SV_Pre-Class_Gas Exchange.pdf

Gas Exchange Beth Flott, EdD, RN  Gas Exchange Definition - The process by which oxygen is transported to cells and carbon dioxide is transported from cells Antecedents Defining Characteristics Positive Consequences Risk Factors Negative...

Gas Exchange Beth Flott, EdD, RN  Gas Exchange Definition - The process by which oxygen is transported to cells and carbon dioxide is transported from cells Antecedents Defining Characteristics Positive Consequences Risk Factors Negative Consequences Interrelated Concepts Exemplars  Ventilation – the process of inhaling oxygen into the lungs and exhaling carbon dioxide Tidal Volume Respiration - Exchange of oxygen and carbon dioxide at alveoli Gas Exchange Atelectasis: collapse of lung tissue  Transport Refers to the availability and ability of hemoglobin to carry oxygen from alveoli to cells for metabolism and to carry carbon dioxide produced by cellular metabolism from cells to alveoli to be eliminated Transport is impaired when the hemoglobin is low Gas Exchange Perfusion The ability of blood to transport oxygen-containing hemoglobin to cells and return carbon dioxide-containing hemoglobin to the alveoli When perfusion is impaired oxygen does not reach cells – resulting in ischemia and potentially necrosis  Gas Exchange – Ventilation/Perfusion Transport Relationship Hypoxemia (Low PaO2) Can be due to impaired ventilation OR impaired perfusion/transport Impaired Ventilation Impaired O2 delivery to alveoli Hypoventilation of alveoli Diffusion of oxygen across the alveolar capillary membrane Impaired Perfusion/Transport Diffusion of oxygen across the alveolar capillary membrane Gas Exchange  Atmosphere (21% Oxygen) Medulla Thorax intact, diaphragm contracts Nose Trachea Bronchi Alveoli Pulmonary capillaries - hemoglobin to carry O2 Perfusion to transport hemoglobin to cells Cell Metabolism Gas Perfusion to transport hemoglobin from cells Exchange Pulmonary capillaries with hemoglobin to carry CO2 Alveoli Bronchi Trachea Nose Thorax intact, diaphragm Atmosphere (21% Oxygen)  Gas Exchange Chemoreceptors – Sense when CO2 levels are high and sends impulse to diaphragm and intercostal muscles to contract Negative Pressure pulls in 21% O2 from the air Nose warms and humidifies the air and it flows to the alveoli through patent airways (trachea/bronchi) Alveolar walls are lined with Alveolar type I & II cells. Alveolar type II are thicker and produce surfactant - a lipoprotein that coats the inner surface of the alveoli to keep them open. Pores of Kohn allow air to pass from one alveolus to another – collateral ventilation and even distribution among alveoli occurs High pressure of O2 causes it to diffuse from the alveoli to the capillaries where O2 attaches to hemoglobin and is carried as oxyhemoglobin O2 is released from hemoglobin and is dissolved in plasma which diffuses into the interstitial space and then into cells to be used in the metabolic process CO2 is transported to the atmosphere in the reverse order of O2 and lowers the arterial CO2 level  Gas Exchange Risk Factors Populations – infants, young children, older adults Smoking, exposure to chemicals/irritants Allergies Tracheal intubation/Endotracheal intubation Immunosuppression Chronic Disease Immobility  Gas Exchange Clinical Manifestations What are signs and symptoms you would anticipate seeing in your patients that exhibit impaired ventilation/gas exchange disorders? Vital sign changes Health assessment/Physical exam Skin, hair nails Respiratory – lung sounds General survey Diagnostic Tests  Gas Exchange Central Oxygenation Peripheral Oxygenation Cyanosis Chest Pain Dyspnea Dyspnea on exertion Orthopnea Paroxysmal Nocturnal Dyspnea Cough Sputum Hemoptysis  Hypoventilation Neuromuscular/respiratory causes CO2 is removed slower than made = hypercapnia Hyperventilation Gas Tachypnea or hyperpnea Anxiety, pain, neurological injury Exchange CO2 is removed faster than made = hypocapnia Gas Exchange - Pneumothorax Gas Exchange – Pleural Effusion  Pneumonia Etiology Bacterial Viral Community-acquired (CAP) Gas Healthcare-acquired (nosocomial) (VAP) Aspiration Exchange Gas Exchange - Pneumonia Gas Exchange – Pulmonary Edema  Gas Exchange Acute Respiratory Distress Syndrome (ARDS) Resolution phase Three phases Diffuse pulmonary scarring alters normal lung, microscopic fibrosis remains Exudative phase Pulmonary function recovers gradually Five to seven days after initial injury Over six months to one year Damage to alveolar–capillary membrane Inflammatory mediators, proteins, fluid, cellular debris collect in alveoli Fibroproliferative phase Persistent hypoxemia, reduced lung compliance Inflammation resolves, macrophages phagocytize hyaline membrane Myofibroblasts deposit collagen - lasts two to three weeks Gas Exchange - ARDS Gas Exchange - ARDS  Population Differences Infants = incomplete development of airways, circulation, chest wall, and immune system Premature infants at even greater risk Gas Manifestations Flaring of nares Exchange – Chest wall retractions Pediatric Grunting on inspiration Disorders Cyanosis around lips Need to stop feeding to breathe  Gas Exchange Pneumonia RSV (respiratory syncytial virus #1 cause) Paramyxovirus – affects epithelial cells of respiratory tract; loss of cilia occurs and fills with mucus and exudate Manifestations: Increased coughing and wheezing, fever, tachypnea and retractions, refusal to nurse or bottle feed, copious secretions Asthma ARDS  Gas Exchange – Infant Respiratory Distress Syndrome Pathogenesis Deficiency of surfactant Immature lung unable to produce enough surfactant Genetic mutation High surface tension Inflammation in lung Pulmonary edema Increased airway resistance  Gas Exchange Bronchopulmonary Dysplasia/Chronic Lung Disease of Prematurity Risk Factors Prematurity Long-term mechanical ventilation Poor formation of alveoli Decreased surface area for gas exchange Persistent inflammation damages capillaries – vasoconstriction Monitor into adulthood for permanent lung damage  Gas Exchange – Cystic Fibrosis  Gas Exchange – Cystic Fibrosis Autosomal-Recessive genetic disorder Gas Exchange - Asthma Gas Exchange – Asthma Types Allergic asthma (most common) Allergen causes type 1 hypersensitivity response Recurrent asthma Airways remodeled Bronchial smooth muscles hypertrophy, increasing capacity for bronchoconstriction  Gas Exchange - COPD Chronic Obstructive Pulmonary Disease (COPD) Chronic Bronchitis Emphysema Gas Exchange - COPD Gas Exchange - COPD Gas Exchange - COPD Gas Exchange - COPD Questions?? 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