David C. Mackenzie

Transient Corticosteroid Treatment Permanently Amplifies the Th2 Response in a Murine Model of Asthma

Corticosteroids (CS) remain the most efficacious pharmacotherapeutic option for the management of asthma. Although the acute anti-inflammatory effects of CS treatment have been amply documented both clinically and experimentally, recent human data intimate that exposure to CS may be associated with retrograde immune phenomena, including enhanced synthesis of IgE in vivo and elevated Th2 cytokine production in vitro. We have investigated the long-term immunologic effects of CS treatment in a murine model of allergic airway inflammation. CS treatment during initial exposure to OVA or upon long-term Ag rechallenge remarkably attenuated eosinophilic airway inflammation and airway hyperresponsiveness. Interestingly, however, Th2 cytokine production by cultured splenocytes from CS-treated mice was significantly elevated, while IFN-γ synthesis was depressed. Moreover, mice rechallenged with OVA several weeks after CS intervention during allergic sensitization not only developed airway inflammation, but also exhibited enhanced Th2 cytokine production in lymphoid tissues and OVA-specific IgE in serum. This amplification of the systemic immune response was associated with an intact APC compartment during CS-conditioned sensitization to OVA. These data indicate that immune processes underlying the allergic phenotype remain impervious to CS treatment and raise the possibility that treatment with CS during sensitization may amplify elements of the allergen-specific immune response.

A Practical Guide to Self-Sustaining Point-of-Care Ultrasound Education Programs in Resource-Limited Settings

The value of point-of-care ultrasound education in resource-limited settings is increasingly recognized, though little guidance exists on how to best construct a sustainable training program. Herein we offer a practical overview of core factors to consider when developing and implementing a point-of-care ultrasound education program in a resource-limited setting. Considerations include analysis of needs assessment findings, development of locally relevant curriculum, access to ultrasound machines and related technological and financial resources, quality assurance and follow-up plans, strategic partnerships, and outcomes measures. Well-planned education programs in these settings increase the potential for long-term influence on clinician skills and patient care.

Assessing volume status and fluid responsiveness in the emergency department

Resuscitation with intravenous fluid can restore intravascular volume and improve stroke volume. However, in unstable patients, approximately 50% of fluid boluses fail to improve cardiac output as intended. Increasing evidence suggests that excess fluid may worsen patient outcomes. Clinical examination and vital signs are unreliable predictors of the response to a fluid challenge. We review the importance of fluid management in the critically ill, methods of evaluating volume status, and tools to predict fluid responsiveness.

IDENTIFICATION OF SPLENIC INFARCTION BY EMERGENCY DEPARTMENT ULTRASOUND

BACKGROUND Splenic rupture or infarction can occur secondary to acute infectious mononucleosis. Patients with abdominal pain and known or suspected infectious mononucleosis mandate evaluation for these complications, which can have significant morbidity or mortality. CASE REPORT An 18-year old man presented to the emergency department (ED) with a 2-day history of left upper quadrant abdominal pain. He had been diagnosed with mononucleosis 4 days before his ED presentation. Physical examination was notable for focal left upper quadrant tenderness. The treating physicians principal diagnostic considerations were splenic rupture or infarction secondary to mononucleosis. Point-of-care ultrasound was performed by the emergency physician, demonstrating multiple hypoechoic areas in the splenic parenchyma with absent Doppler flow, consistent with multiple splenic infarcts. The patient was admitted for observation, managed conservatively, and had an uneventful course. CONCLUSION Emergency ultrasound of the spleen can allow rapid diagnosis of splenic infarction and exclusion of splenic rupture in a patient at risk for splenic pathology.

Point-of-care ultrasound facilitates diagnosing a posterior shoulder dislocation.

BACKGROUND Posterior shoulder dislocation is an uncommon disruption of the glenohumeral joint. Risk factors include seizure, electric shock, and underlying instabilities of the shoulder joint. CASE REPORT A 27-year-old man with a history of recurrent posterior shoulder dislocation presented to the Emergency Department with sudden shoulder pain and reduced range of motion about the shoulder after abducting and internally rotating his arm. Radiographs did not show fracture or dislocation. The treating physician suspected an occult posterior shoulder dislocation, but wanted to avoid performing a computed tomography scan of the shoulder, as the patient had undergone numerous scans during the evaluation of similar complaints. Instead, a point-of-care ultrasound was performed, demonstrating posterior displacement of the humeral head relative to the glenoid rim, confirming the presence of a posterior shoulder dislocation. The patient received procedural sedation, and the shoulder was reduced with real-time ultrasound visualization. The patient tolerated the procedure well, and had decreased pain and improved range of motion. He was discharged with a sling, swathe, and orthopedic follow-up. CONCLUSION Point-of-care ultrasound of the shoulder may be used to demonstrate posterior shoulder dislocation. This may have particular utility in the setting of non-diagnostic radiographs.

Aortoenteric Fistula Identified By Clinical Ultrasound

BACKGROUND Aortoenteric fistula is a rare but serious cause of gastrointestinal bleeding. Early diagnosis and definitive treatment with fistula repair may improve patient outcomes. We report the use of point-of-care ultrasound to identify an aortoenteric fistula in a patient presenting with abdominal pain and shock. CASE REPORT A 78-year old man presented to the Emergency Department with abdominal pain and 5 days of minimal hematochezia. He was hypotensive and had diffuse abdominal tenderness. Point-of-care ultrasound was performed, demonstrating an abdominal aortic aneurysm with a hypoechoic projection into a segment of bowel abutting the aorta. Color flow was present through the structure, consistent with an aortoenteric fistula. After resuscitation with red blood cells, computed tomography was performed to confirm the diagnosis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Clinical ultrasound has a well-established role in the detection of aortic aneurysm. This case illustrates that point-of-care ultrasound can also be used to rapidly identify an aortoenteric fistula and expedite timely care and surgical evaluation.

Point-of-Care Ultrasound Use, Accuracy, and Impact on Clinical Decision Making in Rwanda Hospitals

Few studies of point‐of‐care ultrasound training and use in low resource settings have reported the impact of examinations on clinical management or the longer‐term quality of trainee‐performed studies. We characterized the long‐term effect of a point‐of‐care ultrasound program on clinical decision making, and evaluated the quality of clinician‐performed ultrasound studies.

Carotid Flow Time Test Performance for the Detection of Dehydration in Children With Diarrhea

Unstructured clinical assessments of dehydration in children are inaccurate. Point‐of‐care ultrasound is a noninvasive diagnostic tool that can help evaluate the volume status; the corrected carotid artery flow time has been shown to predict volume depletion in adults. We sought to determine the ability of the corrected carotid artery flow time to identify dehydration in a population of children presenting with acute diarrhea in Dhaka, Bangladesh.

Dural sinus thrombosis identified by point-of-care ultrasound

Dural sinus thrombosis (DST), or cerebral venous thrombosis, is an uncommon cause of stroke. It has a variable presentation, and the symptoms and signs can be non-specific. The diagnosis of DST can be difficult to make and is often delayed or missed. Computed tomography venography or magnetic resonance venography are the typical imaging modalities used to diagnose DST. However, computed tomography venography and magnetic resonance venography both have limitation for emergency department patients. In this article, we report the use of point-of-care ultrasound to facilitate the diagnosis of DST.

Test performance of point-of-care ultrasound for gastric content

Objective: We sought to determine test performance characteristics of emergency physician ultrasound for the identification of gastric contents. Methods: Subjects were randomized to fast for at least 10 h or to consume food and water. A sonologist blinded to the patients status performed an ultrasound of the stomach 10 min after randomization and oral intake, if applicable. The sonologist recorded their interpretation of the study using three sonographic windows. Subsequently 2 emergency physicians reviewed images of each study and provided an interpretation of the examination. Test performance characteristics and inter‐rater agreement were calculated. Results: 45 gastric ultrasounds were performed. The sonologist had excellent sensitivity (92%; 95% CI 73%–99%) and specificity (85%; 95% CI 62%–92%). Expert review demonstrated excellent sensitivity but lower specificity. Inter‐rater agreement was very good (&kgr; = 0.64, 95%CI 0.5–0.78). Conclusion: Emergency physician sonologists were sensitive but less specific at detecting stomach contents using gastric ultrasound.