Tissue Hypoxia and Oxygen Therapy

Tissue Hypoxia and Oxygen Therapy ก ก ก ก ก ก 1. ก ก 2. ก ก 3. tissue hypoxia 4. ก ก ก 5. ก ก ก 6. ก กก ก 7. ก ก tissue hypoxia ก ก ก ก 1. Pathway of oxygen transport 2. Causes of tissue hypoxia 3. Effect of oxygen administration 4. Oxygen devices with spontaneous breathing 5. Selection of patient for oxygen devices with spontaneous breathing 6. Effects of inadequate humidification of inspired gases 7. Humidifier and nebulizer 8. Evaluation of oxygen therapy 9. Oxygen hazard ก ก ก ก ก ก ก ก ก ก ก ก ก 21% ก ก ก ก ก ก ก ก

ก ก ก ก (diffusion) ( pulmonary capillaries) ก ก ก oxidative phosphorylation ก ATP (adenosine triphosphate) ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก กก ก ก ก ก ก (tissue hypoxia) ก ก กก ก ก ก ก ก ก ก (pathway of oxygen transport) ( 1 ) 2 FiO 2 ventilation http://www.niehs.nih.gov/factsheets/ozone/ithurts.htm diffusion cell http://www.rnceus.com/course_frame.asp?exam_id=18& directory=abgs http:www.biology.eku.edu/ritchiso/301 notes6.htm 1 Oxygen transport

กก FiO 2 ก ก FiO 2 0.2 ก ก ก ก (pulmonary gas exchange) ก ก ก ก ก ก ก ก ก ก 1. Alveolar ventilation ก ก ก ก ก ก ก ก (atelectasis) (pneumonia) (pulmonary edema) 2. Diffusion ก ก (alveoli) ( pulmonary capillaries) ก ก (pulmonary embolism) (pulmonary hypertension) 3. Perfusion ก ก ก ก ก (ventilation/perfusion matching) ก ก ก ก ก กก (capillary gas exchange) ก ก ก 1. Capillary perfusion systemic circulation pulmonary circulation ก (congestive heart failure) 2. Oxygen delivery ก ก ก ก ก ก plasma ก (cardiac output) ก Arterial O 2 content = Dissolved O 2 + Hb-bound O 2 = (0.003 x PaO 2 ) + (1.34 x Hb x SaO 2 ) Oxygen delivery = Cardiac output x arterial O 2 content = Heart rate x stroke volume x O 2 content ก ก ก, oxygen saturation, PaO 2 cardiac output ก ก ก ก ก ก oxyhemoglobin dissociation curve ก ก ก ก (O 2 affinity) ph, PaCO 2, ก 2-3-DPG (2-3-diphosphoglycerate) ก PaO 2 SaO 2 ก ก ก ก ก ph 7.4, ก 37 PaCO 2 40. ก ก ก ก ก ก (oxygen - hemoglobin affinity changes) oxyhemoglobin dissociation curve ( 2 ) 3

4 http:www.nursingceu.com/nceu/courses/acidbase2/ 2. Oxygen - hemoglobin affinity changes ก ก ก ก ก ก ก ก ก ก (tissue hypoxia) (ph, alkalosis), (hypothermia), ก (hypocarbia), ก 2-3-DPG ก ก ก ก ก ก ก ก ก ก ก (ph,acidosis), (hyperthermia), ก (hypercarbia), ก 2-3- DPG ก ก ก ก ก ก ก ก (cellular gas exchange) ก ก ก cell membrane mitochondria ก metabolism ก ก Tissue hypoxia tissue hypoxia ก ก ก ก 1. Hypoxic hypoxia ก ก ก ก ก ก (pulmonary gas exchange) ก ก (PaO 2 ) ก hypoxemia ก ก ก กก ก ก ก 1.1 FiO 2 (high altitudes) 1.2 Alveolar hypoventilation ก ก ก ก (PAO 2 )

1.3 Ventilation/perfusion mismatch ก hypoxemia asthma, hemo/pneumothorax, atelectasis, pneumonia 1.4 Diffusion defect ก ก ก 1.5 Shunt effect ก ก ก ก hypoxemia ก ก ventilation/perfusion mismatch, hypoventilation diffusion defect 2. Anemic hypoxia ก ก ก 3. Circulatory hypoxia ก shock, arterial occlusion 4. Histotoxic hypoxia ก cyanide toxic ก ก ก 5. Hypermetabolic hypoxia ก metabolism กก ก supply ก ก ก ก Oxygen therapy tissue hypoxia ก ก ก ก กก 1. ก ก (correct document/suspected acute hypoxemia) ก ( alveolar oxygen tension; PAO 2 ) (PaO 2 ) 2. ก ก ก (decrease symptoms of chronic hypoxemia) ก ก ก chronic hypoxemia 3. ก (decrease cardiopulmonary workload) ก ก ก ก ก ก ก ก ก ก 1 5

6 ก ก ก 1 ก ก hypoxemia 1. PAO 2 PaO 2 2. work of breathing ก 3. myocardial workload ก ก (myocardial ischemia) (right heart failure) ก ก ก ก AARC Clinical Practice Guideline 2002 oxygen therapy ก ก กก ก (ambient air) ก ก ก ก ก hypoxia ก ก (indication of oxygen therapy) 1) ก ก ก (documented hypoxemia) PaO 2 < 60. SaO 2 < 90% ก ก PaO 2 SaO 2 ก ก ก 2) ก hypoxemia ก ก ก 3) (severe trauma) 4) ก ( acute myocardial infarction) 5) ก ก ก ก ก ก ก (contraindication) ก ก

ก ก 1) ก ก ก PaO 2 กก ก 60. PaCO 2 ก ก 2) ก (absorption atelectasis), ก (oxygen toxicity) ก ก ก ก (ciliary) ก (leukocytic) ก (FiO 2 ) > 0.5 3) ก ก ก paraquat bleomycin 4) ก ก ก ก 5) ก ก ก ก 6) ก ก ก ก (nebulizer) 7 ก ก ก ก ก ก ( 1) ก ก ก 2 1 ก ก ก ก ก ก

8 ก ก ก ก ก ก Tunnel vision Loss of coordination ก ก ก Manic-depressive activity 2 ก ก ก ก ก ก (oxygen devices with spontaneous breathing)

1. Low-flow systems devices ก 100 % ก flow ก 10 LPM ก variable performance ก flow ก inspiratory flow rate demand ก ก ก ก FiO 2 ก ก reservoir, flow ก ก minute ventilation ก low-flow 1.1 Nasal cannula nasal prongs ( 3) ก 24-40% flow 1 LPM FiO 2 0.04 ก flow ก 4 LPM flow กก 6 LPM ก ก ก ก ก 1.2 Cannulocollar mask ( 8) ก ก ก ก tracheostomy mask ก humidifier flow 3 LPM ก ก ก nasal cannula ก ก ก nebulizer กก humidifier 1.3 Simple face mask ( 4) ก 35-50%, flow 5-10 LPM flow 5 LPM ก rebreathing (exhaled CO 2 ) mask ก ก ก ก ก ก FiO 2 กก nasal cannula 1.4 Partial rebreathing mask ( 5) simple mask with reservoir bag. flow. ก bag ก 1 3 bag FiO 2 ก flow 6-10 LPM ก 40-70% ก 1 3 ก reservoir bag ก ก exhalation port flow ก ก FiO 2 ก ก FiO 2 humidifier 1.5 Non-rebreathing mask ( 6 ) ก partial rebreathing mask ก one-way valves 2 ก bag mask ก ก (exhaled CO 2 ) ก bag 2 exhalation port ก ก ก ก flow 10 LPM ก ก ก ก 60-80% ก 100% ก variable performance 9

ก FiO 2 ก flow ก ก 10 Exhalation port 3 Nasal cannula 4 Simple face mask 5 Partial rebreathing mask 6 Non-rebreathing mask flow FiO 2 ก low-flow systems devices ( 2 ) 2 Guidelines for estimating FiO 2 with low-flow oxygen devices

11 2. High-flow systems devices flow ก กก respiratory flow demand ก ก ก ก flow ก ก ก ก FiO 2 ก ก FiO 2 fixed performance ก 2.1 Air-entrainment system air-entrainment port ก ก jet orifice flow ก กก venturi effect ( 7) negative pressure ก ก ก ก ก ก ก nebulizer ก artificial airway tracheostomy mask ( 8) T- piece ( 9) ก 35% ก ก ก aerosol mask ( 10) ก ก ก air-entrainment system ก corrugate tube ก ก Entrainment port Jet 7 Venturi effect

12 8 Tracheostomy mask 9 T-piece 10 Aerosol mask ก flow ก magic box high flow system, fixed performance flow FiO 2 ก ก magic box O 2 100 40 Air 20 60 40 O 2 100 : Air 40 : 40 1 : 1 ก FiO 2 0.6 flow กก ก respiratory flow demand 3-4 minute ventilation ก 50 kg 20 flow minute ventilation = 5-7(ml/kg) x RR = (7 x50) x 20 = 7 LPM peak inspiratory flow rate = 3-4 minute ventilation = 21-28 LPM ก FiO 2 0.6 flow O 2 air 1:1 flow = 21/2 28/2 = 11-14 LPM ก ก ก magic box ก FiO 2 ก 3 3 Approximate oxygen to air ratios for common oxygen concentration

13 ก ก (Effects of inadequate humidification of inspired gases) ก ก ก ก ก ก ก 1. cilia ก 2. 3. ก necrosis 4. ก ก 5. ก ก 6. ก ก 7. (atelectasis) 8. (pneumonia) ก ก ก ก (Humidifier and nebulizer) ก ก ก ก ก ก ก ก 2 humidifier nebulizer 1. Humidifier ( 11) ก nebulizer ก ก ก ก ก ก bubble humidifier ก ก low flow system ก ก ก 2. Nebulizer ( 12) ก pneumatic jet nebulizer, ultrasonic nebulizer ก ก ก venture effect ก ก กก ก ก ( 13) ก ก ก ก artificial airway ก ก T piece, artificial nose ( heat and moisture exchanger)

ก nebulizer ก corrugate tube ก ก flow ก ก FiO 2 ก ก ก ก ( 14 ) 14 11 Humidifier 12 Nebulizer 13 Nebulizer with venturi effect

15 14 Nebulizer corrugate tube ก humidifier nebulizer 4 4 ก humidifier nebulizer Humidifier Nebulizer Humidification gaseous aerosol Airway target upper airway lower airway Flow system low-flow high-flow FiO2 variable fixed Tubing small-bored corrugated Cost cheaper expensive Nosocomial infectious less more ก ก (evaluation of oxygen therapy) ก ก ก ก ก ก ก ก ก 1. Patient ก 1.1 Clinical assessment ก cardiovascular, pulmonary neurologic status ก 1.2 Assessment of physiologic parameters ก ก PaO 2 oxygen saturation ก ก - ก ก 12 ก ก ก FiO 2 < 0.4

- 8 ก ก ก FiO 2 > 0.4 ( postanesthetic care unit) - 72 myocardial infarction - 2 (COPD) 2. Equipment ก ก 2.1 ก ก ก 1 2.2 ก ก กก 1 ก ก - ก ก high-flow blending systems - artificial airways - heated gas mixture - ก FiO 2 > 0.5 2.3 ก ก ก ก ก 16 ก ก ( oxygen hazard) ก ก ก ก ก ก ก oxygen toxicity ก 1. Physiological hazard from hyperoxygenation 1.1 CNS ก tremors, twitching, paralysis convulsion ก ก hyperbaric pressure ( ก กก 1 ก ) 1.2 ก retinopathy of prematurity ก ก ก ก ก PaO 2 ก ก ก retinal vasoconstriction necrosis 1.3 - ก cilia - ก ก ก hypoxic drive - hypoxic pulmonary vasoconstriction - ก absorption atelectasis ก ก

- ก bronchopulmonary dysplasia pulmonary hypertension & fibrosis 3 17 3 pulmonary hypertension & fibrosis ก ก high FiO 2 1.4 metabolic ก 1.5 ก pulmonary vasodilatation systemic & cerebral vasoconstriction 2. Psychological dependent 3. Mechanical hazard ก ก 4. Bacterial contamination ก ก ก nebulizer ก ก ก oxygen toxicity ก 100% ก 24 70% ก 48 50% ก 5 ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก ก

1. Scanlan CL, Heuer A. Medical Gas Therapy. In: Scanlan CL, Wilkin RL, Stoller JK, editors. Egan s Fundamentals of Respiratory Care. 7 th ed. St. Louis : Mosby; 1999: 738-765. 2. Chang DW. AARC Guideline : Oxygen Therapy for Adults in Acute Care Facility. Respiratory Care 2002; 47(6):717-20. 3. Stoelting RK. Lungs. In: Stoelting RK, editor. Pharmacology and Physiology in Anesthetic Practice. 3 rd ed. Philadelphia : Lippincott-Roven; 1999: 682-691. 4. Stoelting RK. Pulmonary gas exchange and blood transport of gases. In: Stoelting RK, editor. Pharmacology and Physiology in Anesthetic Practice. 3 rd ed. Philadelphia : Lippincott-Roven; 1999: 692-701. 5. Wojciechowski WV. Mathematics. In: Wojciechowski WV, editor. Respiratory Care Sciences : An Integrated Approach. 3 rd ed. Albany : Delmar ; 2000: 19-22. 6. Branson RD. Gas delivery systems: regulators, flowmeters, and therapy devices. In: Branson RD, Hess DR, Chatburn RL, editors. Respiratory Care Equipment. 2 nd ed. Philadelphia : Lippincott Williams & Wilkins; 1999: 55-85. 7. Shapiro BA, Peruzzi WT. Hypoxemia and oxygen therapy. In: Shapiro BA, Peruzzi WT, editors. Clinical Application of Blood Gases. 5 th ed. St. Louis : Mosby ; 1994 : 127-155. 8. Saposnick AB, Hess DR. Oxygen therapy: administration and management. In: Hess DR, MacIntyre NR, Mishoe SC, Galvin WF, Adams AB, Saposnick AB, editors. Respiratory Care: Principles and Practices. Philadelphia : W.B. Saunders Co.; 2002: 592-611. 9. Fink JB, Hess DR. Humidity and aerosal therapy. In: Hess DR, MacIntyre NR, Mishoe SC, Galvin WF, Adams AB, Saposnick AB, editors. Respiratory Care: Principles and Practices. Philadelphia : W.B. Saunders Co.; 2002: 633-664. 10. Centers for Disease Control and Prevention. Guideline for prevention of nosocomial pneumonia. Respir Care 1994; 39(12):1191-236. 11. Centers for Disease Control and Prevention. Guidelines for prevention of nosocomial pneumonia. MMWR Recomm Rep 1997; 46(RR-1):1-79. 12. Ball C. Medical devices and their role in the incidence of ventilator-associated pneumonia challenging some sacred cows! Intensive Crit Care Nurs 2005; 21(3):131-4. 18