Point-of-Care Ultrasound (POCUS)

Point-of-Care Ultrasound (POCUS)

David Ray Velez, MD

Table of Contents

Point-of-Care Ultrasound (POCUS)
Cardiac Ultrasound
Pulmonary Ultrasound
Inferior Vena Cava (IVC) Ultrasound

Point-of-Care Ultrasound (POCUS)

Definition

  • Definition: Advanced Diagnostic Ultrasonography Performed and Interpreted by the Physician at Bedside
  • More Rapid Use and Results are Optimal in the Critical Care Setting When Formal Diagnostic Imaging May Delay Diagnosis and Treatment
  • Highly Operator Dependent

Applications and Assessment

  • Cardiac Ultrasound
    • Regional Wall Motion Abnormalities or Global Hypokinesis
    • Calculate Left Ventricular Ejection Fraction (LVEF)
    • Pericardial Fluid
    • Right Ventricular Function and Evaluate for Pulmonary Embolism
    • Inferior Vena Cava (IVC) Ultrasound
    • Fluid Responsiveness
  • Pulmonary Ultrasound
    • Pleural Effusion
    • Pneumothorax (PTX)
    • Pulmonary Edema or Pneumonia
  • Abdominal Ultrasound
    • Cholelithiasis and Cholecystitis
    • Appendicitis
    • Intussusception
    • Hydronephrosis
    • Focused Assessment with Sonography for Trauma (FAST)
      • *See Focused Assessment with Sonography for Trauma (FAST)
    • Gestational Age
  • Vascular Ultrasound
    • Deep venous Thrombosis (DVT)
    • Abdominal Aortic Aneurysm (AAA)
    • Ultrasound-Guided Peripheral and Central Venous Catheters
  • Skin and Soft Tissue Ultrasound
    • Abscess
    • Soft Tissue Mass
    • Foreign Body

Cardiac Ultrasound

Four Primary Views

  • Using a Phased-Array Probe
  • Parasternal Long-Axis View (PLAX): Left Sternal Border at the 3rd-4th Intercostal Space, Probe Indicator to the Right Shoulder
  • Parasternal Short-Axis View (PSAX): Left Sternal Border at the 3rd-4th Intercostal Space, Probe Indicator to the Left Shoulder
  • Apical 4-Chamber View (A4C): Just Inferior to the Left Nipple, Probe Indicator to the Left Flank
  • Subcostal View: 2-3 cm Below the Xyphoid

Cardiac POCUS: (A) Parasternal Long-Axis 1; (B) Parasternal Short-Axis 2; (C) Apical 4-Chamber 1 [Right Atrium (RA), Right Ventricle (RV), Left Atrium (LA), Left Ventricle (LV), Aortic Outflow (AO)]

Left Ventricle (LV) Evaluation

  • Evaluate for Regional Wall Motion Abnormalities or Global Hypokinesis
  • Evaluate Ejection Fraction (Normal 50-70%)
  • Qualitative Assessment of EF:
    • Left Ventricle Wall Movement
    • Anterior Mitral Valve Movement
  • Quantitative Assessment of EF:
    • E-Point Septal Separation (EPSS): Estimates LVEF By Assessing Mitral Valve Leaflet Movement Toward the Ventricular Septum
    • Fractional Shortening: Estimates LVEF By Assessing Change in Diameter of the LV
    • Fractional Area Change: Estimates LVEF By Assessing Change in Cross-Sectional Area of the LV
    • Simpson (Biplane) Method: Estimates LVEF By Assessing Change in Volume of the LV
  • *See POCUS: Left Ventricular Ejection Fraction (LVEF)

Right Ventricle (RV) Evaluation

  • Evaluate for Regional Wall Motion Abnormalities or Global Hypokinesis
  • D-Sign: LV is “D” Shaped Due to Flattening of the Interventricular Septum from RV Overload
    • Normally the LV is Round with RV Wrapped Around it on Parasternal Short-Axis View
  • Tricuspid Annular Plane Systolic Excursion (TAPSE): A4C View Using M Mode to Quantify the Tricuspid Annulus Movement Toward the Apex
    • TAPSE < 16 mm Indicates Poor RV Function

TAPSE on POCUS 3

Pericardial Effusion

  • Dark Hypoechoic Fluid Seen Around the Heart
  • Best Seen in Parasternal Long-Axis or Subcostal View
  • Differentiate from Pathology with a Similar Appearance:
    • Pericardial Fat Pad – Usually Located Anteriorly and Will Not Be Completely Anechoic (Pericardial Effusion May Be More Circumferential and More Hypoechoic)
    • Pleural Effusion – Will Be Seen Posterior to the Descending Aorta (Pericardial Effusion is Seen Anterior to the Descending Aorta)
  • Signs of Cardiac Tamponade:
    • Systolic Right Atrial Collapse – First Sign
    • Diastolic Right Ventricular Collapse
    • Dilated and Noncollapsible IVC
    • “Swinging Heart” with Pendular Motion from Circumferential Fluid Accumulation

Pericardial Effusion on POCUS: Anterior to the Descending Aorta 4

Pleural Effusion on POCUS: Posterior to the Descending Aorta 4

POCUS Evaluation for Pulmonary Embolism (PE)

  • Left Ventricle (LV): Normal Function
  • Right Ventricle (RV): Severely Dilated with Reduced Systolic Function and Wall Hypokinesis
    • Septal Flattening (From RV Pressure Overload)
  • Pulmonary Artery Hypertension
  • McConnell Sign: RV Dysfunction with Akinesia of the Mid-Free Wall but Normal Motion at the Apex
    • Highly Specific for PE
  • D-Sign: Left Ventricle is “D” Shaped Due to Flattening of the Interventricular Septum from Right Ventricular Overload

PE POCUS: (A) Significant Right-Sided Distention 1; (B) “D-Sign” on Short-Axis View with Dilated RV, Flattened Septum (Arrows), and D-Shape of LV 2

Pulmonary Ultrasound

A-Lines

  • Echogenic Horizontal Lines that Gradually Fade at Equal Intervals from the Pleural Line
  • Represents Artifact Reflecting Back and Forth from the Probe and Pleura Due to Air Beneath the Pleura
  • Indicates Normal Parenchyma

B-Lines (Lung Comets/Rockets)

  • Vertical Artifacts Originating from the Pleural Line
  • Due to Increased Density of Lung Parenchyma
  • Occasional B-Lines (1-2) Can Be Normal – Particularly in the Lung Bases
  • Frequent B-Lines (≥ 3 in a Single-View) Represent Abnormal Tissue

Lung Sliding

  • Movement of the Two Pleural Layers During Respiration
  • Indicates that the Two Layers are in Apposition
  • Represents a Normal Finding
  • Absent Lung Sliding Can Be Due to Pneumothorax or Pleural Effusion
  • Lung Sliding on M-Mode:
    • Seashore Sign: Pleura and Chest Wall Appear as Horizontal Lines (Sea) While Lung Parenchyma Appears as Grainy Sand (Shore)
      • Indicates Lung Sliding and Represents Normal Parenchyma
    • Barcode (Stratosphere) Sign: Entirely Uniform Horizontal Lines (Resembling a Barcode)
      • Indicates a Lack of Underlying Lung Sliding Concerning for Pneumothorax
  • Lung Point: The Interface Between Normal Lung Tissue (With Lung Sliding) and a Pneumothorax (Absent Sliding)
    • Used to Evaluate the Size of a Pneumothorax – More Lateral/Posterior Lung Point Indicates a Larger Size
Pulmonary POCUS: (A) A-Lines (Arrows) 5; (B) B-Lines 6; (C) Seashore Sign 6; (D) Barcode Sign 6

Inferior Vena Cava (IVC) Ultrasound

Fluid Responsiveness

IVC Diameter

  • A Static Measurement of IVC Diameter
  • Normal Diameter: 13-17 mm and Not Completely Compressible
    • < 13 mm: Unlikely to Be Volume Responsive
    • > 25 mm: Likely to Be Volume Responsive
  • Generally Poor Accuracy, Although Extreme Values (Flat vs Full) May Be More Predictive

IVC Collapsibility Index (Caval Index)

  • Change in IVC Diameter Throughout the Respiratory Cycle in Spontaneously Breathing Patients
  • IVC CI (%) = (Max – Min) / Max Diameter
    • Maximum Diameter on Expiration
    • Minimum Diameter on Inspiration
  • Interpretation:
    • Near 50-100% Indicatives Fluid Responsiveness
    • Near 0% Indicatives Fluid Non-Responsiveness
  • Positive Pressure Ventilation is a Contraindication – Positive Pressure on Inspiration Prevents IVC Collapse

IVC Distensibility Index

  • Change in IVC Diameter Throughout the Respiratory Cycle in Mechanically Ventilated Patients
  • IVC DI (%) = (Max – Min) / Min Diameter
    • Maximum Diameter on Inspiration
    • Minimum Diameter on Expiration
  • Increase ≥ 18% Indicates Fluid Responsiveness

IVC Collapsibility POCUS: (A) Normal 1; (B) Collapse 2

References

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Cover Photo: Lichtenstein DA, Mauriat P. Lung Ultrasound in the Critically Ill Neonate. Curr Pediatr Rev. 2012 Aug;8(3):217-223. (License: CC BY-2.5)