Oxygenation

Oxygenation Prep Guide: Detailed Study Notes

Overview of Oxygenation

  • Systems Involved:

    • The Respiratory System:

    • Function: Responsible for bringing oxygen into the lungs and removing carbon dioxide from the body.

    • The Cardiovascular System:

    • Function: Transports oxygenated blood to the tissues and returns deoxygenated blood to the lungs.

Steps in the Process of Oxygenation

  • Ventilation:

    • Definition: The process of moving air in and out of the lungs, comprising inspiration (inhaling) and expiration (exhaling).

  • Perfusion:

    • Definition: The flow of blood through the pulmonary capillaries, delivering oxygen and removing carbon dioxide from the blood.

  • Diffusion:

    • Definition: The exchange of gases, specifically oxygen (O₂) and carbon dioxide (CO₂), between the alveoli and the pulmonary capillaries at the alveolar-capillary membrane.

Work of Breathing (WOB)

  • Definition: The effort required to expand and contract the lungs during respiration.

  • Factors Influencing WOB:

    • Lung compliance

    • Airway resistance

    • Respiratory muscle effort

  • Implications: Increased WOB can lead to fatigue or respiratory failure.

Respiratory Gas Exchange and Oxygen Transport

  • Transport Mechanism:

    • Oxygen relies on ventilation, diffusion, and perfusion to reach tissues.

  • Hemoglobin Role:

    • Definition: A protein in red blood cells responsible for carrying oxygen from the lungs to tissues and returning carbon dioxide to the lungs.

Factors Influencing Oxygen Carrying Capacity

  1. The amount of hemoglobin available.

  2. The availability of inspired oxygen (PaO₂).

  3. The ability of hemoglobin to bind with oxygen, which is influenced by:

    • pH levels

    • Temperature

    • CO₂ levels

Regulation of Breathing

  • Regulators:

    • Neural and Chemical Regulators:

    • Influence the rate and depth of respiration based on changing tissue oxygen demands.

  • Neural Regulation:

    • Brain Control: Involuntary control governed by the medulla oblongata and pons in the brainstem.

    • Controls:

    • Rate of breathing

    • Depth of breathing

    • Rhythm of breathing

Chemical Regulation

  • Receptors Monitoring:

    • Blood levels of:

    1. Oxygen (PaO₂)

    2. Carbon dioxide (PaCO₂)

    3. Hydrogen ion concentration (pH)

Cardiovascular Physiology

  • Deoxygenated Blood:

    • Travels to the right side of the heart, then to the lungs for oxygenation.

  • Oxygenated Blood:

    • Returns from the lungs to the left side of the heart, then to the tissues.

Structure and Function of the Heart

  • Cardiac Output (CO):

    • Definition: The volume of blood pumped by the left ventricle per minute, calculated using the formula:
      CO = HR imes SV

    • Normal Range: 4–8 L/min.

  • Coronary Artery Circulation:

    • Network of arteries supplying oxygenated blood to the myocardium (heart muscle).

  • Systemic Circulation:

    • Movement of blood from the left ventricle through body tissues and back to the right side of the heart.

Factors Affecting Oxygenation

Physiological Factors

  • Decreased Hemoglobin:

    • Impact: Reduces oxygen-carrying capacity, leading to hypoxia.

    • Examples: Anemia, hemorrhage, chronic kidney disease.

  • Hypovolemia:

    • Impact: Decreased blood volume reduces tissue perfusion.

    • Examples: Dehydration, shock, blood loss.

  • Decreased Inspired Oxygen Concentration:

    • Impact: Reduces oxygen availability for diffusion.

    • Examples: Airway obstruction, high altitude, hypoventilation.

  • Increased Metabolic Rate:

    • Impact: Raises oxygen demand and CO₂ production.

    • Examples: Fever, infection, pregnancy, hyperthyroidism, exercise.

Conditions Affecting Chest Wall Movement

  • Decreased Chest Wall Movement:

    • Impact: Limits lung expansion and decreases ventilation.

    • Examples: Obesity, pregnancy, trauma, neuromuscular disorders.

Alterations in Respiratory Function

  • Hypoventilation:

    • Impact: CO₂ retention, leading to respiratory acidosis.

    • Examples: Sedation, pain, muscle weakness.

  • Hyperventilation:

    • Impact: Excessive ventilation leads to low CO₂, causing respiratory alkalosis.

    • Examples: Anxiety, fever, metabolic acidosis.

  • Hypoxia:

    • Impact: Low oxygen in tissues, resulting in cell injury or fatigue.

    • Early Signs: Restlessness, tachycardia, confusion.

    • Late Signs: Cyanosis, bradycardia, hypotension.

Changes in Cardiac Function

  • Changes in Cardiac Output:

    • Impact: Decreased cardiac output results in reduced oxygen delivery to tissues.

    • Examples: Heart failure, myocardial infarction, dysrhythmias, valvular disease.

Focus on Older Adults

  • Cough Mechanism:

    • Decreased cough reflex and reduced respiratory muscle strength decrease effectiveness in clearing airways.

  • Immune System:

    • Weakened immune response and reduced ciliary function increase the risk of infections.

  • Diminished Respiratory Muscle Strength:

    • Reduced diaphragm and intercostal strength lead to shallow breathing and lower lung expansion.

Lifestyle Factors Affecting Oxygenation

  • Nutrition:

    • Poor nutrition impairs respiratory muscle function and decreases oxygen-carrying capacity.

  • Hydration:

    • Fluid overload can cause pulmonary edema; dehydration can thickening secretions.

  • Exercise:

    • Regular exercise enhances lung expansion and perfusion.

    • Inactivity leads to reduced physiological reserve.

  • Smoking:

    • Causes vasoconstriction, reduces ciliary function, and lowers oxygen delivery.

Environmental Factors

  • Risks:

    • Air pollution, allergens, dust, and chemicals can induce bronchospasm and diminish oxygen exchange.

  • Common Contributors:

    • Workplace hazards and exposure to secondhand smoke will also harm respiratory function.

Nursing Process and Critical Thinking

  • Critical Thinking Use:

    • Nurses utilize critical thinking to interpret assessment findings, recognize abnormal breathing patterns, identify hypoxia causes, plan interventions, and evaluate outcomes.

Assessment of Oxygenation

  • Pulse Oximetry:

    • Noninvasive measure of oxygen saturation (SpO₂).

    • Normal Range: 95–100% (may be lower in chronic lung diseases).

  • Capnography (End-Tidal CO₂):

    • Measures CO₂ at the end of exhalation (ETCO₂), with normal values between 35-45 mmHg, indicating the effectiveness of ventilation.

  • Pain and Fatigue:

    • Both increase oxygen demand and may limit the effectiveness of deep breathing and coughing.

  • Dyspnea:

    • Subjective sensation of difficulty breathing; assessment includes onset, severity, and aggravating factors.

  • Cough:

    • Assessment includes frequency, duration, sputum characteristics, and effectiveness.

  • Allergies:

    • Environmental or medication-related triggers that may instigate airway inflammation should be identified.

Physical Examination Components

  • Inspection:

    • Evaluate rate and rhythm of breathing, chest shape, color, and use of accessory muscles.

  • Palpation:

    • Assess chest expansion and fremitus (vibration felt on the chest wall during speaking).

  • Percussion:

    • Observe for resonance or dullness.

  • Auscultation:

    • Listen to breath sounds, which may include crackles, wheezes, or absent sounds.

Signs of Poor Oxygenation Found During Physical Assessment

  • Indicators:

    • Restlessness, cyanosis, confusion, tachycardia, dyspnea, nasal flaring, intercostal retractions, altered level of consciousness (LOC).

  • Hypoxia Signs:

    • Early: Restlessness, anxiety, tachycardia.

    • Late: Cyanosis, bradycardia, hypotension.

Diagnostic Tests for Oxygenation

  • Complete Blood Count (CBC):

    • Assesses red and white blood cells, hemoglobin, hematocrit to determine oxygen-carrying capacity and detect infections or anemia.

  • Hemoglobin (Hgb):

    • Normal Levels:

    • Males: 14–18 g/dL

    • Females: 12–16 g/dL

    • Low levels relate to hypoxia.

  • Red Blood Cells (RBCs):

    • Evaluates oxygen transport capability; low count signifies anemia, hindering tissue oxygen delivery.

  • Arterial Blood Gases (ABGs):

    • Measures:

    • Oxygen (PaO₂)

    • Carbon Dioxide (PaCO₂)

    • pH

    • Bicarbonate (HCO₃⁻)

    • Used to evaluate ventilation, oxygenation, and acid-base balance.

  • Sputum Culture:

    • Identifies microorganisms in the respiratory tract causing infections to guide antibiotic therapy.

  • Imaging:

    • Chest X-ray / CT Scan:

    • Visualizes lung structure and pathology (infiltrates, effusions, tumors).

    • CT scans offer detailed 3D imaging for in-depth evaluation.

  • Pulmonary Function Tests (PFT):

    • Assess lung volumes and flow rates for diagnosing obstructive and restrictive lung diseases (e.g., asthma, COPD).

  • Peak Expiratory Flow Rate (PEFR):

    • Measures maximum flow during exhalation.

    • Used to monitor asthma control and treatment response.

  • Bronchoscopy:

    • A flexible scope for direct airway visualization, which can be diagnostic or therapeutic.

Nursing Diagnoses for Oxygenation

  1. Impaired Gas Exchange related to alveolar-capillary membrane changes.

  2. Ineffective Airway Clearance related to retained secretions.

  3. Activity Intolerance related to imbalance between oxygen supply and demand.

Planning and Outcome Identification

  • Goals:

    • SpO₂ ≥ 92% on prescribed oxygen

    • Respiratory rate within patient's baseline

    • Effective cough with clear breath sounds

    • Patient verbalizes and demonstrates proper breathing techniques.

Teamwork and Collaboration

  • Interdisciplinary Team Includes:

    • Respiratory Therapist: Administers oxygen therapy and performs PFTs.

    • Physician/NP: Orders and oversees treatment.

    • Nurse: Monitors, educates, and evaluates patient outcomes.

    • Dietitian: Addresses nutritional needs.

    • Physical/Occupational Therapist: Enhances mobility and endurance.

Implementation and Health Promotion

  • Health Promotion Role:

    • Focused on preventing respiratory illness and improving lung health via:

    • Smoking cessation

    • Weight control

    • Regular exercise

    • Balanced nutrition

    • Early treatment of infections.

Important Vaccinations

  • Vaccination Recommendations:

    • Annual influenza vaccine for all adults.

    • Pneumococcal vaccine for adults ≥ 65 or with chronic illnesses (COPD, diabetes, heart disease).

    • COVID-19 vaccine/boosters as recommended.

    • Tdap vaccine every 10 years.

    • Immunocompromised and older adults should be encouraged to stay up to date with vaccinations.

Environmental Pollutants Avoidance

  • Client Education:

    • Avoid smoking and secondhand smoke exposure.

    • Use air filters or purifiers indoors; ensure proper ventilation and avoid heavily polluted areas.

    • For occupational exposure, wear appropriate protective equipment and adhere to workplace safety protocols.

Acute Care Nursing Interventions

  • Dyspnea Management:

    • Elevate head of bed.

    • Encourage pursed-lip breathing.

    • Administer oxygen as ordered.

    • Employ relaxation techniques to alleviate anxiety.

  • Airway Maintenance:

    • Keep airway patent, using suction if necessary.

    • Encourage coughing and deep breathing, repositioning, and adequate hydration to help clear secretions.

  • Hydration:

    • Adequate fluid intake (2–3 L/day if not contraindicated) thins secretions, facilitating effective expectoration.

  • Humidification:

    • Prevents drying of mucous membranes, especially important at oxygen flow rates >4 L/min, always use sterile water in humidifiers to avoid infections.

  • Nebulization:

    • Delivers aerosolized medications (e.g., bronchodilators) or saline to enhance airway clearance and relieve bronchospasm.

  • Cough and Deep Breathing Techniques:

    • Teach patients to take deep breaths and use effective coughing to clear secretions, employing splinting for post-operative patients to minimize discomfort.

  • Chest Physiotherapy (CPT):

    • Techniques include percussion, vibration, and postural drainage to help mobilize secretions and enhance airway clearance.

  • Postural Drainage:

    • Involves positioning the patient to exploit gravity for draining secretions from specific lung segments into larger airways for removal.

  • Ambulation:

    • Encourages lung expansion, mobilizes secretions, and improves circulation, crucial to preventing complications such as pneumonia or atelectasis.

  • Positioning:

    • High-Fowler's position enhances chest expansion; side-lying with the good lung down optimizes ventilation-perfusion matching.

  • Pursed-Lip Breathing:

    • Inhale through the nose and exhale slowly through pursed lips to help control breathing, relieve dyspnea, and prevent airway collapse in patients with COPD.

  • Positive Expiratory Pressure (PEP) Device:

    • Provides resistance during exhalation to maintain airway openness and mobilize secretions.

  • Incentive Spirometer (ICS):

    • Encourages sustained deep inspiration to expand alveoli, prevent atelectasis, and enhance gas exchange by using it 10 times per hour while awake post-operative.

Oxygen Therapy

  • Oxygen Administration:

    • Nurses typically require an order to apply or titrate oxygen. In emergencies, protocols may allow nurses to initiate oxygen.

  • Goals of Oxygen Therapy:

    • Relieve hypoxemia

    • Maintain adequate oxygen saturation

    • Decrease work of breathing

    • Prevent complications such as hypoxia or oxygen toxicity.

  • UAP Role:

    • Can assist in applying oxygen devices, reporting changes in patient conditions, and providing comfort, but cannot adjust oxygen flow rates or assess patient responses.

Oxygen Safety Precautions

  • Safety Measures:

    • No smoking or open flames near oxygen equipment.

    • Keep oxygen cylinders secured and away from heat sources.

    • Use only grounded electrical equipment.

    • Avoid petroleum-based products near oxygen devices.

    • Post “Oxygen in Use” notices to alert others.

Oxygen Delivery Devices

Low-Flow Delivery Devices

  • Nasal Cannula:

    • Flow: 1–6 L/min (provides 24–44% FiO₂).

  • Simple Face Mask:

    • Flow: 6–12 L/min (provides 35–50% FiO₂).

  • Venturi Mask:

    • Flow: 4–12 L/min (provides precise control, 24–60% FiO₂).

  • Nonrebreather Mask:

    • Flow: 10–15 L/min (provides 60–90% FiO₂, contains one-way valves to prevent CO₂ rebreathing).

High-Flow Delivery Devices

  • High-Flow Nasal Cannula:

    • Delivers up to 60 L/min (provides 21–100% FiO₂); supplies positive pressure and controls temperature.

  • CPAP/BiPAP:

    • Provides continuous or bilevel positive pressure to assist ventilation.

Noninvasive Ventilation (NPPV)

  • CPAP:

    • Maintains continuous airway pressure to keep alveoli open