Lung Contusion - Types, Symptoms, and Management

Introduction:

Any injury to the alveolar capillaries without harm to the lung tissues is known as a lung contusion. It will lead to blood and interstitial fluid pooling within the lung tissues. This will further interfere with the gaseous exchange, ultimately leading to hypoxia. It can be caused by blunt trauma, penetrating, or even explosion injuries.

What Are the Types of Lung Contusions?

Lung contusions of various types.

It includes

• Type 1: Occurs due to a direct chest wall compression against the lung parenchyma. It is the most common type of lung contusion.

• Type 2: It is due to the shearing of lung tissue across the vertebral bodies.

• Type 3: Localized lesions due to fractured ribs directly injuring the underlying lung.

• Type 4: It is due to underlying pleuropulmonary adhesions from prior lung injury tearing the parenchyma.

What Are the Mechanisms of Lung Contusion?

The three possible mechanisms of the development of lung contusion are

• Inertial Effect: The lighter alveolar tissue is sheared from, the heavier hilar structures due to different tissue densities at other lung areas and, therefore, different acceleration or deceleration rates.

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• Spalling Effect: Lung tissue bursts or is sheared where a shock wave meets the lung tissue at interfaces between gas and liquid. The spalling effect occurs in areas with large differences in density, and the particles of the spalled denser tissue are thrown into the less dense particles.

• Implosion Effect: It may occur when a pressure wave passes through a tissue containing gas bubbles; the bubbles first implode, then rebound and expand beyond their original volume. The overexpansion of these gas bubbles stretches and tears the alveoli.

What Are the Signs and Symptoms of Lung Contusion?

The signs and symptoms depend on the extent of the injury. Sometimes, patients may be asymptomatic. Typically, patients present with respiratory difficulty. At first, the patients may complain of shortness of breath.

The most common signs and symptoms include

• Respiratory distress.

• Coughing up blood or hemoptysis.

• Bronchorrhea or the production of watery sputum.

• Wheezing.

• Dyspnea or difficulty in breathing.

• Tachypnea or increased breathing rate.

• Tachycardia or increased heart rate.

• Hypotension.

• Ecchymosis.

• Cyanosis.

• Cold and clammy skin.

• Chest pain.

• Decreased breath sounds on the ipsilateral side.

• Crackles and tenderness may be elicited if an associated chest wall injury occurs.

What Are the Laboratory Investigations to Be Carried Out?

The laboratory investigations to be carried out are

Chest X-Ray:

• The findings on chest X-ray include focal or diffuse opacification on multiple lung segments and lobes, particularly when the opacities are outside the boundaries of the normal anatomical limits.

• It does not estimate the contusion size and usually needs to catch up with the clinical presentation. Therefore, the extent of the contusion is not apparent until 24 to 48 hours after the injury.

Computed Tomography (CT):

• It is easily obtained, highly accurate, and readily available in most emergency departments. It is a sensitive diagnostic tool for lung contusion.

• It can detect a contusion almost immediately after the injury. The primary value lies in its ability to quantify the amount of lung injury, as this can estimate the overall hospital stay.

• Mild should be less than eighteen percent of the lung volume affected, and there is no need for intubation.

• Moderate should be eighteen to twenty-eight percent of the lung volume affected, and intubation may be required on a case-to-case basis.

• Severe should be more than twenty-eight percent of the lung volume affected and requires intubation immediately.

• It can also detect other blunt thoracic injuries such as rib fractures, pneumothoraces, hemothorax, and aortic injuries that may be of clinical importance compared to a normal chest X-ray.

Multi-Detector Computed Tomography (MDCT):

• It is a type of computer tomography for diagnosing imaging. It can comprehensively examine all the structures of the chest with a sensitivity and specificity almost nearing a hundred percent.

• It is usually performed in more than just clear findings or cases. If a more detailed assessment is required, then only go for this type of imaging. In case of high-energy trauma, the chest MDCT should be performed as a screening method.

What Is the Management of Lung Contusion?

The patient should be immediately examined and treated following advanced trauma life support (ATLS) protocols. The management of lung contusion involves healing on its own, supportive care, supplemental oxygen therapy, close monitoring, and even intensive care may be required. Intravenous fluid replacement is required to ensure adequate blood volume, but this should be done carefully as a fluid overload can worsen pulmonary edema, which may be damaging. Intubation should be provided to reduce parenchymal edema, thereby reducing shunting, improving functional residual capacity, and decreasing hypoxia.

The primary goal of managing lung contusion involves e maintenance of adequate oxygenation. The treatment modalities include invasive and non-invasive ventilation, high-frequency ventilation, and surfactant replacement. High-frequency ventilation may decrease the incidence of ventilator-associated lung injury.

The role of surfactant is stabilizing the alveoli, which may improve the recruitment of non-ventilated alveoli or prevent end-expiratory collapse. The patients need to perform deep breathing and coughing. Drugs may be administered to improve ventilation and physiotherapy.

What Are the Differential Diagnosis for Lung Contusion?

The differential diagnosis for lung contusion includes

• Aspiration pneumonia.

• Segmental or focal atelectasis.

• Pulmonary hemorrhage.

• Pneumonia.

• Fat embolism.

Conclusion:

Although the latest techniques and advances in medicine, the disease still has a high risk of morbidity and mortality. As there is often a delay in the presentation of respiratory symptoms, diligent attention to worsening vital signs, physical examination findings, and repetitive imaging are important in such cases.

The asymmetric lung pathology in lung contusions leads to under-ventilation of the injured areas and over-distension of the non-injured areas of the lung, which can result in barotrauma. In addition, the mismatch can lead to refractory hypoxemia that can only be managed surgically by ventilatory strategies, such as one-lung ventilation or even lobectomy.

Most patients heal within one to two weeks. However, patients with larger contusions and additional traumatic injuries may have increased morbidity. In addition, they may have long-term problems associated with chronic dyspnea, lung fibrosis, and reduced pulmonary function, ultimately decreasing their quality of life.