Transcript Oxygenation
Chapter 40: Oxygenation Bonnie M. Wivell, MS, RN, CNS Structure and Function of the Heart • Right ventricle pumps blood through the pulmonary circulation • Left ventricle pumps blood through the systemic circulation • The circulatory system exchanges respiratory gases, nutrients, and waste products between the blood and tissues Myocardial Pump • Four chambers: 2 atria, 2 ventricles • Fill with blood during diastole, empty during systole • CAD and cardiomyopathy result in decreased pumping action and decreased stroke volume • Frank-Starling’s law: the more stretch on the ventricle muscle, the greater the contraction and the greater the stroke volume ▫ Diseased heart = contractile response resulting in insufficient stroke volume → “back up” in pulmonary → Left heart failure ▫ “back up” in circulation → Right heart failure Myocardial Blood Flow • Blood flow is unidirectional • Diastole = AV valves (mitral and tricuspid) open and blood flows from higher pressure atria to relaxed ventricles • Represents S1 or the first heart sound • Systole = Semilunar (aortic and pulmonic) valves open, and blood flows from the ventricles into the aorta and pulmonary artery • Closer of semilunar valves represents S2 • Murmur caused by regurge from diseased valve Coronary Artery Circulation • Supplies the myocardium with oxygen and nutrients and removes waste • Left and right coronary arteries rise from the aorta just above and behind the aortic valve through the coronary openings • The left coronary artery, the most abundant blood supply, feed the left ventricle, which does most of the heart’s work • Cardiac Function • http://www.youtube.com/watch?v=D3ZDJgFDdk0&feat ure=related Blood Flow Regulation • Cardiac Output (CO) = amount of blood ejected form the left ventricle each minute • CO changes according to the oxygen and metabolic needs of the body • CO = SV x HR • Stroke Volume (SV) = amount of blood ejected from the left ventricle with each contraction • Preload = amount of blood in the LV at the end of diastole • Afterload = the resistance to LV ejection Conduction System • Heart’s conduction system generates impulses needed to pump blood • Trace the impulse • http://www.youtube.com /watch?v=nK0_28q6Wo M&NR=1 Normal Sinus Rhythm Respiratory System • Lungs transfer O2 from atmosphere to aveoli • Ventilation • Perfusion • Diffusion • Respirations • http://www.youtube.com /watch?v=hpgCvW8PRY&feature=rela ted Work of Breathing • Intrapleural pressure is negative or different than the atmosphere ▫ Punctured lung – lung collapses • Inspiration – active process stimulated by chemical receptors in aorta (O2, CO2) • Expiration – passive process that depends on elastic recoil • Surfactant – a chemical produced in the lungs to maintain the surface tension of the alveoli and keep them from collapsing • Decreased surfactant from disease can develop atelectasis • Difficulty breathing – use accessory muscles (elevation of the clavicles) • Seen in COPD, causes fatigue • Compliance – ability of the lungs to distend or to expand in response to increased intraalveolar pressure; decreased compliance increases airway resistance Lung Volumes Pulmonary Circulation Respiratory Gas Exchange • Diffusion – thickness of membrane affects the rate of diffusion • Pulm edema, pulm infiltrates, pulm effusion • Ventilation – amount of O2 entering the lungs • Perfusion – blood flow to lungs and tissues • What influences capacity of blood to carry oxygen? • Venous blood transports the majority of CO2 Regulation of Respiration • • • • • Neural regulators Cerebral Cortex Medulla Oblongata Chemical regulation Chemoreceptor Factors Affecting Oxygenation • Decrease in Hgb (O2 carrying capacity) ▫ Anemia – s/s fatigue, decreased activity tolerance, SOB, pallor, tachycardia • Decreased inspired O2 concentration • Hypovolemia • Increase metabolic rate increases O2 demand ▫ Normal in pregnancy, wound healing, and exercise as the body is building tissue ▫ Fever Conditions Affecting Chest Wall Movement • Pregnancy – baby pushes up against diaphragm resulting in dyspnea • Obesity • MSK abnormalities – pectus excavatum, kyphosis, lordosis, or scoliosis • Trauma – multiple rib fractures develop into a flail chest (unstable chest wall); incisions • Neuromuscular diseases – Myasthenia gravis, Guillain Barre syndrome, poliomyelitis • CNS – brain or spinal cord injury, phrenic nerve damage → diaphragm does not descend properl → reduces inspiration • Influence of chronic disease (COPD) influences the body to produce more RBCs (polycythemia vera) Disturbances in Cardiac Functioning • Disturbances in conduction – Dysrhythmias • Altered CO ▫ Left-sided heart failure: decreased CO, pulmonary congestion ▫ Right-sided heart failure: result of pulm disease or long term left-sided failure; increase pulm vascular resistance; congestion in systemic circulation (edema) • Impaired valvular function – stenosis • Myocardial ischemia ▫ Angina ▫ MI – females and elderly present differently Alterations in Respiratory Function • Goal: PaCO2 between 35-45 mm Hg and PaO2 95-100 mm Hg • Hyperventilation: state of ventilation in excess of that required to eliminate the CO2 produced by cellular metabolism; sometimes chemically induced (salicylate poisoning, amphetamines) • Hypoventilation: alveolar ventilation is inadequate to meet the body’s O2 demand or to eliminate sufficient CO2; atelectasis • Hypoxia: inadequate tissue oxygenation at the cellular level; cyanosis (central vs peripheral) COPD vs Asthma • Physiology, emphysema • http://www.youtube.com/watch?v=aktIMBQSXMo • http://www.youtube.com/watch?v=82gn_rDRpHk Developmental Factors • Infants and toddlers: at risk for URIs which are usually not dangerous • School-age children and adolescents: second hand smoke exposure, may start smoking • Young and middle-age adults: multiple risk factors such as unhealthy diet, lack of exercise, stress, OTC and RX meds not used as intended, illegal substances, and smoking • Older adults: calcification of heart valves, SA node and costal cartilages; osteoporosis changes size and shape of thorax Lifestyle • Modify risk factors ▫ Weight reduction ▫ Smoking cessation ▫ Low-cholesterol, low-Na+ diet ▫ Management of HTN ▫ Moderate exercise • Substance abuse • Stress • Environmental factors Nutrition • Cardio-protective nutrition ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ Fiber Whole grains Fresh fruit Vegetables Nuts Antioxidants Lean meats, fish, chicken Omega-3 fatty acids Assessment • Nursing History ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ Pain Fatigue Smoking Dyspnea/Orthopnea Cough/hemoptysis Wheezing Environmental or geographical exposures Respiratory infections Allergies Health risks Medications Physical Exam • Inspection – symmetry, breathing patterns, chest movement, barrel shape in COPD • Pink puffers/Blue bloaters • Palpation • • • • Thoracic excursion Tenderness Tactile fremitus, thrills, heaves, PMI CMS, edema • Percussion • Auscultation Diagnostic Tests • • • • • • CBC Cardiac Enzymes Myoglobin Serum Electrolytes Cholesterol Sputum (AFB, C/S, Cytology) • ECG • Stress test (Exercise vs Thallium) • Cardiac cath • PFTs • Bronchoscopy • Lung Scan • Thoracentesis Nursing Diagnosis • • • • • • Activity intolerance Anxiety Decreased cardiac input Fatigue Impaired gas exchange Ineffective airway clearance • Risk for infection • Impaired spontaneous ventilation • Impaired verbal communication • Ineffective breathing pattern • Ineffective health maintenance • Risk for imbalanced fluid volume Planning • Goals and outcomes ▫ ▫ ▫ ▫ Pt. will have clear lungs to auscultation Pt. will achieve bilateral lung expansion Pt. will have a productive cough Pt. will have maintain/improve pulse ox • Setting priorities • Collaborative care ▫ ▫ ▫ ▫ Family members Colleagues Other specialists Pulmonary rehab Implementation • Health Promotion ▫ Vaccinations • Healthy Lifestyle Behavior ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ Low-fat, high-fiber diet Reduce stress Exercise Maintain a good BMI Monitor cholesterol, triglycerides, HDL, LDL Eliminate smoking Avoid pollutants/second hand smoke Adequate hydration and sodium intake (especially if on diuretics Acute Care • • • • • • Dyspnea management Airway maintenance Mobilization of pulmonary secretions Hudification Nebulization Chest physiotherapy (CPT) ▫ Postural drainage (see pages 932-933) • Suctioning ▫ Oropharyngeal, nasopharyngeal, orothracheal, nasotracheal Acute Care Continued • Artificial airways (for decreased LOC) • Oral airway (displaces tongue) • Endotracheal and tracheal airway (high risk for infection) • Maintenance and promotion of lung expansion ▫ Positioning (turn, cough, deep breath) ▫ Incentive Spirometry (IS) Procedures • Thoracentesis ▫ http://www.youtube.com/watch?v=6-9WY2dbpc&feature=related • Chest tube insertion ▫ http://www.youtube.com/watch?v=B0wGmWn8 Ubs&feature=related • Pleur-Evac ▫ http://www.youtube.com/watch?v=-I4bj0qwhM0 Chest Tubes • Pneumothorax – a collection of air in the pleural space; loss of negative pressure in the intrapleural space • Spontaneous, or trauma • Often caused by the rupture of an air-filled sac in the lung, called a bleb or bulla • From procedure such as insertion of central line • Hemothorax – accumulation of blood and fluid in the pleural cavity usually as a result of trauma • Tension pneumo – air pressure builds in the pleural space, collapsing the lung and creating a life-threatening event Oxygen Therapy • Goal • Purpose • Safety Methods of Delivery • Nasal cannula • Simple face mask • Venturi mask • Home O2 ▫ Compressed ▫ Liquid ▫ Concentrator Restorative and Continuing Care • Hydration • Coughing techniques • Respiratory muscle training • Breathing exercises ▫ Pursed-lip breathing to blow off CO2 • Diaphragmatic breathing Evaluation