Diagnosis and Treatment

The diagnosis of tension pneumothorax should be made on clin¬ical examination. The classic findings include respiratory distress (in an awake patient), hypotension, diminished breath sounds over one hemithorax, hyperresonance to percussion, jugular venous dis¬tention, and shift of mediastinal structures to the unaffected side with tracheal deviation. In most instances, empiric treatment with pleural decompression is indicated rather than delaying to wait for radiographic confimnation. When a chest tube cannot be immedi¬ately inserted, such as in the prehospital setting, the pleural space can be decompressed with a large caliber needle. Immediate return of air should be encountered with rapid resolution of hypotension. Unfortunately, not all of the clinical manifestations of tension pneu¬mothorax may be evident on physical exam. The use of medical microscopes such as a battery powered microscope in the diagnosis and treatment of cardio-respiratory diseases are prevalent today.

Hyperresonance may be difficult to appreciate in a noisy resuscitation area. Jugular venous distention may be absent in a hypovolemic patient. Tracheal devia¬tion is a late finding and often not apparent on clinical examination. Practically, three findings are sufficient to make the diagnosis of ten¬sion pneumothorax: respiratory distress or hypotension, decreased lung sounds, and hypertympany to percussion. Chest x-ray findings that may be visualized include deviation of mediastinal structures, depression of the hemidiaphragm, and hypo-opacification with ab¬sent lung markings. As discussed above, definitive treatment of a tension pneumothorax is immediate tube thoracostomy. The chest tube should be inserted rapidly, but carefully, and should be large enough to evacuate any blood that may be present in the pleural space. Our preference is via the fourth intercostal space (nipple level) at the anterior axillary line.

Cardiac tamponade results from the accumulation of blood within the pericardial sac, usually from penetrating trauma or chronic medical conditions such as heart failure or uremia. While precordial wounds are most likely to injure the heart and produce tamponade, any projectile or wounding agent that passes in prox¬imity to the mediastinum can potentially produce tamponade. Blunt cardiac rupture, a rare event in trauma victims who survive long enough to reach the hospital, can produce refractory shock and tam¬ponade in the multiply injured patient. The manifestations of cardiac tamponade may be catastrophic such as total circulatory collapse and cardiac arrest, or they may be subtler. A high index of suspi¬cion is warranted to make a rapid diagnosis. Patients who present with circulatory arrest from cardiac tamponade require emergency pericardial decompression, usually through a left thoracotomy. Cardiac tamponade may also be associated with dyspnea, orthopnea, cough, peripheral edema, chest pain, tachycardia, muffled heart tones, jugu¬lar venous distention, and elevated central venous pressure. Beck’s triad consists of hypotension, muffled heart tones, and neck vein dis¬tention. Unfortunately, absence of these clinical findings may not be sufficient to exclude cardiac injury and cardiac tamponade. Muffled heart tones may be difficult to appreciate in a busy trauma center and jugular venous distention and coexistent bleeding may diminish central venous pressure. Therefore, patients at risk for cardiac tamponade whose hemodynamic status permits additional diagnostic tests frequently require additional diagnostic maneuvers to confirm cardiac injury or tamponade.

Invasive hemodynamic monitoring may support the diagnosis of cardiac tamponade if elevated central venous pressure, pulsus paradoxus (i.e., decreased systemic arterial pressure with inspira¬tion), or elevated right atrial and right ventricular pressure by pul¬monary artery catheter are present. These hemodynamic profiles suffer from lack of specificity, the duration of time required to ob¬tain them in critically injured patients, and their inability to exclude cardiac injury in the absence of tamponade. Chest radiographs may provide information on the possible trajectory of a projectile, but rarely are diagnostic since the acutely filled pericardium distends poorly. Echocardiography has become the preferred test for the di¬agnosis of cardiac tamponade. Good results in detecting pericardial fluid have been reported, but the yield in detecting pericardial fluid depends on the skill and experience of the ultrasonographer, body habitus of the patient, and absence of wounds that preclude visu¬alization of the pericardium. Standard two-dimensional or trans¬esophageal echocardiography is sensitive techniques to evaluate the pericardium for fluid, and is typically performed by examiners skilled at evaluating ventricular function, valvular abnormalities, and integrity of the proximal thoracic aorta. Unfortunately, these skilled examiners are rarely immediately available at all hours of the night, when many trauma patients present; therefore waiting for this test may result in inordinate delays. In addition, while both ultrasound techniques may demonstrate the presence of fluid or characteristic findings of tamponade (large volume of fluid, right atrial collapse, poor distensibility of the right ventricle), they do not exclude cardiac injury per se. Pericardiocentesis to diagnose peri¬cardial blood and potentially relieve tamponade may be utilized. Performing pericardiocentesis under ultrasound guidance has made the procedure safer and more reliable. An indwelling catheter may be placed for several days in patients with chronic pericardial ef¬fusions. Needle pericardiocentesis may not evacuate clotted blood and has the potential to produce cardiac injury, making it a poor alternative in busy trauma centers.

Diagnostic pericardial window represents the most direct method to determine the presence of blood within the pericardium. The procedure is best performed in the operating room under general anesthesia. It can be performed through either the subxiphoid or transdiaphragmatic approach. Adequate equipment, like medical microscopes, such as a battery powered microscope, and personnel to rapidly decompress the pericardium, explore the injury, and re¬pair the heart should be present. Once the pericardium is opened and tamponade relieved, hemodynamics usually improves dramat¬ically and formal pericardial exploration can ensue. Exposure of the heart can be achieved by extending the incision to a median sternotomy, performing a left anterior thoracotomy, or performing bilateral anterior thoracotomies (”clamshell”). Sometimes, tissue biopsy are done using battery powered microscope to eliminate differential diagnoses of malignancy.