Pleural effusion (ultrasound)
Slowly progressive dyspnoea.
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Pleural effusion initially identified with transducer in standard cephalo-caudad orientation. Of note, screen orientation was mistakenly reversed from usual bedside sonography convention.
Transducer is rotated 90 degrees, now perpendicular to the long axis of the patient's body. Effusion remains visible as an anechoic, crescentic area surrounding a prominent and heterogenously hyperechoic triangular protrusion representing atelectatic lung (plausible etiology compressive atelectasis given size of effusion)
The still image depicts how one would then calculate interpleural distance in keeping with a Balick formula calculation of pleural effusion volume.
This case details how one would calculate a pleural fluid volume in a supine patient using the Balick formula. In the above orientation, the cine-loop was paused at maximal inspiration.
The distance is measured between the visceral pleura, adherant to the atelectatic lung, and the parietal pleura, adherent to the (in this case, dorsolateral) chest wall. Given a resultant interpleural distance of 3.8cm, the Balick formula is used to estimate the volume as follows:
Volume (mL) = 38mm x 20 = 760mL 1
- 1. Balik M, Plasil P, Waldauf P, Pazout J, Fric M, Otahal M, Pachl J. Ultrasound estimation of volume of pleural fluid in mechanically ventilated patients. (2006) Intensive care medicine. 32 (2): 318. doi:10.1007/s00134-005-0024-2 - Pubmed