PubMed Health⌕ Search

Biomedical subjects

C Craig Blackmore

Publications and source records attributed to C Craig Blackmore.

18 recordsLinked to original sources
PubMed2007

Predicting urethral injury from pelvic fracture patterns in male patients with blunt trauma.

PURPOSE: Precise definition of pelvic fracture location may enable prediction of which subjects are at risk for urethral injury and understanding of the pathophysiological mechanism of injury. We determined the specific anterior pelvic injury locations associated with urethral injury. MATERIALS AND METHODS: We completed a retrospective, nested case-control study of 119 male patients evaluated at a single large level 1 trauma center between January 1, 1997 and July 15, 2003. We performed detailed measurements of the location, displacement and direction of force of each anterior pelvic fracture from computerized tomography and pelvic radiographs. Multiple logistic regression was used to determine associations between specific fracture locations and urethral injury after controlling for age, injury mechanism, injury severity and direction of force. RESULTS: Urethral injury was present in 25 patients and all had anterior pelvic fracture (inclusive of pubic symphysis diastasis). There were no urethral injuries in patients with fractures isolated to the acetabulum. Pelvic fractures that were independently associated with urethral injury from multiple regression analysis included displaced fractures of the inferomedial pubic bone, OR 6.4 (95% CI 1.6 to 24.9), and symphysis pubis diastasis, OR 11.8 (95% CI 4.0 to 34.5). Each millimeter of symphysis pubis diastasis or inferomedial pubic bone fracture displacement was associated with an approximately 10% increased risk of urethral injury. CONCLUSIONS: The location and displacement of anterior pelvic fractures in males predict risk of urethral injury and may be valuable in determining when evaluation of the urethra is appropriate.

Adolescent↗
PubMed2006

Radiographic and clinical predictors of bladder rupture in blunt trauma patients with pelvic fracture.

RATIONALE AND OBJECTIVES: Bladder rupture is a potentially serious injury in blunt trauma patients. We determined whether location and displacement of pelvic fractures and the degree of hematuria can accurately predict bladder injury. MATERIALS AND METHODS: A retrospective database of 721 blunt trauma pelvic fractures that presented to a single large regional level 1 trauma center between January 1, 1997, and July 15, 2003, was expanded to include data on bladder injury and the initial urinalysis. Multiple logistic regression was performed to determine if an association exists between pelvic fracture pattern, degree of hematuria, and bladder injury. A potential clinical prediction rule was then derived using a point system for four independent, significant risk factors identified from the logistic regression results. RESULTS: There were 37 bladder ruptures (5.0%), all of which presented with hematuria >30 red blood cells per high-powered field (RBC/HPF). Pelvic injuries that were independently associated with bladder injury included diastasis of the pubic symphysis >1 cm, RR = 9.8 (95% CI 4.6-20.9), and fracture of the obturator ring with displacement >1 cm RR = 3.2 (95% CI 1.6-6.5). No patient with isolated acetabular fractures sustained bladder injury. A clinical prediction rule was derived, consisting of a single point for each of the significant pelvic injury sites in patients with hematuria >30 RBC/HPF. Patients with a prediction score of 0 had a 2.3% probability of bladder injury, whereas patients with scores of 1 and 2 had probabilities of bladder injury of 9.2% and 43.7%, respectively. CONCLUSIONS: Patients with isolated acetabular fractures and patients with <30 RBC/HPF did not sustain bladder injury. In addition to hematuria, specific pelvic injury patterns are associated with bladder rupture. If validated, a clinical prediction rule derived from this data has the potential to guide the care of the blunt trauma patient.

Adult↗
PubMed2006

Predicting major hemorrhage in patients with pelvic fracture.

BACKGROUND: Pelvic fractures can be an important source of major hemorrhage in victims of blunt trauma. However, no rapid and reliable noninvasive method exists for predicting which subjects will have major hemorrhage. The objective of this study is to use information available upon presentation to the trauma center to develop a clinical prediction rule to identify subjects with pelvic fracture who are at high risk of major hemorrhage. METHODS: A retrospective cohort study was performed on all subjects with pelvic fracture from blunt force mechanism at a single level one trauma center during a 4.3 year period. Chart review identified findings from initial pelvic radiographs and from emergency department care including mechanism of injury, and hemodynamic status. Major hemorrhage was defined by angiographic findings, transfusion requirement and pelvic hemorrhage volume. Logistic regression was used to formulate a clinical prediction rule to stratify subjects based on probability of major hemorrhage. RESULTS: Complete data were available on 627 of 783 eligible subjects. Predictors of major hemorrhage included emergency department hematocrit 30 or less, pulse rate of 130 or greater, displaced obturator ring fracture and pubic symphyseal wide diastasis. Combinations of predictors defined groups with probability of major hemorrhage from 1.6% to 66%. CONCLUSIONS: Probability of major pelvic fracture related hemorrhage can be estimated from initial pelvic radiograph, pulse, and hematocrit.

Adult↗
PubMed2005

Clinical prediction rules in trauma imaging: who, how, and why?

Clinical prediction rules are multifactorial tools used to aid in clinical decision making. In radiology, clinical prediction rules are an important method for determining who should undergo imaging and, in combination with cost-effectiveness analysis, how imaging should be performed. To be useful, clinical prediction rules should be clinically important, have face validity, be reproducible and easy to use, be clinically relevant, and suggest a course of action. To insure generalizability, clinical prediction rules should also be validated in subjects distinct from those used to develop the rule. In this review, several examples from trauma imaging are used to demonstrate the development, validation, and use of clinical prediction rules.

Cost-Benefit Analysis↗
PubMed2004

Cervical spine fractures in patients 65 years and older: a clinical prediction rule for blunt trauma.

PURPOSE: To determine clinical predictors of cervical spine fracture in the elderly and to develop a clinical prediction rule to guide appropriate imaging in high-risk patients. MATERIALS AND METHODS: Institutional review board approval was received with waiver of informed consent. A retrospective case-control study was performed on blunt trauma patients 65 years and older with cervical spine fractures and on randomly selected control subjects without fracture. Potential predictors of fracture were evaluated through simple and multivariate logistic regression. Simple predictors were grouped into clinically similar composite variables and were analyzed with multivariate logistic regression and recursive partitioning. A clinical prediction rule was generated. The receiver operating characteristic curve was calculated and adjusted through bootstrap validation. Absolute cervical spine fracture probabilities were calculated by using Bayes theorem for all elderly patients and for patients who underwent computed tomography. Results were compared with a previous prediction rule for all adults. RESULTS: Composite predictors of fracture in the elderly included focal neurologic deficit (adjusted odds ratio, 17.7; 95% confidence interval [CI]: 3.8, 83.4), severe head injury (odds ratio, 3.2; 95% CI: 1.5, 7.1), high-energy mechanism (odds ratio 6.7; 95% CI: 3.1, 14.8), and moderate-energy mechanism (odds ratio 3.3; 95% CI: 1.3, 8.3). The prediction rule stratified patients into risk groups with fracture probabilities ranging from 0.4% (95% CI: 0.1%, 1.3%) to 24.2% (95% CI: 5.7%, 100%). CONCLUSION: Clinical factors can be used to stratify patients 65 years and older into risk groups with a wide range of probabilities of cervical spine fracture. Knowledge of cervical fracture risk can help guide appropriate imaging in high-risk patients.

Aged↗
PubMed2004

Systematic review: computed tomography and ultrasonography to detect acute appendicitis in adults and adolescents.

BACKGROUND: Although clinicians commonly use computed tomography or ultrasonography to diagnose acute appendicitis, the accuracy of these imaging tests remains unclear. PURPOSE: To review the diagnostic accuracy of computed tomography and ultrasonography in adults and adolescents with suspected acute appendicitis. DATA SOURCES: The authors used MEDLINE, EMBASE, bibliographies, review articles, textbooks, and expert opinion to retrieve English- and non-English-language articles published from 1966 to December 2003. STUDY SELECTION: The authors included prospective studies evaluating computed tomography or ultrasonography followed by surgical confirmation or clinical follow-up in patients at least 14 years of age with suspected appendicitis. DATA EXTRACTION: One assessor (for non-English-language studies) or 2 assessors (for English-language studies) independently reviewed each article to abstract relevant study characteristics and results. DATA SYNTHESIS: Twelve computed tomography studies and 14 ultrasonography studies met inclusion criteria. Computed tomography had an overall sensitivity of 0.94 (95% CI, 0.91 to 0.95), a specificity of 0.95 (CI, 0.93 to 0.96), a positive likelihood ratio of 13.3 (CI, 9.9 to 17.9), and a negative likelihood ratio of 0.09 (CI, 0.07 to 0.12). Ultrasonography had an overall sensitivity of 0.86 (CI, 0.83 to 0.88), a specificity of 0.81 (CI, 0.78 to 0.84), a positive likelihood ratio of 5.8 (CI, 3.5 to 9.5), and a negative likelihood ratio of 0.19 (CI, 0.13 to 0.27). Verification bias and inappropriate blinding of reference standards were noted in all of the included studies. LIMITATIONS: The summary assessment of the diagnostic accuracy for both tests was limited by the small number of studies, heterogeneity among study samples, and poor methodologic quality in the original studies. CONCLUSIONS: Computed tomography is probably more accurate than ultrasonography for diagnosing appendicitis in adults and adolescents. Prospective studies that apply gold standard diagnostic testing to all study participants would more reliably estimate the true diagnostic accuracy of these tests.

Acute Disease↗
PubMed2004

Critically assessing the radiology literature.

To practice evidence-based radiology, knowledge of how to critically assess the literature is vital. This article outlines how to evaluate the radiology literature by asking these questions: Is it true?, Is it relevant?, and Is it sufficient? Clinical examples are used to explain several important causes of bias, as well as to clarify how these biases can affect the relevance of a particular study to a given clinical situation. Finally, discussion centers on the strength of evidence for both positive and negative findings in a research study.

Bias↗
PubMed2003

Assessment of volume of hemorrhage and outcome from pelvic fracture.

HYPOTHESIS: Measurement of pelvic hemorrhage on computed tomographic (CT) scans can estimate the pelvic fracture component of total patient blood loss and predict the need for angiography. DESIGN: Retrospective cohort study. SETTING: Large level 1 trauma center. PATIENTS: We examined data from 759 consecutive, nonreferral blunt trauma patients who sustained pelvic fracture. MAIN OUTCOME MEASURES: Pelvic-fracture-specific outcomes included estimation of extraperitoneal pelvic hemorrhage volume from emergency department CT scans and determination of arterial injury from angiograms. General patient outcomes determined from medical record review included transfusion requirement, estimated blood loss, and mortality. Subanalysis was performed on subjects with only pelvic fracture as a source of major hemorrhage (derived from discharge International Classification of Diseases, Ninth Revision, Clinical Modification codes). RESULTS: Overall mortality was 96 (13%) of 759 patients. Blood transfusion was given to 418 (55%) patients, and 258 (34%) received 6 or more units in the first 72 hours. Pelvic-fracture-related hemorrhage averaged 149 mL (range, 0-1423 mL). Angiography was performed on 163 patients, of whom 113 had arterial injury. Higher pelvic hemorrhage volumes on CT scans were seen in subjects with pelvic arterial injury demonstrated on angiograms (P<.001). In subjects without another source of major hemorrhage, pelvic CT hemorrhage volumes were strongly associated with transfusion requirement (P<.001). Subjects with large pelvic hemorrhage volumes (>500 mL) were more likely to have pelvic arterial injury (risk ratio, 4.8; 95% confidence interval, 3.0-7.8; P<.001) and require large-volume (>/=6 U) transfusions (risk ratio, 4.7; 95% confidence interval, 1.8-12.3; P<.001) than patients with smaller pelvic hemorrhage volumes. CONCLUSION: Pelvic hemorrhage volumes derived from pelvic CT scans were predictors of the need for pelvic arteriography and transfusions.

Adolescent↗
PubMed2003

Evidence-based approach to using CT in spinal trauma.

Computed tomography has revolutionized the diagnosis and treatment planning of the acutely injured spine. In the cervical spine, its appropriate use can improve outcome and save money. Although there are no clinical prediction rules validated outside of the cervical spine, these proven capabilities have been extrapolated to the thoracolumbar spine.

Evidence-Based Medicine↗
PubMed2003

Evidence-based imaging evaluation of the cervical spine in trauma.

Despite the relatively low frequency of cervical spine fractures in trauma patients, tremendous resources are expended on the use of imaging to exclude fracture. Some level 2 evidence can direct the selection of subjects for imaging and optimization of the imaging strategy. A suggested algorithm for evidence-based cervical spine imaging is shown in Fig. 1. This algorithm is based on the sequential assessment of two questions: (1) Is imaging necessary? (2) If imaging is necessary, what is the optimal strategy? The NEXUS and the Canadian cervical spine prediction rule investigations are large methodologically sound observational studies of clinical indications for cervical spine imaging that have addressed the question of who should undergo imaging. The results of these studies indicate that simple clinical criteria can be used to exclude fracture safely without imaging in many low-risk subjects. Data from these studies suggest that the implementation of such prediction rules into practice may reduce unnecessary imaging, although more research is necessary to document the actual effects. In subjects in whom imaging is indicated, cost-effectiveness analysis can be performed to determine the optimal imaging strategy. For high-risk subjects, cost-effectiveness analysis suggests that CT is the preferred initial strategy. When compared with radiography, the higher short-term costs of CT are counter-balanced by the decreased need for further imaging in patients without injury and by the increased sensitivity for fracture. The high-risk cervical spine criteria used at the author's center seem to be valid for identifying appropriate patients for initial imaging with CT.

Cervical Vertebrae↗
PubMed2003

Conventional radiography, rapid MR imaging, and conventional MR imaging for low back pain: activity-based costs and reimbursement.

PURPOSE: To incorporate personnel and equipment use time in an activity-based cost comparison of conventional radiography and conventional and rapid magnetic resonance (MR) imaging for low back pain (LBP). MATERIALS AND METHODS: At each of four Seattle Lumbar Imaging Project (SLIP) sites, patients were randomized to undergo conventional radiography or rapid MR imaging of the lumbar spine. For sample SLIP patients and for similar non-SLIP patients undergoing conventional lumbar spine MR imaging as usual care in calendar year 2000, measured imaging room use and technologist and radiologist times were multiplied by costs per minute of standard equipment acquisition, personnel compensation, and related expenses. Resulting provider-perspective costs and Seattle area Medicare reimbursements for conventional MR imaging and radiography for calendar year 2001 were used to estimate future "normative" reimbursement for rapid MR imaging. RESULTS: For 23 conventional radiography, 27 rapid MR imaging, and 38 conventional MR imaging examinations timed in calendar year 2000, all rapid MR imaging times exceeded those of conventional radiography but were less than those of conventional MR imaging. All 0.3- and 0.35-T MR imaging room and technologist times exceeded those for 1.5-T MR imaging. Average costs (in 2001 dollars) were $44 for conventional radiography, 126 US dollars for 1.5-T rapid MR imaging, 128 US dollars for 0.3-0.35-T rapid MR imaging, 267 US dollars for 1.5-T conventional MR imaging, and 264 US dollars for 0.3-0.35-T conventional MR imaging. Conclusions regarding cost differences between conventional radiography and rapid MR imaging were robust to plausible parameter value changes evaluated in sensitivity analyses. Conventional radiography reimbursement was 44 US dollars. Applying the ratio of reimbursement (620 US dollars) to costs (264-267 US dollars) for conventional MR imaging to rapid MR imaging costs predicted reimbursement of 292-300 US dollars for the new modality. CONCLUSION: Times and costs for rapid MR imaging are roughly three times those for conventional radiography but about half those for conventional MR imaging for LBP. While current conventional radiography costs exceed reimbursement, current conventional MR and projected rapid MR imaging reimbursements exceed costs.

Cost-Benefit Analysis↗
PubMed2003

Web-based image review and data acquisition for multiinstitutional research.

OBJECTIVE: In this article, we describe a user-friendly Web-based interface that allows review of images combined with integrated data collection and entry for use at multiple sites involved in a large multicenter research project. CONCLUSION: The Web-based system that we present uses a commercially available Internet browser and Web platform and allows automated data entry that can be easily uploaded into standard data analysis programs. The system simplifies the complex logistics of using multiple sites and reviewers for radiology research and can preserve human subject confidentiality. We tested the system using a large-scale multicenter cohort study of pelvic fracture-related hemorrhage (the "Evaluating Pelvic Hemorrhage" study). Program testing revealed seamless remote image interpretation and data acquisition.

Biomedical Research↗
PubMed2002

Can CT predict the source of arterial hemorrhage in patients with pelvic fractures?

The objective of the study was to evaluate the ability of hemorrhage site and location as demonstrated on pelvic CT to predict the source of arterial hemorrhage in patients with traumatic pelvic fractures. CT scans of 104 consecutive patients who had sustained traumatic pelvic fracture and undergone emergent pelvic angiography were digitized, and fracture-related hemorrhage area and volume were measured at multiple locations within the pelvis. Clots that measured greater than 10 cm(2) were compared to angiographic results. The chi(2) test was used to find locations on CT that were significantly associated with specific arterial injuries found on angiography. Sixty-one (58%) of the patients had arterial bleeding at angiography. The most commonly injured arteries were the internal pudendal and the superior gluteal. Specific locations on CT were statistically significant indicators of injury to the superior gluteal artery (relative risk=2.9, 95% CI 1.2-7.3, P=0.013), the anterior division of the internal iliac artery (relative risk=3.2, 95% CI 1.4-4.1, P=0.006), and the internal pudendal arteries (relative risk=2.0, 95% CI 1.1-4.0, P=0.037). More blood was visible on CT when an artery was injured (mean volume with negative angiogram=318 ml, mean volume with positive angiogram=554 ml, ( P=0.007)). The rectus sheath region at the top of the iliac crest ( P=0.004), pelvic sidewalls at the L5-S1 disk space level ( P=0.001), and gluteal regions also at the L5-S1 disk space level ( P=0.012) were significant indicators of a positive arteriogram. CT can help predict the specific bleeding artery to potentially guide angiographic intervention.

Journal Article↗
PubMed2002

Can we rely on mediastinal widening on chest radiography to identify subjects with aortic injury?

Widening of the mediastinum on chest radiography is widely promoted as a useful criterion for detecting aortic injury. We sought to determine the reliability, sensitivity, and specificity of this sign. The initial chest radiographs from 30 subjects with aortic injury and 47 controls were independently reviewed by six radiologists, who were blinded to diagnosis. The radiologists were asked to decide whether the mediastinum was normal or not normal, as well as whether the mediastinum was widened. Agreement, sensitivity, and specificity were assessed. Agreement for overall assessment of the mediastinum was substantial (kappa = 0.64). Individual radiologists had sensitivity varying from 0.77 to 0.97 and specificity varying from 0.62 to 0.89. For "widening" of the mediastinum, agreement was moderate (kappa = 0.49). "Widening" was less sensitive than the radiologists' overall impression (P = 0.01), varying from 0.50 to 0.83, but no difference was detected in specificity (P = 0.36), varying from 0.81 to 0.94. Mediastinal width has unacceptable sensitivity for predicting aortic injury, with substantial inter-reader variability. Medical education has ingrained the widely promoted concept of mediastinum widening, which may be misleading.

Journal Article↗
PubMedDate not supplied

Bony injuries of the shoulder.

The complex anatomy and functioning of the shoulder may challenge the radiologist. In this review the patterns of injury and radiographic findings for bony injuries of the shoulder are illustrated. The radiographic and cross-sectional imaging findings in fractures of the clavicle, scapula, and proximal humerus and in dislocations of the sternoclavicular, acromioclavicular, and glenohumeral articulations are discussed.

Humans↗