Respiratory Conditions Associated with Trauma

Trauma in RESP 105

Flail Chest

Flail chest is characterized by the presence of double fractures of at least three or more adjacent ribs, resulting in the thoracic cage becoming unstable or flail-like, which refers to a wave-like or swinging motion. The affected ribs cave in during inspiration due to the generation of sub-atmospheric intrapleural pressure. This condition compresses the underlying lung, leading to several complications including:

  • Rib instability
  • Lung volume restriction
  • Atelectasis (lung collapse)
  • Lung contusion
  • Secondary pneumonia

Etiology

The primary cause of flail chest is usually a blunt or crushing injury to the chest. Common examples include:

  • Motor vehicle accidents
  • Falls
  • Blast injuries
  • Direct compression by a heavy object
  • Occupational and industrial accidents
  • Cardiopulmonary resuscitation (CPR)

Patient Presentation

Patients presenting with flail chest display several clinical signs and symptoms, which may include:

  • Paradoxical movement of the chest wall
  • Tachypnea (increased respiratory rate)
  • Hypoxemia (decreased oxygen in the blood)
  • Tachycardia (increased heart rate)
  • Diminished breath sounds
  • Acute ventilatory failure

Chest X-ray (CXR) findings typically show:

  • Increased opacity indicative of atelectasis
  • Visible rib fractures

Disease Management

Management strategies for flail chest depend on the severity of the condition:

  • Mild Cases: Managed with pain medications and routine procedures for hyperinflation and bronchial hygiene
  • Severe Cases: Require mechanical ventilation (MV) and stabilization of the chest:
    • Positive End-Expiratory Pressure (PEEP): Helps stabilize the flail chest
    • Typically, 5-10 days of mechanical ventilation allows for bone healing
    • In some cases, paralytic medications may be necessary for ventilatory control
    • Surgical fixation could be required in severe instances

Pneumothorax

Pneumothorax is defined as the abnormal presence of gas (free air) accumulating in the pleural space, causing the visceral and parietal pleura to separate. This condition enhances the natural tendency of the lung to recoil while the chest wall tends to expand, which results in the compression of alveoli and, subsequently, the formation of atelectasis. Pneumothorax is classified as a restrictive lung disorder and can lead to:

  • Lung collapse
  • Atelectasis
  • Chest wall expansion, specifically in tension pneumothorax
  • Compression of great veins and decreased cardiac venous return

Etiology

Gas may enter the pleural space via three mechanisms:

  1. From lungs through perforation of the visceral pleura
  2. From surrounding atmosphere via perforation of the chest wall and parietal pleura
  3. From gas-forming microorganisms in an empyema within the pleural space
Classification of Pneumothorax
  • Open Pneumothorax: The pleural space is in direct contact with the atmosphere, allowing gas to move freely in and out.
  • Closed Pneumothorax: The gas in the pleural space is not in direct contact with the atmosphere.
  • Tension Pneumothorax: The intrapleural pressure exceeds the intra-alveolar pressure; gas enters during inspiration but cannot leave during expiration. This type is the most serious as it compresses surrounding mediastinal structures.

Types of Pneumothorax

  • Traumatic Pneumothorax: Caused by penetrating wounds to the chest (e.g., knife, bullet, impaled objects); classified as open pneumothorax, such as in a sucking chest wound.
  • Spontaneous Pneumothorax: Occurs suddenly without any identifiable underlying cause; classified as closed pneumothorax and is common among tall, thin individuals aged 15-35 years.
  • Iatrogenic Pneumothorax: Occurs due to specific diagnostic or therapeutic procedures, such as:
    • Lung, pleural, or liver biopsy
    • Thoracentesis
    • Cannulation of a subclavian vein
    • Tracheostomy
    • Hazard associated with positive pressure mechanical ventilation

Patient Presentation

Patients may exhibit several signs and symptoms, including:

  • Abrupt chest pain
  • Abrupt dyspnea
  • Hypoxemia
  • Tachypnea
  • Asymmetric lung expansion
  • Absent breath sounds on the affected side
  • Pulsus paradoxus (a drop in blood pressure during inhalation)
  • Tracheal shift away from the affected side in tension pneumothorax

Chest X-ray (CXR) findings typically include:

  • Dark lung fields on the affected side
  • Flattened diaphragm
  • Sign of atelectasis
  • Absence of vascular markings on the affected side

Note: The severity of symptoms is dependent on the amount of air present in the pleural space.

Hospital Management

Management strategies for pneumothorax depend on the degree of lung collapse:

  • Pneumothorax 15-20%: Bed rest or activity limitation; gas typically reabsorbs on its own.
  • Pneumothorax >20%: Requires evacuation of the gas.
  • Tension Pneumothorax: Requires immediate needle decompression.
  • Chest Tube Insertion: A chest tube may be placed in the pleural space to evacuate air, enhance re-expansion, and facilitate pleural adherence of the affected lung, usually positioned at the mid-clavicle, specifically in the 2nd or 3rd intercostal space and may be attached to suction.

Pleurodesis

Pleurodesis involves the injection of a chemical substance (commonly talc powder) into the chest cavity, which initiates an intense inflammatory reaction aimed at causing the lung's surface to adhere to the chest cavity, thus preventing or reducing recurrent pneumothorax.

Video Assisted Thoracoscopic Surgery (VATS)

This is a minimally invasive procedure employed to remove accumulated air in the pleural space by fusing the pleural lining to the chest wall.

Pneumomediastinum

Pneumomediastinum is the presence of gas (free air) in the mediastinum, which can occur in two forms:

  • Spontaneous Pneumomediastinum: Free air appears without injury or known underlying disease.
  • Secondary Pneumomediastinum: Free air is introduced as a result of a medical procedure or trauma.
Causes

Causes of pneumomediastinum include:

  • Illicit drug ingestion
  • Vigorous vomiting or coughing
  • Activities leading to barotrauma, such as scuba diving or flying
Patient Presentation

Patients may present with:

  • Dyspnea (difficulty breathing)
  • Dysphonia (difficulty speaking)
  • Fever
  • Subcutaneous emphysema (trapped air under the skin)
  • Hamman sign (a specific type of chest sound)
Treatment

Treatment options may consist of:

  • Rest and pain medications
  • Chest tube insertion

Hemothorax

Hemothorax refers to the presence of blood in the pleural space, generally caused by:

  • Penetrating or blunt trauma to the chest.
    Diagnosis is established when the pleural fluid shows a hematocrit of at least 50%.