A-lines and B-lines: lung ultrasound as a bedside tool for predicting pulmonary artery occlusion pressure in the critically ill.

BACKGROUND: The risk of pulmonary edema is the main limiting factor in fluid therapy in the critically ill. Interstitial edema is a subclinical step that precedes alveolar edema. This study assesses a bedside tool for detecting interstitial edema, lung ultrasound. The A-line is a horizontal artifact indicating a normal lung surface. The B-line is a kind of comet-tail artifact indicating subpleural interstitial edema. The relationship between anterior interstitial edema detected by lung ultrasound and the pulmonary artery occlusion pressure (PAOP) value was investigated. METHOD: We performed a prospective study in medicosurgical ICUs of university-affiliated teaching hospitals. We enrolled 102 consecutive mechanically ventilated patients who all underwent pulmonary artery catheterization. We defined A-predominance as a majority of anterior A-lines and B-predominance as a majority of anterior B-lines. These patterns were correlated with PAOP. RESULTS: For diagnosing PAOP