Types of Oxygen Therapy

Types of Oxygen Therapy Causes of hypoxemia • • • • • • • • low inspired oxygen -> not enough O2 in the blood. Hypoventilation. V/Q mismatch COPD Emphysema Asthma Pneumothorax Diffusion abnormalities. Guidelines Suggestions • • • • • In acute care patients suspected of having hypoxemia. In severe trauma, In acute MI. For short term therapy. During surgical interventions, post anaesthesia and recovery. Safety considerations • • • • Fire risk -> no smoking or vaping allowed and must not be used in an area with potential ignition sources. Oil/grease -> must not be in contact with. Compressed gas -> portable oxygen cylinders contain compressed oxygen and should not be damaged or dropped. If possible, store oxygen cylinders in holders. Risk of running out of oxygen. Side effects and complications • • Oxygen is not addictive and causes no side effects when used as prescribed. Complications are infrequent. But some include: - Incorrect amount of oxygen administration. - Concentrations of O2 must be carefully titrated in CAL/COPD patients. High levels of oxygen in patients with emphysema and high blood CO2 levels can reduce the respiratory drive which can lead to respiratory failure and even death. ✓ Important note: the risk of losing the respiratory drive, are far outweighed by the risk of withholding • O2, and therefore emergency administration is NEVER contraindicated. - Incorrect route of administration. - Flammable -> no smoking near oxygen tanks. Complications from equipment of oxygen therapy: - Perforation of the nasal septum. - Bacterial contamination of nebuliser and humidification systems -> may lead to pneumonia. - High flow systems -> poses a risk of infection. Important note • • Oxygen requirements increasing -> patient is developing respiratory distress (this is something that is often missed). NEEDS URGENT MEDICAL REVIEW. - Respiratory depression. - Oxygen toxicity. Cases Where Emergency Services Need to be Notified. • • • • • • • Frequent headaches. Anxiety. Blue lips or fingertips. Drowsiness. Confusion. Restlessness. Slow, shallow, difficult and irregular breathing. Oxygen Prescription • • Oxygen is indicated for hypoxaemia, not breathlessness. Aim for oxygen saturations of 94-98%, or 88-92% in those at risk of type 2 respiratory failure. • • • • Use an ABCDE approach. If the patient is not breathing, call for help and commence resuscitation. This would involve inserting airway adjuncts and applying high-flow oxygen (15L/min) via bag-valve-mask ventilation. If the patient is breathing, you should assess how unwell they are. Critically unwell patients: - If the patient is critically unwell and not at risk of type 2 respiratory failure (or you are unsure about their risk), initially prescribe high-flow oxygen (15L/min) through a non-rebreather mask. - If the patient is at risk of type 2 respiratory failure (e.g., COPD patients who are known to be CO2 retainers), it may be safer to start at a lower FiO2 using a Venturi mask and up-titrate if required. Aim for oxygen saturations of 88-92%. Non-critically unwell patients: - Aim for 100% oxygen saturations in patients with pneumothorax as this reportedly increases the resolution speed. • Oxygen prescriptions: - Increasing Oxygen Since oxygen is a drug, it must be prescribed on a drug chart. the prescriber would need to specify the target oxygen saturations, oxygen delivery device and desired flow rate/FiO2. if oxygen can be stopped, then the prescription on the drug chart should be crossed off (or discontinued on electronic prescribing platforms). • • • • • If a patient’s oxygen saturations do not reach their target within 3-5 minutes of administering oxygen, the flow rate/FiO2 (if using a Venturi mask) should be increased.2 If the patient becomes critically unwell, increase to 15L/min via a non-rebreather mask. If the patient is not critically unwell, consider increasing oxygen by increments (e.g., from 3L via nasal cannula to a white Venturi mask – FiO2 28% at 4L/min). If a patient’s oxygen requirements increase so much that they do not respond to 15L/min via a non-rebreather mask. Consider the patient’s ceiling-of-care/escalation status. If they are for full escalation, they may need high-flow nasal oxygen (HFNO)/continuous positive airway pressure (CPAP)/noninvasive ventilation (NIV)/intubation and ventilation. This is a complex decision based on various factors, including the patient’s ABG results (summarised below and covered in detail here). Administration of Oxygen Nasal cannula • • • • 2-4L/min -> Nasal cannula deliver 24 – 30% O2. For patients with hypoxemia. Nasal cannula (NC) is used for mild hypoxia, typically in non-acute situations. Procedure: The NC tubing is placed around a patient’s face with the prongs positioned at the nostrils. The NC tubing can be secured behind the patient’s head or around their ears. • Issues: - High flows will dry and irritate nasal passages. - Do not allow close control of FiO2. Simple face mask (Hudson mask) • • • Used to treat mild to moderate hypoxia. The mask delivers 30 – 40% O2 (flow rate 5-10 L/min). Procedure: The mask is positioned over the patient’s nose and mouth with the elastic strap behind their head. • Issues: - They do not allow close control of FiO2. There is a risk of aspiration if the patient vomits whilst wearing the mask. Non-rebreather mask (reservoir mask) • • • • Treats patients with a significant degree of hypoxia. (Moderate to severe). deliver high FiO2 concentrations as the oxygen is inhaled from both the reservoir bag as well as the direct oxygen source. Delivers approximately 70% O2 when used with a 15L oxygen flow rate. Procedure: 1. The mask fits over the patient’s nose and mouth and can be secured to the face using elastic straps. 2. Ensure the reservoir bag fills by temporarily obstructing the valve before positioning the non-rebreather mask on the patient. • Issues: - - For the mask to work effectively, the reservoir bag needs to be filled before the mask is fitted to the patient. To fill the reservoir bag, obstruct the valve with your finger until the bag is filled with oxygen. Reservoir masks don’t have a true seal, so some entraining of the surrounding air is unavoidable. A reservoir mask is therefore not a fixed performance device. Venturi mask • Venturi masks are designed to deliver constant FiO2 regardless of the patient’s respiratory rate and flow pattern (i.e., a fixed-performance device). • They are used to deliver oxygen to patients with chronic obstructive pulmonary disease (COPD) due to the risk of type 2 respiratory failure. • Procedure: 1. The Venturi mask fits over the patient’s nose and mouth like other face masks. 2. Details of the required flow rate and percentage of oxygen delivery are shown on the coloured mask fittings (see below). Weaning and Discontinuing Oxygen • • • • Wean down the flow rate/FiO2 if the patient’s oxygen saturations are at least at the higher end of their target saturations for 4-6 hours consecutively. Wean by small increments (e.g. from a yellow Venturi/35% FiO2 to a white Venturi/28% FiO2). This is usually performed by nursing staff, but ensure you document clear instructions. Once the patient is stable on 1-2L/min via nasal cannula, you can cease oxygen completely. Monitor the patient’s oxygen saturations for 5 minutes without supplemental oxygen. If they remain within their target saturations, measure their oxygen saturations in 1 hour (and then use clinical judgment regarding when you will measure them again). Pulse Oximetry • • • • • • Normal SpO2 -> 95% - 100%. Two wavelengths: - infrared @ 940nm (oxyhaemoglobin). - red @ 660nm (reduced haemoglobin) via LEDs (light emitting diodes). Oximeters measure how much of the haemoglobin is saturated, but they are not specific for oxygen. when a patient is suffering from carbon monoxide poisoning, their saturation level may be high, but it is the carbon monoxide that is binding to the haemoglobin, not oxygen. - The patient’s oxygen level may, in fact, be very low. - When suspicious of carbon monoxide poisoning, (e.g., burns victims) oximetry can not be relayed on and instead use ABGs. Advantages: - Accurate/dependable. - Fast response time. - Non-invasive. - Multiple sensing sites. - Continuous measurement. - Monitors peripheral blood flow. Disadvantages: - Poor function with poor perfusion. - Delayed detection of hypoxic events. - Erratic performance with irregular rhythms. - Light interferences. - Motion artefacts. ✓ Examples include nail polish, hypotension, met Hb, carbon monoxide poisoning. - Measures functional saturation only (saturation may be falsely high when Hb is bound by carbon monoxide).