Gas Exchange & Collaboration1

Gas Exchange & Collaboration

Gas Exchange Overview

• Defined as the process of transporting oxygen to cells while removing carbon dioxide from cells.

• Requires interaction among:

  • Neurologic system

  • Respiratory system

  • Cardiovascular system

Key Terms to Know

• Ischemia: Insufficient flow of oxygenated blood to tissues, may lead to hypoxemia (decreased O2 in blood), resulting in cell injury or death.
  Examples of conditions that can lead to ischemia (insufficient flow of oxygenated blood) include:
  - Atherosclerosis: Hardening and narrowing of the arteries due to plaque buildup, reducing blood flow.
  - Myocardial Infarction: Blockage of blood flow to the heart muscle, leading to tissue damage.
  - Stroke: Occurs when blood flow to the brain is obstructed, resulting in brain cell damage.
  - Peripheral Arterial Disease: Narrowing of the blood vessels in the limbs, leading to decreased blood flow to the extremities.
  - Shock: A condition where insufficient blood flow to organs occurs due to low blood volume or heart function.

• Hypoxia: Condition when insufficient oxygen reaches the cells.

• Anoxia: Total absence of oxygen in body tissues.

Normal Physiological Process

• Breathing is involuntary, regulated automatically by the nervous system to maintain arterial blood gases within normal ranges.

• Medulla receptors detect elevated carbon dioxide levels and transmit impulses to:

  • Diaphragm

  • Intercostal muscles

• Diaphragm contraction creates negative pressure, pulling in oxygen (21% from air).

• Air is humidified by nasal passages before reaching the lungs.

Age-Related Differences

• Infants and Older Adults experience:

• Infants: Higher respiratory rates and less efficient gas exchange due to smaller lung volumes.

• Older Adults: Decreased elasticity of lung tissue, leading to reduced airflow and overall gas exchange efficiency.

• Older Adults: Decreased elasticity of lung tissue and reduced respiratory muscle strength, leading to a decline in overall lung function.

  • Diminished strength of respiratory muscles.

  • Less elastic and more fibrous alveoli. Can cause SOB(shortness of breath) during physical activity and may increase the risk of respiratory infections due to impaired gas exchange.

  • Reduction in erythrocytes.

Variation & Context of Gas Exchange Problems

• Older adults face gas exchange issues due to aging and chronic conditions.

• Disorders affecting gas exchange include:

  • Pneumonia

  • Asthma (longterm)

  • COPD (emphysema & chronic bronchitis)(longterm)

• Related conditions include:

  • Neurologic disorders

  • Cardiovascular issues

  • Hematologic conditions (e.g., anemia)

Categories of Problems Impacting Gas Exchange

1. Ventilation-

2. Transport-

3. Perfusion-

Ventilation

• Process of inhaling oxygen and exhaling carbon dioxide.

• Can be impaired by:

  • Disorders affecting airways, lungs, or respiratory muscles.

Situations Leading to Impaired Ventilation

1. Inadequate function of bone, muscle, or nerve to move air into the lungs.

2. Narrowed airways due to bronchoconstriction (e.g. asthma) or obstruction (e.g. COPD).

3. Poor gas diffusion in alveoli (e.g. pulmonary edema, ARDS, pneumonia).

Transport

• Refers to the availability of hemoglobin(protein in red blood cells) for oxygen transport from alveoli to cells and carrying carbon dioxide back to alveoli.

• Altered transport can occur with insufficient erythrocytes or low hemoglobin levels.

Perfusion

• Ability of blood to transport oxygen-rich hemoglobin to cells and return carbon dioxide.

• Inadequate perfusion may result from:

  • Decreased cardiac output- leads to hypotension,low bp and reduced oxygen delivery to tissues, which can compromise cellular metabolism and function.

  • Thrombi-

  • Emboli- blood clot in artery/vein cause decreased blood flow to the clotte area, leading to decreased perfusion

  • Vessel narrowing or vasoconstriction-high bp can occur as a compensatory mechanism, but prolonged high blood pressure may lead to vascular damage and further complications in gas exchange.

  • Blood loss-hypotension

  • Cardiac output-decreased due to reduced blood volume can impair the delivery of oxygen to tissues, exacerbating issues related to gas exchange and overall organ function.

Consequences of Impaired Gas Exchange

• Aware that they have

• Fatigue

• Increased heart rate

• Increased respirations

• Acid build-up-reduce oxygen levels in the blood, leading to a higher demand for oxygen and further strain on the respiratory system. (respiratory acidosis) can occur when the body retains too much carbon dioxide, causing the blood to become more acidic, which may worsen fatigue and impair gas exchange efficiency.

• Cellular ischemia and necrosis can occur as a result of prolonged hypoxia, leading to tissue damage and further complications in gas exchange. This emphasizes the importance of maintaining adequate oxygen delivery to tissues and the need for prompt medical intervention in cases of respiratory distress.

• Possible death

Risk Factors for impaired gas exchange

• High-risk populations:

  • Infants

  • Young children

  • Older adults (due to expected physiologic changes)

• Non Modifiable risks include:

  • Age

  • Air pollution

  • Allergies

• Tobacco is the leading preventable cause of death in the US, primarily impacting gas exchange.

• Additional risks include:

  • Altered consciousness increasing aspiration risk

  • Prolonged immobility increasing risk of atelectasis(collapsed lung)and pneumonia.

  • Chronic diseases such as cystic fibrosis, COPD, or heart failure.

Assessment of Adequate Ventilation

• Signs include:

  • Quiet, effortless breathing at age-appropriate rates.

  • Oxygen saturation between 95-100%.

  • Normal coloration in skin, nail beds, and lips.

  • Midline trachea.

  • Clear bilateral breath sounds.

  • 1:2 anteroposterior chest diameter ratio.

  • Aligned spinous processes with symmetric scapulae.

Diagnostic Tests for Gas Exchange

• Arterial Blood Gases (ABGs)

  • Measures pH, oxygen, carbon dioxide, and bicarbonate concentrations.

  • Detects:

    • Respiratory acidosis (due to hypoventilation)

    • Respiratory alkalosis (due to hyperventilation)

ABG Components & Interpretation

• pH:

  • Normal: 7.35-7.45

  • <7.35 = acidosis

  • 7.45 = alkalosis

• SaO2:

  • Normal: 95-100%

• PaO2:

  • Normal: 80-100 mm Hg

• PaCO2:

  • Normal: 35-45 mm Hg

• HCO3 (bicarbonate):

  • Normal: 22-26 mEq/L

Complete Blood Count (CBC)

• Measures:

  • RBCs, hemoglobin, hematocrit, and WBCs.

  • RBC Count: Indicates oxygen-carrying capacity.

  • Hemoglobin: Reflects RBC count and transport capabilities.

  • Hematocrit: Percentage of blood volume from RBCs.

  • WBC Count: Number of leukocytes present.

Clinical Management

• Goal: Optimize gas exchange via health promotion and management of conditions affecting it.

Primary Prevention Strategies

1. Infection control.

2. Smoking cessation.

3. Immunizations.

4. Preventing postoperative pulmonary complications (e.g., encouraging deep breathing, use of incentive spirometry).

Collaborative Interventions for Gas Exchange

• Pharmacotherapy: Agents to open airways for improved gas exchange.

• Oxygen Therapy: Critical for gas exchange; delivered via various mechanisms for those needing more than 21% oxygen.

Oxygen Delivery Mechanisms

• Nasal Cannula: 24-44% oxygen (1-6L), allows patient mobility.

• Simple Face Mask: Covers nose/mouth, delivers 35-50% oxygen (6-12L/min), uncomfortable for long-term use.

• Partial Non-Rebreather: 60-90% humidified oxygen (10-15L/min) for short term needs.

• Venturi Mask: Precise high flow of humidified oxygen (24%-50%).

• Tracheostomy Collar: Provides humidified oxygen for patients with trach tubes. ### Oxygen Delivery Mechanisms in Gas Exchange Therapy - **Nasal Cannula**: - Delivers oxygen concentration between 24-44% depending on the flow rate. - Flow rate: typically 1-6 liters per minute (L/min). - Advantages: Allows for patient mobility, can be used during eating and speaking, non-invasive, and comfortable for longer durations. - Limitations: May not provide adequate oxygen for patients with severe hypoxemia or require higher oxygen concentrations. - **Simple Face Mask**: - Covers both the nose and mouth, delivering oxygen concentrations ranging from 35-50% with a flow rate of 6-12 L/min. - Advantages: Provides a higher concentration of oxygen than a nasal cannula. - Limitations: It can be uncomfortable for long-term use, may cause claustrophobia, and does not provide a consistent oxygen concentration due to possible exhalation of room air. - **Partial Non-Rebreather Mask**: - Delivers 60-90% humidified oxygen at a flow rate of 10-15 L/min. - Features a bag that partially inflates with the patient's exhaled air and has exhalation ports that prevent room air from entering. - Advantages: Useful for short-term needs in emergencies as it allows for higher concentrations of oxygen delivery. - Limitations: Must be kept inflated during use; not suitable for long-term use due to discomfort and potential for rebreathing carbon dioxide if not correctly fitted. - **Venturi Mask**: - Provides a precise, high flow of humidified oxygen, with concentrations ranging from 24% to 50% based on the color-coded adapters. - Flow rate varies depending on the adapter used, typically from 4-15 L/min.

• - Advantages: Ideal for patients needing controlled oxygen levels, often used in COPD management to avoid hypercapnia. - -Limitations: Inflexible in terms of oxygen delivery, may obstruct patient's mobility compared to other devices.

• - **Tracheostomy Collar**: - Designed for patients with tracheostomy tubes, it provides humidified oxygen directly to the trachea.

• - Delivers oxygen concentrations based on system design, usually in conjunction with a standard respiratory therapy setup.

• - Advantages: Essential for patients who have difficulty using other methods; helps prevent mucus buildup and provides humidification to the airway. - Limitations: Requires regular monitoring to ensure adequate oxygenation and may need additional humidification to prevent airway dryness.

Additional Collaborative Interventions

• Airway Management & Breathing Support

• Chest Physiotherapy & Postural Drainage

Invasive Procedures for Gas Exchange Issues

• Chest Tube

• Thoracentesis

• Bronchoscopy

• Nutrition Therapy

• Positioning helps gravity push it up and facilitates easier drainage of fluid from the pleural space during thoracentesis. Proper patient positioning, such as sitting upright or leaning forward, can significantly improve the effectiveness of the procedure. moves diaphragm away from the lungs, allowing for better expansion of the lungs and enhancing overall respiratory function. Additionally, maintaining an optimal position can reduce discomfort for the patient and minimize the risk of complications associated with the procedure. lying horizontally for patients who are hypoxemic can lead to fluid accumulation in the lungs, making it difficult for them to breathe effectively and increasing the risk of respiratory distress. and acute lung diseases to shift blood flowto areas of the lungs that are better ventilated, thereby improving oxygenation and promoting more efficient gas exchange.

Interrelated Concepts Affecting Gas Exchange

• Anxiety

• Acid-Base Balance shifting of O2 AND CO2

• Perfusion

• Nutrition

• Mobility

• Fatigue