Lieu phap oxy

OXY Liệu pháp Bs Lê Thượng Vũ Chung  Định nghĩa  Sinh lý vận chuyển oxy  Chỉ định  Các hệ thống giao oxy  Biến chứng  Hyperbaric oxygen therapy Oxy liệu pháp gì?  cung cấp cho bệnh nhân khí thở vào phổi nồng độ oxy cao nồng độ oxy khí trời (Fi O2 21%-100%) Oxy 100% Khí trời Oxy 21% Khí bệnh nhân thở Oxy 21- 100% Vận chuyển O2 Thác Oxy Khí trời (khô) (159 mm Hg) ↓ humidification Đường hô hấp (ẩm) (150 mm Hg) ↓ O2 consumption and alveolar ventilation Phế nang PAO2 (104 mm Hg) ↓ venous admixture Động mạch PaO2 (100 mm Hg) ↓ tissue extraction Tĩnh mạch PV O2 (40 mm Hg) ↓ Ty thể PO2 (7 – 37 mmHg) Oxygen Content (Co2) Lượng O2 chứa 100 ml máu Co2 = O2 hòa tan + O2 chuyên chở Hb Co2 = Po2 × 0.0031 + So2 × Hb × 1.34 (Normal Cao2 = 20 ml/100ml blood Normal Cvo2 = 15 ml/100ml blood) C(a-v)o2 = ml/100ml blood Co2 = arterial oxygen content (vol%) Hb = hemoglobin (g%) 1.34 = oxygen-carrying capacity of hemoglobin Po2 = arterial partial pressure of oxygen (mmHg) 0.0031 = solubility coefficient of oxygen in plasma O2Hb dissociation curve 100 % Hb Sat with O2 80 60 40 20 0 20 40 60 80 PO2 mmHg 100 120 140 160 Chỉ định O2 liệu pháp Mục tiêu lâm sàng Sữa chữa giảm oxy máu Giảm triệu chứng giảm oxy máu Giảm hoạt động hệ tim phổi giảm oxy máu Chỉ định  Giảm oxy  PaO < 60 mmHg SaO < 90% thở khí trời 2  PaO SaO thấp số trường hợp đặc biệt 2/  Nghi giảm oxy máu: hen, XHTH, sau gây mê, chấn thương…  Nhồi máu tim Respir Care 2002;47:707-720 Interstitial edema Thickened alveolar capillary membrane ↓ Pulmonary fibrosis and hypertension A Vicious Cycle How much O2 is safe? 100% - not more than 12hrs 80% - not more than 24hrs 60% - not more than 36hrs Goal should be to use lowest possible FiO2 compatible with adequate tissue oxygenation Indications for 70% - 100% oxygen therapy Resuscitation Periods of acute cardiopulmonary instability Patient transport Depression of Ventilation  Seen in COPD patients with chronic hypercapnia  Mechanism ↑PaO2 suppresses peripheral V/Q mismatch chemoreceptors depresses ventilatory drive ↑PaCO2 ↑ dead space/tidal volume ratio Retinopathy of prematurity (ROP)  Premature or low-birth-weight infants who receive supplemental O  Mechanism ↑PaO2 ↓ retinal vasoconstriction ↓ necrosis of blood vessels ↓ new vessels formation ↓ Hemorrhage → retinal detachment and blindness To minimize the risk of ROP - PaO2 below 80 mmHg Absorption atelectasis 100% O2 nitrogen oxygen A A B B B A PO2 =673 PCO2 = 40 PH2O = 47 A – UNDERVENTILATED B – NORMAL VENTILATED Denitrogenation Absorption atelectasis The “denitrogenation” absorption atelectasis is because of collapse of underventilated alveoli (which depends on nitrogen volume to remain above critical volume ) ↓ Increased physiological shunt Fire hazard  High FiO increases the risk of fire  Preventive measures  Lowest effective FiO should be used  Use of scavenging systems  Avoid use of outdated equipment such as aluminium gas regulators  Fire prevention protocols should be followed for hyperbaric O2 therapy Oxygen challenge concept ↑ FiO2 by 0.2 ↑ PaO2 > 10 mmHg ( true shunt – 15 %) ↑ PaO2 < 10 mmHg ( true shunt – 30 %) ↑ PaO2 < 10 mmHg in response to an oxygen challenge of 0.2 – refractory hypoxemia Implications of Oxygen challenge concept  To identify refractory hpoxemia (as it does not respond to increased FiO2)  Refractory hpoxemia depends on increased cardiac output to maintain acceptable FiO2  Potentially deleterious effect of increased FiO2 can be avoided SUMMARY  Therapeutic effectiveness of oxygen therapy is limited to 25% - 50% • Low V/Q hypoxemia is reversed with less than 50% • DAA occurs with FiO2 more than 50% • Pulmonary oxygen toxicity is a potential risk factor with FiO2 more than 50%  Bronchodilators, bronchial hygiene therapy and diuretic therapy decreases the need for high FiO2 Oxygen is a drug When appropriately used, it is extremely beneficial When misused or abused, it is potentially harmful References  Medical gas therapy Egan’s Fundamentals of respiratory care 9th ed  Oxygen delivery systems, inhalation therapy and respiratory therapy Benumof’s Airway management 2nd ed  Shapiro BA Hypoxemia and oxygen therapy Clinical application of blood gases 5TH ed  Oxygen and associated gases Wiley 5th ed  Miller’s Anaesthesia 7th ed  Paul L Marino The ICU Book 3rd ed Thank you… ... lý vận chuyển oxy  Chỉ định  Các hệ thống giao oxy  Biến chứng  Hyperbaric oxygen therapy Oxy liệu pháp gì?  cung cấp cho bệnh nhân khí thở vào phổi nồng độ oxy cao nồng độ oxy khí trời (Fi... phổi nồng độ oxy cao nồng độ oxy khí trời (Fi O2 21%-100%) Oxy 100% Khí trời Oxy 21% Khí bệnh nhân thở Oxy 21- 100% Vận chuyển O2 Thác Oxy Khí trời (khơ) (159 mm Hg) ↓ humidification Đường hô hấp... arterial oxygen content (vol%) Hb = hemoglobin (g%) 1.34 = oxygen-carrying capacity of hemoglobin Po2 = arterial partial pressure of oxygen (mmHg) 0.0031 = solubility coefficient of oxygen in