Foundations of Nursing - Topic 7: Chapter 41 - Oxygenation Part 1

Understanding Oxygenation

  • Oxygen as a Basic Human Need

    • Decreased oxygen levels lead to inability to perform vital functions.

    • Disturbances in oxygenation often arise from:

    • Ineffective gas exchange in the lungs.

    • Ineffective cardiac function.

  • Role of Cardiac and Respiratory Systems

    • Work in tandem to supply oxygen essential for life.

    • Facilitate respiratory and metabolic processes necessary to sustain life.

Key Terminology

  • Respiration

    • Exchange of oxygen and carbon dioxide during cellular metabolism. Not to be confused with:

    • Ventilation: Active movement of air into and out of the lungs.

Anatomy and Physiology of the Respiratory System

  • Airway Functionality

    • Transfers oxygen from atmosphere to alveoli.

    • Alveolar capillary membrane is the site for gas exchange.

    • Essential components:

    • Respiratory muscles.

    • Pleural space.

    • Lungs and alveoli.

  • Ventilation Mechanics

    • Gases move via pressure changes.

    • Intrapleural Pressure: Negative compared to atmospheric pressure.

    • Facilitates air flow into the lungs.

  • Inspiration and Expiration

    • Diaphragm and external intercostal muscles contract for inspiration.

    • For expiration, diaphragm relaxes; internal intercostal muscles contract.

  • Work of Breathing

    • Defines effort needed to expand and contract lungs.

    • Influenced by:

    • Depth and rate of breathing.

    • Lung compliance: ability to expand.

    • Airway resistance.

    • Increased work results in higher energy expenditure, increased metabolic rate, and oxygen demand.

Lung Volumes

  • Normal Lung Volumes

    • Varies by age, gender, and height.

    • Tidal Volume: Volume of air exhaled after normal inspiration.

    • Residual Volume: Volume remaining in alveoli after full expiration.

  • Factors Affecting Lung Volume

    • Alterations due to health status, activity levels, and conditions (obesity, pregnancy, etc.).

Pulmonary Circulation

  • Primary Function: Move blood to and from alveolar capillary membrane for gas exchange.

  • Process:

    • Blood begins at the pulmonary artery carrying deoxygenated blood from right ventricle.

    • Blood travels to pulmonary capillaries for gas exchange, returns as oxygen-rich blood via pulmonary veins to the left atrium.

Diffusion of Respiratory Gases

  • At Alveolar Capillary Membrane:

    • Thickness of membrane affects diffusion rate.

    • Increased thickness impedes diffusion.

    • Decrease in surface area due to conditions (emphysema, pulmonary edema) slows gas exchange.

  • Oxygen Transport System

    • Composed of lungs and cardiovascular system.

    • Influenced by ventilation amount, blood flow (perfusion), and rate of diffusion.

  • Oxygen-Carrying Capacity

    • Three components influence this capacity:

    1. Dissolved oxygen in plasma.

    2. Hemoglobin amount.

    3. Hemoglobin's ability to bind with oxygen.

Regulation of Ventilation

  • Neural and Chemical Regulators

    • Neural regulation via CNS controls respiratory rate and depth.

    • Cerebral cortex allows voluntary respiration control.

    • Chemical regulation maintains breath rates based on carbon dioxide, oxygen, and pH in blood.

Cardiopulmonary Physiology

  • Flow of Blood:

    • Deoxygenated blood from right heart to lungs for oxygenation; oxygenated blood from lungs to left heart, and then to body's tissues.

  • Heart Functionality

    • Four heart valves ensure unidirectional blood flow.

    • Stroke volume defines volume of blood ejected from ventricles during systole.

Factors Influencing Cardiac Output

  • Normal Ranges

    • Healthy adult: 4 to 8 liters/minute.

  • Key Factors

    • Preload: Blood volume in left ventricle at end of diastole.

    • Afterload: Resistance faced by left ventricle during blood ejection.

    • Myocardial contractility: Heart’s ability to eject blood.

Dysrhythmias and Cardiac Function

  • Conduction Disturbances

    • Dysrhythmias deviate from normal heart rhythm.

    • Types include tachycardia (>100 bpm) and bradycardia (<60 bpm).

  • Consequences

    • Both types can decrease cardiac output and blood pressure.

Cardiac Pathologies

  • Heart Failure Symptoms

    • Fatigue, dizziness, pulmonary congestion, and confusion due to tissue hypoxia.

    • Left-Sided Heart Failure: Reduced ejection fraction causing pulmonary congestion.

    • Right-Sided Heart Failure: Back-up of blood causing systemic venous congestion.

Myocardial Ischemia and Infarction

  • Differences Between Angina and Myocardial Infarction (MI)

    • Angina: Transient oxygen supply-demand imbalance.

    • Symptoms include chest pain; typically relieved by rest or nitroglycerin.

    • MI: Sudden drop in blood flow; severe symptoms lasting over 20 minutes.

Clinical Case Study: Mr. King

  • Clinical Details

    • 62-year-old male with a history of COPD and heavy smoking.

    • Symptoms: Chest pain, shortness of breath, and generalized malaise.

  • Potential Barriers to Health

    • Long-term smoking history, chronic conditions, and limited activity due to breathing difficulties.

Developmental Lifestyle and Environmental Factors

  • Risk Factors:

    • Age: Infants, toddlers, school-aged children, and adults all face unique risks related to respiratory infections and behaviors.

    • Lifestyle: Diet, smoking, exercise habits affect cardiopulmonary health.

  • Nutrition Impacts:

    • Good nutrition supports metabolic functions, while poor nutrition contributes to obesity and cardiopulmonary diseases.

Conclusion

  • Role of Nursing in Oxygenation Care

    • Assess with critical thinking and integrate knowledge from the nursing process to ensure safe patient care.

    • Use professional standards for guidance in patient management.