Pulmonology Lecture Notes

Instructor Information

• Instructor: Bryan Bledsoe, DO, FACEP, FAEMS, EMT-P
• Course Focus: Standard Medicine with an emphasis on Respiratory Competency and clinical reasoning in the prehospital environment.

Core Competency

The competency integrates assessment findings with principles of epidemiology and pathophysiology to formulate a field impression and implement a comprehensive treatment/disposition plan for a patient with a medical complaint.

Learning Objectives

Terminal Performance Objective

• After reading this chapter, students should be able to: Integrate patient assessment findings, patient history, anatomy, physiology, pathophysiology, and both basic and advanced life support interventions to recognize and manage patients with pulmonary disorders.

1. Anatomy and Physiology of the Pulmonary System

1. Upper Airway
   • Nose and Mouth: Primary entry points; the nose warms, filters, and humidifies air.
   • Pharynx: Divided into the nasopharynx, oropharynx, and laryngopharynx.
   • Larynx: Transitions to the lower airway; contains the thyroid cartilage, cricoid cartilage, and vocal cords. The glottis is the narrowest part of the adult airway.
2. Lower Airway
   • Trachea: Protected by C-shaped cartilaginous rings; it bifurcates at the carina into the left and right mainstem bronchi.
   • Alveoli: The functional units where gas exchange occurs via the alveolar-capillary membrane.
3. Mechanics of Breathing
   • Inspiration: An active process where the diaphragm and intercostal muscles contract, increasing thoracic volume and creating negative pressure.
   • Expiration: Usually a passive process involving the muscular relaxation and the elastic recoil of the lungs.

2. Pathophysiologic Changes

1. Ventilation ($V$): The physical movement of air in and out of the lungs. Interrupted by airway obstruction or trauma.
2. Diffusion: The movement of gas from an area of higher concentration to an area of lower concentration across the alveolar-capillary membrane.
3. Perfusion ($Q$): The circulation of blood through the pulmonary capillaries.
4. $V/Q$ Mismatch:
   • Refers to an imbalance where either ventilation is impaired (e.g., fluid in alveoli, atelectasis) or perfusion is blocked (e.g., pulmonary embolism).

3. Patient Assessment Steps

1. Scene Size-Up: Identify environmental triggers (e.g., chemicals, allergens) and evaluate potential safety risks.
2. Primary Assessment: Observe for the "look test" (level of consciousness, skin color, position). Identify the "Tripod Position" or use of accessory muscles indicating work of breathing.
3. Obtain Patient History: Utilize OPQRST (Onset, Provocation, Quality, Radiation, Severity, Time) and SAMPLE (Signs/Symptoms, Allergies, Medications, Past History, Last Meal, Events).
4. Secondary Assessment:
   • Auscultation:
   • Wheezing: High-pitched whistling indicating lower airway bronchoconstriction.
   • Crackles (Rales): Popping sounds indicating fluid in the lower airways/alveoli.
   • Rhonchi: Coarse, low-pitched sounds indicating mucus in the larger airways.
   • Stridor: High-pitched sound on inspiration indicating upper airway obstruction.
5. Monitoring Technology:
   • Pulse Oximetry ($SpO_{2}$): Measures arterial oxygen saturation; normal range is typically $94\%-99\%$.
   • Capnography ($EtCO_{2}$): Provides real-time data on ventilation status; normal ranges are $35-45$ mmHg.

4. Common Respiratory Disorders

1. Asthma: Reversible airway obstruction caused by bronchial inflammation, smooth muscle contraction (bronchospasm), and mucus production.
2. COPD (Chronic Obstructive Pulmonary Disease):
   • Emphysema: Destruction of alveolar walls and loss of lung elasticity, leading to air trapping.
   • Chronic Bronchitis: Chronic productive cough and excessive mucus production for at least 3 months for 2 consecutive years.
3. Pneumonia: Infection of the lung parenchyma leading to inflammation and accumulation of fluid/pus in the alveoli.
4. Pulmonary Edema: Fluid accumulation in the lungs, often secondary to Left-Sided Heart Failure (CHF), causing impaired diffusion.
5. Pulmonary Embolism (PE): A blockage in the pulmonary arteries, often by a blood clot (DVT), resulting in a sudden perfusion deficit.

5. Recognition of Clinical States

1. Airway Compromise: Immediate threat to the airway (e.g., foreign body, swelling).
2. Respiratory Distress: Compensated state where the patient is struggling to breathe but maintaining adequate gas exchange (tachypnea, tachycardia).
3. Respiratory Failure: Decompensated state; inadequate gas exchange to support life; signs include altered mental status, cyanosis, and bradypnea. Requires immediate ventilation support.