Chapter 5. Oxygen Therapy Show
Tissue oxygenation is dependent on optimal or adequate delivery of oxygen to the tissues. Increasing the concentration of inhaled oxygen is an effective method of increasing the partial pressure of oxygen in the blood and correcting hypoxemia. Simply stated, oxygen therapy is a means to provide oxygen according to target saturation rates (as per physician orders or hospital protocol) to achieve normal or near normal oxygen saturation levels for acute and chronically ill patients (British Thoracic Society, 2008). Those administering oxygen must monitor the patient to keep the saturation levels within the required target range. Oxygen should be reduced or discontinued in stable patients with satisfactory oxygen saturation levels (Perry et al., 2014). Hypoxemia or hypoxia is a medical emergency and should be treated promptly. Failure to initiate oxygen therapy can result in serious harm to the patient. The essence of oxygen therapy is to provide oxygen according to target saturation rates, and to monitor the saturation rate to keep it within target range. The target range (SaO2) for a normal adult is 92% to 98%. For patients with COPD, the target SaO2 range is 88% to 92% (Alberta Health Services, 2015; British Thoracic Society, 2008; Kane, et al., 2013). Although all medications given in the hospital require a prescription, oxygen therapy may be initiated without a physician order in emergency situations. Most hospitals will have a protocol in place to allow health care providers to apply oxygen in emergency situations. The health care provider administering oxygen is responsible for monitoring the patient response and keeping the oxygen saturation levels within the target range. The most common reasons for initiating oxygen therapy include acute hypoxemia related to pneumonia, shock, asthma, heart failure, pulmonary embolus, myocardial infarction resulting in hypoxemia, post-operative states, pneumonthorax, and abnormalities in the quality and quantity of hemoglobin. There are no contraindications to oxygen therapy if indications for therapy are present (Kane et al., 2013). Oxygen Delivery SystemsThere is a wide variety of devices available to provide oxygen support. Delivery systems are classified as low-flow or high-flow equipment, which provide an uncontrolled or controlled amount of supplemental oxygen to the patient (British Thoracic Society, 2008). Selection should be based on preventing and treating hypoxemia and preventing complications of hyper-oxygenation. Factors such as how much oxygen is required, the presence of underlying respiratory disease, age, the environment (at home or in the hospital), the presence of an artificial airway, the need for humidity, a tolerance or a compliance problem, or a need for consistent and accurate oxygen must be considered to select the correct oxygen delivery device (British Thoracic Society, 2008). Table 5.2 lists the types of oxygen equipment. Table 5.2 Types of Oxygen Equipment
Special considerations:
Increasing Oxygen in the LungsThe use of oxygen delivery systems is only one component to increasing oxygen to the alveolar capillary bed to allow for optimal oxygenation to the tissues. Additional methods to increase oxygen saturation levels in the body include (Perry et al., 2014):
What percentage of oxygen is delivered by a pocket face mask?Resuscitation Masks (Pocket Mask)
With the addition of oxygen, these masks can deliver a concentration of oxygen around 40% as opposed to the 16% of oxygen with mouth-to-mouth rescue breathing only.
What percentage of exhaled oxygen is delivered during mouth to mask breathing without supplemental oxygen?The amount of oxygen available to the patient in mouth-to-mouth is around 16%. If this is done through a pocket mask with an oxygen flow, this increases to 40% oxygen. If either a bag valve mask or a mechanical ventilator is used with an oxygen supply, this rises to 99% oxygen.
What percentage of oxygen can be delivered using a bag valve mask connected to supplemental oxygen?Bag-valve-mask devices are the preferred equipment to deliver positive pressure ventilation to the apneic patient. A typical BVM device is illustrated in Figure 3. With oxygen flow at 15 L/min, a BVM with reservoir will provide 90–95% inspired oxygen concentrations.
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