Ventilation is the body’s ability to move air in and out of the chest and lung tissues. Oxygenation is the process of delivering oxygen to the blood by diffusion from the alveoli following inhalation into the lungs. A thin membrane called the pleura covers each side of the thoracic cavity. The inner wall is covered by the parietal pleura, and the outer one is called the visceral pleura. Tidal volume is the amount of air moved in and out of the lungs with a single breath. If you multiply it by the rate of breaths, you would get the minute volume. Open chest injuries are typically caused by penetrating trauma. Do not remove impaled objects. Closed chest injuries are typically caused by blunt trauma.
To recognize the signs of chest injury, see if there is pain at the site of injury, pain increasing as you breathe, dyspnea, hemoptysis, low oxygen saturation, failure of one or both sides to expand normally, and cyanosis. Visualize the chest for rise and fall. Patients with chest injuries often have tachypnea (rapid respirations) and shallow respirations (because the chest hurts). When breathing, the pain is sharp, which will tell us if there is damage or irritation to the pleural surfaces. This sharp pain is called pleuritic pain and is typical of chest injuries. Hemoptysis may indicate that the lung itself or the air passages have been damaged. A rapid, weak pulse and low blood pressure are signs of hypovolemic shock, which can result from extensive bleeding from lacerated structures within the chest cavity.
Life-threatening hemorrhage should be addressed first. Paradoxical motion is when the chest moves in opposition, so one segment of the chest wall moves opposite the rest of the chest. Positive pressure ventilation is ideal in this situation. Use a vented chest seal or an occlusive dressing for all penetrating injuries to the chest. Secondary assessment should include pulse, respirations, blood pressure, skin condition, oxygen saturation, and pupils. In later stages of injuries, pulse rate can slow, increased pressure on the heart from air or blood in the pericardial space may occur, and blood pressure may exhibit a narrowing pulse pressure as the systolic and diastolic pressures come closer together.
Pneumothorax is the accumulation of air in the pleural space, a dangerous condition called a pneumothorax (collapsed lung). Air enters through a hole in the chest wall, causing the lung on that side to collapse, and oxygenation is impaired, leading to hypoxia if the body is not provided with enough O₂. Absent breath sounds are a significant finding and may indicate the development of a tension pneumothorax. You may hear sucking sounds as the patient inhales and the sound of rushing air as he or she exhales. This is often called an open pneumothorax or a sucking chest wound. It is important to rapidly transport after sealing the open wound with a one-way valve called a flutter valve or a semi-occlusive dressing. An occlusive dressing can be used if taped to the patient on three sides, allowing the air to leak from the fourth side and not be sucked into the chest cavity. Always watch for a possible tension pneumothorax, which can occur with a flutter valve.
A simple pneumothorax is where the lung has to collapse significantly before effects will be heard as decreased breath sounds. Positive pressure could make things worse. A tension pneumothorax is a significant ongoing air accumulation in the pleural space. This will first cause the complete collapse of the affected lung and then push on the mediastinum into the opposite pleural cavity. It occurs more often in closed blunt injuries in which a fractured rib lacerates a lung or bronchus. The patient may experience jugular vein distention or tracheal deviation, but the signs are not always present.
Hemothorax is when blood collects in the pleural space from bleeding around the rib cage or great vessels. There is virtually no way to control bleeding, and fast transport is advised. Cardiac tamponade occurs when the space between the protective membrane around the heart (pericardium) and the heart fills with blood or fluid. When the heart cannot pump enough, the signs and symptoms are referred to as Beck’s triad: distended or engorged jugular veins seen on both sides of the trachea, narrowing pulse pressure, and muffled heart sounds. There is also a decrease in mental status as blood flow to the brain decreases.
In a rib fracture, the rib may penetrate into the pleural space, which may lacerate the surface of the lung, causing a pneumothorax, a tension pneumothorax, a hemothorax, or a hemopneumothorax. It is a flail chest if two or more adjacent ribs are fractured and a segment of the chest wall becomes detached. In what is called paradoxical motion, the detached portion of the chest wall moves opposite of normal. Clavicle fractures are dangerous because the first rib protects a large neurovascular bundle.
Traumatic asphyxia occurs when a person is compressed too fast or pinned under a vehicle. Blunt myocardial injury is blunt trauma to the chest that may make the heart unable to maintain adequate blood pressure and mimics a heart attack. Commotio cordis is a blunt force during the heartbeat that leads to a lethal abnormal heart rhythm called ventricular fibrillation.
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