Mechanism
Although the mechanism is unknown, it is proposed that a blow to the abdomen may raise the pressure within the abdomen so high that the diaphragm ruptures. Blunt trauma creates a large pressure gradient between the abdominal and thoracic cavities; this gradient, in addition to causing the rupture, can also cause abdominal contents to herniate into the thoracic cavity. Abdominal contents in the pleural space interfere with heart function and lung function. High intrathoracic pressure results in an increase in right atrial pressure, disrupting the filling of the heart and venous return of blood. As venous return determines cardiac output, this results in a reduction of cardiac output. If ventilation of the lung on the side of the tear is severely inhibited, hypoxemia (low blood oxygen) results. Usually, the rupture is on the same side as an impact. A blow to the side is three times more likely to cause diaphragmatic rupture than a blow to the front. Diagnosis
Physical examinations are not accurate, as there is usually no specific physical sign that can be used to diagnose this condition. Thoracoscopic and laparoscopic methods can be accurate. Chest X-ray is known to be unreliable in diagnosing diaphragmatic rupture; it has low sensitivity and specificity for the injury. Often another injury such as pulmonary contusion masks the injury on the X-ray film. Half the time, initial X-rays are normal; in most of those that are not, hemothorax or pneumothorax is present.
Another diagnostic method is laparotomy, but this misses diaphragmatic ruptures up to 15% of the time. Often diaphragmatic injury is discovered during a laparotomy that was undertaken because of another abdominal injury. Because laparotomies are more common in those with penetrating trauma than compared to those who experienced a blunt force injury, diaphragmatic rupture is found more often in these people. Thoracoscopy is more reliable in detecting diaphragmatic tears than laparotomy and is especially useful when chronic diaphragmatic hernia is suspected. Location
Between 50 and 80% of diaphragmatic ruptures occur on the left side. It is possible that the liver, which is situated in the right upper quadrant of the abdomen, cushions the diaphragm. However, injuries occurring on the left side are also easier to detect in X-ray films. Half of diaphragmatic ruptures that occur on the right side are associated with liver injury. Injuries occurring on the right are associated with a higher rate of death and more numerous and serious accompanying injuries. Bilateral diaphragmatic rupture, which occurs in 1–2% of ruptures, is associated with a much higher death rate (mortality) than injuries that occur on just one side. Treatment
Since the diaphragm is in constant motion with respiration, and because it is under tension, lacerations will not heal on their own. The injury usually becomes larger with time if not repaired. The main goals of surgery are to repair any injuries to the diaphragm and to move any herniated abdominal organs back to their original place.