Fundamentals – Oxygenation PDF

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Kristen Needler...

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Fundamentals – Oxygenation/Gas Exchange 

Oxygenation – mechanisms that facilitate or impair the body’s ability to supply oxygen to all cells of the body o The function of the respiratory system is to obtain oxygen from atmospheric air, to transport this air through the respiratory tract into the alveoli, and ultimately to diffuse oxygen into the body that carries oxygen to all the cells of the body.

Pulmonary system 

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Process of oxygenation o Ventilation  Process of moving gases into and out of the lungs o Perfusion  Ability of the cardiovascular system to pump oxygenated blood to the tissues and return deoxygenated blood to the lungs o Diffusion  Exchange of respiratory gases in the alveoli and capillaries of the body tissues  The thickness of the alveolar capillary membrane affects the rate of diffusion  Diffusion of respiratory gases occurs at the alveolar capillary membrane  Patients with pulmonary edema, pulmonary infiltrates, or pulmonary effusion have a thickened membrane  Resulting in slow diffusion, slow exchange of respiratory gases, and decreased delivery of oxygen to tissues  Chronic diseases (emphysema), acute diseases (pneumothorax), and surgical processes (lobectomy) often alter the amount of alveolar capillary membrane surface area Oxygen transport = lungs + cardiovascular (CV) system Hemoglobin carries O2 and CO2 The oxygen transport system consists of the lungs and cardiovascular system o Delivery depends on the amount of oxygen entering the lungs (ventilation), blood flow to the lungs and tissues (perfusion), the rate of diffusion, and the oxygen-carrying capacity. o The airways of the lung transfer oxygen from the atmosphere to the alveoli, where the oxygen is exchanged for CO2 Three things influence the capacity of the blood to carry oxygen: o Amount of dissolved oxygen in the plasma o Amount of hemoglobin o Tendency of hemoglobin to bind with oxygen Hemoglobin – carrier for oxygen and carbon dioxide, transports most (97%) oxygen o Decreased hemoglobin levels alter the patient’s ability to transport oxygen

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Conditions and diseases that changed the structure and function of the pulmonary system alter respiration Gases move into and out of the lungs through pressure changes. o Intrapleural pressure is negative, or less than atmospheric pressure, which is 760 mm Hg at sea level. o For air to flow into the lungs, intrapleural pressure becomes more negative, setting up a pressure gradient between the atmosphere and the alveoli. o The diaphragm and external intercostal muscles contract to create a negative pleural pressure and increase the size of the thorax for inspiration. Relaxation of the diaphragm and contraction of the internal intercostal muscles allow air to escape from the lungs.

Cardiovascular physiology 

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Cardiopulmonary physiology involves delivery of deoxygenated blood (blood high in carbon dioxide and low in oxygen) to the right side of the heart and then to the lungs, where it is oxygenated. Oxygenated blood (blood high in oxygen and low in carbon dioxide) then travels from the lungs to the left side of the heart and the tissues. o The cardiac system delivers oxygen, nutrients, and other substances to the tissues and facilitates the removal of cellular metabolism waste products by way of blood flow through other body systems such as respiratory, digestive, and renal. o The primary functions of the heart are to deliver deoxygenated blood to the lungs for oxygenation, and oxygen and nutrients to the tissues. Systemic circulation o Arteries and veins deliver nutrients and oxygen and remove waste products Blood flow regulation o

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Normal cardiac output is 4 to 6 L/min in the healthy adult at rest.

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The volume of blood ejected from the ventricles during systole is the stroke volume. Hemorrhage and dehydration cause a decrease in circulating blood volume and a decrease in stroke volume.  The amount of blood in the left ventricle at the end of diastole (preload), resistance to left ventricular ejection (afterload), and myocardial contractility all affect stroke volume. Heart rate affects blood flow because of the relationship between rate and diastolic filling time.

Factors affecting oxygenation 

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Physiological factors o Decreased oxygen-carrying capacity  Anemia o Hypovolemia  Dehydration and hemorrhage o Decreased inspired oxygen concentration  High altitudes o Increased metabolic rate  Fever o Any condition that affects cardiopulmonary functioning directly affects the body’s ability to meet oxygen demands o When patients take opioids, their respiratory center is depressed Factors affecting chest wall movement o Pregnancy o Obesity o Musculoskeletal abnormalities  Kyphosis, pectus excavatum o Trauma  Flail chest is a condition in which multiple rib fractures cause instability in part of the chest wall. o Neuromuscular disease  myasthenia gravis, Guillain-Barre syndrome, and poliomyelitis. o CNS alterations  Cervical trauma at C3 to C5 usually results in paralysis of the phrenic nerve. o Chronic disease  COPD Alterations in respiratory functioning o Hypoventilation: alveolar ventilation inadequate to meet the body’s oxygen demand; respiratory rate and depth is low  Caused by atelectasis and collapsed alveoli  Signs and symptoms:  Mental status changes, cardiac dysrhythmias, convulsions, dizziness, headache upon awakening, lethargy, electrolyte imbalances, coma, and cardiac arrest

Hyperventilation: ventilation in excess of that required; rate and depth of respirations increase  Can be caused by anxiety, infection, drugs, acid-base imbalance, fever, aspirin poisoning, or amphetamine use.  Signs and symptoms:  Rapid respirations, sighing breaths, numbness and tingling of hands/feet, light-headedness, loss of consciousness o Hypoxia: Inadequate tissue oxygenation at the cellular level, late sign cyanosis  Causes may include: anemia, carbon monoxide poisoning, septic shock, cyanide poisoning, pneumonia atelectasis, cardiomyopathy, spinal cord injury, and head trauma  Decrease in hemoglobin and lowered O2 carrying-capacity of blood, diminished inspired O2, a decrease in diffusion of O2 from the alveoli to the blood, impaired ventilation  Signs and symptoms:  Spprehensive, restlessness, inability to concentrate, decreased LOC, dizziness, behavioral changes, agitated, increased RR and HR  What is a late sign of hypoxia? o Cyanosis, and lowered RR and HR Lifestyle factors o Nutrition  Cardioprotective nutrition = diets rich in fiber, whole grains, fresh fruits and vegetables, nuts, antioxidants, lean meats, and omega-3 fatty acids  Severe obesity decreases lung expansion, and increased body weight increases tissue oxygen demands.  Patients who are morbidly obese and/or malnourished are at risk for anemia.  Diets high in carbohydrates play a role in increasing the carbon dioxide load for patients with carbon dioxide retention. o Exercise  people who exercise 30-60 mins daily have a lower pulse rate and BP, cholesterol level, increased blood flow, and greater oxygen extraction be working muscles o Smoking  Associated with heart disease, COPD, and lung cancer  The risk of lung cancer is 10 times greater for a person who smokes than for a nonsmoker.  Cigarette smoking and secondhand smoke are associated with a number of diseases, including heart disease, COPD, and lung cancer. Cigarette smoking worsens peripheral vascular and coronary artery diseases.  Women who take birth control pills and smoke cigarettes are at increased risk for thrombophlebitis and pulmonary emboli.  Exposure to secondhand smoke is also dangerous. o Substance abuse  Excessive use of alcohol and other drugs impairs tissue oxygenation. o Stress o

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A continuous state of stress or severe anxiety increases the metabolic rate and oxygen demand of the body.  The body responds to anxiety and other stresses with an increased rate and depth of respiration. Most people adapt, but some, particularly those with chronic illnesses or acute life-threatening illnesses such as an MI, cannot tolerate the oxygen demands associated with anxiety. Environmental factors o The incidence of pulmonary disease is higher in smoggy, urban areas than in rural areas. o A patient’s workplace sometimes increases the risk for pulmonary disease.  Asbestosis  Asbestosis is an occupational lung disease that develops after exposure to asbestos. The lung with asbestosis often has diffuse interstitial fibrosis, creating a restrictive lung disease. Patients exposed to asbestos are at risk for developing lung cancer, and this risk increases with exposure to tobacco smoke.  Others include: talcum powder, dust, and airborne fibers.  For example, farm workers in dry regions of the southwestern United States are at risk for coccidioidomycosis, a fungal disease caused by inhalation of spores of the airborne bacterium Coccidioides immitis. 

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Pneumonia   

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Acute inflammation of the lung that is most frequently caused by a microorganism Fluid and exudate in the alveoli o Streptococcus pneumoniae Interventions: o Positioning HOB up – semi fowlers  Helps to drain secretions from specific segments of the lungs and bronchi into the trachea o Nasal cannula  Delivers flow rate up to 6 L/min  24% to 44% oxygen  Starting at 1 L/min, increasing the oxygen flow by 1 L/min will increase the inspired oxygen concentration about four percentage points:  1 L/min = 24%  2 L/min = 28%  3 L/min = 32%  4 L/min = 36%  5 L/min = 40%  6 L/min = 44% o Incentive spirometry o Deep breathing and coughing  Diaphragmatic breathing/belly breathing  Technique used that increases airflow to the lower lungs. It also opens the pores of Kohn between alveoli to allow sharing of oxygen between alveoli which is especially important since this pt has a lot of mucus.

Cascade and cascade cough  Methods of coughing that will keep the throat open longer in order to help move the mucous from the lungs more effectively. o Encourage fluids  Hydration, humidification, nebulization, oral and IV  Hydration keeps mucociliary clearance normal. With adequate hydration, pulmonary secretions are thinner, whiter, and more watery thus making it easier to expel. Methods of Oxygen Delivery o Simple face mask  Delivers 35%-50% at liter flows of 6-12 L/min  Minimum of 6 L/min is required o A plastic face mask with a reservoir bag is capable of delivering higher concentrations of oxygen. A partial rebreather mask is a simple mask with a reservoir bag that should be at least one third to one half full on inspiration and delivers from 60% to 90% with a flow rate of 10-15 L/min  Non-Rebreather Mask  Oxygen 60% to 90% 10-15 L/min flows into reservoir bag and mask. Valve prevents expired air from flowing back into bag.  Partial Rebreather Mask  Reservoir bag conserves oxygen concentrations of 40-60% at 6-10 L/min only difference is valve between mask and bag is removed. The oxygen reservoir bag is attached allows the client to rebreathe about the first third of the exhaled air in conjunction with oxygen o Venturi mask delivers higher oxygen concentrations of 24%-50% with oxygen flow rates of 4 to 12 L/min, depending on the flow-control meter selected  Minimum of 4 L/min 

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Oxygen Safety    

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Oxygen must be prescribed and adjusted only with a HCP’s order. Determine that all electrical equipment in the room is functioning correctly and properly grounded. An electrical spark in the presence of oxygen can result in a serious fire. Check the oxygen level of portable tanks before transporting a patient to ensure there is enough oxygen in the tank. Secure oxygen cylinders so they do not fall over; store them upright and either chained or secured in appropriate holders Parts of a tracheostomy tube. o Tracheostomy tube inserted in airway with inflated cuff. o Fenestrated tracheostomy tube with cuff, inner cannula, decannulation plug, and pilot balloon. o Tracheostomy tube with foam cuff and obturator (one cuff is deflated on tracheostomy tube). Suctioning

Necessary when patients are unable to clear respiratory secretions from the airways by coughing or other less invasive procedures o Contraindications to nasotracheal suctioning  Occluded nasal passages  Nasal bleeding  Epiglottitis  Croup  Acute head, facial, or neck injury or surgery  Coagulopathy or bleeding disorder  Irritable airway  Laryngospasm or bronchospasm  Gastric surgery with high anastomosis  Myocardial infarction o Key points: o Use sterile procedure o Suction set on continuous suction up to120 mm Hg for open suctioning o Suction set on continuous suction up to160 mm Hg for closed suctioning. o Insert catheter, suction intermittently 10 seconds and slowly rotate and withdraw o Allow 20-30 seconds between passes o Monitor patient: o Risk for hypoxia o Hypotension o Arrhythmias o Trauma o Irritation o Vagal stimulation  Potentially hazardous complication from suctioning, can lead to bradycardia o Review the skill in the book for specific steps Changing a tracheostomy tube o A, A slit is cut about 1 inch (2.5 cm) from the end. The slit end is put into the opening of the cannula. o B, A loop is made with the other end of the tape. o C, the tapes are tied together with a double knot on the side of the neck. o D, A tracheostomy tube holder can be used in place of twill ties to make tracheostomy tube stabilization more secure. o A two-person technique, one to stabilize the tracheostomy and one to change the ties, is best to assure that the tracheostomy does not become accidentally dislodged during the procedure. Patient is having Acute Dyspnea o Acute dyspnea for patient with tracheostomy is most commonly caused by partial or complete blockage of the tracheostomy tube retained secretions. To unblock the tracheostomy tube: o 1. ASK THE PATIENT TO COUGH: A strong cough may be all that is needed to expectorate secretions. o

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2. REMOVE THE INNER CANNULA: If there are secretions stuck in the tube, they will automatically be removed when you take out the inner cannula. The outer tube – which does not have secretions in it – will allow the patient to breath freely. Clean and replace the inner cannula. o 3. SUCTION: If coughing or removing the inner cannula do not work, it may be that secretions are lower down the patients airway. Use the suction machine to remove secretions. o 4. If these measures fail – commence low concentration oxygen therapy via a tracheostomy mask, and call for medical assistance. Passy-Muir speaking tracheostomy valve o The valve is placed over the hub of the tracheostomy tube after the cuff is deflated. Multiple options are available and can be used for ventilated and nonventilated patients. The valve contains a one-way valve that allows air to enter the lungs during inspiration and redirects air upward over the vocal cords into the mouth during expiration. o

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Oxygenation: chest tubes  

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Chest tubes o A catheter placed through the thorax to remove air and fluids from the pleural space Purpose o To remove air and fluids from the pleural space o To prevent air or fluid from reentering the pleural space o To re-establish normal intra-pleural and intra- pulmonary pressures Chest tube interventions o Maintain secure, airtight dressing o Maintain underwater seal o Monitor and secure all connections o Observe for bubbling o Monitor tubing for patency o Record output (quantity, characteristics) o Monitor patient o Dressing changes per agency

Summary of interrelated concepts with Gas Exchange     

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Anxiety Perfusion Fatigue Nutrition Mobility...