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Novel Uses for ED Ultrasound

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  1. More than just another stethoscope Novel Uses for ED Ultrasound Mark Bromley Emergency Medicine PGY3

  2. Intubation

  3. Ocular

  4. Ultrasound in the ED - Outline • Undifferentiated Hypotension - Echo • LV function • Volume Status • JVP • Procedures • Guided Lumbar Puncture • Abscess Drainage • Pleural effusion/Thoracentesis • Paracentesis • Suprapubic aspiration • Vascular Access • Joint taps

  5. Other Novel Uses • Galbladder • DVT • Ocular • Fracture Detection • Fracture Management • Renal • Pneumothorax • Intubation

  6. Undiferentiated Hypotension ...for the cardiologist in you

  7. Case • 67 ♂ • Hx of CAD and CHF • Unwell over last 2-3 days • HypotensiveTachycardic SOB

  8. Why US? Why us? • Urgent diagnostic evaluation • Timely • Limited diagnostic options due to the clinical condition → transportation of sick patients • Allow appropriate intervention and improve the course of disease

  9. Unexplained Hypotension • Cardiogenic shock • Hypovolemia - Distributive • Right ventricular infarct/large PE • Tamponade

  10. Unexplained Hypotension • As a clinician → trying to choose between inotropy, fluid resuscitation, or a needle • The ventricle is either moving well or not • The RV is dilated or not • There is an effusion or there is not • The IVC is full or not • The JVP is up or not

  11. LV Failure – fractional shortening Fractional shortening • Look at the black (i.e. blood) in the left ventricle • Systole: the black decreases in size • The ↓in size with systole is fractional shortening • Normal ejection fraction is ~ 60% • Mathematically → single dimension • (diameter rather than volume) • Change of diameter ≥30% → Gr 1 fxn • Change of diameter <30% → ↓LV systolic fxn

  12. LV Failure – fractional shortening

  13. LV Failure – LV dilatation LV dilatation • Mid-LV diameter ≤5.2cm at end-diastole • If diameter >5.2cm → LV dilatation

  14. Specific Diagnoses

  15. LV Failure • ↓ shortening fraction • LV Dilatation

  16. Hypovolemic or Distributive Shock • End-diastole → LV chamber unusually small • Systole → virtually all LV blood ejected • Cardiac Activity → hyperdynamic • fast heart rate • very vigorous contractions • Ejection fraction → exceeds 70% • IVC → low CVP

  17. Massive Pulmonary Embolus • RV is usually 2/3 the size of the LV • RV function is less formally quantified • (mathematically) complex shape • PE → RV diameter can exceed the LV diameter • Such a finding may guide diagnosis and management in the acutely dyspneic or hypotensive patient

  18. Bottom Line

  19. IVC – how to • Identify the IVC: • Just anterior to the spine • To the right of the aorta in > 99.9%. • Thin-walled (vs. the thicker-walled aorta) • Compressible with pressure • Size varies with respiration • Diameter ≤ 1.5cm→ possibly c/w ↓CVP • Diameter ≤ 1.0 cm definitely c/w ↓CVP • ↑inspiratory↑ in IVC (>25%) →↑ chance pt is dry

  20. IVC

  21. JVP – How Good Are We • Methods: • 84 consecutive patients referred for right-sided cardiac catheterization • RA pressure was acquired • Internal residents underwent 4h of formal US training and performed 20 supervised studies • Blinded to cath results examined the IVC <1h before catheterization • RA pressure was also estimated by JVP in 40 patients before right-sided cardiac catheterization • Results: • RA pressure was successfully estimated from US images of the IVC in 90% of patients, compared with 63% from JVP examination • The sensitivity for predicting RA pressure >10mm Hg was 82% with US and 14% from JVP inspection

  22. JVP …why should medicine residents have all the fun?

  23. JVP – image generation

  24. JVP

  25. Case

  26. Case

  27. Can we do it? How long does it take? Does it change what we do?

  28. Methods: • Prospective, observational study • 4 EP investigators with prior US experience → focused echo training • A convenience sample of 51 adult pts with hypotension • Exclusion criteria: • History of trauma • Chest compressions • EKG diagnostic of acute MI • Echocardiogram was recorded by an EP investigator - estimated EF and categorized LVF as normal, depressed, or severely depressed. • Blinded cardiologist reviewed all 51 studies for EF, categorization of function, and quality of the study • A second cardiologist reviewed 20 of the tapes to assess inter-observer variability between cardiologists

  29. Pearson’s correlation coefficient for EP and cardiologist estimation was R=0.86 • Pearson’s correlation coefficient for the two cardiologists’ estimations was R=0.84 • Agreement between EPs in the convenience subset of eight patients who underwent echo by two EPs yielded an R = 0.94

  30. Methods: • Prospective observational study of aconvenience sample of patients admitted to ICU • All patients underwent BLEEP followed by an independentformal echocardiogram by an experienced paediatric echocardiographyprovider (PEP) • EPs had 3 hours of focused cardiac US training including 5-proctored BLEEP examinations on unenrolled patients • IVC volume was assessed by measurement of themaximal diameter of the IVC • LVF was determined by calculatingshortening fraction (SF) • Estimates of SF and IVC volume obtained on the BLEEP were compared with those obtained by the PEP Results: • N=31 • Mean age=5.1 years (range: 23 days–16 years) • Agreementbetween the EP and the PEP for estimationof SF (r = 0.78) • The mean difference in the estimate of SFbetween the providers was 4.4% (95% CI: 1.6%–7.2%) • This difference in estimate of SF was not thought to be clinically significant • Agreement between the EP and the PEPfor estimation of IVC volume (r = 0.8). • The mean differencein the estimate of IVC diameter by the PEP and the EP was 0.068mm (95% CI: –0.16 to 0.025 mm). Conclusions: • PEP sonographers are capableof accurate assessment of LVF andIVC volume • BLEEP can be performed with focused training andoversight by a pediatric cardiologist

  31. Design: • Randomized, controlled trial of immediate vs. delayed ultrasound. • Urban, tertiary emergency department, census >100,000. • Non-trauma emergency department patients, aged >17 yrs, and initial emergency department vital signs consistent with shock (SBP<100 mm Hg or shock index >1.0), and agreement of two independent observers for at least one sign and symptom of inadequate tissue perfusion Interventions: • Group 1 (immediate ultrasound) received standard care plus goal-directed US at time 0 • Group 2 (delayed ultrasound) received standard care for 15 min and goal-directed US b/w 15-30 min Results: • Outcomes included the number of viable physician diagnoses at 15 mins and the rank of their likelihood of occurrence at both 15 and 30 mins. • N=184 • Group 1 (n = 88) had a smaller median number of viable diagnoses at 15 mins (median = 4) than did group 2 (n = 96, median = 9, Mann-Whitney U test, p < .0001). • Physicians indicated the correct final diagnosis as most likely among their viable diagnosis list at 15 mins • Group 1 80% (95% confidence interval, 70–87%) of group 1 subjects • Group 2 50% (95% confidence interval, 40–60%) in group 2 ...difference of 30% (95% confidence interval, 16–42%)

  32. 7 views • Each intended to answer a binary question: • Pericardial effusion • Pericardial tamponade • Left ventricular dysfunction • Right ventricular dilation • Intravascular volume depletion • Intraperitoneal fluid • Aortic aneurysm • On average, this information was obtained in < 6 min

  33. Conclusions: • Incorporation of a goal-directed ultrasound protocol in the evaluation of nontraumatic, symptomatic, undifferentiated hypotension in adult patients results in fewer viable diagnostic etiologies. • More accurate physician impression of final diagnosis.

  34. We can do easily We can do safely Procedures

  35. Guided Lumbar Puncture ...when you need the bariatric needle • Accurate identification of landmarks by palpation is impaired in obese patients • At least 65% of adults in the US are overweight or obese • Increasing the accuracy of landmark identification for LP may be useful

  36. Objective: • The objective of the study was to determine EPs’ ability to apply a standardized US technique for visualizing landmarks surrounding the dural space • Methods: • 2 EPs sought to identify relevant anatomy in emergency patients • Visualization time for 5 anatomical structures (spinous processes or laminae, ligamentumflavum, dura mater, epidural space, subarachnoid space), BMI, and perception of landmark palpation difficulty • Results: N=76 • Soft tissue and bony anatomical structures were identified in all subjects • Mean BMI was 31.4 (95% confidence interval, 29.1 - 33.6). • High-quality images were obtained in < 1 minute in 153 (87.9%) scans < 5 minutes in 174 (100%) scans • Mean acquisition time was 57.19 seconds; SD, 68.14 seconds; range, 10 to 300 seconds. • Conclusion: • In this cohort, EPs were able to rapidly obtain high-quality ultrasound images relevant to lumbar puncture

  37. Guided Lumbar Puncture

  38. Methods: • Cross-sectional study • Patients categorized by BMI • Recorded the difficulty in palpating traditional LP landmarks • Identification and measurement of the spatial relationships of the sacrum; spinous processes of L3, L4, L5; ligamentum flavum; and the spinal canal by US • Results: • Difficulty in palpating landmarks Normal BMI - 5% Overweight – 33% Obese - 68% ( P .0001) • Successful identification of pertinent structures Normal BMI – 100% Overweight – 95% Obese -- 74% ( P = .011) • In subjects with difficult-to-palpate landmarks, US identified pertinent structures in 16/21 (76%; 95%CI 53-92) • The average distance from skin to ligamentum flavum was 44 mm - normal BMI 51 mm - overweight 64 mm - obese • Conclusion: • As people get bigger they are harder to landmark • Ultrasound is helpful in this population – but not perfect

  39. Abscess Drainage ...where’s the pus

  40. Abscess Drainage • Cellulitis vs Abscess • Abscesses may not be clinically obvious • Is there an abscess? • What is the best area for I&D? • Are there structures near the abscess (i.e. vessels or nerves) risk?

  41. Methods: • Prospective observational ED study of adult patients with clinical STI without obvious abscess • The treating physician’s pretest opinions • need for drainage procedures • probability of subcutaneous fluid collection • Emergency US of the infected area • Effect on management plan was recorded Results: • Ultrasound changed the management in 71/126 (56%) of cases • Pretest Group • believed not to need drainage - US changed management in 39/82 (48%) • (33 drained and 6 more imaging or consultation) • believed drainage to be needed, US changed the management in 32/44 (73%) • (16 not drained and 16 more diagnostics) • US had a management effect in all pretest probabilities for fluid from 10% to 90%

  42. Conclusion • US changes ED management • Hopefully for the better

  43. Methods: • Prospective, convenience sample of adult patients with ?cellulitis +/- abscess • US was performed by EPs or residents who had attended a ½h training session in soft tissue US • yes/no assessment (of abscess) • I&D was the standard when performed • Resolution on 7d follow-up was the standard when I&D was not performed Results • N=107 • 64/107 patients had I&D–proven abscess • 17/107 had negative I&D • 26/107 improved with antibiotic therapy alone (clinically negative) • Clinical examination • Sensitivity of : 86% (95% [CI] = 76% to 93%) • Specificity: 70% (95% CI = 55% to 82%). • US • Sensitivity: 98% (95% CI = 93% to 100%) • Specificity was 88% (95% CI = 76% to 96%) • Of 18 cases in which US disagreed with the clinical examination, US was correct in 17 (94%) (x2=14.2, p = 0.0002)

  44. Clinical examination • Sensitivity of : 86% • Specificity: 70% • US • Sensitivity: 98% • Specificity was 88% • Of 18 cases in which US disagreed with the clinical exam, US was correct in 17 (94% of cases with disagreement, x2 = 14.2, p = 0.0002) Conclusions: • ED bedside US improves accuracy in detection of superficial abscesses

  45. Thoracentesis

  46. Thoracentesis – How to... • The probe should be perpendicular to the chest to ensure an accurate assessment of pleural fluid collection size, shape, and depth • Identify the diaphragm and liver or spleen • Slide the probe in the longitudinal plane towards the head and feet and then anterior-posterior or medial-lateral to locate the largest pocket of fluid