Barotrauma: detection, recognition, and management.

ARDS = adult respiratory distress syndrome; CT computed tomography; FIo2 fractional inspired oxygen concentration; MAP = mean airway pressure; PA mean alveolar pressure; PCV= pressure-controlled ventilation; PEEP positive end expiratory pressure; PIP peak inspiratory pressure B arotrauma is an important and potentially lethal compli cation ofmechanical ventilation. All physicians working with patients receiving mechanical ventilation must be familiar with the different clinical manifestations of baro trauma, the recognition of these manifestations, and their management. Perhaps the most important aspect of man agement is the use ofventilatory strategies that may prevent or limit the development of barotrauma. This portion of the symposium will first review different types of lung injury related to barotrauma, including one type that has only recently been recognized (systemic gas embolism), and another type that has only recently been attributed to barotrauma (diffuse lung injury). Next, the pathogenesis of these manifestations of barotrauma will be reviewed as this underlies the rationale of newer ventilatory strategies. congestive heart failure or patients intubated for neurologic disease .@ The consequences of a pneumothorax in a patient receiv ing positive pressure ventilation can include impaired gas exchange, but, perhaps more importantly, adverse hemo dynamic effects. Intrathoracic extra-alveolar air may increase intrathoracic pressure, decreasing venous return to the right side of the heart. Compression of the lung and pulmonary vessels may increase afterload to the right side of the heart, and geometric changes in the heart itself may decrease myocardial performance.9b0 Studies in animals on positive pressure ventilation demonstrate that there is an almost linear decrease in cardiac output as the volume of an experimentally induced pneumothorax is increased .‘¿¿ ° A significant fall in cardiac output may occur without a corresponding decrease in xy'° Therefore, changes in arterial blood gases may not be sensitive indicators of a hemodynamically important pneumothorax. These data also support the clinical maxim that even a small pneumothorax must be evacuated in a patient receiving positive pressure ventilation as it may be causing hemodynamic effects or it could rapidly progress to one that would. Unfortunately, it is difficult to make a radiographic diag nosis of a pneumothorax on portable x-ray films taken in the ICU setting.'†• '5 The traditional radiographic hallmark of a pneumothorax†" an apicolateral collection of air with the visceral pleura visible as a thin white line in the upper hemithorax †" ¿¿ may not be present on portable supine films of …