Assessment of Semi-automated Computed Tomographic Measures of Segmental Perfusion Defects in a Swine Model (Sus scrofa) of Intermediate Coronary Lesions.

Computed tomographic myocardial perfusion (CTP) imaging is a tool that shows promise in emergent settings for defining the hemodynamic significance of coronary artery disease. In this study, we examined the accuracy with which the transmural perfusion ratio (TPR) derived through semiautomated CTP analysis reflected segmental perfusion defects associated with intermediate coronary artery lesions in swine. Lesions (diameter stenosis, 65% ± 11%) of the left anterior descending coronary artery (LAD) were created in 10 anesthetized female swine (weight, 47.5 ± 1.9 kg) by using a pneumatic occlusion device implanted on the LAD. Occluder inflation pressures were adjusted to maintain fractional flow reserve (FFR, 74.3 ± 1.7) during adenosine infusion (140ug/kg/min). Static CTP imaging using a stress-rest protocol and segmental TPR derived from semiautomated CT perfusion software was compared with microsphere-derived TPR (mTPR) by using a 16-segment model and polar mapping. Intermediate LAD stenosis was verified through multiplanar coronary CT angiography. Receiver operating characteristic analysis identified an optimal threshold for segmental perfusion defects for intermediate lesions (TPR threshold, ≤0.80); however, the area under the receiver operating characteristic curve was 0.58, and the overall accuracy was 63%. At this threshold, the sensitivity and specificity were 65% and 61%, and the positive and negative predictive values were 61% and 65%, respectively. Although CTP-TPR illustrated segmental perfusion defects with intermediate lesions, the disparity between CTP-TPR and mTPR measures of segmental perfusion suggests that further advances in analysis software may be necessary to improve the localization of segmental defects for intermediated lesions.

Gradient variability in hypertrophic cardiomyopathy: New insights from computer-assisted, high fidelity, rest and exercise hemodynamic analysis.

OBJECTIVES: This study examines the intrapatient variability in peak instantaneous left ventricular outflow tract (LVOT) gradients and aortic pulse pressures during rest, exercise, and after ventricular ectopy. BACKGROUND: Although the variability in LVOT gradients in patients with hypertrophic cardiomyopathy (HCM) is well known, the predictors of such variation are not. We hypothesized that quantitative invasive analysis of gradient variation could identify useful predictors of maximal gradients. METHODS: Variability in continuously recorded, high-fidelity left ventricular and aortic pressure waveforms were evaluated by computer-assisted analysis in the resting state (N = 659 beats) and during supine exercise (N = 379 beats) in a symptomatic patient with a resting LVOT gradient >30 mmHg and frequent ventricular ectopy. RESULTS: At rest, the peak left ventricular and aortic pressures at the time of the peak instantaneous LVOT gradient for all sinus and postectopic beats followed consistent regression slopes characterizing the potential energy loss between the LV cavity and aorta. During exercise, similar regression slopes were identified, and these converged with the resting slopes at the point of the maximal measured LVOT gradient. Component analysis of the LVOT gradient suggests that resting beat-to-beat variability provides information similar to post-ectopic pressures for predicting maximal gradients in obstructive-variant HCM. CONCLUSIONS: Our study suggests that computer-assisted analysis of hemodynamic variability in HCM may prove useful in characterizing the severity of obstruction. Further study is warranted to confirm the reproducibility and utility of this finding in a population with clinically significant exercise-induced gradients.

Rest and exercise hemodynamic and metabolic findings in active duty soldiers referred for cardiac catheterization to exclude heart disease: Insights from past invasive cardiopulmonary exercise testing using multisensor high fidelity catheters.

OBJECTIVE: This study describes results of iCPET from the past, which used submaximal stress and multisensor high-fidelity catheters to exclude heart disease in a unique population of young adults. BACKGROUND: There has been resurgence in comprehensive hemodynamic evaluation of complex cardiovascular patients. Although dynamic assessments during cardiac catheterization have become commonplace, there remains limited information regarding left and right heart hemodynamic changes during supine exercise in young adults. METHODS: The study population was derived from a retrospective review of catheterization records at Brooke Army Medical Center for active duty patients (ages: 19-40 years) in whom hemodynamic waveforms were obtained with multisensor high-fidelity catheters and supine exercise testing (53.1 ± 12.6 watts) and angiography performed to exclude heart disease. We report findings from 41 males and 1 female (ages: 19-40 years) found free of heart disease. RESULTS: Submaximal exercise was associated with ≈ fourfold (P < 0.001) increase in minute ventilation (VE), O2 consumption (VO2 ) and carbon dioxide production (VCO2 ). VE/VCO2 ratio decreased (-16.8 ± 13.9%, P < 0.001) and VE/VCO2 slope was 22.6 ± 0.6 (±SE). Cardiac index (CI) increased with VO2 (ΔCI/ΔVO2 slope = 7.6 ± 2.2). Heart rate increased nearly 10 bpm per 100 mL O2 /min/M2 , whereas, changes in stroke volume were more variable. Pulmonary artery (PA) saturations fell from 77 to 55% (P < 0.001). No change was noted in mean right atrial pressures; PA pressures increased ≈10 mm Hg (P < 0.001). Pulmonary capillary wedge and left ventricular end-diastolic pressures increased ≈2 mm Hg (P < 0.001) but variability noted between individuals. CONCLUSION: This study provides insight into past practices of invasive cardiopulmonary testing and furthers the understanding of metabolic and hemodynamic changes in a young population during supine submaximal exercise. © 2017 Wiley Periodicals, Inc.

Use of carbonated water in reduction of adjacent gastric activity in 456 consecutive technetium-99m myocardial perfusion imaging studies.

BACKGROUND: Small, observational trials have suggested a reduction in adjacent gastric activity with ingestion of soda water in myocardial perfusion imaging (MPI). We report our findings prior to and after implementation of soda water in 467 consecutive MPI studies. METHODS: Consecutive MPI studies performed at a high-volume facility referred for vasodilator (VD) or exercise treadmill testing (ETT) were retrospectively reviewed before and after implementation of the soda water protocol. Patients undergoing the soda water protocol received 100 ml of soda water administered 30 min prior to image acquisition and after stress. Studies were performed using a same day rest/stress protocol. Incidence of adjacent gastric activity, diaphragmatic attenuation, stress and rest perfusion defects, and major adverse cardiovascular events (MACE) outcomes defined as death, myocardial infarction, stroke, reevaluation for chest pain, and late revascularization (>90 days from MPI) were abstracted using International Classification of Diseases, Ninth Revision (ICD-9) search. RESULTS: Two hundred and eighteen studies were performed prior to implementation of the soda water protocol and 249 studies were performed with the use of soda water. Baseline demographic data were equal between the groups with the exception of more patients undergoing VD stress receiving soda water (p < 0.001). Soda water was not associated with a decreased incidence of adjacent gastric activity with stress (54.7% versus 61.9% with no soda water, p = 0.129) or rest (68.6% versus 69.5% with no soda water, p = 0.919) imaging. Less adjacent gastric activity was observed with patients undergoing ETT who received soda water (42.5% versus 56.9% with no soda water, p = 0.031), but no difference was observed between the groups with VD stress (69.0% versus 68.1% with no soda water, p = 1.000). CONCLUSION: The use of soda water prior to technetium-99m MPI was associated with lower rates of adjacent gastric activity only in patients undergoing ETT stress but not rest or VD stress. This differs from previously published data.

Fat Intravasation from Intraosseous Flush and Infusion Procedures.

STUDY HYPOTHESIS: The primary study objective was to delineate the procedural aspects of intraosseous (IO) infusions responsible for fat intravasation by testing the hypothesis that the fat content of effluent blood increases during IO infusions. METHODS: IO cannulas were inserted into the proximal tibiae of 35 anesthetized swine (Sus scrofa, 50.1 ± 3.5 kg) and intravasated fat was assessed using a lipophilic fluoroprobe (Nile red) and by vascular ultrasound imaging. Effluent blood bone marrow fat was assessed at baseline, during flush, and with regimens of controlled infusion pressures (73-300 mmHg) and infusion flow rates (0.3-3.0 mL per second). Fat intravasation was also assessed with IO infusions at different tibial cannulation sites and in the distal femur. In 7 animals, the lipid uptake of alveolar macrophages and lung tissue assessed for fat embolic burden using oil red O stain 24 hours post infusion. Additionally, bone marrow shear-strain was assessed radiographically with IO infusions. RESULTS: Fat intravasation was observed during all IO infusion regimens, with subclinical pulmonary fat emboli persisting 24 hours post infusion. It was noted that initial flush was a significant factor in fat intravasation, low levels of intravasation occurred with infusions ≤300 mmHg, fat intravasation and bone marrow shear-strain increased with IO infusion rates, and intravasation was influenced by cannula insertion site. Ultrasound findings suggest that echogenic particles consistent with fat emboli are carried in fast and slow venous blood flow fields. Echo reflective densities were observed to rise to the nondependent endovascular margins and coalesce in accordance with Stoke's law. In addition, ultrasound findings suggested that intravasated bone marrow fat was thrombogenic. CONCLUSION: Results suggest that in swine the intravasation of bone marrow fat is a common consequence of IO infusion procedures and that its magnitude is influenced by the site of cannulation and infusion forces. Although the efficacy and benefits of IO infusions for emergent care are well established, emergency care providers also should be cognizant that infusion procedures affect bone marrow fat intravasation.

Variability in intraosseous flush practices of emergency physicians.

OBJECTIVE: Intramedullary pressure changes during intraosseous (IO) procedures have been implicated in the intravasation of bone marrow fat and with pain in conscious patients. The objective of this study was to demonstrate inter-provider variability in pressures generated during initial flush procedures. METHODS: IO cannulas were inserted into the proximal tibiae and humeri by study personnel. A second cannula was placed in the mid diaphysis of each bone to record intramedullary pressures. Fifteen emergency physicians performed 60 flushes in random order in two cadavers while flush duration and IO pressure were continuously recorded. Providers were blinded to the flush pressures they generated and the flush techniques of others. RESULTS: The median IO pressure (IOP) generated by providers was 903 mm Hg (range, 83-2941 mm Hg) and the median flush duration was 5.2 seconds (range, 1.0-13.4 seconds). Significant differences were noted among providers in peak IOP generated (analysis of variance P<.001). Providers were consistent in the forces they generated relative to each other. An inverse, nonlinear relationship was observed between flush duration and the peak IOP generated. Significant differences were noted in intramedullary flush pressures at flush sites within cadavers (analysis of variance P: cadaver #1 P<.001; cadaver #2 P=.012). CONCLUSIONS: The IO compartment pressures generated by physicians demonstrated significant interoperator variability with greater than 35-fold difference in flush forces, and an inverse relationship between intraosseous pressure and flush duration. It may be prudent practice for providers to extend the flush over several seconds, thus limiting maximal pressures.

Assessment of major adverse cardiovascular events and ischemic stroke with coronary computed tomography angiography based upon angiographic diagnosis in a high-volume single center.

BACKGROUND: Patient prognosis has been shown to directly correlate with the severity of coronary artery disease diagnosed by coronary computed tomography angiography (CCTA). Although the presence of coronary artery calcium has been associated with increased incidence of ischemic stroke, there are no data on the incidence of ischemic stroke based upon the severity of coronary artery disease by CCTA. Therefore, we sought to investigate the rate of major adverse cardiovascular events, including ischemic stroke, based upon the severity of coronary artery disease by CCTA over a 6-year period in a high-volume single military center. METHODS: We performed a retrospective chart review of all CCTA studies to evaluate the incidence of all-cause mortality, non-fatal myocardial infarction, ischemic stroke, and late revascularization (>90 days following CCTA) from January 2005 until July 2012. We reviewed 1518 CCTA reports, dividing patients into groups with obstructive (≥50% stenosis), non-obstructive (<50% stenosis), and no coronary artery disease (no angiographic disease). Subsequent major adverse cardiovascular events data (incidence of all-cause mortality, ischemic stroke, non-fatal myocardial infarction, and late revascularization) were obtained. RESULTS: Over a review period of 6 years with a resultant median follow-up period of 22 months (interquartile range = 13-34 months), the major adverse cardiovascular events rate was significantly higher with obstructive coronary artery disease compared to both non-obstructive coronary artery disease and no coronary artery disease (8.9% vs 0.7%, p < 0.001; 8.9% vs 1.6%, p < 0.001). The incidence of ischemic stroke alone was also significantly higher in those with obstructive coronary artery disease compared to those with no coronary artery disease (3.8% vs 0.4%, p < 0.001). CONCLUSION: Being free of disease on CCTA was associated with excellent cardiovascular prognosis. Obstructive coronary artery disease was associated with a significantly increased incidence of ischemic stroke. There was also a direct correlation between the severity of coronary artery disease on CCTA and cardiovascular prognosis over the follow-up period of 24 months.

The effects of body mass index on surface electrocardiograms in young adults.

INTRODUCTION: While BMI is known to affect ECG measurements, these effects have not been well characterized in young adults. METHODS: We retrospectively reviewed all ECGs performed in adults 18 to 35 years old at a single institution over a 30 year period. ECG measurements were derived electronically and stratified by WHO BMI category. RESULTS: A total of 55,218 ECGs were included. Increasing BMI led to increased P wave duration and decreasing P, R, and T wave axes. Additionally, while increasing BMI led to less R wave voltage, J point elevation, and T wave amplitude in patients with a BMI ≥ 18.5 kg/m(2), there was also a decrease in the measured parameters in patients with a BMI <18.5 kg/m(2). DISCUSSION: BMI had significant effects on ECG measurements. For accurate assessment of ECGs, these data should be incorporated into established nomograms. Further investigation into the effects of BMI on the ECG is warranted.

Variability in intraosseous pressure induced by saline flush of an intraosseous cannula by multiple practitioners.

Intraosseous cannulation is an accepted means to achieve vascular access when peripheral venous access is not available. It is common practice to flush the intraosseous cannula with saline prior to establishing infusions. The objective of this study was to evaluate changes in intraosseous pressure during the flush procedure and to assess the variability of pressure changes induced by different practitioners. Two intraosseous cannulas were placed in an isolated cadaveric femur collected from a swine. Intraosseous pressure and the rate of change in pressure were recorded continuously during a series of saline flushes into a distal femoral intraosseous cannula by 21 members of the veterinary research staff at the authors' institution. Median peak intraosseous pressures exceeded 600 mmHg, and an inverse relationship was noted between peak intraosseous pressure and the duration of flush. Bone marrow fat emboli were grossly evident in flush effluents and their presence was confirmed by microscopic examination. Until the practitioners were informed of the pressure changes induced by the intraosseous cannula flush, few had appreciated the magnitude of the pressures that they had generated, suggesting that an instrumented intraosseous flush preparation like the one used in this study may prove useful as a training tool for flush procedures.

Using multidetector computed tomography in a swine model to assess the effects of sublingual nitroglycerin and intravenous adenosine on epicardial coronary arteries.

This study examines the effects of intravenous infusion of adenosine and sublingual nitroglycerin on coronary angiograms obtained by current-generation multidetector computed tomography. We assessed coronary vasodilation at baseline and after intravenous adenosine (140 microg/kg/min) or sublingual nitroglycerin spray (800 microg) in 7 female swine (weight, 40.9 +/- 1.4 kg) by using electrocardiogram-gated coronary angiography with a 64-detector scanner (rotation time, 400 ms; 120kV; 400 mA) and intravenous contrast (300 mg/mL iohexol, 4.5 mL/s, 2 mL/kg). Cross-sectional areas of segments in the left anterior descending, circumflex, and right coronary arteries were evaluated in oblique orthogonal views. Images were acquired at an average heart rate of 73 +/- 11 beats per minute. Changes in aortic pressure were not significant with nitroglycerin but decreased (approximately 10%) with adenosine. Of the 76 segments analyzed (baseline range, 2 to 39 mm2), 1 distal segment could not be assessed after adenosine. Segment cross-sectional area increased by 11.3% with nitroglycerin but decreased by 9.6% during adenosine infusion. The results of the present study are consistent with the practice of using sublingual nitroglycerin to enhance visualization of epicardial vessels and suggest that intravenous adenosine may hinder coronary artery visualization. This study is the first repeated-measures electrocardiogram-gated CT evaluation to use the same imaging technology to assess changes in coronary cross-sectional area before and after treatment with a vasodilator. The nitroglycerin-associated changes in our swine model were modest in comparison with previously reported human studies.

The 'mill-wheel' murmur and computed tomography of intracardiac air emboli.

The 'water-wheel' or 'mill-wheel' murmur is classically associated with large intracardiac air emboli and described as a "characteristic splashing auscultatory sound due to the presence of gas in the cardiac chambers." We used 64-slice computed tomography (slice thickness, 0.5 mm; revolution time, 400 msec) and 3D fly-through software imagery to capture previously unreported intracardiac air-blood interface dynamics associated with this murmur and ineffective right ventricular contraction in a porcine model.

Comparison of a chromogenic factor X assay with international normalized ratio for monitoring oral anticoagulation therapy.

The purpose of the present study was to compare the international normalized ratio with a chromogenic factor X (CFX) assay for monitoring patients on oral anticoagulant therapy using the DiaPharma CFX method on a STA-R Evolution coagulation analyzer. International normalized ratio values were correlated with the CFX for determining normal, subtherapeutic, therapeutic and supratherapeutic ranges for these patients. Specimens were analyzed and grouped as normal or patients on oral anticoagulant therapy with international normalized ratios of less than 2.0, 2.0-3.0, and more than 3.0. Three hundred and nine randomly selected oral anticoagulant therapy patients were tested. The range of international normalized ratio and CFX in oral anticoagulant therapy patients was 0.92-12.76 and 9-132%, respectively. CFX was inversely related to international normalized ratio; R = 0.964 (P < 0.0001) (CFX = 13.2 + (5.3/international normalized ratio) + (81.3/international normalized ratio). Results by group were as follows: normal (n = 30), CFX range 72-131%, mean CFX 96%; international normalized ratio less than 2.0 (n = 70), CFX range 32-132%, mean CFX 53%; international normalized ratio 2.0-3.0 (n = 135), CFX range 18-48%, mean CFX 28%; international normalized ratio more than 3.0 (n = 104), CFX range 9-46%, mean CFX 21%. Sensitivity and specificity crossed at a CFX of 35.5%, which yielded a sensitivity of 91.7% and a specificity of 91.9% for discriminating international normalized ratio of at least 2.0. Area under the curve on receiver-operator curve using international normalized ratio was 0.984 (P < 0.001). In this randomly selected group of oral anticoagulant therapy patients and normal individuals at varying levels of anticoagulation, CFX correlated well with international normalized ratio as determined by R = 0.964. The data suggests that the CFX can be a useful tool for monitoring oral anticoagulation in patient populations in which confounders to international normalized ratio may be present. Further investigation with the use of CFX for monitoring is warranted in large patient populations on oral anticoagulant therapy, including follow-up for clinical outcomes.

The incidence of phlebitis with intravenous amiodarone at guideline dose recommendations.

Postoperative atrial fibrillation following cardiothoracic surgery is common and frequently managed with intravenous (IV) amiodarone. Phlebitis is the most common complication with peripheral infusion of this agent. Current practice guidelines for peripheral IV administration of <2 mg/mL amiodarone were established to reduce the risk of phlebitis. The present study examines the incidence of phlebitis in a postoperative patient population given current dose recommendations. A total of 273 patient charts were reviewed. The incidence of phlebitis in patients given IV amiodarone (n = 36) was 13.9% (95% confidence interval, 2.6-25.2%; p = 0.001). Logistic regression analysis with backward elimination of other therapeutic risk factors suggests that the odds ratio for phlebitis using current dose regimens without IV filters is 19-fold greater than baseline risk in this population. Phlebitis remains a significant complication associated with peripheral infusion of amiodarone within recommended dosing limits.

Respiratory changes in the pulse-oximetry waveform associated with pericardial tamponade.

BACKGROUND: Timely identification of hemodynamic compromise in patients with acute pericardial effusion and tamponade is critical in patient management. Respiratory variability in pulse-oximetry waveforms has been correlated with pulsus paradoxus, but has not been reported with cardiac tamponade in adult patients. HYPOTHESIS: This study describes changes in respiratory variability in pulse-oximetry waveform pre and post pericardiocentesis in patients with hemodynamically significant pericardial effusions. METHODS: A single-center, catheterization laboratory hemodynamic database was reviewed for all patients who underwent pericardiocentesis for clinically suspected tamponade and had continuous digital pulse-oximetry, electrocardiographic, and respiration waveforms recorded during the procedure. Phasic respiratory changes in pulse-oximetry waveform amplitude (maxima-minima) were expressed as an expiratory/inspiratory ratio and compared pre and post pericardiocentesis. RESULTS: The study population consisted of 12 patients (6 men:6 women, age 60 +/- 10 years) with pericardial effusion documented by echocardiography on the day of pericardiocentesis. Phasic respiratory variability in the pulse-oximetry waveform was evident in all patients prior to aspiration (respiratory ratio = 1.9 +/- 0.5). Following pericardiocentesis (aspirated volume: 650 +/- 300 ml), the respiratory ratio decreased in all patients (1.2 +/- 0. 1, p = 0.001). Receiver operator characteristic curve analysis suggests that pulse-oximetry respiratory ratios > or = 1.5 should raise suspicion of hemodynamic compromise in high-risk populations. CONCLUSIONS: Pulse-oximetry is a commonly used tool for monitoring critically ill patients. The present study suggests that increased respiratory variability in the pulse-oximetry waveform should raise suspicion for hemodynamic compromise in patients at risk for pericardial effusion.

Use and limitations of magnetic resonance phase-contrast assessment of coronary flow reserve in a model of collateral dependence.

Phase-contrast magnetic resonance imaging (PC-MRI) is useful for assessing coronary artery flow reserves (CFR) in man and acute animal models with intermediate coronary lesions. The present study examines the use of PC-MRI for assessing CFR in a model with critical stenosis and collateral dependence. PC-MRI quantitative flow measurements from the proximal left anterior descending (LAD) and left circumflex (LCX) coronary arteries were compared with myocardial tissue perfusion reserve measurements (microsphere techniques) after placement of a 2.25-mm ameroid constrictor on the proximal LCX in a porcine model; measurements were obtained at implantation (n = 4) and at 3 to 4 weeks (n = 4) and 6 weeks (n = 5) postimplantation. CFR is defined as the ratio of maximal hyperemic flow to baseline flow. Hyperemia was induced using intravenous adenosine (140 mg/kg/min). Collateral dependence in the LCX distri bution was evidenced by angiographic findings of critical stenosis with minimal myocardial histological changes and normal baseline myocardial perfusion (microsphere techniques). In this setting, PC-MRI CFR was correlated with microsphere measures of perfusion reserve. Collateral dependence was confirmed by Evan's blue dye injection. This study provides angiographic, myocardial perfusion, and histological correlates associated with PC-MRI epicardial CFR changes during chronic, progressive coronary artery constriction. It also demonstrates the disparity between epicardial and myocardial measures of coronary flow reserve with collateral dependence and the caveats for PC-MRI use in models of progressive coronary constriction.

Detection of acute atrial thrombus in a porcine model with atrial fibrillation with tc 99m-apcitide.

RATIONALE AND OBJECTIVES: Technetium-99m apcitide (AcuTect) is a peptide with high affinity and specificity for glycoprotein IIb/IIIa receptors on platelets and is currently approved for the diagnosis of deep venous thrombosis. This study evaluates the use of Tc-99m apcitide for detecting intracardiac thrombus in an animal model with atrial fibrillation. METHODS: Thrombogenic material (0.23+/- 0.03 g) was implanted within the left atrium of 5 swine with induced atrial fibrillation. Scintigraphy was performed with a small field of view gamma camera (minimum of 400000 counts) 1 hour after implantation at 10, 60, and 120 minutes after the injection of the Tc-99m apcitide. Animals were then euthanized and a postmortem examination performed to confirm thrombus formation. RESULTS: : In all animals, thrombi and microthrombi were confirmed within the left atrial appendage. The average wet weight of the thrombus was 1.4 +/- 0.2 g. Tc-99m apcitide detected left atrial thrombus in all animals. CONCLUSIONS: This study suggests that AcuTect may prove useful for detecting intracardiac thrombus in future clinical studies in man.

Satellite and mobile wireless transmission of focused assessment with sonography in trauma.

OBJECTIVES: Focused assessment with sonography in trauma (FAST) can define life-threatening injuries in austere settings with remote real-time review by experienced physicians. This study evaluates vest-mounted microwave, satellite, and LifeLink communications technology for image clarity and diagnostic accuracy during remote transmission of FAST examinations. METHODS: Using a SonoSite, FAST was obtained on three patients with pericardial and intraperitoneal effusions and two control subjects in a remotely located U.S. Army Combat Support Hospital. A miniature vest-mounted video transmitter attached to the SonoSite sent wireless ultrasound video 20 m to a receiving antenna. The signal was then transferred over VSAT satellite systems at 512 kilobaud per second (kbps), INMARSAT satellite systems at 64 kbps, and over LifeLink on a moving ambulance through a metropolitan wireless traffic-management network. Clarity and absence or presence of effusions were recorded by 15 staff emergency physicians. RESULTS: Average sensitivity, specificity, and accuracy were 87% (95% confidence interval [CI]=79% to 95%), 85% (95% CI=81% to 89%), and 86% (95% CI=82% to 90%) for the Premier Wireless Vest; 98% (95% CI=97% to 99%), 83% (95% CI=75% to 91%), and 86% (95% CI=82% to 90%) for VSAT; 95% (95% CI=94% to 96%), 70% (95% CI=58% to 82%), and 75% (95% CI=70% to 80%) for INMARSAT; and 82% (95% CI=73% to 91%), 83% (95% CI=74% to 92%), and 82% (95% CI=78% to 86%) for LifeLink with clarity of 3.0 (95% CI=2.7 to 3.3), 2.9 (95% CI=2.6 to 3.2), 1.3 (95% CI=1.2 to 1.4), and 2.1 (95% CI=1.8 to 2.4), respectively. CONCLUSIONS: Accuracy correlated with clarity. Roaming vest transmission of FAST provides interpretable, diagnostic imagery at the distances used in this study. VSAT provided the best clarity and diagnostic value with the lighter, more portable INMARSAT serving a lesser role for remote clinical interpretation. LifeLink performed well, and further infrastructure improvements may increase clarity and accuracy.

Wireless and satellite transmission of prehospital focused abdominal sonography for trauma.

OBJECTIVE: As military operations become smaller and more remote and as humanitarian missions increase, ultrasound technology is emerging as a valuable asset for defining injuries in austere settings. This study evaluated the feasibility of focused abdominal sonography for trauma (FAST) examinations in a field environment with real-time images sent wireless to an antenna and over satellite. METHODS: Using a 6-lb SonoSite portable ultrasound device with battery pack, FAST examinations were performed on a healthy volunteer, transferred wireless at distances of 1,000 and 1,500 feet from the receiving antenna using a vest-mounted microwave transmitter, and then redirected over satellite (INMARSAT) to a remote hospital for review by emergency physicians, and a radiologist. RESULTS: Real-time wireless transmissions at 1,500 feet reliably yielded images without quality or interpretability drop compared with those recorded digitally at the examination site. A 32% reduction in image quality and interpretability was seen with still images and a 42% reduction was noted with cine loops using INMARSAT. The authors did not find the upper distance limit of the wireless transmitter used. CONCLUSION: This study suggests 1) that remote FAST examinations are plausible for prehospital care and triage using new-generation portable ultrasound units, 2) that line-of-sight transmission of FAST examinations when compared with on-site images results in no degradation in image quality or interpretability at distances used, 3) that ranges greater than 1,500 feet are feasible for interpretable examinations and therefore line-of-site mass casualty or field triage sites, and 4) that real-time INMARSAT transmission of FAST examinations at 64 kbps may serve a limited role for remote clinical interpretation.

Feasibility of real-time echocardiographic evaluation during patient transport.

Echocardiography is a key diagnostic tool in evaluating patients with cardiac emergencies and chest trauma. The lack of qualified real-time interpretation limits its use by emergency first responders. Early diagnosis of cardiac emergencies has the potential to facilitate triage and medical intervention to improve outcomes. We investigated the feasibility of remote, real-time interpretation of echocardiograms during patient transport. Echocardiograms using a hand-carried ultrasound device were transmitted from an ambulance in transit to a tertiary care facility using a distributed mobile local area network. Transmitted studies were reviewed by a cardiologist for ability to interpret predefined features. Transmission quality and reliability were assessed. Echocardiographic images were successfully transmitted greater than 88% of transport time. The evaluation of left-ventricular size and function, and presence of pericardial effusion were greater than 90% concordant, but only 66% of all echocardiographic features were concordant. Most transmission losses were brief (

Unusual sonographic finding in a patient with late recurrence of a perianal fistula.

We describe a case of late recurrence of a perianal fistula in a 51-year-old man with a 4.5-year history of recurrent perianal fistulas and abscesses. This was the fourth recurrence he had experienced; at each occurrence, he had undergone various examinations, including sigmoidoscopy, anoscopy, barium enema, fistulography, probe exploration, instillation of hydrogen peroxide, and/or sonography, and he had also undergone surgery. At our examination, transperineal sonography with a portable ultrasound scanner revealed an echogenic linear structure within the fistulous tract. Under endoanal sonographic guidance, surgery was performed, and a tan solid cylindrical structure longer than 2 cm was removed. Histopathologic examination revealed stratified squamous epithelium and soft tissue with substantial fibrosis and mild chronic inflammation, findings consistent with the characteristics of a remnant cast from a previous fistulous tract. Our findings suggest that some patients may benefit from relatively inexpensive sonographic examination with appropriate transducers.