Biomedical subjects

William R Mower

Publications and source records attributed to William R Mower.

26 records · Page 2Linked to original sources

PubMed2003

Prospective evaluation of criteria for obtaining thoracolumbar radiographs in trauma patients.

This study examined if use of clinical screening criteria for selective radiography of blunt trauma patients can identify all patients with thoracolumbar (TL) spine injuries. The study was a prospective cohort of patients undergoing TL spine radiographs following blunt trauma. Patients were considered at risk for TL spine injury if they had any of the following clinical criteria: 1) complaints of TL spine pain, 2) TL spine tenderness, 3) a decreased level of consciousness, 4) intoxication with ethanol or drugs, 5) a neurologic deficit, or 6) a painful distracting injury. Patients without any of these findings were considered at low risk for TL spine injury. Severity of mechanism of injury was also recorded. Data sheets were completed prior to TL radiography. Injury status was determined by the final faculty radiologist interpretation of all radiographic studies. A total of 2404 patients were enrolled. TL spine injuries were identified in 152 patients. Of these 152 patients with spine injuries, all 152 (100%, 95% confidence interval 98-100%) were considered high risk by having at least one of the high-risk criteria. These criteria have a specificity of 3.9%, a positive predictive value of 6.6%, and a negative predictive value of 100%. All of the high-risk criteria but intoxication with ethanol or drugs were important as sole predictors of TL spine injury. The use of high-risk clinical screening criteria identified virtually all blunt trauma patients with acute TL spine injuries. These criteria, however, have poor specificity and positive predictive value.

Adolescent↗

PubMed2003

Interrater reliability of criteria used in assessing blunt head injury patients for intracranial injuries.

OBJECTIVE: To determine the interrater reliability of potential predictor variables that may be used to construct a clinical decision rule for emergency computed tomography of the head in blunt head injury victims. METHODS: As a substudy of the NEXUS II study of blunt head trauma, physicians from 21 different emergency departments performed paired evaluations of patients undergoing computed tomography of the head after blunt head injury. Each physician independently determined, for each subject, the presence or absence of each of 19 separate clinical characteristics. The physicians were either residents or attending physicians in the participating emergency departments. Paired responses on a sample of 3,951 patients were compared for raw level of agreement and for interrater concordance using the kappa statistic. If the lower margin of the 95% confidence interval for raw agreement was at least 85% and was equal to or greater than 0.50 for kappa, this was predetermined to represent substantial interrater agreement. RESULTS: There was substantial interobserver agreement by both measures for 17 of the 19 candidate variables in patients with blunt head trauma. Interobserver agreement was substantial for all candidate variables except presence of seizure (kappa = 0.57 [95% CI = 0.47 to 0.67]; raw agreement = 96.5%) and abnormal cerebellar function (kappa = 0.54 [95% CI = 0.41 to 0.67]; raw agreement = 96.5%). CONCLUSIONS: The clinicians in our study had a substantial level of agreement regarding most clinical criteria assessed in this large sample of patients with blunt head injury.

Analysis of Variance↗

PubMed2002

The reliability of vital sign measurements.

STUDY OBJECTIVE: Vital sign measurements, specifically heart rate, respiratory rate, and blood pressure, play a fundamental role in many medical evaluations, yet little is known about the reliability of noninvasive vital sign measurements. We sought to determine whether trained observers can reproducibly assess vital signs in the clinical setting. METHODS: Two trained observers independently measured vital signs on 140 patients presenting to an urban emergency department with acute medical complaints. Heart rate and respiratory rate were each measured by auscultation of heart and breath sounds for 1 minute. Systolic and diastolic blood pressures were determined by auscultating Korotkoff sounds while viewing pressure measurements from a standard cuff and mercury manometer. The mean value of each vital sign and Bland-Altman statistics (mean difference between observers [MDO], expected range of agreement [ERA]) were used to provide absolute and relative indices of reliability. RESULTS: The observers found a mean heart rate of 78.5 beats/min, with an MDO of 0.02 beats/min (0.03%), and an ERA of +/- 10.6 beats/min (+/- 13.5%). Respiratory rate exhibited a mean of 17.5 breaths/min, an MDO of 0.04 breaths/min (0.2%), and an ERA of +/- 6.2 breaths/min (+/- 35.5%). The mean systolic blood pressure of 127.1 mm Hg was associated with an MDO of 1.3 mm Hg (1.0%), and an ERA of +/- 24.2 mm Hg (+/- 19.0%). Diastolic blood pressure exhibited a mean of 77.4 mm Hg, an MDO of 0.3 mm Hg (0.4%) with an ERA of +/- 19.9 mm Hg (+/- 25.7%). CONCLUSION: The reproducibility of vital sign measurements may be limited by significant interobserver variability. Clinicians should recognize this inherent variability and interpret vital signs with caution.

Adolescent↗

PubMed2002

Validity of a decision rule to reduce cervical spine radiography in elderly patients with blunt trauma.

STUDY OBJECTIVES: A decision instrument based on 5 clinical criteria has been shown to be highly sensitive in selecting patients who require cervical spine imaging after blunt trauma, while simultaneously reducing overall imaging. We examine the performance of this instrument in the elderly and explore some of the common features of geriatric cervical spine injury (CSI). METHODS: The National Emergency X-radiography Utilization Study (NEXUS) was a prospective, observational, multicenter study conducted at 21 geographically diverse centers. We analyzed the performance of the NEXUS decision instrument among patients at least 65 years of age. RESULTS: The study group consisted of 2,943 (8.6%) geriatric patients, representing 8.6% of the entire NEXUS sample. The rate of CSI was twice as great in these patients as it was in nongeriatric patients (4.59% versus 2.19%). Odontoid fractures were particularly common in geriatric patients, accounting for 20% of geriatric fractures compared with 5% of nongeriatric fractures. The frequency of patients meeting NEXUS criteria was similar in the 2 groups, with 14% of geriatric patients and 12.5% of nongeriatric patient classified as low risk. CSI occurred in only 2 low-risk geriatric patients, and these patients' injuries met our preset definition of a clinically insignificant injury. The sensitivity of the NEXUS decision instrument for clinically significant injury in the geriatric group was therefore 100% (95% confidence interval 97.1% to 100%). CONCLUSION: The prevalence of CSI, and especially odontoid fracture, is relatively increased among geriatric patients with blunt trauma. The NEXUS decision instrument can be applied safely to these patients, with an expected reduction in cervical imaging comparable with that achieved in nongeriatric patients.

Adult↗

PubMed2002

Developing a clinical decision instrument to rule out intracranial injuries in patients with minor head trauma: methodology of the NEXUS II investigation.

The fear of failing to identify brain injury has led to the liberal and potentially excessive use of computed tomographic (CT) scanning of patients with blunt head trauma who have even a remote possibility of intracranial injury. This practice exposes large numbers of patients to the expense and radiation exposure associated with CT imaging while detecting injuries in a small minority. Previous studies suggest that it might be possible to develop a decision instrument to identify patients with blunt head injury who have essentially no risk of significant intracranial injury and for whom CT scanning is therefore unnecessary. Development of such a decision instrument has been identified as a priority among practicing emergency physicians. The National Emergency X-Radiography Utilization Study II (NEXUS II) is a large, multicenter, prospective study designed to derive a decision rule for CT imaging of patients with blunt head injury. This study, conducted in 21 different emergency departments across the United States and Canada, will enroll more than 10 times as many patients with head trauma as any currently published study. NEXUS II should be able to definitively answer questions about the validity and reliability of clinical criteria as a preliminary screen for blunt head trauma.

Brain Injuries↗

PubMed2002

Spinal cord injury without radiographic abnormality: results of the National Emergency X-Radiography Utilization Study in blunt cervical trauma.

BACKGROUND: The purpose of this study was to better define the incidence and characteristics of patients with spinal cord injury without radiographic abnormality (SCIWORA), using the database of the National Emergency X-Radiography Utilization Study (NEXUS). METHODS: This was a prospective, observational study of blunt trauma patients in 21 U.S. medical centers undergoing plain cervical radiography. SCIWORA was defined as spinal cord injury demonstrated by magnetic resonance imaging, when a complete, technically adequate plain radiographic series revealed no injury. RESULTS: Of the 34,069 patients entered, there were 818 (2.4%) with cervical spine injury, including 27 (0.08%) patients with SCIWORA. Over 3,000 children were enrolled, including 30 with cervical spine injury, but none had SCIWORA. The most common magnetic resonance imaging findings among SCIWORA patients were central disc herniation, spinal stenosis, and cord edema or contusion. Central cord syndrome was described in 10 cases. CONCLUSION: In the large NEXUS cohort, SCIWORA was an uncommon disorder, and occurred only in adults.

Adult↗

PubMed2002

Variability in computed tomography and magnetic resonance imaging in patients with cervical spine injuries.

OBJECTIVE: The purpose of this study was to describe the performance of adjunctive radiologic imaging in patients with cervical spine injury. METHODS: All patients undergoing cervical spine radiography were prospectively enrolled at 16 diverse emergency departments. We recorded the imaging modalities and radiographic interpretations rendered by unblinded faculty radiologists at each center. Only patients with cervical spine injury were included in this analysis. Findings revealed by individual modalities were compared with the final diagnosis (after all evaluations) in each patient. RESULTS: Six hundred eighty-eight patients with 1,302 separate cervical spine injuries were enrolled. Four hundred seventy-six (69%) patients had magnetic resonance imaging (MRI) and/or computed tomography (CT) of the cervical spine. MRI identified the following injuries among 124 imaged patients: osseous fractures, 85 of 154 (55%); spinal cord injury, 69 of 69 (100%); vertebral subluxation/dislocation, 37 of 43 (86%); ligamentous injury, 38 of 38 (100%); and unilateral/bilateral locked facets, 14 of 18 (78%). Among 418 patients undergoing CT, the following injuries were identified: osseous fractures, 721 of 740 (97%); spinal cord injury, 0 of 30 (0%); vertebral subluxation/dislocation, 76 of 88 (86%); ligamentous injury, 9 of 36 (25%); and unilateral/bilateral locked facets, 34 of 35 (97%). CT identified 29 patients with fractures who had normal plain radiographs. Cervical myelograms were obtained in two patients and cervical tomograms in seven patients. CONCLUSION: The majority of patients with cervical spine injury undergo MRI and/or CT imaging. In clinical practice, MRI is superior at identifying soft tissue injuries, whereas CT performs better in identifying bony injuries. Cervical myelograms and tomograms are rarely obtained.

Cervical Vertebrae↗

PubMed2002

Selective tomographic imaging of patients with new-onset seizure disorders.

OBJECTIVE: Significant benefit could be realized by developing a clinical decision rule for new-onset seizure victims that would be capable of discriminating between patients having relevant structural lesions visible on computed tomographic (CT) imaging and those who do not. This study sought to determine whether a reliable decision rule could be developed using a limited number of clinical and demographic characteristics. METHODS: Chi-squared recursive partitioning was applied in a secondary analysis of the EMERGEncy ID NET database of new-onset seizure victims. Variables in this database (age, sex, race, ethnicity, seizure type, history of HIV or cysticercosis, and presence or absence of lateralizing neurologic findings or altered mentation) provided the partitioning variables, while CT imaging results provided outcome measures. The study sought to develop a decision rule with 100% sensitivity for detecting any intracranial lesions, and a separate rule with 100% sensitivity for detecting lesions of emergent concern. RESULTS: A decision rule using age > or = 65 years, lateralizing neurologic findings, altered mentation, high risk or known HIV infection, history of cysticercosis, and Hispanic ethnicity showed a sensitivity of 91.9% [95% confidence interval (95% CI) = 88.8% to 94.9%] in detecting individuals who had any tomographic finding. This rule had a sensitivity of 90.1% (95% CI = 83.4% to 96.7%) in detecting individuals with emergent tomographic findings. CONCLUSIONS: Recursive partitioning failed to produce a decision rule capable of reliably identifying new-onset seizure patients who have important lesions identified on CT. Future attempts to formulate such an instrument may need to include additional variables. In the interim, physicians should use liberal tomographic imaging in evaluating patients who present with new-onset seizures.

Acute Disease↗