Computed tomographic imaging in the pediatric patient with a seatbelt sign: still not good enough.

PURPOSE: Considering the improvements in CT over the past decade, this study aimed to determine whether CT can diagnose HVI in pediatric trauma patients with seatbelt signs (SBS). METHODS: We retrospectively identified pediatric patients with SBS who had abdominopelvic CT performed on initial evaluation over 5 1/2years. Abnormal CT was defined by identification of any intra-abdominal abnormality possibly related to trauma. RESULTS: One hundred twenty patients met inclusion criteria. CT was abnormal in 38/120 (32%) patients: 34 scans had evidence of HVI and 6 showed solid organ injury (SOI). Of the 34 with suspicion for HVI, 15 (44%) had small amounts of isolated pelvic free fluid as the only abnormal CT finding; none required intervention. Ultimately, 16/120 (13%) patients suffered HVI and underwent celiotomy. Three patients initially had a normal CT but required celiotomy for clinical deterioration within 20h of presentation. False negative CT rate was 3.6%. The sensitivity, specificity and accuracy of CT to diagnose significant HVI in the presence of SBS were 81%, 80%, and 80%, respectively. CONCLUSIONS: Despite improvements in CT, pediatric patients with SBS may have HVI not evident on initial CT confirming the need to observation for delayed manifestation of HVI. LEVEL OF EVIDENCE: Level II Study of a Diagnostic Test.

Incidence of blunt cerebrovascular injury in low-risk cervical spine fractures.

BACKGROUND: It has been suggested that specific cervical spine fractures (CSfx) (location at upper cervical spine [CS], subluxation, or involvement of the transverse foramen) are predictive of blunt cerebrovascular injury (BCVI). We sought to determine the incidence of BCVI with CSfx in the absence of high-risk injury patterns. METHODS: We performed a retrospective study in patients with CSfx who underwent evaluation for BCVI. The presence of recognized CS risk factors for BCVI and other risk factors (Glasgow coma score ≤ 8, skull-based fracture, complex facial fractures, soft-tissue neck injury) were reviewed. Patients were divided into 2 groups based on the presence/absence of risk factors. RESULTS: A total of 260 patients had CSfx. When screened for high-risk pattern of injury for BCVI, 168 patients were identified and 13 had a BCVI (8%). The remaining 92 patients had isolated low CSfx (C4-C7) without other risk factors for BCVI. In this group, 2 patients were diagnosed with BCVI (2%). Failure to screen all patients with CSfx would have missed 2 of 15 BCVIs (13%). CONCLUSIONS: We propose that all CS fracture patterns warrant screening for BCVI.

Use of computed tomography in the initial evaluation of anterior abdominal stab wounds.

BACKGROUND: The purpose of this study was to assess the ability of computed tomography (CT) to facilitate initial management decisions in patients with anterior abdominal stab wounds. METHODS: A retrospective review was conducted of patients with anterior abdominal stab wounds who underwent CT over 4.5 years. Any abnormality suspicious for intra-abdominal injury was considered a positive finding on CT. RESULTS: Ninety-eight patients met the study's inclusion criteria. Positive findings on CT were noted in 30 patients (31%), leading to operative intervention in 67%. Injuries were confirmed in 95% of cases, but only 70% were therapeutic. Ten patients had nonoperative management despite positive findings on CT, including 5 patients with solid organ injuries. One patient underwent operative intervention for clinical deterioration, with negative findings. No computed tomographic evidence of injury was noted in the remaining 68 patients (69%), but 1 patient was noted to have a splenic injury while undergoing operative evaluation of the diaphragm. All remaining patients were treated nonoperatively with success. CONCLUSIONS: In patients with anterior abdominal stab wounds, CT should be considered to facilitate initial management decisions, as it has the ability to delineate abnormalities suspicious for injury.

A remote in situ monitor based on continuous flow analysis for the quantitation of sub-micromolar levels of hexavalent chromium in natural waters.

We describe the design, optimization, and application of a small, lightweight, deployable monitoring instrument for accurately measuring parts-per-billion levels of hexavalent Cr in surface waters at hourly intervals. The monitor quantifies Cr(vi) using a standard molecular absorbance spectroscopic method, i.e. by formation of a complex with 1,5-diphenylcarbazide (DPC). The continuous flow analysis (CFA) design uses narrow conduits (0.90 mm) that are hot-forged onto poly(methyl methacrylate) ('Plexiglas') plates based on the method of Jannasch et al.(Anal. Chem., 1994, 66, 3352). The sample stream is drawn through the manifold at 25 microl min(-1) using a mini-peristaltic pump; osmotic pumps (10 microl h(-1)) are used to continuously inject reagent (2.0 mM DPC, 0.60 M HNO(3), 5.0% w/v acetone, and 0.10% w/v Brij-35) and to periodically introduce quality control standards and a cleaning solution (0.50 M HNO(3)). The 'Z-type' optical cell uses a liquid-core waveguide (10 mm) to collimate the light-emitting diode source beam (lambda(max) 574 nm) to a broadband photodiode detector. Figures of merit are: 7 min cycle time, response within 28 min and clear-down within 31 min, low waste generation (<40 ml d(-1)), detection limit (3sigma) of 48.4 microg l(-1) as Cr(vi) or 0.411 microM as chromic acid, 1.54% relative standard deviation at 100 microg l(-1), and selectivity for dissolved Cr(vi) in authentic surface water samples containing moderate levels (>0.21% w/v) of total particulate matter. Using a test chamber containing Milwaukee Harbor water that was periodically fortified with Cr(vi) standards, continuous testing over a 15 day period (354 h) yielded results that were in excellent agreement (<5% variation) with measurements made using an ICP-MS reference method. Drift in the calibration model over the test period was 1.23% and the variation in a 0.50 mg l(-1) Cr(vi) standard was 3.8%(n= 11). Known interferences to the DPC chemistry (Mo, V, and Hg at >5 mg l(-1)) were undetected in the harbor water by ICP-MS.