Key Concepts in Respiratory Care and Oxygenation

Topic 5: Oxygenation

Key Takeaways

  • Takeaway 1: The Process of Ventilation

    • Definition: Mechanical process of moving air into and out of the lungs, allowing oxygen (O2) to enter the blood and carbon dioxide (CO2) to exit the body.

    • Mechanics of Lung Expansion:

    • Inspiration (Innotation):

      • Diaphragm contracts, moving downward.

      • Intercostal muscles lift the rib cage.

      • Results in increased thoracic cavity volume.

      • Leads to decreased intrapulmonary pressure, allowing air to flow into the lungs.

    • Expiration (Exnaction):

      • Normally a passive process where diaphragm and intercostals relax.

      • Lung tissue recoils, thoracic volume decreases, pushing air out.

    • Factors Affecting Compliance:

    • Decreased lung expansion can occur due to conditions like pulmonary edema or fibrosis.

    • Surfactant Role:

    • Reduces surface tension in alveoli, preventing collapse.

    • Absence of surfactant leads to atelectasis, commonly seen in premature infants.

    • Gas Exchange Mechanism:

    • Occurs at the alveolar-capillary membrane.

    • O2 diffuses from a high concentration in alveoli to a low concentration in capillary blood.

    • CO2 diffuses from capillary blood (high concentration) into the alveoli (low concentration) to be exhaled.

    • Factors Influencing Gas Exchange:

    • Adequate alveolar surface area (reduced in emphysema).

    • Thickness of alveolar-capillary membrane (increased in pulmonary edema).

    • Blood flow (perfusion) to the lungs.

    • Airway Resistance:

    • Defined as the opposition to airflow within airways.

    • Normally, this resistance is minimal; increased resistance is seen in conditions like asthma and bronchoconstriction.

    • Higher resistance increases the work of breathing.

    • Integration with Fluid, Electrolyte Acid-Balance:

    • Normal blood pH range: 7.35 - 7.45.

    • Oxygen transport depends on hemoglobin binding, influenced by pH and CO2 levels.

    • CO2 regulation is tied to acid-base balance, affecting the respiratory function and pH.

  • Takeaway 2: Oxygenation Concepts

    • Definition: The delivery of O2 to the body's tissues via the bloodstream, essential for cellular function.

    • Key Processes:

    • Ventilation: Movement of air in and out of the lungs.

    • Perfusion: Blood flow to tissues carrying oxygen and removing CO2.

    • Diffusion: Gas exchange across the alveolar-capillary membrane.

    • Transport: Oxygen binding to hemoglobin in red blood cells.

    • Importance in Cellular Function:

    • Cellular respiration: requires O2 to produce ATP through aerobic metabolism.

    • CO2 Removal: Adequate oxygenation expels CO2, a waste product of metabolism, thus preventing acid accumulation.

    • Acid-Base Balance: Ventilation regulates CO2 levels, directly influencing blood pH (normal range 7.35-7.45).

    • Overall Health Implications:

    • Adequate oxygenation enables energy production.

    • Maintains acid-base balance essential for organ function.

    • Supports prevention of organ failure.

  • Takeaway 3: Hypoxia

    • Definition: Inadequate oxygen availability at the cellular level, potentially leading to organ dysfunction or death.

    • Causes:

    • Hypoventilation, anemia, poor circulation, impaired diffusion (e.g., pneumonia, COPD, pulmonary edema).

    • Early Signs/Symptoms:

    • Restlessness, anxiety, confusion, altered heart rate (HR) and respiratory rate (RR).

    • Late Signs/Symptoms:

    • Decreased level of consciousness (LOC), cyanosis, hypotension, bradycardia, dysrhythmias.

    • Dyspnea: Subjective sensation of difficult or labored breathing, often reported by patients as feeling unable to breathe or "air hungry".

    • Causes include hypoxia, pulmonary and cardiac conditions, anxiety.

    • Clinical Presentation: Use of accessory muscles, nasal flaring, tripod positioning; nursing actions include positioning patient upright, administering oxygen, encouraging pursed-lip breathing.

    • Abnormal Breath Sounds:

    • Crackles: Fine or coarse popping sounds caused by air passing through fluid/mucus in small airways or alveoli.

    • Wheezes: High-pitched musical sounds usually heard during expiration caused by narrowed airways.

    • Rhonchi: Low-pitched snoring/gurgling sounds caused by secretions in larger airways.

    • Stridor: Harsh, high-pitched sound due to upper airway obstruction; indicates serious condition.

    • Pleural Friction Rub: Grating sound indicating inflamed pleura rubbing together.

    • Summary: Hypoxia leads to early restlessness and late cyanosis; dyspnea is indicated by accessory muscle use; abnormal sounds vary based on affected causes (fluid for crackles, airway constriction for wheezes).

  • Takeaway 4: Lower Respiratory Tract Diseases

    • Asthma:

    • Definition: Chronic lung disease that inflames, swells, and narrows the airway, making it hyperresponsive to triggers.

    • Primary Causes: Exposure to allergens, exercise, stress.

    • Clinical Manifestations: Wheezing, cough, dyspnea, anxiety, sudden fatalities, prolonged symptoms.

    • Chronic Obstructive Pulmonary Disease (COPD):

    • Definition: Chronic respiratory disease characterized by over-inflation of alveoli due to decreased elasticity; includes emphysema and chronic bronchitis.

    • Primary Causes: Long-term exposure to irritants such as smoking leading to alveolar destruction.

    • Clinical Manifestations: Wheezing, pursed-lip breathing, tripod positioning, barrel chest, dyspnea, prolonged expiratory times.

    • Chronic Obstructive Bronchitis:

    • Definition: Inflammation of the bronchi causing excessive mucus production; considered chronic if cough and mucus are produced most days for three months over two consecutive years.

    • Symptoms: Productive cough, excessive secretions, wheezing, dyspnea, chronic hypoxemia.

    • Pulmonary Edema:

    • Definition: Accumulation of fluid in alveoli impairing gas exchange.

    • Causes: Heart failure, fluid overload.

    • Symptoms: Bubbly, frothy, pink sputum, marked dyspnea, crackles.

    • Atelectasis:

    • Definition: Incomplete expansion or collapse of alveoli resulting in poor gas exchange.

    • Common Cause: Obstruction from mucus or shallow breathing (often postoperative).

    • Symptoms: Decreased lung sounds, dyspnea, cyanosis.

    • Pulmonary Embolism:

    • Definition: Dislodged blood clot or foreign material lodging in pulmonary artery affecting perfusion.

    • Symptoms: Dyspnea, chest pain, tachypnea.

    • Pneumonia:

    • Definition: Infection leading to inflammation of alveoli and impairment of gas exchange.

    • Causes: Aspiration, infection, decreased cough reflex, immobility.

    • Symptoms: Fever, chills, productive cough, crackles.

    • Hemothorax/Pneumothorax:

    • Definitions: Accumulation of blood or air in the pleural space leading to lung collapse.

    • Symptoms: Dyspnea, chest discomfort, cyanosis.

  • Takeaway 5: Nursing Interventions

    • Positioning:

    • High Fowler’s position maximizes chest expansion and reduces the work of breathing for dyspneic or hypoxic patients.

    • Orthopenic/tripod positioning helps patients with COPD and asthma.

    • Frequent repositioning mobilizes secretions and improves perfusion.

    • Breathing Exercises:

    • Pursed-lip breathing prolongs exhalation, prevents alvelolar collapse, and promotes CO2 removal.

    • Diaphragmatic breathing increases lung expansion.

    • Incentive spirometry encourages lung expansion and prevents atelectasis postoperatively.

    • Controlled/huff coughing mobilizes secretions without causing excess fatigue.

    • Oxygen Therapy:

    • Low-flow devices include nasal cannula (1-6 L/min) and simple face masks (6-12 L/min).

    • High-flow includes non-rebreather masks (10-15 L/min) and Venturi masks (4-12 L/min), best for COPD patients.

    • Humidification is crucial to maintain moist air for comfort and gas exchange.

    • Monitoring Responses:

    • Continuous monitoring of pulse oximetry for oxygen saturation.

    • Assess respiratory rate, work of breathing, and patient responses.

    • Ensure that devices are used correctly and assess for complications.

  • Takeaway 6: Appropriate Devices and Monitoring

    • Oxygen Delivery Systems: Discussed types include nasal cannula, simple face masks, partial rebreather and non-rebreather masks, and Venturi masks.

    • Monitoring Responses:

    • Key parameters include pulse oximetry, respiratory assessment, and arterial blood gases (ABGs).

    • Assess for hypoxia and if interventions are effective.

Conclusion

  • Essential Components for Respiratory Health:

    • Integrity of the airway for gas transport, functioning alveoli, cardiovascular and blood supply adequacies for nutrient and waste transport, and effective pulmonary function.

  • Special Considerations in Older Adults:

    • Changes in lung structure and function can increase risk for respiratory conditions; nursing care must adapt to these physiological changes and needs for effective interventions.