Chapter 11 Intensive Care Unit

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SECTION 1 • Techniques and Methods in Critical Care

Normal PA CXR

Normal AP Obese

FIGURE 11-1. Left: Normal posterior–anterior (PA) upright chest radiograph. Note the definition and dimensions of the heart and vas- cular structures. Right: Supine AP chest radiograph in massively obese normal subject. Note the widened mediastinum, enlarged heart shadow, and symmetrically elevated hemidiaphragms.

phase of the respiratory cycle, and with comparable tidal volume and end-expiratory pressure. (Clearly, such an ideal for interpretation may not be feasible or clinically advisable, but such influences should be borne in mind.) Infusions of large volumes of flu- ids, the development of oliguria, or superimposed myocardial dysfunction produce a rapidly deterio- rating radiographic picture. Bronchoalveolar lavage may cause the appearance of localized infiltrates because of residual lavage fluid and atelectasis.

Bedside lung US for lung and pleural interrogation by the ICU provider has the potential to obviate the need for repeated radiation exposure to resolve diag- nostic questions or track progress. Film Timing Because of the high likelihood of finding significant abnormalities (e.g., tube malposition, pneumotho- rax), it is worthwhile to obtain a CXR on almost all

Brachiocephalic veins

Superior vena cava

Azygos vein

Right atrium

FIGURE 11-2. Distention of azygos vein, indicating higher than normal pressures in the SVC, is seen on frontal chest film as a circular or lenticular shadow ( arrow ) at its point of anatomic insertion.