1. Position patient at 30° head elevation, as standard of care for mechanically ventilated patients, ensuring overall comfort |
2. Rotate the head slightly <30° to expose right or left IJV |
3. Place transducer transversely across the patient neck, the area lateral to the level of the cricoid cartilage |
4. IJV vessel identification was done by identifying 2 vessels lateral to the trachea and IJV is identified by compressibility, color flow or pulse wave Doppler |
5. Applying minimum pressure, enough to obtain adequate ultrasound image of the right/left IJV |
6. Rotate the transducer clockwise or counter-clockwise to obtain the most circular cross-sectional image of the IJV |
7. Store the image of the patient’s complete respiratory cycle |
8. Measure the AP diameter during maximum and minimum distention during a respiratory cycle. On occasion, M mode was used to determine max and min AP diameter |
9. Calculate IJV collapsibility index = [(Max diameter − Min diameter)/(Max diameter)] × 100% |