High Flow Oxygen Delivery Systems

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Introduction   

Oxygen therapy is a prescribed treatment that is administered to patients who are hypoxic or in respiratory distress. There are several types of delivery devices for high-flow oxygen therapy. A typical device is the high-flow nasal cannula. High-flow nasal cannula oxygen therapy was implemented for premature neonates in the 2000s [2]. This therapy was created to be used as an alternate type of therapy to continuous positive air pressure (CPAP) that was used to help with apnea [2].  

High-flow oxygen therapy is now commonly used in pediatrics and even for adult patients. High-flow oxygen can be administered through a high-flow nasal cannula where the oxygen is humidified and heated, making this therapy more tolerable for the patient [2]. High-flow oxygen therapy can deliver 2 liters up to 60 liters per minute [1].  

This course will explore when high-flow oxygen is necessary for a patient and the nurse’s role when caring for these patients. This course will provide nurses with information to use in everyday practice to better educate their patients and families.  

Definition 

As stated earlier in this course, high-flow oxygen via a high-flow nasal cannula can deliver between 2 liters to 60 liters per minute of oxygen [1]. The flow nasal cannula can only give up to 4 to 6 liters of oxygen per minute [1]. The low-flow cannula is an open system in which there is a significant amount of leaking oxygen when administered [1]. With this therapy, fiO2 is directly related to the oxygen flow rate [1]. If the patient requires a higher percentage of fiO2, the flow rate must be increased [1].  

The dryness of the oxygen delivered can irritate the patient’s nares and cause bleeding [1]. A standard oxygen delivery device, such as a nasal cannula, is not heated or humidified [1]. The flow of oxygen is cold and dry, which can lead to increased inflammation and resistance of the airway [1].  

High-flow nasal cannulas can administer up to 100% fiO2, which can be increased independently from the flow rate [5]. High-flow oxygen delivery devices are heated and humidified [1]. Patients tolerate the high-flow nasal cannula, which keeps them more comfortable. 

High Flow Oxygen Delivery Devices 

A venturi mask is a type of high-flow oxygen delivery device that allows the provider to administer a specific fiO2. This device is cone-shaped and must have a good seal over the mouth and nose to reduce the retention of CO2 [6] [7]. It is not meant to help with breathing work and is usually used for adult patients [4]. This device does not produce gastric distention [4]. It can be used with any source of O2 [4].  

Continuous positive air pressure devices use a facemask that opens the upper airway and increases lung volumes [4]. These devices may decrease the need for intubation for some patients [4]. CPAP can use a mask or a different interface to increase the lung volume and open the upper airway [4]. Positive end-expiratory pressure (PEEP) can be titrated in adults aged 5 to 15 [4]. For pediatric patients the PEEP is typically 5-10 [4]. This type of therapy can prevent atelectasis [4].  

Noninvasive positive pressure ventilation applies greater inspiratory pressure than during the exhalation phase. It is also used with a mask [4]. Bilevel positive airway pressure can decrease the work of breathing and add positive end-expiratory pressure [4]. 

Components of High Flow Oxygen Nasal Cannula 

Specific components make providing high-flow oxygen possible. An air-oxygen blender must be present to increase the fiO2 from 21% to 100% without changing the flow rate [1]. A flow generator that administers flow up to 60 liters per minute is in the device [1]. There is also a heated humidifier, which keeps the temperature of the gas mixture between 31 to 37 C [1]. The tubing used is heated, which helps minimize the condensation [1].  

The nasal prongs used are more comprehensive than those from a low-flow cannula. The heating and humidification of the high-flow cannula are thought to increase compliance due to increasing the comfort for the patient [1]. As with any therapy, there can be some disadvantages. A high-flow nasal cannula can be more expensive than a low-flow delivery device [4]. This device also requires specialized training and can be complex to set up [1]. A high-flow nasal cannula is more challenging to transfer a patient on than a standard low-flow nasal cannula [1]. 

History/ Background 

Oxygen therapy is commonly prescribed for patients in respiratory distress or hypoxia. Conventional oxygen therapy, such as a traditional nasal cannula, may not be enough support the patient requires. In this case, noninvasive ventilation may be needed [4]. Noninvasive ventilation can be difficult for patients to tolerate [4].  

High-flow nasal cannulas have been increasingly on the rise since the early 2000s [2]. In certain instances, patients can eat while on a high-flow nasal cannula and speak, which may not be the case with traditional noninvasive ventilation such as CPAP. 

Indications of Use 

High-flow oxygen can help with a patient’s increased work of breathing. Patients experiencing acute respiratory failure can be tachypneic, and the increased flow of oxygen can help them reach their peak inspiratory flows [5]. Pediatric patients with acute bronchiolitis and asthma exacerbations can benefit from the use of high-flow nasal cannulas to help decrease their work of breathing [2]. 

 Adult patients with community-acquired pneumonia in respiratory distress would be an indication for the use of a high-flow nasal cannula [5]. Because the oxygen is humidified, it allows the secretions to move secretions and either cough or have them suctioned [5].  

FiO2 is the fraction of inspired oxygen in a gas mixture [3]. These devices can give a more accurate amount of FiO2 than a low-flow device. Certain patients, such as patients with chronic obstructive pulmonary disease, require specific amounts of supplemental oxygen [6].  

 A high-flow nasal cannula also gives the patient a flow of fresh gas instead of rebreathing excessive amounts of carbon dioxide [5]. Usually, when a patient breathes, it is a mixture of a new gas, which would be 21% fiO2, and gas that was previously exhaled, which would contain high carbon dioxide and less than 21% oxygen [5]. Because the high flow continuously gives the patient a new mixture of gas. This helps patients with acute respiratory failure not retain increased carbon dioxide [5]. This is called dead space washout [5].  

Studies have shown that pre-oxygenating with a high-flow nasal cannula before intubation improves oxygenation during the intubation process as opposed to the nonrebreather mask [1]. This would be appropriate in an alert and awake patient [1]. The high amounts of flow and fiO2 would increase the PO2, allowing for more time for the intubation process [1]. High-flow nasal cannulas can also be used to oxygenate for post-extubating [1]. 

Case Study #1 

A seven-month-old male is brought into the emergency department by the mother of the infant. The mother reports the patient has had a cough and fever for two days. The mom states that the infant appeared to be working hard to breathe when the patient woke up. Upon arrival at the emergency department, the patient was irritable and had a coarse cough. The patient is tachypneic with nasal flaring and moderate subcostal retractions. The patient’s vitals are T 38.4 C, HR 184, RR 75, BP 85/48, and O2 sat 92%. The patient weighs 8kg. The patient tests positive for respiratory syncytial virus (RSV). The provider orders a high-flow nasal cannula for the patient. 

Case Study #2 

A 70-year-old patient is admitted to a progressive care unit with a diagnosis of community-acquired pneumonia. The patient was initially placed on a 2L nasal cannula. Throughout the day, the patient has increased work of breathing and now is on a 4L nasal cannula. The patient’s vitals are T 37.8C, HR 110, RR 28, BP 110/68, O2 sat 88%. The patient has a course cough with thick yellow secretions. The nurse notes the patient cannot complete sentences due to shortness of breath. The patient cannot transfer to the bedside commode without shortness of breath. The nurse notifies the provider and the respiratory therapist.  

Nursing Care 

When caring for all patients, a multi-disciplinary team is used. Patients on high-flow oxygen therapy are just the same. All oxygen is considered a medication and must be prescribed by a provider.  

The bedside nurse caring for that patient must collaborate with the provider and respiratory therapist to give the patient the highest level of care [1]. The bedside nurse should monitor the patient’s vitals and communicate them to the respiratory therapist and provider to ensure they are on adequate support. The nurse will also assess the patient’s work of breathing while on high-flow oxygen therapy [1]. It is essential to work closely with the respiratory therapist and provider to titrate the flow and fiO2, so the patient is not over-oxygenated or causes barotrauma to the patient [1].  

While the respiratory therapist is often in control of the oxygen delivery device, the nurse needs to be familiar with the device. The nurse should complete safety checks to ensure the equipment is properly functioning and that all tubing is not kinked or obstructed [6]. The nurse also needs to ensure the patient receives the required fiO2 and flow rate as specified by the provider [6].  

The nurse is responsible for positioning the patient to promote chest expansion and improve work of breathing [6]. When completing a skin assessment, the nurse should inspect the patient’s skin under the oxygen delivery device for skin breakdown [6].  

Safety Considerations 

As mentioned earlier in this course, the patient should be monitored closely while receiving high-flow oxygen therapy to reduce adverse effects for the patient. When receiving high-flow oxygen therapy, patients have an increased aspiration risk [1].  

Pediatric patients on flow cannula can commonly only feed by mouth when the flow is at 2 liters per minute due to the risk of aspiration. Over-oxygenation is possible, and with the ability to provide an increased flow, this should be considered when a patient is on high-flow oxygen therapy [1].  

While a patient is undergoing oxygen therapy, especially for a considerable amount of time, it is essential to monitor for skin breakdown [6]. Securement devices should be moved frequently to prevent breakdown, especially with older adults and pediatric patients [7]. As discussed earlier, assessing the patient’s bridge of nose and nares is essential for pressure injury [7]. 

When using high-flow nasal cannulas with neonates and pediatric patients, there are specific considerations to make. The diameter of the prongs should be at most 50% of the diameter of the nares [4]. This ensures adequate flow around the cannula to decrease the risk of extra pressure being delivered [4].  

The flow is usually titrated by the patient’s weight in neonates and pediatrics [4]. In patients 0-10kg, the flow rate is usually 2L/kg/ minute, with the maximum flow being 8 liters per minute [4] [5]. The flow rate in patients 10-20kg is usually 1L/kg/ minute [4]. In patients 20-40kg, the flow rate is usually 0.5L/kg/ minute, with a maximum of 30 liters per minute [4]. Patients more significant than 40kg are the same at 0.5-1L/kg/ minute flow, with the maximum being 60 liters per minute [4]. These calculations may vary depending on the facility policy. 

Patient and Family Education 

While caring for patients, patient education is part of the nurse’s role. Nurses should educate their patients and families to understand their disease process better and make informed healthcare decisions. The nurse should explain high-flow oxygen therapy and how it can be used to treat their symptoms or disease process [7]. Due to the high liter flow, the patient is informed that there is a risk of nose bleeds and irritation to the nasal passages [7]. While most patients use high-flow oxygen in acute settings, in some instances, patients can be on high-flow oxygen at home [7]. Extensive education in at-home use would then be provided to the patient and family.  

Conclusion

High-flow oxygen therapy is a prescribed treatment that delivers oxygen at a high flow rate and fiO2 up to 100%. Different delivery devices can be used to administer this oxygen therapy. This type of oxygen therapy can be used in neonates, pediatric patients, and adults. High-flow nasal cannulas are becoming more present in clinical practice. Research is still being conducted on the effectiveness of this type of oxygen therapy and when to use it. As nurses, it is our role to assess changes in respiratory status, monitor vital signs, and educate patients and their families while caring for patients on high-flow oxygen therapy. As new therapy develops, educating ourselves to provide better care for our patients is essential. 

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