Management of post traumatic respiratory failure

For patients who have been critically injured, acute respiratory distress syndrome (ARDS) represents the first step on the final common pathway to death. The lung, when compromised from a variety of direct and secondary stressors, exhibits a pathophysiology that is uniform and classic. Pulmonary physiology is exquisitely sensitive to a systemic inflammatory state, and the respiratory system is generally the first system to demonstrate evidence that the patient is failing to meet the physiologic challenges of their injury. Acute respiratory distress syndrome was described first by Ashbaugh [1] in the mid-1960s. Coincidently, trauma surgeons involved with the Vietnam conflict identified morbidity in their patients that they called DaNang Lung. The recognition of these syndromes was caused in part to improvements in non-pulmonary critical care, because the patients were able to survive hemorrhage, infection, and renal insufficiency to reach the point where ARDS could manifest fully. The characteristics of ARDS include acute onset of severe hypoxemia accompanied by characteristic radiographic changes in the absence of cardiogenic pulmonary edema (Box 1). Several criteria have been used to standardize the definition of ARDS, but the most widely used is from the American-European Consensus Conference on ARDS of 1994 [2]. Although variations exist between the different classification systems, in general, there is agreement on which patients in fact have ARDS [3]. The advantage of the American-European consensus criteria is that these variables are based upon patients and their disease state as opposed to interventions of the intensive care specialist. Some classifications are contingent upon ventilator settings, and because these are affected by practitioner style, these classifications are less objective and consequently less helpful. Because ARDS frequently is the first step in a more generalized cascade of decompensation, it is important to understand the pathophysiology and epidemiology of ARDS. Perhaps the most important single aspect of managing a patient with ARDS is to identify the inciting event and treat that problem aggressively. Unless the underlying stressor can be managed effectively, whether it is a direct lung insult such as aspiration or contusion or some distant process such as missed injury, the patient will deteriorate progressively and die. This article's aim is to provide an approach to the management of ARDS such that patients in this situation will survive the pulmonary compromise while the underlying issues are addressed.