Ultrasound Localization of Resuscitative Endovascular Balloon Occlusion of the Aorta in a Human Cadaver Model.

OBJECTIVE: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a method of gaining proximal control of noncompressible torso hemorrhage (NCTH). Catheter placement is traditionally confirmed with fluoroscopy, but few studies have evaluated whether ultrasound (US) can be used. METHODS: Using a pressurized human cadaver model, a certified REBOA placer was shown one of four randomized cards that instructed them to place the REBOA either correctly or incorrectly in Zone 1 (the distal thoracic aorta extending from the celiac artery to the left subclavian artery) or Zone 3 (in the distal abdominal aorta, from the aortic bifurcation to the lowest renal artery). Once the REBOA was placed, 10 US-trained locators were asked to confirm balloon placement via US. The participants were given 3 minutes to determine whether the catheter had been correctly placed, repeating this 20 times on two cadavers. RESULTS: Overall, US exhibited an average sensitivity of 83%, specificity of 76%, and accuracy of 80%. For Zone 1, US showed a sensitivity of 78% and specificity of 83%, and for Zone 3, a sensitivity of 88% and specificity of 76%. In addition, US exhibited a likelihood positive ratio (LR+) of 3.73 and a likelihood negative ratio (LR-) of 0.22 for either position, with similar numbers for Zone 1 (+4.57, -0.26) and Zone 3 (+3.16, -0.16). CONCLUSION: Ultrasound could prove to be a useful tool for confirming placement of a REBOA catheter, especially in austere environments.

Comparison of thromboelastography versus conventional coagulation tests in simulated Crotalus atrox envenomation using human blood.

INTRODUCTION: Pit viper bites are a source of significant morbidity and mortality. Pit viper bites can cause venom-induced consumptive coagulopathy (VICC), typically evaluated with laboratory-based conventional coagulation tests (CCTs). However, CCTs require a laboratory and average 1 h to conduct. Thromboelastography (TEG) provides real-time, point-of-care tests of coagulation that are fast and require no separate laboratory facilities, which could be advantageous in both hospital and austere settings. However, the relative efficacy of TEG versus CCTs was unclear, particularly at low venom concentrations. Therefore, the objectives of this study were to test human blood with various concentrations of pit viper venom using CCTs and TEG to determine dose-dependent changes, lowest observed effect concentration (LOEC), and sensitivity to detecting samples out of normal diagnostic range. METHODS: Blood samples from 20 volunteers were mixed with varying concentrations of western diamond back rattlesnake (Crotalus atrox) venom based on the mouse LD50IV (none, 0.5%, 1%, 2%, 33%, 66%, and 100% LD50IV). Samples were split and assessed with both CCTs including prothrombin time (PT), international normalized ratio (INR), partial thromboplastin time (PTT), fibrinogen, and D-dimer, along with TEG measures of reaction time (R), kinetic time (K), rate of clot formation (α-angle), and clot strength (MA). Data were analyzed as dose-dependent concentration-based changes in raw values and in percent of samples exceeding diagnostic thresholds using ANOVA and nonparametric statistics at the p < .05 threshold. RESULTS: All evaluations showed significant concentration-dependent changes, and 100% of samples exceeded diagnostic thresholds at 33%LD50IV and above, save D-dimer. At 0.5%LD50IV, R, K, α-angle, PT, and INR were significantly different from controls, and at 1%LD50IV, mean values exceeded diagnostic thresholds for R, K, α-angle, MA, PT, and INR, but not for PTT, D-dimer, or fibrinogen. At 2%LD50IV, 100% of samples were out of normal range for K, α-angle, and PT. CONCLUSION: TEG is effective in coagulopathy evaluations of in vitro simulated pit viper envenomation. At low venom concentrations, TEG performed as well or better than the majority of CCTs. These findings provide empirical evidence supporting the use of TEG to rapidly and accurately evaluate VICC.

Emergency department patient knowledge, opinions, and risk tolerance regarding computed tomography scan radiation.

BACKGROUND: Computed tomography (CT) scanning use for emergency department (ED) patients has increased exponentially since its inception. STUDY OBJECTIVES: This study aimed to determine what patients view as the risk of radiation from CT scans, their risk tolerance and preference for alternative testing, and their opinions about informed consent and malpractice regarding CT scans. METHODS: A 25-question survey was administered to a random convenience sample of ED patients aged ≥ 18 years by trained research associates. RESULTS: There were 487 patients approached to be surveyed; 78 patients were excluded, leaving 409 patients (84.0%) responding. Mean patient age was 40.5 (standard deviation [SD] 16.8) years, and 51.5% were female. Three hundred ninety of 409 (95.4%) believed doctors should explain the risks and benefits of CT, and 316/409 (77.3%) thought an informed consent form should be signed. One hundred seventy-nine of 409 (43.8%) patients recognized that there was more radiation from a CT scan than a single chest x-ray study. Three hundred twenty-four of 409 (79.2%) preferred CT angiography over lumbar puncture to exclude subarachnoid hemorrhage. To diagnose appendicitis, 199/409 (48.7%) preferred an ultrasound first even if it meant needing a subsequent confirmatory CT, and 193/409 (47.2%) preferred a CT right away. One hundred sixty-nine of 409 (41.3%) patients would still like to have a CT scan of the head after head trauma even if their physician did not believe the test was indicated. CONCLUSION: This study elucidates patient preference and knowledge regarding CT scans. Overall, patients have a poor understanding of CT scan radiation, and desire to have risks explained to them as informed consent prior to the scan.