Oxygen Therapy PDF

## Oxygen Therapy ### Normal Values - PaO2: 80 to 100 mmHg - SaO2: 90 to 100% ### Oxygen Therapy Indications - **PaO2 < 60 mmHg** - **SaO2 < 90%** ### When should Oxygen Therapy be given? - When a patient's PaO2 or SaO2 falls below normal. ### Indications of Oxygen Therapy - **Severe trauma*...

## Oxygen Therapy ### Normal Values - PaO2: 80 to 100 mmHg - SaO2: 90 to 100% ### Oxygen Therapy Indications - **PaO2 < 60 mmHg** - **SaO2 < 90%** ### When should Oxygen Therapy be given? - When a patient's PaO2 or SaO2 falls below normal. ### Indications of Oxygen Therapy - **Severe trauma** - **Acute myocardial infarction** - **Short-term therapy after anesthesia** ### Assessment of Oxygen Therapy #### How to check? - **ABG**: This shows PaO2 and SpO2. - **Clinical assessment**: We look for the following findings. #### Clinical Assessment Findings | | Mild | Moderate | Severe | | ---------------- | --------------------------- | ---------------------------- | --------------------------------------------- | | **CNS** | - Restlessness | - Restlessness | - Desire to sleep | | | - Disorientation | - Disorientation | - Loss of coordination | | | - Headache | - Headache | - Impairment of Judgement | | **Cardiac** | - Tachycardia | - Tachycardia | - Bradycardia, hypotension | | | - Mild hypotension | - Mild hypotension | - Arrhythmia | | | - Vasoconstriction of peripheries | - Vasoconstriction of peripheries | - Increased dyspnea | | **Respiratory** | - Dyspnea | - Dyspnea | - Tachypnea | | | - Tachypnea | - Tachypnea | - Shallow and labored breathing | | | - Shallow and labored breathing | - Shallow and labored breathing | - Possible bradypnea | | **Skin** | - Paleness | - Paleness | - Cyanosis | | | - Cold | - Cold | | ### Monitoring Hypoxia #### How do we monitor hypoxemia? 1. **Physical Examination**: Check for clinical findings of hypoxemia. 2. **Pulse Oximetry** 3. **ABG Analysis**: This includes the following: - PaO2 - pH - PCO2 4. **Mixed venous blood oxygenation** #### How do we classify Oxygen Delivery Systems? 1. **Low-flow systems**: - Variable performance devices - Oxygen does not meet patients needs - Specifically peak inspiration demands 2. **Reservoir System**: - Variable performance devices - Oxygen store, that gives a tidal volume that **equals** to or **exceeds** patients tidal volume - Moderate to high FiO2 3. **High-flow system**: - Fixed performance device - Gas flow will be equal to meet patients needs - Regardless of patients breathing pattern 4. **Enclosures** ### Low-flow Devices #### Nasal Cannula - FiO2: 24-40% - Flow: 8L/min (adult), 2L/min (child) - Plastic disposable device, consists of two prongs and tubing - Tubings should be connected to oxygen. - Inserted into the vestibule of the nose. #### What is the difference between flow and FiO2? - **Flow**: About how much gas is delivered. - **FiO2**: About how much oxygen the patent is actually breathing. - If we increase the flow by 1 litre, the FiO2 increases by 4%. #### Nasal Catheter - It is used to fill up the dead space with oxygen. - It is very irritating and uncomfortable so it is not used anymore. #### Transtracheal Catheter - FiO2: 22-35% - Flow: 4L/min - Inserted between the 2nd and 3rd tracheal rings. - Increased anatomic reservoir. ### Reservoir System #### Nasal Reservoir - Moustache #### Pendant Reservoir #### Merits - Lower O2 use - Cost - Increased mobility - Can be transported - Less discomfort because of lower flow. #### Demerits - Unattractive - Difficult to use - Poor compliance - Must be regularly replaced - Breathing pattern matters. ### Simple Mask - It can store 100-200mL - Variable performance device - FiO2 varies with flow - O2 input flow - Mask volume - How much air leaks - How's the pattern of breathing - The patients minimum flow should be 5L/min to prevent rebreathing of CO2. - FiO2: 40-60% - Flow: 5-10 L/min #### Merits - Moderate but variable FiO2 - Good for patients with blocked nasal passages - Easy to apply #### Demerits - Uncomfortable - Proper pitting is required - Risk of aspiration when unconscious - Rebreathing can happen if the flow is less than 5L/min. ### Partial Rebreathing Mask - FiO2: 60%-80% - Flow must be 8 to 10L/min to ensure the bag remains inflated. - No valves - During inhalation, fresh O2 is going inside, but during exhalation some CO2 enters into the bag which is rebreathed. ### Non-rebreathing Mask - FiO2: 80-100% - Store fresh O2 - One valve helps in inhalation (opens during inhalation) - The other valve is exhalation valve and opens during exhalation only. (To remove CO2) - Factors affecting FiO2: - Air leakage - Patients breathing pattern ### Tracheostomy Mask - Used to humidify the oxygen that flows. - Variable performance device. #### High Flow Device: - Based on **Bernoulli's principle** - As the tube is narrowed from wider, the velocity of the gas increases which creates the negative pressure at the lateral sides. ### Venturi Mask - Mask consists of fixed orifice that has fined flows - Many venturi mask varieties are available. - FiO2: Low to moderate (0.24 - 0.68) ### Air Entrainment Nebulizer - Works based on Bernoulli's principle - Provides humidification, and you can also give medications. - FiO2: 28-100% - Man/gas flow: 14-16 L/min ### Types of Enclosures (for infants) 1. **Oxygen Tent**: - Variable device - Covers all over body. - Rebreathing happens. - Difficult to use. - Leakage happens. - FiO2: 40-50% - Oxygen flow: 12/15/min 2. **Oxygen Hood**: - Covers only head of the infant. - Fixed performance device. - Has blending system which allows mixing of oxygen and air at perfect range. - FiO2: 21-100% 3. **Incubator**: - Variable performance device. - Keeps body warm - Can give oxygen. - FiO2: 40-50% ### Hyperbaric Oxygen Therapy - 100% oxygen - Pressure greater than 1 atm which is equal to 760mmHg at sea level. #### Indications of HBO 1. **Bubble reduction**: - In case of decompression sickness, the NO2 makes bubbles in blood. If the person doesn't stay at each levels before coming to land (Boyle's law). - We give HBO to treat that. 2. **Hypertonia of blood**: - With fallen HBO given, it mixes with blood to bring back the normal oxygenation. The O2 mixes with plasma to increase oxygenation. 3. **Enhanced host immune infection**: - When O2 is more, it increases the WBC in blood. 4. **Neovascularization**: - New vessels formation for better circulation. This takes time. 5. **Vasoconstriction**: - Hyperbaric oxygen therapy causes vasoconstriction which will help in reducing bleeding and inflammation. 6. **Hyperonia of blood**: - When the hemoglobin is attached to carbon monoxide, we give HBO to dissolve the O2 with plasma. The gas dissolves with liquid (Henry's law). #### Methods of giving hyperbaric oxygen therapy 1. **Multichamber**: - Can treat many patients. 2. **Monochamber**: - Can only treat one patient at a time. ### Problems with HBO 1. **Barotrauma**: - Ear trauma - Tympanic membrane rupture - Pneumothorax. 2. **Oxygen toxicity (excess of O2)**: - Can cause central nervous system toxicity, including seizures and convulsions. - Increased pressure causes the vessel cells to leak the fluid that causes fibrosis and shunt happens. 3. **Retinopathy**: - It happens in infants because the vessels will have necrosis and retina is lost. 4. **100% O2 is safe if it is not more than 12 hours** - 80% -> 24 hours - 60% -> 36 hours 5. **Denitrogenation Atelectasis**: - Increased O2 can causeNO2 to be washed out, which causes atelectasis. 6. **Fire hazard**: - O2 helps in combustion which can increase fire.