Pulmonary POCUS · Echo Physics Lab
M-mode: Depth and Time
M-mode follows one scan line over time. Depth runs down, time runs across. Try the heart, the lung and the IVC.
2D · Parasternal long axis
What the line crosses (top to bottom)
M-mode
Hover the M-mode to read depth, time and structure.
Drag on the 2D image to move the line. Click the M-mode twice to measure depth and time (the display freezes while you measure).
Controls
Line position
Pattern
Heart rate 70 bpm
Pleura
Respiratory rate 14 /min
Line position
LV long-axis function
RV function
Heart rate 70 bpm
Volume status
Respiratory rate 14 /min
Patient effort
Line angle -3°
Sweep speed
Gain 50
Feigenbaum patterns to recognize
Quiz
Some questions ask you to do something in the simulator.Real scans from pulmonarypocus.com
How to read M-mode
- M-mode samples one scan line (the "ice pick") about a thousand times per second. Only structures on that line appear. The vertical axis is depth from the transducer; the horizontal axis is time.
- Heart: at the mitral leaflet tips the anterior leaflet draws an "M" (E point with early filling, A point with atrial contraction) and the posterior leaflet a smaller "W". A large E-point septal separation (EPSS) suggests a dilated LV with reduced ejection fraction.
- Lung: everything above the pleural line is still, so it draws horizontal lines ("waves"). With normal lung sliding, the lung below the pleura moves and draws a grainy "sand" pattern: the seashore sign. With a pneumothorax there is no sliding, so the whole screen is horizontal lines: the barcode or stratosphere sign.
- Ribs block sound. If the line sits on a rib, everything below is an acoustic shadow. Move the line into the intercostal space.
- IVC: measure about 2 cm from the right atrial junction, perpendicular to the IVC. With spontaneous breathing the IVC narrows on inspiration. Collapsibility index = (max diameter - min diameter) / max diameter.
- ASE estimate of RA pressure: IVC 2.1 cm or less that collapses more than 50% with a sniff suggests about 3 mmHg; IVC over 2.1 cm that collapses less than 50% suggests about 15 mmHg; anything in between suggests about 8 mmHg. These rules do not apply during positive pressure ventilation.
Schematic educational model. Dimensions and motion are representative, not patient specific. pulmonarypocus.com