Pharm 111 Week 1 Class Notes #2

Intubation Techniques

• Glidescope Overview

  • A device with a camera on the blade for visualization during intubation.

  • Allows the clinician to see the screen while intubating.

  • Older method still used by many physicians.

Anatomy Overview During Intubation

• Airway Structures:

  • Glottis: Opening between the vocal cords.

  • Vocal Folds: Located at the entrance to the trachea.

  • Epiglottis: Flap that closes to protect the airway during swallowing.

• Patient Positioning:

  • The patient lies looking up with their tongue out, which aids visualization during intubation.

Trachea and Bronchi Anatomy

• Trachea:

  • Known as the windpipe.

  • Extends from the cricoid cartilage to the fifth thoracic vertebra.

  • Composed of C-shaped cartilaginous rings for support.

• Carina: Landmark at the bifurcation of the trachea into right and left bronchi.

• Bronchi Structure:

  • Right Main Stem Bronchus: More in line with the trachea, larger in diameter, leading to a higher incidence of right main stem intubation.

  • Left Main Stem Bronchus: Longer and at an angle due to the heart's anatomy.

• Foreign Body Aspirations:

  • More common in the right bronchus due to its structure.

The Trachea's Functionality

• C-shaped cartilage rings provide rigidity and protection.

• Sympathetic Stimulation:

  • Increases the diameter of the airways, resulting in bronchodilation, facilitating airflow.

• Conducting Airways:

  • Consist of trachea, main stem bronchi, lobar bronchi, and segmental bronchi.

  • Finally leading to the smooth muscle-dominated bronchioles which contain no cartilage.

Branching of Bronchi

• The right lung consists of three lobes, while the left lung consists of two lobes.

• Each lobe has its own respective segments for gas exchange via alveoli.

• Terminal Bronchioles:

  • Divide into respiratory bronchioles that ultimately contain alveoli for gas exchange.

Alveolar Structure

• Alveoli:

  • Each lung contains around 50 million alveoli, providing a massive surface area for gas exchange, likened to half of a tennis court per lung.

  • Composed of simple squamous epithelium.

• Surfactant:

  • A fluid secreted by type II alveolar cells to reduce surface tension and facilitate lung expansion.

  • Nascent in premature infants leading to complications in breathing due to insufficient lung compliance.

• Pores of Kohn:

  • Small pores in alveolar walls that allow for gas movement and sharing between adjacent alveoli.

Types of Gas Exchange

• External Respiration:

  • Exchange of gases between alveoli and bloodstream (pulmonary capillaries).

• Internal Respiration:

  • Exchange of gases between bloodstream and body tissues (systemic capillaries).

Factors Affecting Breathing Mechanics

• Diaphragm:

  • Primary muscle of respiration accounting for 75% of airflow; functions through contraction to increase lung volume during inspiration.

• Intercostal Muscles:

  • External intercostals lift ribs, contributing to breathing (>25% of lung airflow).

• Accessory Muscles:

  • Activated during respiratory distress, visible during labored breathing.

Monitoring and Assessing Breathing

• Look for signs of respiratory distress such as accessory muscle movement and abnormal breathing patterns.

• Conditions affecting compliance include pulmonary fibrosis and insufficient surfactant production.

Important Respiratory Terms to Know

• Hypoxia: Low oxygen levels in tissues.

• Hypoxemia: Low oxygen levels in the blood.

• Anoxia: Complete absence of oxygen.

• Apnea: Absence of breathing.

Summary of Pulmonary Ventilation

• Involves the movement of air in and out of the respiratory tract.

• Tidal Volume (VT): Volume of air inhaled or exhaled during one breath.

• Minute Ventilation: Calculated by multiplying respiratory rate by tidal volume, essential for assessing and preventing CO2 buildup.

Understanding Pressure Gradients and Boyle's Law

• Air flow occurs from high to low pressure.

• Inhalation reduces lung pressure allowing air to flow in, while exhalation increases lung pressure pushing air out.

Breathing Patterns

• Normal quiet breathing (eupnea) vs. breathing during effort (forced breathing) reflecting respiratory distress.

• Apnea entails a total lack of breathing.