急診超音波簡介 原理、心臟、胸部、骨骼肌肉軟組織 新光醫院急診醫學科 陳國智醫師 中華民國醫用超音波學會指導醫師 1
急診超音波的角色為何 ?
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臨床情境 • 50M, MVA patient, HR 130bpm, BP 70/40 – Internal bleeding ?
• 85M, sudden onset right flank pain, 8/10 – Renal colic or AAA ?
• 48F, RUQ pain with fever – Cholecystitis ?
• 28F, low abdominal pain with shock, EIA (+) – Ectopic pregnancy ? 3
急診超音波三部曲 • 操作者 –熟悉超音波的機器
• 判讀者 –熟悉超音波影像及解剖學
• 決策者 –與臨床工作整合協助決策 4
Cardiovascular Assessment
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Heart Anatomy
Thoracic Cavity
Cardiac Axes
Transducer consideration
Classic routes of heart
Subxiphoid Four-Chamber View
Subxiphoid Short-Axis View
Subxiphoid Long-Axis View (IVC view)
Central Venous Pressure IVC size for volume assessment IVC size (cm)
Resp. change
<1.5
Total collapse
RA pressure (cm) 0-5
1.5-2.5
>50% collapse
5-10
1.5-2.5
<50% collapse
11-15 (>10)
>2.5
<50% collapse
16-20
>2.5
No change
>20
IVC size assessment
Parasternal Long-Axis View
Parasternal Short-Axis View
Parasternal Short-Axis View papillary muscle level
Parasternal Short-Axis View mitral valve level
Parasternal Short-Axis View aortic valve level
Mercedes Benz sign
Apical Four-Chamber View
Primary Indications • Detection of pericardial effusion and/or tamponade • Evaluation of gross cardiac activity during CPR
• Evaluation of global LV systolic function
Secondary Indications • Gross evaluation of intravascular volume status and cardiac preload • Indentify acute RV dysfunction and/or acute pul. HTN for chest pain / dyspnea/or
hemodynamic instability • Pericardiocentesis guidance
Limitations for EUS • • • •
Focal wall motion abnormality Diastolic dysfunction Valvular abnormalities and function Intracardiac mass or thrombus, ventricular aneurysm, septal defect, AD, myocarditis, HCM, and vegetation
Technical limitations • • • • •
Thorax abnormalities Pulmonary hyperinflation Obesity Patient can’t cooperate Subcutaneous emphysema
Key component • Evaluation of pericardial effusion – Anechoic or hypoechoic fluid – Complex echogenicity: inflammation, infection, malignancy, hemorrhage
• Classification – None – Small, <10 mm in width in dastole, noncircumferential – Moderate, circumferential, not greater than 10 mm – Large, 10-20mm in width – Very large, > 20 mm and/or evidence of tamponade
Pericardial Effusion
Pericardial Effusion
Key component • Echocardiographic evidence of tamponade – Diastolic collapse of any chamber in the presence of moderate or large effusion – Hemodynamic instability with a moderate or large pericardial effuion
Cardiac Tamponade
US Guided- Pericardiocentesis • Subcostal approach – Traditional approach – Blind – Increased risk of injury to liver, heart
• Echo-guided – Left parasternal preferred for needle entry or… – Largest area of fluid collection adjacent to the chest wall
Technique
Pericardial Effusion / Tamponade • Tamponade – Clinical diagnosis – Circulatory collapse due to pericardial effusion
• Subxiphoid approach is the best window – Effusion location – inferior & posterior
• Echo evidence of tamponade – Diastolic collapse of the right side of the heart – Plethoric IVC without inspiratory collapse
Chest
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Why such a delay for lung ultrasound to become popular ?
Principles of Lung Ultrasound 1. 2. 3. 4. 5. 6. 7.
Dependent versus Nondependent disorders Lung surface is extensive All lung signs arise from the pleural line Analyze artifacts Dynamic signs Acute disorders contact the thorax surface A simple & 2-D device meets this task
Earth-Sky Axis • Fluids want to descent, gases to rise. • Lung disorders – Dependent: PLE, consolidation, …. – Non-dependent: PTX, interstitial syndrome, ….
• Define the scanning situation
Patient position
Landmarks of the chest wall • Lung surface: 1500cm2 • Position: as stethoscope • 9 areas – Anterior zone (1-4) – Lateral zone (5,6) – Posterior zone (S,M,L)
• 4 stages – – – –
1. anterior 2. lateral 3. portion of posterior 4. posterior
Landmarks of the chest wall • Lung surface: 1500cm2 • Position: as stethoscope • 9 areas – Anterior zone (1-4) – Lateral zone (5,6) – Posterior zone (S,M,L)
• 4 stages – – – –
1. anterior 2. lateral 3. portion of posterior 4. posterior
Degree of aeration and US signs Key concepts: Air versus Water Degree Pathologic disorder
Ultrasound pattern
100%
Pneumothorax
A lines & Lung sliding (-)
98%
Normal lung
A lines & Lung sliding (+)
95%
Thickening of the interlobular septa B7 lines
80%
Ground-glass areas
B3 lines
10%
Alveolar consolidation
Hepatization & air bronchograms (++)
5%
Atelectasis
Hepatization & air bronchograms (-)
0%
Pleural effusion
Anechoic collection
Normal Landmark Bat sign
Rib
Pleural line A-line
Normal dynamic lung pattern Lung sliding: all-or-nothing rule ”Seashore sign”
Rule out pneumothorax
Normal static lung pattern A line & B line
A lines and B lines cannot be visible at the same location
Comet-tail artifact ”Lung rockets”
B-line
Rule out pneumothorax Indicate interstitial syndrome
88F with respiratory failure
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Normal versus APE
Comet-tail artifact
E-line
Parietal emphysema
Pneumothorax
Rule out pneumothorax all-or-nothing rule
Stratosphere sign (Barcode Sign) Lung sliding (-) Sensitivity 100% Specificity 78% A line sign (No B line) Sensitivity 100% Specificity 60%
Pneumothorax
Sensitivity 66% Specificity 100%
Lung point
Pneumothorax Lichtenstein DA, et al. Inten Care Med 2000;26:1434-1440
Explanation of lung point
Sensitivity 66% Specificity 100%
Lung point
Pneumothorax Lichtenstein DA, et al. Inten Care Med 2000;26:1434-1440
Signs of PTX • • • •
No lung sliding No B line No lung pulse Presence of lung point
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MSK
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Outlines • US anatomic considerations • Skin and soft tissue infection • Long Bony fracture evaluation
正常組織超音波影像 •
Skin
•
Subcutaneous tissue
•
Fascial planes
•
Muscles
•
Tendon
•
Vascular structures
•
Lymph nodes
•
Bones
– Echogenic
– Hypoechoic – Traverse by irregular strands of hyperechoic connective tissue – Hyperechoic; regular thickness – Striated appearance on long axis scan – Fibrillar; echogenic – Anechoic (Artery versus Vein) – Irregular, circular, echogenic; with hypoechoic rim – Echogenic cortices and dense acoustic shadows
掃描注意事項 高解析線形探頭 (5-10MHz)為第一首選 注意深度(depth)和焦點(focus)的設定 適當應用探頭施壓 至少掃描兩個介面 (longitudinal & transverse) 考慮和對側比較 & 呈現在同一畫面 (Split screen) • 如何改善掃描品質 • • • • •
– Stand-off pad – Water/gel-filled glove – Water bath technique
Water/gel-filled glove
EUS在皮膚 & 軟組織感染的應用 • 須熟悉正常超音波軟 組織影像 • 認識週遭組織及結構 • 協助設定最佳切除及 引流路徑
• 正確診斷不明顯膿瘍 診斷 • 正確定位不明顯膿瘍 定位 • 協助膿瘍引流 處置
皮膚 & 軟組織感染 •
Cellulitis
•
Subcutaneous abscess
– Cobblestone-like appearance – Variable appearance – Most: hypoechoic; spherical mass – Content: • • • • •
Hyperechoic sediment Septae Gas Isoechoic or hyperechoic Liquefied pus – induced motion of the content
•
Necrotizing fasciitis
– Marked thickened of SC layer – A layer of anechoic fluid, • greater than 4 mm • adjacent to deep fascia
– Subcuatneous gas
• Acoustic shadow • Reverberation artifact
Cellulitis • Nonspecific • Indicative of edema • Skin • Subcutaneous tissue • Compare to unaffected side
Normal v.s. Cellulitis
EUS improves accuracy of superficial abscess detection
Squire BT, et al. AEM. 2005;12:601-606
NTUH experience • diffuse thickening of the SC tissue • a layer of fluid accumulation more than 4 mm in depth along the deep fascial layer • 66 patients (17,NF) • Sensitivity: 88.2% • Specificity: 93.3% • PPV: 83.3% • NPV: 95.4% • Accuarcy: 91.9 Yen ZS, et al. AEM. 2002;9:1448-1451
骨折評估 • • • • • • •
肋骨骨折 胸骨骨折 長骨骨折 堅困環境骨折 骨折復位 脫位復位
FASTER
骨折評估 • • • •
骨表面產生不連續線條 骨折周圍低回音血腫 掃描時注意最痛點 至少進行兩個介面掃描
Rib
Rib fracture
Rib fracture
Normal sternum
Sternal body fracture
Femur
Femoral shaft fracture
Tibial shaft fracture
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