Lesson 2 – Ventilation in Depth

Welcome to Lesson 2

This lesson dives deep into ventilation. Understanding breathing intricacies is crucial for effective patient assessment and treatment.

Respiratory system anatomy

Divided into upper and lower airways. Upper airway: nose, nasal cavity, pharynx, larynx. Lower airway: trachea, bronchi, lungs.

Function of the nose and nasal cavity

Warm, humidify, and filter incoming air.

Pharynx

Also called throat; common site for airway obstruction.

Larynx

Houses vocal cords and epiglottis, which protects the airway during swallowing.

Lower airway structure

Trachea divides into two main bronchi, which branch into smaller bronchioles.

Alveoli

Tiny air sacs where gas exchange occurs; surrounded by capillaries to maximize surface area.

Importance of respiratory anatomy

Crucial for assessing breathing difficulties and localizing problems.

Mechanics of inhalation

Active process: diaphragm contracts and moves down; external intercostals lift rib cage; thoracic cavity volume increases creating negative pressure that draws air in.

Mechanics of exhalation

Usually passive: diaphragm and intercostals relax, lungs recoil pushing air out. In distress, exhalation can become active using accessory muscles like sternocleidomastoid and abdominals.

Pressure gradient significance

Negative pressure during inhalation is key to understanding conditions like pneumothorax.

Gas exchange at alveoli

Oxygen diffuses from alveoli (high concentration) to blood (low concentration); carbon dioxide diffuses from blood to alveoli for exhalation.

Factors affecting diffusion rate

Thickness of alveolar-capillary membrane and partial pressure gradients of gases.

Disruptions in gas exchange

Lung damage, fluid in alveoli, or circulation problems can impair gas exchange (e.g., pulmonary edema, ARDS).

Factors affecting ventilation

Rate and depth of breathing, airway patency, lung compliance, chest wall integrity, neurological control.

Normal adult respiratory rate

Typically 12-20 breaths per minute; varies with age and condition.

Airway patency importance

Obstructions like foreign bodies or laryngeal edema impair ventilation.

Lung compliance

Ability of lungs to expand and contract; affected by COPD, pulmonary fibrosis.

Chest wall integrity

Injuries like rib fractures or flail chest can impact breathing.

Neurological control

Brain respiratory centers and nerves controlling respiratory muscles can be compromised by injury or conditions like opioid overdose or spinal cord injury.

Field assessment of ventilation

Observe rate, rhythm, depth, signs of effort (nostril flaring, accessory muscles), speech ability, breath sounds, chest expansion, air movement, pulse oximetry.

Interpretation of breath sounds

Wheezes indicate bronchoconstriction; crackles suggest fluid in alveoli; absence or abnormal sounds indicate specific conditions.

Limitations of pulse oximetry

Normal oxygen saturation does not always mean no respiratory distress (e.g., increased work of breathing, hypercapnia).

Positioning during respiratory emergencies

Sitting patient upright helps diaphragm move better and eases breathing.

Airway opening maneuvers

Head-tilt chin-lift for non-trauma patients; jaw-thrust for suspected spinal injuries to maintain airway patency.

Purpose of airway maneuvers

Align oral, pharyngeal, and laryngeal axes to open the airway.

Bag-valve-mask ventilation

Critical skill to assist or take over breathing; requires good seal and proper ventilation rate.

Ventilation vs oxygenation

In emergencies, ensuring ventilation (removing CO₂) can be as important as oxygen delivery.

Summary of ventilation importance

Knowing respiratory anatomy and physiology helps assess and treat patients; look, listen, and feel during assessment; use BLS interventions like positioning and assisted ventilation.

Continuous reassessment

Respiratory status can change rapidly; correlate findings with clinical picture and reassess frequently.

Preview of next lesson

Next, we’ll explore perfusion and its interaction with ventilation, focusing on how disturbances in one affect the other.