Chapter 11 Intensive Care Unit

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SECTION 1 • Techniques and Methods in Critical Care

FIGURE 11-22. B- and M-mode ultrasonograms of pleural effusion in patient with lung edema and small pleural effusion. The white arrows identify the pleural edge. Effusion is black and echo free. The 2D images (left and center) are accom- panied by white linear streaks suggesting lung tissue edema. The wavy M-mode pattern (right) is produced by the to-and-fro motion of the lung under the stationary transducer as inflation and deflation occur over time.

point” is confirmed by a “seashore”-like appearance on continuous M-mode tracing (Fig. 11-23). Use of these characteristics in conjunc- tion with limited cardiovascular ultrasonography directed toward leg clotting and right ventricular dilation is made in systematic protocols designed to rapidly determine the cause of acute dyspnea

(e.g., the BLUE protocol). Thoracic interrogation is performed sequentially at three sites (anterior, lateral, and posterolateral) in the semirecumbent patient as evidence is sought for pneumothorax, lung edema, and consolidation or lung collapse. US of the cardiac and femoral zones completes the appraisal.

Normal “Seashore”

Pneumothorax “Bar Code”

Pneumothorax Transition at the “Lung Point”

A

B

C

FIGURE 11-23. Ultrasonic profiles in M mode (focal, time based). The stationary transducer in A and B paints patterns that indicate blurring caused by lung motion beneath it (A) or monotonous reverberation in response to the air barrier caused by pneumothorax (B) . When the transducer is positioned at the interface between noncollapsed lung and pleural air, there is an abrupt transition between these ultrasonic M-mode patterns during the phases of the breathing cycle (C) .