Breathing & Ventilation

Once a patent airway is established, you must ensure adequate oxygenation and ventilation. Oxygen is the fuel for cellular metabolism; without it, anaerobic metabolism begins, leading to acidosis and cellular death.

Assessment of Breathing

Assess breathing rate, depth, and effort.

• Normal Rate: 12-20 breaths per minute (adult).
• Bradypnea (< 10 bpm): Often caused by CNS depression (e.g., opioid overdose, head injury). Requires assisted ventilation.
• Tachypnea (> 24 bpm): Often caused by hypoxia, shock, anxiety, or pain.

<biodigital id="thoracic-cage" title="Thoracic Anatomy" caption="The lungs, pleura, and rib cage mechanics during respiration." />

Critical Chest Trauma

In the pre-hospital setting, you must rapidly identify and manage the "Lethal Six" chest injuries, particularly these two that can be managed at the BLS/PHLS L1 level:

Tension Pneumothorax

• Pathophysiology: Air enters the pleural space through a one-way valve mechanism (usually a lung laceration) and cannot escape. Pressure builds, collapsing the lung and shifting the mediastinum, which compresses the vena cava and stops venous return to the heart.
• Signs: Severe respiratory distress, hypotension, unilateral absent breath sounds, jugular venous distension (JVD), tracheal deviation (late sign).
• PHLS L1 Management: High-flow O2, immediate rapid transport. (Decompression is an NACP-level skill).

<redflag> Tension pneumothorax is a clinical diagnosis, NOT a radiological one. Do not wait for an X-ray to suspect it. </redflag>

Open Pneumothorax (Sucking Chest Wound)

• Pathophysiology: A defect in the chest wall allows air to enter the pleural space directly from the outside, bypassing the trachea.
• Management: Apply a vented chest seal immediately at the end of exhalation. If a vented seal is unavailable, use a 3-sided occlusive dressing.

<goldenrule> If a patient with a chest seal suddenly deteriorates, suspect the seal has caused a tension pneumothorax. Immediately "burp" the seal to release trapped air. </goldenrule>

Oxygen Therapy Devices

1. Nasal Cannula: 1-4 L/min. Provides 24-36% FiO2. Used for mild hypoxia.
2. Non-Rebreather Mask (NRBM): 10-15 L/min. Provides 85-100% FiO2. The standard for trauma, shock, and severe distress. Ensure the reservoir bag is inflated before placing it on the patient.
3. Bag-Valve-Mask (BVM): 15 L/min. Used for apneic patients or those breathing < 10 or > 30 bpm with poor tidal volume.

BVM Ventilation Technique

• Use the CE-grip (or two-person VE-grip) to ensure a tight mask seal.
• Ventilate once every 5-6 seconds for adults (10-12 breaths/min).
• Squeeze the bag only until you see visible chest rise. Do not over-ventilate!

<redflag> Hyperventilation is lethal in trauma and cardiac arrest. It increases intrathoracic pressure, decreases venous return to the heart, and reduces cardiac output. Squeeze the bag gently. </redflag>