EM Command Center / Procedures & Anesthesia • 3 min read • 5 sections

Bedside POCUS & Echocardiography Atlas

Comprehensive emergency point-of-care ultrasound (POCUS) reference. Details standard 5-view focused cardiac ultrasound (FoCUS), left ventricular ejection fraction quantification via EPSS, right ventricular strain and McConnell's sign, cardiac tamponade collapse physiology, the BLUE lung protocol, the VEXUS venous congestion grading score, and ocular optic nerve sheath diameter (ONSD).

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5 Core Cardiac Views:Parasternal Long Axis (PLAX), Parasternal Short Axis (PSAX), Apical 4-Chamber (A4C), Subxiphoid 4-Chamber, and IVC Collapsibility.

Left Ventricular Function:Measure EPSS on PLAX (distance between anterior mitral leaflet and septum in early diastole; normal < 7 mm, severe depression > 10 mm).

Right Ventricular Strain (Acute PE):RV:LV basal diameter ratio > 1:1, McConnell's sign (apical hyperkinesis with mid-free-wall akinesis), TAPSE < 17 mm, D-shaped LV on PSAX.

Cardiac Tamponade Signs:Anechoic effusion + early diastolic right ventricular free wall collapse + late systolic right atrial collapse + dilated non-collapsing IVC.

Lung POCUS (BLUE Protocol):Lung sliding rules out pneumothorax; B-lines (>= 3 per rib space bilaterally) = alveolar-interstitial syndrome / pulmonary edema; Lung Point = 100% specific for pneumothorax.

Ocular ONSD:Measure optic nerve sheath diameter 3 mm posterior to the retina; ONSD > 5.0 mm indicates intracranial hypertension (ICP > 20 mmHg).

Bottom-Line Clinical Pearl

In focused cardiac ultrasound, E-point septal separation (EPSS > 10 mm measured on PLAX M-mode) is a highly reliable surrogate for severely depressed left ventricular ejection fraction (LVEF < 30%), independent of geometric distortion.

1. Focused Cardiac Ultrasound (FoCUS): Standard 5 Views

Cardiac View	Probe Placement & Marker	Key Anatomic Structures Visualized	Clinical Pathologies Evaluated
Parasternal Long Axis (PLAX)	3rd-4th intercostal space immediately left of sternum; probe marker pointing to patient's right shoulder	Right ventricle outflow tract, interventricular septum, left ventricle, left atrium, aortic root, mitral valve, descending aorta	LV systolic function, pericardial vs. pleural effusion (pericardial fluid tracks ANTERIOR to descending thoracic aorta), aortic root dilatation, EPSS.
Parasternal Short Axis (PSAX)	Same intercostal space as PLAX; rotate probe 90 degrees with marker pointing to left shoulder	Mid-papillary cross-section of LV ('donut' view), crescent-shaped RV wrapped around LV	LV regional wall motion abnormalities, RV pressure overload ('D-shaped' septum in diastole = volume overload; in systole = pressure overload).
Apical 4-Chamber (A4C)	Apex of heart (5th ICS midclavicular line or point of maximal impulse); marker pointing to patient's left axilla	All four chambers: LV, RV, LA, RA, mitral and tricuspid valves	RV:LV size comparison (normal RV is <= 2/3 size of LV), TAPSE measurement, McConnell's sign, tricuspid regurgitation.
Subxiphoid 4-Chamber	Subcostal angle beneath xiphoid process; probe flattened against abdomen; marker pointing to left shoulder	Liver acoustic window into RV, LV, RA, LA, pericardium	Best view during active CPR; rapid rule-out of pericardial effusion/tamponade.
Inferior Vena Cava (IVC)	Subxiphoid area, sagittal plane; marker pointing to patient's head; track IVC entering right atrium	Hepatic vein entering IVC, IVC diameter measured 2 cm caudal to right atrial junction	Central venous pressure estimation: IVC < 2.1 cm with > 50% inspiratory collapse = normal CVP (0-5 mmHg); IVC > 2.1 cm with < 50% collapse = high CVP (10-20 mmHg).

2. Quantitative Bedside Echo Metrics (EPSS & TAPSE)

Metric	Acquisition Method	Normal Value	Pathologic Threshold & Significance
E-Point Septal Separation (EPSS)	Place M-mode cursor through tip of anterior mitral valve leaflet in PLAX view. Measure minimal vertical distance from the E-point (early diastolic peak) to the interventricular septum.	< 7 mm	> 10 mm: Strongly predictive of severely reduced LVEF (< 30-35%). (Caveats: Falsely elevated in aortic regurgitation or mitral stenosis; falsely normal in severe concentric LVH).
Tricuspid Annular Plane Systolic Excursion (TAPSE)	Place M-mode cursor along lateral tricuspid valve annulus in Apical 4-Chamber view. Measure total vertical excursion from end-diastole to peak systole.	>= 17 mm	< 17 mm: Indicates significant Right Ventricular Systolic Dysfunction (correlates with poor prognosis in acute pulmonary embolism and pulmonary hypertension).

3. Pericardial Tamponade Ultrasound Features

Tamponade is a hemodynamic diagnosis where intrapericardial pressure exceeds intracardiac chamber filling pressures. Ultrasound findings progress chronologically:

Pericardial Effusion: Anechoic fluid stripe within the pericardial sac (must track anterior to descending thoracic aorta on PLAX to rule out pleural effusion).
Late Diastolic / Early Systolic Right Atrial Collapse: Inversion of the RA free wall during late diastole/early systole lasting > 1/3 of the cardiac cycle. Highly sensitive earliest ultrasound sign of elevated intrapericardial pressure.
Early Diastolic Right Ventricular Collapse: Inward buckling/indentation of the RV free wall during diastole (when mitral valve is open). Highly SPECIFIC for clinical tamponade.
Plethoric, Non-collapsing IVC: Dilated IVC (> 2.1 cm) with < 50% collapse with respiration. Nearly 100% sensitive (absence of dilated IVC virtually excludes tamponade, except in low-pressure/hypovolemic tamponade).
Mitral / Tricuspid Inflow Respiratory Variation (Sonographic Pulsus Paradoxus): Pulsed-wave Doppler across mitral valve shows > 25% variation in E-wave peak velocity between inspiration and expiration.

4. The BLUE Protocol (Bedside Lung Ultrasound in Emergency)

Ultrasound Profile	Key Sonographic Features	Clinical Pathology Diagnosed
A-Profile	Prominent lung sliding + horizontal reverberation A-lines (predominant)	Normal lung, COPD exacerbation, or acute severe Asthma
A'-Profile	ABSENCE of lung sliding + presence of A-lines (stratosphere / barcode sign on M-mode)	PNEUMOTHORAX. Confirm with Lung Point (pathognomonic, 100% specific).
B-Profile	Lung sliding + bilateral diffuse vertical comet-tail B-lines (>= 3 per intercostal rib space)	Pulmonary Edema / Acute Heart Failure, ARDS, bilateral interstitial pneumonia
B'-Profile	ABSENT lung sliding + multiple vertical B-lines	Severe Pneumonia, acute focal ARDS
C-Profile	Subpleural alveolar consolidation, hypoechoic tissue with irregular boundaries ('shred sign'), air bronchograms	Pneumonia / Lung Consolidation
PLAPS (Posterolateral Alveolar and/or Pleural Syndrome)	Anechoic fluid in dependent posterolateral lung bases + thoracic spine visible above diaphragm ('spine sign')	Pleural Effusion, Empyema, or Hemothorax

5. Ocular Ultrasound for Elevated ICP

The optic nerve is an anatomical extension of the central nervous system enveloped by the dural sheath. Increased intracranial pressure transmits directly down the subarachnoid space surrounding the optic nerve:

Technique: High-frequency linear probe placed gently over closed eyelid with copious ultrasound gel (avoid applying direct ocular pressure).
Measurement Landmark: Measure the Optic Nerve Sheath Diameter (ONSD) exactly 3.0 mm posterior to the global-optic nerve junction (retina).
Diagnostic Threshold: An ONSD > 5.0 mm in adults (> 4.5 mm in children > 1 yr) correlates with an elevated ICP > 20 mmHg with > 90% sensitivity and specificity.
Papilledema Sign: Look for elevation of the optic nerve head protruding > 1 mm into the vitreous chamber.

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