Oxygen Therapy Patchanee Pasitchakrit Department of Anesthesiology Srinakharinwirot

Oxygen Therapy Patchanee Pasitchakrit Department of Anesthesiology Srinakharinwirot University

Oxygen tissue - Ventilation - Diffusion - Perfusion Oxygen cascade Pi. O 2 ~ 150 mm. Hg PAO 2 ~ 110 mm. Hg Pa. O 2 80 -100 mm. Hg Pt. O 2 20 -40 mm. Hg Pv. O 2 35 -40 mm. Hg

Oxygen Therapy Ø ������������ oxygen ���������� Fi. O 2 Ø �������� , ������������ , ��������� ( Indications ) 1. Hypoxemia 2. Supportive treament of tissue hypoxia 3. Miscellaneous - enhance absorption of air space - specific treatment for CO poisoning - hyperbaric oxygen therapy

Oxygen therapy �� ���� hypoxemia �������� 1) Prevent and correct hypoxemia 2) Decrease cardiopulmonary work

������ 1) Prevent and correct hypoxemia - Pa. O 2 > 60 mm. Hg หรอ Sa. O 2 > 90% (no tissue hypoxia or clinically significant hypoxemia)

������ Hypoxemia 1. Low Pi. O 2 ����� Fi. O 2 2. Impaired pulmonary gas exchange - hypoventilation - diffusion defect - V/Q abnormality correct ���� Fi. O 2 ������� 0. 5 ������ airway pressure therapy ���� - shunt ควรแกไขสาเหตของกลไกยอย

3. Low mixed venous oxygen saturation - ���� O 2 demand > O 2 supply ���� severe - ������ Impaired pulmonary มากขน state hypermetabolic gas exchange hypoxemia

������ 2) Decrease cardiopulmonary work - hypoxemia compensate with TV, RR work of breathing, heart - ������ MI , heart failure โดยเฉพาะในผปวยท ��CAD หรอ cardiac reserve ���

Oxygen therapy ������ tissue hypoxia Tissue hypoxia 1. Hypoxemic hypoxia ���� 4 ������ tissue hypoxia ����� hypoxemia 2. Hypoxia due to abnormal oxygen transport ������ , CO poisoning, methimoglobinemia 3. Circulatory hypoxia (stagnant hypoxia ) ������� circulation ทำใหมภาวะ ischemia ���� low cardiac output, vascular occlusion ไมด 4. Histotoxic hypoxia ��������� oxygen �������� septic shock , gangrene ����� tox. sub. ���� cyanide poisoning

Enhance absorption of air space - ����� oxygen therapy ������������� ���������� Lap. , ������� pneumothorax Specific treatment CO poisoning - ���� Fi. O 2 1. 0 ����� 1 ������ CO-Hb ��� 4 ��. ����� 40 ���� half-life Hyperbaric oxygen therapy

Hyperbaric oxygen therapy

Oxygen delivery devices ������ 2 ���� 1. High Flow system (fixed performance device) - Fi. O 2 - คอนขางคงท ไมเปลยนตาม ventilatory pattern ���� total flow ใหได peak inspiratory flow rate ���� Fi. O 2 ������ ไมเปลยนแปลง ( ����� 3 ������� minute ventilation )

- ������� Bernoulli’s law : ����������� �� ������� subatmospheric pressure �������������� main stream ��������� » changing in size of entrainment port changing in Fi. O 2

ใชไดดเมอ EX • air-entrainment mask (venturi mask) Fi. O 2 ไมเกน • air-entrainment nebulizer 0. 4 ตอกบ ควบคมอณหภมและความชนได , ใหยา aerosol mask, face tent, T-piece • gas blending system สามารถให Fi. O 2 ได 0. 21 -1. 0 ได ,

Venturi mask

Aerosol mask

Face tent

T-piece

Air oxygen blender

2. Low flow system (variable performance device) - ������� ������������ - ������ flow ������ peak inspiratory flow rate - minute ventilation ������������ room air - Fi. O 2 ������������������������ • oxygen flow rate • ������� reservoir • ventilatory pattern

Nasal cannula

Simple face mask - O 2 5 -8 L/M ( Fi. O 2 0. 4 -0. 6 ) - ��� < 5 L/M CO 2 retention ��� > 8 L/M เกด rebreathing ได �������� eye irritation ���

Simple mask

Partial rebreathing mask - O 2 6 -10 L/M ( Fi. O 2 0. 6 -0. 99 ) ม reservoir bag ระวงไมใหแฟบ - ถา < 6 L/M หรอ - rebreathing filled with O 2 ~ 1/3, reservoir แฟบ partial

Partial rebreathing mask

Non-rebreathing mask One way valve

Complications of oxygen therapy 1. Cut of hypoxemic ventilatory drive esp. COPD hypoventilation CO 2 narcosis ������ 2. Denitrogenation absorptive atelectasis - nitrogen กาซเฉอย - Fi. O 2 1. 0 ~ 15 ���� alveoli - พบมากขนถาปอดมพยาธสภาพ พยง alveoli ���� denitrogenation collapsed

3. Pulmonary oxygen toxicity ��� O 2 free radical ������ O 2 ������������ - ������ enzyme superoxide dismutase - ����� cell wall ��� mitochondria - ���������� protein �� DNA - ����� pneumocyte type 1 ��� surfactant ����� - clinical : �� ���������� pulmonary - edema

4. Retinopathy of prematurity (ROP) esp. premee - Pa. O 2 necrosis สง blindness neovascularization - ไมควรให retinal vessel แผลท retina Pa. O 2 > 80 mm. Hg เกด vasoconstriction hemorrhage ใน 5. Fire hazard : support combustion premee

��������� oxygen ����� (70 -100%) - ������ CPR - acute cardiopulmonary instability - ������� transfer

Humidifier (cont. ) 3. Jet humidifier ������������������������ 4. Condensing humidifier or heat and moisture exchanger ( HME ) ���� passive humidifier ������������������������

Heat and moisture exchanger

Heat and moisture exchanger Inspired limb To patient Expired limb

Complications of airway temperature and humidity therapy 1. Overheating ���� hyperthermia ��� 2. Contamination and infection 3. Increase inspiratory resistance HME �����