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Giddens Concept 19 Gas Exchange Outline
Health/Illness Concepts (NSG 170)
Germanna Community College
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Giddens Concept 19 I. Definition A. The process by which oxygen is transported to cells and carbon dioxide is transported from cells B. The lungs deliver oxygen to pulmonary capillaries, where it is carried by hemoglobin to cells C. After cellular metabolism, carbon dioxide is carried in hemoglobin to the lungs, where it is exhaled D. Hypoxia is insufficient oxygen reaching cells E. Anoxia is the total lack of oxygen in body tissues F. Hypoxemia is reduced oxygenation of arterial blood II. Scope A. From the broadest perspective, the scope of gas exchange represents a spectrum of optimal gas exchange and impaired gas exchange B. The further gas exchange is impaired, the more compromised the body becomes due to insufficient oxygen C. Cessation of gas exchange leads to anoxia III. Normal Physiological Process A. The process of gas exchange is as follows
Oxygen a) Atmosphere (21% oxygen) b) Medulla c) Thorax intact, diaphragm contracts d) Nose e) Trachea f) Bronchi g) Alveoli h) Pulmonary capillaries with hemoglobin to carry oxygen i) Perfusion to transport hemoglobin to cells
Cell Metabolism
Carbon Dioxide a) Perfusion to transport hemoglobin from cells b) Pulmonary capillaries with hemoglobin carrying carbon dioxide c) Alveoli d) Bronchi e) Trachea f) Nose g) Thorax intact, diaphragm relaxes h) Atmosphere B. Age-Related Differences
Babies a) If born after 30 weeks of gestation have a sufficient surfactant to prevent alveoli from collapsing after every exhalation
Infants a) infants are obligate nose breathers until approximately 3 months
Newborns a) Respiratory patterns may be irregular, with brief pauses between breaths of no more than 10-15 seconds
Older Adults a) Diminished strength of respiratory muscles reduces the maximal inspiratory and expiratory force (1) This may result in a weaker cough b) The alveoli become less elastic and more fibrous, causing dyspnea more frequently c) Older adults experience a reduction in erythrocytes, which increases their risk of anemia IV. Variations and Context A. Disorders that lead to changes in gas exchange include acute illnesses such as asthma or pneumonia and chronic disorders such as chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis B. Conditions that specifically involve gas exchange include neurologic, cardiovascular, and hematologic C. Conditions in these body systems can be caused from congenital defects, genetic conditions, injury, inflammation, infections, and malignant neoplasms D. The three broad categories that represent problems associated with this concept are ventilation, transport, and perfusion E. Ventilation
Ventilation is the process of inhaling oxygen into the lungs and exhaling carbon dioxide from the lungs
Ventilation may be impaired by the unavailability of oxygen, such as high altitudes, as well as by any disorder affecting the nasopharynx and lungs
Impaired ventilation may occur in the following situations: a) Inadequate bone, muscle, or nerve function to move air into the lungs, such as rib fracture that reduces inhalation due to pain, muscle weakness that prevents full thoracic expansion, or cervical spinal cord injury that limits movement of the
associated with transport or perfusion C. Prolonged or severe impairment of gas exchange
- Cellular ischemia and necrosis can occur
- A complete cessation of gas exchange occurs when breathing or perfusion stops and quickly results in death VI. Risk Factors A. Populations at Risk
- Infants a) Infants have fetal hemoglobin (1) Fetal hemoglobin is present for the first five months of life and results in shortened survival of erythrocytes, causing physiological anemia by age 2 or 3 months b) Contributing to anemia at approx 6 months of age is the lower level of hemoglobin caused by gradually diminishing maternal iron stores c) They have less alveolar surface area for gas exchange d) Narrow branching of peripheral airways that are easily obstructed by mucus, edema, or foreign objects
- Young Children a) They have less alveolar surface area for gas exchange b) Narrow branching of peripheral airways that are easily obstructed by mucus, edema, or foreign objects
- Older Adults a) At risk for impaired gas exchange because of anatomic and physiological changes that are expected with advanced age b) The chest wall becomes stiffer with loss of elastic recoil c) Respiratory muscles become weaker, reducing the effectiveness of coughing -- normally a protective mechanism to prevent aspiration d) Additional expected changes are dilation of alveoli, decreased surface area for gas diffusion, and decreased pulmonary capillary network e) The ability to initiate an immune response to infection is decreased in older adults B. Individual Risk Factors
- Nonmodifiable Risk Factors a) Age b) Air pollution c) Allergies
- Tobacco use is the single most preventable cause of death and disease in the United States and is the most significant risk factor
for impaired gas exchange 3. Risk for aspiration is increased during an altered state of consciousness such as from a) A chemical alteration (1) Alcoholism (2) Drug overdose (3) Anesthesia b) A neurologic disorder (1) Head injury (2) Seizure (3) Stroke 4. Patients requiring tracheal intubation are at risk because of the bypassing of protective mechanisms for the alveoli 5. Bed rest and prolonged immobility reduce thoracic expansion, which can increase the risk for atelectasis and pneumonia 6. Chronic diseases, such as cystic fibrosis, COPD, or heart failure, increase risk because of mucus and fluid accumulation in the airways and alveoli 7. Immunosuppression alters the body’s natural ability to fight infection, whether it is from a systemic disorder (ex. Aplastic anemia), a cancer (ex. leukemia), or a treatment regimen (ex. Cancer chemotherapy) VII. Assessment A. Adequate ventilation is apparent when the following occur
- Breathing is quiet and effortless at a rate appropriate for age
- Oxygen saturation is between 95 and 100%
- Skin, nail beds, and lips are appropriate colors for the patient’s race
- Thorax is symmetric with equal thoracic expansion bilaterally
- Spinous processes are in alignment; scapulae are bilaterally symmetric
- Anteroposterior (AP) diameter of the chest is approx a 1:2 ratio of AP to lateral diameter
- Trachea is midline
- Breath sounds are clear bilaterally B. History
- Baseline History a) Nurses ask about: (1) Lifestyle behaviors (a) Diet (b) Exercise (c) Smoking habits
(b) How long the pain lasts (c) If the onset of chest pain was gradual or sudden (d) A description of the pain, such as sharp or dull (e) Pain radiation (f) Severity of the pain C. Examination Findings
- Vital Signs a) Inadequate gas exchange is noticed by changes in vital signs such as: (1) Increase in respiratory rate (a) Due to increased work of breathing (2) Decrease in oxygen saturation (a) When oxygen is not being transported by hemoglobin to cells (3) Increase in heart rate (a) Anxiety caused by not being able to breathe well (b) Anemia (4) Increase in temperature (a) Because of an infection, such as pneumonia or respiratory syncytial virus
- Inspection a) The nurse may notice: (1) The patient is assuming a position to ease the work of breathing (a) Sitting leaning forward (2) Patient appears anxious because of the sensation of not getting enough air or a feeling of suffocation (3) Patients may use accessory muscles on inspiration to help get air into the lungs (4) Patient may use pursed-lip breathing on exhalation to keep airways open longer (5) The skin and lips may appear pale because of anemia or hypoxemia (6) Clubbing of nails (7) Barrel chest (8) Asymmetric thorax b) Assessment findings commonly noted in infants and young children include: (1) Flaring of the nares
(2) Chest wall retractions on inspiration (3) Grunting on inspiration (4) Cyanosis around the lips when sucking (5) The need to stop during feeding to breathe 3. Auscultation a) Narrowed bronchi may produce expiratory and/or inspiratory wheezing or stridor b) Mucus or secretions in the bronchi may create rhonchi c) Fluid in alveoli may generate crackles D. Diagnostic Tests
- Laboratory Tests a) Arterial blood gases (1) Reveal measurements of pH, oxygen, carbon dioxide, and bicarbonate concentrations in arterial blood (2) Used to detect respiratory acidosis and alkalosis (3) Respiratory acidosis (a) Develops during hypoventilation when carbon dioxide is retained, such as in patients with COPD (4) Respiratory alkalosis (a) Develops during hyperventilation when excessive carbon dioxide is exhaled, such as during anxiety or hysteria b) Complete blood count (1) RBC count determines the oxygen-carrying capacity of the blood (a) Patients who have anemia have decreased number of RBCs, which reduces the patient’s oxygen-carrying ability (2) Hemoglobin (Hb) level reflects the number of RBCs in the venous blood and determines the oxygen and carbon dioxide transport capability (3) Hematocrit (Hct) measures the percentage of venous blood volume that is composed of RBCs. The Hct closely reflects the Hb and RBC values (4) WBC count measures the number of leukocytes in venous blood. The WBC differential measures the percentage of each leukocyte contained within the total number of WBCs c) Sputum examination (1) Culture and sensitivity are performed on a single
(1) V/Q scans use radioactive particles to diagnose disorders involving both perfusion and ventilation (2) Also injected into peripheral veins to detect impaired perfusion to the lungs (3) Inhaled radioactive particles are used to detect impaired lung function (4) This scan is used to diagnose pulmonary emboli d) Positron emission tomography (1) PET scans use IV injection of radioactive chemical compounds to distinguish benign from malignant pulmonary nodules 3. Pulmonary Function Studies a) Pulmonary function tests assess the presence and severity of diseases in large and small airways b) A spirometer measures the volume of air moving in and out of the lungs and then calculates the lung capacities (1) An example of its use is for patients with asthma (a) Because their bronchoconstriction worsens, they exhale less air (b) This finding is reported as decreased forced expiratory volume c) Pulmonary function tests are also used to distinguish between obstructive and restrictive pulmonary diseases d) Patients may develop restrictive lung diseases from intrapulmonary or extrapulmonary causes (1) Intrapulmonary causes include pulmonary fibrosis or empyema (2) Extrapulmonary causes include chest include chest wall trauma or cervical spinal cord injury e) Restrictive lung diseases impair the patient’s ability to get air into the lungs, as reflected in a decreased tidal volume 4. Endoscopy Examination a) Bronchoscopy is an endoscopic examination in which a flexible fiber-optic bronchoscope is extended through the bronchi for the purpose of diagnosis, specimen collection, or tissue biopsy VIII. Clinical Management A. Primary Prevention
- Infection Control a) Proper hand hygiene helps to prevent respiratory tract infections
b) Individuals should be instructed to clean surfaces that are frequently touched, such as doorknobs and countertops c) Coughing or sneezing into a tissue or into the elbow or sleeve reduces the particles delivered into the air d) Avoiding large groups of people reduces the airborne transmission of microorganisms 2. Smoking Cessation a) Healthy People 2020 goals related to tobacco use include: (1) Reducing tobacco use and initiation by adolescents and adults (2) Adopting policies and strategies to increase access, affordability, and use of smoking cessation services and treatments (3) Establish policies to reduce exposure to secondhand smoke, increase the cost of tobacco, restrict tobacco advertising, and reduce illegal sales to minors b) Smokers often report lack of success in smoking cessation because of stress, weight gain, and withdrawal symptoms, which include irritability, anxiety, difficulty concentrating, and increased appetite c) People who are successful at smoking cessation greatly reduce their risk for disease and premature death 3. Immunizations a) Immunizations prevent infection by bacteria or viruses, such as diphtheria, Hib, H1N1 flu, influenza, measles, pneumococcal pneumonia, pertussis, and rubella 4. Preventing Postoperative Pulmonary Complications a) After surgery, patients are encouraged to deep breathe and cough at least every 2 hours and/or use an incentive spirometer to prevent pneumonia and atelectasis (1) This device encourages deep breathing for patients and measures the air inhaled as an outcome indicator that is useful for nursing assessment b) Preventing deep vein thrombosis is essential for all patients who are less active than usual so that pulmonary emboli are prevented (1) Interventions for DVTs and pulmonary emboli include: (a) Subcutaneously administer an anticoagulant to reduce clotting of platelets (b) Apply elastic stockings to the legs or use intermittent compression devices to the lower
eosinophils and leukocytes; and decrease edema of airway mucosa (c) May be given by inhalation, orally, or intravenously (2) Sympathomimetic agents (a) Agonists that act on these receptors to relax bronchial smooth muscle of the lung to relieve bronchospasm (b) These agents stimulate the normal sympathetic nervous system to open airways (3) Anticholinergics (a) Improve lung function by blocking muscarinic receptors in the bronchi, causing bronchodilation (b) These agents block the normal parasympathetic nervous system so it cannot stimulate constriction of airways c) Agents to help cough up mucus (1) Mucolytics (a) React directly with the mucus to make it more liquid (2) Expectorants (a) Cause the cough to be more productive by stimulating the flow of respiratory tract secretions d) Agents to suppress cough (1) Coughing is a protective mechanism and is useful to expectorate sputum (2) When coughing is chronic and nonproductive, it may prevent sleep or tire the patient, making cough suppression therapeutic (3) Most antitussives act within the central nervous system e) Antimicrobials (1) Respiratory tract infections are treated with antimicrobials to kill or limit the growth of microorganisms f) Agents to aid smoking cessation (1) Many products available as first-line treatment for smoking cessation are used as nicotine replacement therapy (NRT)
(a) Available in gum, lozenge, patch, inhaler, or nasal spray form (2) NRT allows smokers to substitute a drug source of nicotine for the nicotine in cigarettes and gradually withdraw the replacement nicotine to wean off nicotine completely 3. Oxygen Therapy a) Oxygen therapy is provided through a variety of delivery mechanisms when patients require more than 21% oxygen b) A nasal cannula is used to deliver 24% oxygen to 44% oxygen c) COPD patients should not use oxygen levels greater than 3L/min 4. Airway Management and Breathing Support a) Patients with an acute disorder causing impaired gas exchange may need airway support b) The nurse may insert an oropharyngeal airway to maintain the patient’s breathing c) Patients may require intubation using an endotracheal tube or tracheostomy tube d) Humidified oxygen is delivered to the trachea and bronchi e) When breathing support is needed, the patient’s respiratory rate and volume are controlled by a ventilator 5. Chest Physiotherapy and Postural Drainage a) Chest physiotherapy and postural drainage are performed for the purpose of loosening and moving secretions into large airways where they can be expectorated b) Chest physiotherapy includes percussion and vibration to loosen secretions c) Postural drainage involves positioning the patient in specific positions to use the benefit of gravity to remove secretions after they are loosened from specific segments of the lungs 6. Invasive Procedures a) Chest tubes (1) Placed in the pleura to remove air (pneumothorax) and/or blood (hemothorax) so that they lungs can be re-expanded after thoracic surgery or trauma b) Thoracentesis (1) A procedure to relieve a pleural effusion by inserting a needle into the pleural space to remove fluid c) Bronchoscopy
A concern for patients who expend more than usual energy to breathe, such as those with emphysema and cystic fibrosis
They require high-calorie, high-protein, and nutritious foods in small servings so they do not tire while eating X. Clinical Exemplars A. Featured Exemplars
Asthma a) A chronic disorder characterized by periods of reversible airflow obstruction b) Asthma attacks are caused by hyperreactive airways leading to contraction of the muscles surrounding the airways and inflamed airways c) Patients experience wheezing, coughing, dyspnea, and chest tightness d) Factors involved in the development of asthma include genetics, inhalation of airborne allergens or pollutants, airway infections, exercise, or emotional stress e) Asthma can be controlled with medication and avoidance of triggers for asthma attacks
Chronic Obstructive Pulmonary Disease a) COPD is characterized by chronic airflow limitation that is not fully reversible b) Includes two obstructive airway diseases: (1) Chronic bronchitis (a) Develops when hypersecretion of mucus obstructs the trachea and bronchi, caused by irritants such as cigarette smoke, air pollution, or respiratory infection (b) Symptoms are productive cough and dyspnea on exertion (2) Emphysema (a) Develops when the alveolar walls are destroyed leading to permanent abnormal enlargement (b) Most common cause is cigarette smoking (c) Emphysemic patients are often underweight with a barrel chest and become short of breath with minimal exertion c) COPD is typically diagnosed in adults approx 50 years of age after a long history of smoking d) It is the third leading cause of death in the United States
Lung Cancer a) Uncontrolled growth of anaplastic cells in the lung describes lung cancer b) Causes include cigarette smoke, asbestosis, ionizing radiation, or other inhaled toxins c) The most common initial symptom is persistent cough d) Lung cancer is the leading cause of cancer-related deaths in the United States
Pneumonia a) An inflammation of terminal bronchioles and alveoli results in pneumonia b) Microorganisms are most frequent causes c) Viral pneumonia tends to produce a nonproductive cough or clear sputum, whereas bacterial pneumonia causes a productive cough of white, yellow, or green sputum d) Other manifestations include fever, chills, dyspnea on exertion, and sharp, stabbing chest pain in inspiration e) Rhonchi or crackles may be heard on auscultation f) Children may experience retractions and nasal flaring g) Viral pneumonias occur more frequently than bacterial pneumonia in children of all ages h) Older adults with pneumonia may experience confusion
Anemia a) Oxygen moves from the alveoli to the cells attached to erythrocytes b) When erythrocytes are in short supply, as occurs in anemia, oxygenation is less than optimal c) Anemia is caused by disorders that interfere with the formation of erythrocytes, premature destruction of erythrocytes, and loss of erythrocytes d) Despite the cause, common manifestations that occur in all anemias include weakness, fatigue, pallor, exertional dyspnea, dizziness, and lethargy
Pulmonary Emboli a) A blockage of pulmonary arteries by a thrombus, fat or air embolism, or tumor tissue creates a pulmonary embolism b) The embolus travels with blood flow through smaller blood vessels until it obstructs perfusion of alveoli c) Most emboli arise from DVT in the legs d) Venous thromboembolism is the preferred terminology to describe the spectrum of pathology from DVT to PE
Giddens Concept 19 Gas Exchange Outline
Course: Health/Illness Concepts (NSG 170)
University: Germanna Community College
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