Pulmonary contusion is a traumatic state of the lung parenchyma that is caused by an acute chest injury, without any laceration of the parenchymal tissue itself. Associated injuries to the chest region may co-exist. It is a life-threatening condition, which can lead to acute respiratory distress syndrome and death.
The destruction of the alveolocapillary membrane and the accumulation of fluid and blood within the alveolar space lead to the impairment of gas exchange, low levels of O2 measured from arterial blood, cyanosis, and low SpO2 . These pathophysiological changes are responsible for the patients' labored breathing and chest pain. Individuals who have sustained pulmonary contusions also exhibit chest bruises, cough and hemoptysis. Usually, not all the symptoms are present; depending on the complications or absence thereof, any combination of the aforementioned symptoms is possible.
In cases of severe pulmonary contusions, the clinical picture may be further complicated by dizziness, excessive sweating, cyanotic lips/nail beds or disorientation. Tachycardia and tachypnea are signs of a severer contusion .
Severe thoracic traumas should always raise suspicion of a concomitant pulmonary contusion, especially when the patient exhibits difficulty in breathing or signs of a more crucial condition, such as cyanosis, tachycardia or tachypnea. Observing the chest will allow the physician to detect bruising. Generally, pulmonary contusions are diagnosed with a combination of tests including arterial blood gases (ABG), chest X-ray and a Computerized Tomography (CT) scan.
Measuring arterial blood gases will give useful insight into the levels of O2, CO2 and bicarbonates in the arterial blood . The patient's status can be evaluated and pulmonary dysfunction will manifest with a disturbance of these values.
A chest radiograph is able to depict the contusion in its full extent after 24 to 48 hours after the injury . The majority of extensive contusions are visible through an X-ray but cannot substitute the vitality of the clinical diagnosis, since they do not illustrate the injury from the beginning.
Lastly, a CT scan may be conducted to diagnose contusions regardless of their extent, as this test is extremely sensitive for their depiction. It also allows for the differentiation between a pulmonary contusion and other lung conditions, such as atelectatic regions or aspiration. The correct size of any injury can be measured via Computer Tomography ; however, not all contusions diagnosed with a CT scan require treatment, as they may cause no symptomatology if they are limited in extent.
The extent to which the lung is damaged further dictates the therapeutic regime in cases of pulmonary contusions. Measures are generally directed towards the relief of pain, oxygenation and removal of blood and fluid that has accumulated in the pulmonary cavities.
Painkillers may be necessary depending on the severity of the symptoms. Medication may be administered intravenously or epidurally. Additionally to relieving the patient of their painful sensations, painkillers also encourage better ventilator chest movements. Furthermore, nasal cannulas or masks are used to supply oxygen, should the patient be in a deoxygenized state .
In severer traumatizations, the quantity of fluids that have built up in the alveoli fail to be absorbed by the organism itself; in these cases, they require suctioning or chest tubes in order to be removed. Suctioning may be performed through the oral cavity, nose or endotracheally. Chest tubes, on the other hand, are directly placed within the thorax via an incision.
Lastly, there may also be a need for noninvasive positive-pressure ventilation, such as CPAP or BiPAP, in cases where oxygenation cannot be achieved otherwise, or the patient exhibits atelectasis . Mechanical ventilation via endotracheal tube is also an option.
The existence of simultaneous thoracic injuries and the degree to which the pulmonary contusion has affected the lungs both cause the rate of mortality to fluctuate between 14 and 40% . In cases where the patient has solely sustained a pulmonary contusion and exhibits no subsequent complications, the contusion is expected to resolve within 3-14 days .
Pulmonary contusions are caused by chest traumatic injuries, inflicted via various mechanisms. Some of them are the following:
Around 20% of the patients who sustain a blunt chest injury also exhibit pulmonary contusions , which are the type of chest trauma most frequently observed in children. Mortality rates fluctuate between 20-25%, with half of the patients being also in need of assisted ventilation. Most of the patients exhibit concurrent chest injuries, including hemothorax, pneumothorax, and flail chest amongst others .
Pulmonary contusions are all induced by chest traumas of various kinds, as described above. In general, fundamental pulmonary structures are disturbed, leading to the loss of its full functionality: the balance between ventilation and perfusion is distorted, shunts are formed, inflammation and edema are exhibited and alveolocapillary membrane becomes increasingly penetrable .
The basic pathophysiologic mechanism behind a pulmonary contusion begins with the initial trauma. Despite the absence of any visible laceration, the force exerted on the thorax results in the destruction of the alveolocapillary membrane and adjacent blood vessels. As a result, water and blood fill the alveoli and subsequently, an edema is caused in case of severe damage. Normal pulmonary elasticity is impaired and the exchange of gases is rendered abnormal, due to the amount of fluid and blood that take up the alveolar space and leads to their destruction . This leads to the clinical manifestations of labored breathing, as well as to reduced O2 and increased CO2 in the peripheral blood.
Simultaneous thoracic injuries , such as hemo- or pneumothorax cause additional strain on the lungs, since the tissue that has not sustained any damage is compressed and therefore dysfunctional. A potentially life-threatening condition connected to chest injuries is tension pneumothorax: air is released from lung tissue into the peural space and tension gradually builds up in the damaged parenchymal region. Continually increasing pressure exerts compresive forces towards the antipodal hemithorax and in some cases, venous return to the right atrium can be impaired , due to compression of the superior vena cava. This can lead to a circulatory compromise.
Protection of the thoracic area in all cases where a forceful traumatization is possible is the optimal means of preventing a pulmonary contusion. Specific cases to which protective measures are available, include seat belts and airbags when driving and specially designed armors used by military recruits. In the first case, airbags and seatbelts prevent the impact from a car crash from affecting only a particular region of the chest, thus contributing to less damage sustain in each location. In the latter case, military armors are made of materials with different acoustic impedance, which protects the thorax from a blast shock wave .
Pulmonary contusion, otherwise referred to as lung contusion or LC, is an injury to the lung's parenchymal tissue, caused by any type of severe chest traumatization, including penetrating traumas, impact traumas or other blunt traumas. The pulmonary parenchyma exhibits no lacerations itself, but alveolar capillaries sustain a significant force-induced trauma. This leads to the increase of blood and water encased within the capillaries, so ventilation is impaired. The severity of functional impairment varies, depending on the force exerted during the chest injury. Various mechanisms account for the functional loss, including the accumulation of fluid, shunts and an imbalance between lung perfusion and ventilatory ability amongst others .
Patients typically experience shortness of breath and decreased circulating oxygen, which can be detected in the blood gases. Treatment is supportive and addresses the potential hypovolemia and ventilatory dysfunction. Depending on the general status of each patient and the co-existence of other injuries, intensive care may be mandatory in order to maintain a stable status and ensure that gas exchange is going to be conducted properly.
A lethal complication of lung contusion is the acute respiratory distress syndrome (ARDS) syndrome, which can prove fatal. Patients receive mechanical ventilation of various types, with the more common one being positive-end expiratory pressure devices (PEEP). Biphasic positive airway pressure ventilation, abbreviated as BiPAP, is an extremely useful tool in cases of simultaneous severe thoracic traumas, since it reduces the need of sedatives to minimize thoracic stress .
A pulmonary contusion includes the accumulation of water and blood in the lung due to a chest injury, which does not, however, involve any tear of the lung's tissue.
A person may sustain a pulmonary contusion when there is a chest trauma. Typically, that may involve a car accident, an explosion, fall from a considerable height, sports-related injuries or injuries due to heavy machinery used in the workplace.
Lacerations may be seen on the skin of the chest, but in the case of pulmonary contusion, the lung itself is not punctured. Symptoms include difficulty in breathing, coughing up blood, rapid breathing and chest pain. Because the patient cannot breathe properly in order to supply their body and tissues with oxygen, in severe cases, low levels of oxygen in the blood may lead to cyanosis, where the skin starts to turn blue. Low blood pressure and wheezing sound when breathing can also be observed.
A physician will suspect the existence of a pulmonary contusion when the patient reports a chest injury and the symptoms mentioned above also exist to a certain extent. A chest X-ray can help to illustrate the contusion but may need to be repeated, since the injury is not expected to be obvious in the first two days. A CT scan can reveal pulmonary contusions of any kind, at any point of time after the chest injury. Arterial blood gases and pulse oximetry can help a physician evaluate the oxygen on your blood and , therefore, how severe the contusion is.
Regarding treatment schemes, painkillers are given to people with pulmonary contusions in order to ease the pain and encourage normal breathing. Fluids are replaced and oxygen is also administered, depending on how severe the trauma is. The blood and water that has accumulated in the lung may be suctioned and mechanical ventilation may be necessary in severe cases. Surgical repairment is reserved for patients whose bleeding cannot be stopped otherwise.