The lung: responses to trauma, surgery, and sepsis

The adult pulmonary distress syndrome is a disease of many etiologies and significantly contributes to the post-traumatic and postsurgical mortality and morbidity. Pulmonary insufficiency associated with shock and hemorrhage is characterized by its relatively short duration, less severe alterations of pulmonary functions, and normal pulmonary vascular resistance. The judicious use of fluids and emphasis in the early use of blood during resuscitation will minimize the magnitude of the pulmonary insult. Severe changes in oxygenation and ventilation, increases in pulmonary vascular resistance, the need for long-term respiratory assistance, and an increase in mortality and morbidity are characteristic of the adult pulmonary distress syndrome that follows severe systemic sepsis. Early aggressive pulmonary support is required in all life-threatening surgical conditions. Endotracheal intubation is preferred to tracheostomy, and the use of a volume respirator will facilitate the control of ventilation and oxygenation. Significant decreases in the functional residual capacity are responsible for refractory hypoxemia and the use of high concentrations of oxygen can be circumvented by the use of positive end expiratory pressure. PEEP is sometimes associated with a decrease in cardiac output and an increase in the pulmonary shunt and occasionally pneumothorax. Continued hemodynamic and pulmonary monitoring of patients is mandatory when using PEEP. Discontinuance of ventilatory assistance is usually possible if the pulmonary shunts are less than 25 per cent, the tidal volumes greater than 5 cc per kg, and the vital capacity at least twice the tidal volume. Recovery from pulmonary insufficiency is predicated on adequate pulmonary management, nutritional support, and the control of the underlying contributory conditions.