Patho Respiratory Spring 2025 RB

## PATHOPHYSIOLOGY OF THE RESPIRATORY SYSTEM
- Presented by Roxanne Bennett, DNP, NP-C

## Learning Objectives
- Describe normal pulmonary airflow and gas exchange mechanisms.
- Discuss how ventilation and perfusion alterations affect blood oxygenation.
- Identify common etiologies and risk factors of pulmonary disease.
- Discuss the physiologic consequences and clinical manifestations of pulmonary disease.
- Distinguish between different lung disease types.
- Describe how pulmonary disease influences cardiac function.

## Function of the Respiratory System
- Primary function: Supply O2 to body cells and remove CO2 & waste products.

## Components of the Respiratory System
- Includes:
- Mouth/nose/pharynx
- Upper/lower airways
- Lungs and alveoli
- Vasculature/capillaries
- Red blood cells and tissue cells

## Mechanisms of Ventilation
- **Inspiration (Inhalation):** Chest cavity increases size, negative intrapleural pressure, air drawn into lungs.
- **Expiration (Exhalation):** Elastic recoil of stretched structures decreases chest cavity size, increasing intrapleural pressure.

## Gas Exchange (Diffusion)
- Transfer of gases between alveoli and pulmonary capillaries, affected by ventilation/perfusion factors.

## Factors Hindering Ventilation
- Mucus or bronchoconstriction (COPD, Asthma)
- Loss of accessory muscle function (Neurological disorders)
- Blocked airway
- Drug-induced bradypnea (sedatives, narcotics)

## Gas Transport in Blood
- **Oxygen Transport:**
- 98% attached to hemoglobin, 2% dissolved in plasma.
- **Carbon Dioxide Transport:**
- 60% as bicarbonate, 30% attached to hemoglobin, 10% dissolved in plasma.

## Lung Compliance
- Refers to lung's ability to stretch and expand.
- Affected by:
- Elastin fibers (stretchable protein)
- Surfactant (reduces surface tension, eases breathing)

## Pulmonary Disorders
### Lung Inflation Disorders
- **Pleural Effusion:** Fluid accumulation in pleural cavity due to imbalance of fluid formation/removal.
- **Pneumothorax:** Air in intrapleural space, causing lung collapse.
- **Atelectasis:** Incomplete lung expansion due to various causes.

### Restrictive Lung Disorders
- **Intrinsic:** Includes interstitial lung disease and pneumonia.
- Caused by inhalants, toxins, pathogens.
- **Extrinsic:** Pressure from outside lungs (obesity, chest deformities).

### Obstructive Airway Disorders
- Impaired expiration leads to air trapping (Asthma, COPD).

## Asthma
- Characterized by airway inflammation, hyper-responsiveness, and obstruction.

## COPD
- Results in chronic airflow obstruction typically caused by smoking.
- Includes emphysema and chronic bronchitis.

### Clinical Features of Emphysema
- Symptoms: Dyspnea, tachypnea, pursed-lip breathing, barrel chest.

### Clinical Features of Chronic Bronchitis
- Symptoms: Chronic cough, purulent sputum, dyspnea.

## Pulmonary Embolism (PE)
- Blockage in pulmonary arteries from various sources (thrombus, air, fat).
- Risk factors: Surgery, malignancy, immobilization, etc.

## Pulmonary Hypertension
- Elevated pressures in pulmonary arteries, leading to symptoms like SOB, dizziness, chest pain.

## Cor Pulmonale
- Right-sided heart failure due to pulmonary causes (COPD, pulmonary hypertension).

## Respiratory Diagnostics
### Arterial Blood Gases (ABG)
- Evaluates oxygen and CO2 levels, pH balance of the blood.
- Important for diagnosing respiratory failures.

## Hypoxia, Hypoxemia, & Hypercapnia
- **Hypoxia:** Insufficient oxygen in tissues.
- **Hypoxemia:** Low arterial blood O2 levels.
- **Hypercapnia:** Increased CO2 levels in the blood.

## Types of Respiratory Failure
- **Type I (Hypoxemia):** PaO2