and intersubject variation of all parameters was very high. Based upon the lowest measured tensile strength for each aneurysm, the intrasac pressure required to cause rupture varied from 142 to 982 mmHg. CONCLUSIONS: Localized "hot spots" of MMP hyperactivity could lead to focal weakening of the aneurysm wall and rupture at relatively low levels of intraluminal pressure. These data suggest that tensile strength of the sac is just as important as intrasac tension in determining the risk of rupture. Moreover, these observations may explain why some small aneurysms rupture and larger aneurysms do not. Assessment of rupture risk based on computation or measurement of wall stress may be subject to error and inaccuracy due to variations in wall tensile strength.

Aorta, Abdominal↗

PubMed2003

Ulcerative ileitis encountered at ileo-colonoscopy: likely role of nonsteroidal agents.

BACKGROUND & AIMS: Ileoscopy is increasingly practiced, but it is unclear what diagnostic and management decisions should ensue if ulcerations are encountered. METHODS: The lead author identified 40 patients with ulcerative ileitis during 1900 consecutive ileoscopies in a community practice. We analyzed the clinical, endoscopic, and histopathologic findings in these patients and related them to drug usage. RESULTS: Although most patients were asymptomatic, ileitis likely contributed to blood loss in 14 and to right lower quadrant pain in one. Endoscopy revealed multiple, discrete, fibrin-covered ulcerations in the prevalvular segment with patches of erythematous stippling, normal intervening mucosa, and occasional mucosal scars or webs. Histologic findings included focal superficial neutrophilic infiltrates, edema, mucosal hemorrhage, lymphatic dilatation, fibromuscular hyperplasia, prominence of the muscularis mucosae, and antral and Paneth cell metaplasia. Granulomas, fissure ulcers, and apoptosis were notably absent. No specific disease process developed in a median follow-up of 3.2 years. Thirty-three patients admitted recently taking nonsteroidal anti-inflammatory drugs (NSAIDs), notably: enteric-coated aspirin at 325 mg/day or less (19), selective cyclooxygenase-2 inhibitors (5), and nonacetylated salicylates (3). Three fourths of nonsteroidal users were taking agents with low or intermediate gastroduodenal toxicity. Lesions disappeared after drug withdrawal, and reappeared on resumption. CONCLUSIONS: Ileoscopy during colonoscopy may identify an ulcerative ileitis. This lesion likely contributes to gastrointestinal blood loss and other clinical manifestations, and likely is caused by NSAID use, including those usually associated with low toxicity or at low doses. Features of NSAID-ileitis overlap with Crohn's ileitis, but differentiation of the 2 entities is critical for appropriate management.

Adult↗

PubMed2003

The role of the emergency physician in emergency medical services for children.

Emergency physicians have a duty to advance the care of pediatric patients in the emergency medical services (EMS) system. This policy resource and education paper, designed to support the American College of Emergency Physicians policy paper "The Role of the Emergency Physician in Emergency Medical Services for Children," describes the development of the federal EMS for Children Program, the importance of the integration of EMS for children into EMS systems, and the role of the emergency physician in EMS for children.

Child↗

PubMed2003

Can intrasac pressure monitoring reliably predict failure of endovascular aneurysm repair?

PURPOSE: To determine if pressure measured at a single location within aneurysm sac thrombus accurately reflects the force applied to the aneurysm wall and the risk of rupture by examining (1) if pressure is distributed uniformly within aneurysm thrombus, (2) the pressure transmission through aneurysm thrombus, and (3) the microstructural basis for pressure transmission. METHODS: Pressure within aneurysm thrombus was measured by direct puncture through the aneurysm wall at 121 sites in 26 patients during open abdominal aortic aneurysm repair. Measurements were taken prior to cross clamping and compared with intrasac pressure measured at 30 sites in 6 patients without aneurysm thrombus (controls). Transmission of pressure through aneurysm thrombus was further examined ex vivo by subjecting fresh thrombus to a pressure gradient in a custom-made pressure cell. Pressure transmission was correlated with matrix density as determined by light microscopy and image analysis. RESULTS: Mean pressure within aneurysm thrombus was higher than mean systemic pressure in 11 patients, lower in 1, and identical in 9. In 5 patients, the pressure was greater than systemic in some areas of the thrombus but less in others. Sac pressure was identical to systemic pressure at all sites in the controls. In 12 thrombus specimens (6 patients) examined in the pressure cell, pressure transmission varied significantly between specimens, correlating directly with matrix density (R(2)=0.747, p=0.001). CONCLUSIONS: Pressure transmission through aneurysm thrombus is variable and depends upon the microstructure of the thrombus. Pressure measured at a single location may not, therefore, accurately reflect the pressure acting on the aneurysm wall.

Angioplasty↗

PubMed2003

Migration versus apparent migration: importance of errors due to positioning variation in plain radiographic follow-up of aortic stent-grafts.

PURPOSE: To demonstrate the influence of radiographic positioning on the assessment of stent-graft migration using plain radiographs following endovascular abdominal aortic aneurysm repair. METHODS: Equations were derived to correct for artifactual stent-graft migration introduced by geometric distortion due to variations in positioning between radiographs acquired at different times. A phantom system was used to validate the equations. RESULTS: Errors in stent position increase with (1) the distance of the aortic stent-graft from the midline and (2) differences in radiographic centering points in the craniocaudal direction; other variables have little effect. For typical stent positions, errors are small if the centering changes by <8 cm. Consistent radiographic positioning to within 4 cm on successive imaging studies limits errors to 1.5 mm. Even if artifactual migration is large, the true migration can be reliably calculated to within 2 mm. CONCLUSIONS: Artifactual migration due to variation in radiographic centering is not usually clinically significant if care is taken to center radiographs consistently. Radiographs in which artifactual migration may be important are readily identified, and mathematical correction is straightforward.

Aortic Aneurysm, Abdominal↗