Getting inspired about oxygen delivery Learn the ins and outs of supplemental oxygen therapy, including which delivery devices device is best for your patient. By Maj. John C. Stich, RN, CCRN, MSA, MSN, and Maj. David M. Cassella, RN, CCNS, CCRN, MSN YOU ENTER YOUR PATIENT’S room for the patient’s clinical situation. (mixes) oxygen and air, creating a at the beginning of the shift and find • an acute care situation in which fixed concentration of oxygen for her in severe respiratory distress. She’s hypoxemia is likely, such as severe delivery to the patient. pale, diaphoretic, tachypneic, and dys- trauma, acute myocardial infarction, Typically in nonemergency situa- 1 pneic, and her SpO2 is 86%. You acti- or surgery. tions, the healthcare provider will vate the rapid response team. While Oxygen therapy has no specific con- specify which oxygen delivery device waiting for help to arrive, you obtain traindications, but like most other to use. Devices can be low-flow or her vital signs and prepare to adminis- drugs, it can cause adverse reactions high-flow. ter supplemental oxygen. Which oxy- and complications. Administer it cau- If you’re choosing an oxygen deliv- gen delivery device would be the most tiously to patients with chronic ery device in an emergency, ask your- appropriate for this patient? obstructive pulmonary disease who self which oxygen concentration the In this article, we’ll help you make have a hypoxic respiratory drive, and device can deliver when connected to the best choice by presenting an over - be aware of the risk of oxygen toxicity.2 an oxygen supply source, and consider view of oxygen therapy for adults in an Potential adverse reactions to oxy- if and how the inspired oxygen con- acute care facility, looking at various gen therapy include: centration varies with the oxygen flow types of supplemental oxygen delivery • ventilatory depression in sponta- rate. The inspired oxygen concentra- devices, and discussing the strengths neously breathing patients with ele- tion typically is expressed as a percent- and limitations of each. vated PaCO2 and PaO2 greater than age for supplemental oxygen, but can 60 mm Hg also be expressed as a decimal (FIO2), Oxygen therapy: What and who? • absorption atelectasis, oxygen toxici- with values between 0.21 (room air) As you know, oxygen therapy treats or ty, and depression of ciliary and leuko- and 1.0 (equivalent to 100% oxygen). prevents hypoxia by administering cyte function at FIO2 values above 0.5. A patient who can protect her own oxygen at concentrations greater than High oxygen concentrations also airway and is breathing spontaneously the level found in ambient air. Room pose a fire hazard, and certain nebu- may be able to use various common air consists of 21% oxygen, 79% nitro- lization and humidification systems oxygen delivery devices. Let’s look at gen, and trace amounts of carbon diox- can become contaminated with bacte- the options. ide and other gases. Oxygen therapy is ria, raising infection risks.2 indicated for patients with: Low-flow devices • documented hypoxemia, or a sub- Types of oxygen delivery devices Low-flow devices deliver oxygen normal PaO2, defined as less than 60 Oxygen delivery devices are used to directly into the patient’s airway at flow 3 mm Hg (or an SaO2 of less than 90%) administer, regulate, and supplement rates of 8 L/minute or less. Because in a patient breathing room air, or a oxygen to increase the patient’s arter- this flow rate is below the normal adult PaO2 or SaO2 below the desirable range ial oxygenation. The device entrains inspiratory requirements, and because www.nursing2009.com September | Nursing2009 | 51 low-flow devices aren’t sealed to the ly new for hospitalized patients. These patient’s face or nares, the patient takes Concentrating on nasal devices store oxygen in a reservoir 5 in a variable mix of room air and deliv- cannulas while the patient is exhaling and deliv- ered oxygen with each breath. As a Starting at 1 L/min, increasing the er a bolus of 100% oxygen on the next result, the inspired oxygen concentra- oxygen flow by 1 L/min will inhalation. Because these devices are tion can vary greatly. For example, if the increase the inspired oxygen con- oxygen-conserving, they can deliver patient is tachypneic, the supplemental centration about four percentage higher oxygen concentrations than a oxygen will be diluted by room air, pro- points: simple nasal cannula despite delivering • ducing a lower inspired oxygen concen- 1 L/min = 24% oxygen at lower flow rates. For exam- • tration. If the patient takes slow, deep 2 L/min = 28% ple, a flow rate of 2 L/minute with a • 3 L/min = 32% breaths, he’ll inhale more supplemental reservoir cannula produces an F O • 4 L/min = 36% I 2 oxygen and less room air, increasing the equivalent to that delivered by a tradi- • 5 L/min = 40% 4 inspired oxygen concentration. • 6 L/min = 44% tional nasal cannula set to deliver Low-flow reservoir devices generally 4 L/minute.1 Sizes vary by manufac - provide a higher inspired oxygen con- turer, but a 20-mL reservoir is typical. centration than nonreservoir low-flow delivered to the alveoli ranges from Reservoir nasal cannulas come in systems, but the concentration remains 24% to 44%. Other factors affecting the two styles: mustache and pendant. The variable. While the patient exhales, the inspired oxygen concentration are the mustache style, which positions the delivered oxygen is stored in the reser- oxygen flow rate through the cannula, reservoir under the nose, may be more voir and is available for the next inspi- mouth breathing, respiratory rate and comfortable for some patients. The ration; as a result, the patient inspires pattern, minute ventilation, and alti- more discreet pendant style is less the stored oxygen and less room air. tude.1 The acceptable oxygen flow rate noticeable but weighs down the ear Low-flow devices include the nasal for this device ranges from 1 to 6 loops. Because reservoir nasal cannulas cannula, simple face masks (simple L/minute. For more on flow rates, see capture water vapor when patients oxygen masks), and rebreather masks Concentrating on nasal cannulas. exhale and return the vapor during (simple masks with a reservoir bag). Oxygen supplied via nasal cannula at inhalation, humidification isn’t Let’s look at each device. flow rates of 4 L/minute or less doesn’t required.1 need to be humidified.2 However, oxy- The reservoir nasal cannula can pro- Nasal cannula gen flow rates above 4 L/minute should vide FIO2 rates of 0.5 or greater while Nasal cannulas are commonly used for be humidified to prevent discomfort letting the patient eat, talk, ambulate, stable patients who can tolerate a low, and prevent nasal mucosa from drying. and use incentive spirometry. Because nonfixed oxygen concentration. These the device is more comfortable and less devices deliver 100% oxygen, but Reservoir nasal cannula anxiety-provoking than other devices, because the patient also breathes room The reservoir nasal cannula, originally the patient may also be more willing to air, the oxygen concentration ultimately designed for outpatient use, is relative- adhere to therapy.1 AST G ATRICIA P Mustache-style Pendant-style reservoir nasal reservoir nasal Nasal cannula cannula cannula LLUSTRATIONS BY I 52 | Nursing2009 | September www.nursing2009.com Simple face mask Partial rebreather mask practice, a concentration over 75% is Like the nasal cannula, the simple face A partial rebreather mask, another type rare because the mask doesn’t create mask (also known as the simple oxy- of reservoir device, consists of a simple a perfect seal on the patient’s face gen mask) mixes oxygen with room face mask with a reservoir bag. It’s a and inspiration of some room air air. But because the mask itself acts as step up from a simple face mask and a is inevitable. (For more, see Non- step down from a non-rebreather rebreather masks: Pumping up the mask. A low-flow device, the partial volume). rebreather mask can deliver 40% to 70% oxygen at flow rates of 6 to 10 L/minute. The oxygen flow should keep the reservoir bag at least one- third to one-half full on inspiration.2 Because this mask’s range of oxygen delivery can be accommodated by either the simple face mask or non- rebreather mask, many hospitals no longer use them. Non-rebreather mask Similar to the partial rebreather mask, the non-rebreather mask also has a series of one-way valves. The valve between the reservoir bag and the mask prevents exhaled air from return- ing to the bag.2 The non-rebreather mask is ideal a reservoir, it can deliver an FIO2 of for emergency situations when the 0.35 to 0.50, using oxygen flow rates patient needs a high inspired-oxygen To maximize function of a non- from 5 to 10 L/minute.2 A minimum concentration (60% to 80%) for a rebreather mask, make sure that the flow rate of 5 L/minute is needed to short time. The mask can be placed mask fits snugly with no visible gaps flush the expired carbon dioxide out quickly and provide a flow rate of up between it and the patient’s face. The of the mask so that the patient doesn’t to 10 L/minute in an emergency.2,5 oxygen flow rate should always main- rebreathe it. Theoretically, an inspired oxygen tain the reservoir bag at least one-third Patients who are mouth breathers concentration of close to 100% could to one-half full on inspiration, just like may also benefit from a face mask over be achieved if the patient breathed in the partial rebreathing mask.