Chest Injuries: Comprehensive Guide for MCCQE1

Introduction

Chest injuries (thoracic trauma) are a significant cause of mortality and morbidity in Canada, accounting for approximately 25% of all trauma-related deaths. For the MCCQE1, understanding the rapid assessment, stabilization, and management of these injuries is paramount.

As a Medical Expert under the CanMEDS framework, you must be able to distinguish between injuries that pose an immediate threat to life (requiring intervention during the Primary Survey) and those that are potentially life-threatening (addressed during the Secondary Survey).

Initial Management: The Primary Survey

The management of chest injuries begins with the ABCDE assessment. Life-threatening thoracic injuries must be identified and treated during the Airway, Breathing, and Circulation phases.

The “Deadly Dozen” of Thoracic Trauma

For MCCQE1 preparation, categorize chest injuries into the Immediate Life Threats (Primary Survey) and the Potentially Life-Threatening Injuries (Secondary Survey).

Immediate Life-Threatening Injuries (The “Lethal Six”)

These must be identified and treated clinically without waiting for imaging.

Potentially Life-Threatening Injuries (Secondary Survey)

These are usually identified after the primary survey or via imaging (CXR, CT).

1. Simple Pneumothorax: Air in pleural space. Confirmed by CXR (expiration film helps). Treatment: Observation (if small) or Chest tube.
2. Hemothorax: Blood in pleural space. Requires drainage.
3. Pulmonary Contusion: Bruising of lung parenchyma. Leads to edema and hypoxia over 24-48 hours. Treatment: Oxygen, careful fluid management (avoid overload), analgesia.
4. Tracheobronchial Injury: Major airway injury. Persistent air leak despite chest tube. Requires bronchoscopy and surgical repair.
5. Blunt Cardiac Injury (BCI): Range from contusion to rupture. Monitor with ECG (risk of dysrhythmias). Troponins are generally not useful for prediction of complications in BCI.
6. Traumatic Aortic Disruption: usually deceleration injury.
   • CXR Findings: Widened mediastinum (>8cm), loss of aortic knob, deviation of NG tube to right.
   • Diagnostic: CT Angiogram is the gold standard.
   • Management: BP control (Beta-blockers) followed by surgical/endovascular repair.
7. Diaphragmatic Injury: More common on the left (liver protects the right). Bowel loops in chest on CXR. Requires surgical repair.

Diagnostic Imaging in Trauma

Understanding the appropriate use of imaging is a key MCCQE1 objective regarding resource stewardship.

Canadian Guidelines & Management Protocols

Indications for Tube Thoracostomy (Chest Tube)

In Canadian practice, the decision to place a chest tube is clinical but guided by imaging when stable.

• Significant pneumothorax or any pneumothorax in a patient on positive pressure ventilation.
• Hemothorax.
• Technique: 5th intercostal space, mid-axillary line (triangle of safety).

Pain Management in Chest Trauma

Poor pain control leads to splinting, atelectasis, and pneumonia, particularly in the elderly.

• Systemic: Acetaminophen, NSAIDs (caution with renal/bleeding risks), Opioids.
• Regional: Intercostal nerve blocks, Paravertebral blocks, Epidural analgesia (Gold standard for multiple rib fractures/flail chest).

Transfer Guidelines

Rural physicians must stabilize and transfer patients with:

• Aortic injuries.
• Major airway injuries.
• Flail chest requiring ventilation.
• Cardiac tamponade (after temporizing).

Key Points to Remember for MCCQE1

• Tension Pneumothorax is a clinical diagnosis; never delay treatment for an X-ray.
• Hypotension + Distended Neck Veins = Tension Pneumothorax OR Cardiac Tamponade. Differentiate by breath sounds (absent in pneumo, present in tamponade).
• Widened Mediastinum on CXR suggests Traumatic Aortic Injury; confirm with CT Angio if stable.
• Pulmonary Contusion may not appear on initial CXR; hypoxia worsens over 24-48 hours.
• Massive Hemothorax is defined as >1500 mL immediate drainage or >200 mL/hr for 2-4 hours.
• Simple Pneumothorax can convert to Tension Pneumothorax if the patient is intubated/ventilated. Always place a chest tube before transport or ventilation if a pneumothorax is known.

Sample Question

Clinical Scenario

A 24-year-old male is brought to the Emergency Department by EMS following a high-speed motor vehicle collision. He was the unrestrained driver and his chest hit the steering wheel. Upon arrival, he is in severe respiratory distress and agitated.

Vitals:

• Heart Rate: 130 bpm
• Blood Pressure: 70/40 mmHg
• Respiratory Rate: 34/min
• O2 Saturation: 84% on non-rebreather mask

Physical Examination:

• Neck: Distended jugular veins; trachea is deviated to the left.
• Chest: Bruising over the right hemithorax. Absent breath sounds on the right side. Hyper-resonance to percussion on the right.
• Heart: Tachycardic, regular rhythm, heart sounds are audible.

Which one of the following is the most appropriate immediate step in management?

Options

• A. Perform a portable chest X-ray
• B. Perform needle decompression of the right chest
• C. Perform pericardiocentesis
• D. Intubate and initiate mechanical ventilation
• E. Administer a 1L bolus of Ringer’s Lactate

Explanation

The correct answer is:

• B. Perform needle decompression of the right chest

Detailed Explanation: The patient presents with the classic triad of a Tension Pneumothorax:

1. Hypotension (Obstructive shock).
2. JVD (Impaired venous return).
3. Absent breath sounds with hyper-resonance (Air accumulation).

The tracheal deviation to the left confirms the high pressure on the right side pushing the mediastinum.

• Option A (CXR): Incorrect. Tension pneumothorax is a clinical diagnosis. Waiting for an X-ray delays life-saving treatment and can lead to cardiac arrest.
• Option B (Needle Decompression): Correct. This converts the tension pneumothorax into a simple pneumothorax, relieving the pressure on the heart and great vessels. This should be followed immediately by a tube thoracostomy (chest tube).
• Option C (Pericardiocentesis): Incorrect. This is the treatment for Cardiac Tamponade. While Tamponade causes hypotension and JVD, it does not cause absent breath sounds or hyper-resonance.
• Option D (Intubation): Incorrect. Positive pressure ventilation will increase intrathoracic pressure and worsen the tension pneumothorax, potentially causing cardiovascular collapse. You must decompress the chest before or simultaneously with intubation if intubation is required.
• Option E (Fluids): Incorrect. While the patient is hypotensive, the cause is obstructive, not primarily hypovolemic. Fluids alone will not fix the mechanical obstruction.

References

1. Advanced Trauma Life Support (ATLS) Student Course Manual. 10th Edition. American College of Surgeons.
2. Toronto Notes 2024. Thoracic Surgery Chapter.
3. The Medical Council of Canada. Objectives for the Qualifying Examination Part I.
4. Mowery, N. T., et al. (2013). “Practice management guidelines for management of hemothorax and pneumothorax.” Journal of Trauma and Acute Care Surgery.
5. Choosing Wisely Canada. Emergency Medicine Guidelines regarding imaging in trauma.