#456 Outpatient Oxygen Therapy

October 7, 2024 | By Leah Witt

Audio

Transcript available via YouTube

Supplemental oxygen is ubiquitous and yet there is a tremendous amount of uncertainty related to prescription and management in the outpatient setting. Have no fear, we’ve got your back! On this episode of The Curbsiders we host special guest Susan Jacobs, RN, MS who is a bonafide, world-class expert in outpatient oxygen therapy. How to prescribe? What’s out there? What do you do when your patient travels? She joins us to tackle these questions and so much more so make sure to tune in and snag some knowledge food for that old brain hole!

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Show Segments

• Intro
• Getting to know our guest
• Basics of oxygen prescribing and devices
• Caveats for the patient who only has exertional hypoxemia
• How to prepare for travel
• Key points & take aways
• Outro

Key Points:

1. Initial Assessment: The first appointment for home oxygen is crucial, as it involves oxygen prescription documentation, deciding about equipment needs in conjunction with the patient’s lifestyle AND patient education. An oxygen prescription is life changing for a patient and their family!
2. Education Is Critical: do not assume durable medical equipment (DME) companies will adequately educate patients on oxygen use! Provide patient education resources (eg from nursing or online videos and websites such as from the COPD Foundation or Pulmonary Fibrosis Foundation).
3. Oxygen Qualification: Patients qualify for supplemental oxygen if they desaturate to 88% or less at rest, during an activity test (eg walking), or sleep (for at least 5 minutes over 2 hours during sleep). The oxygen dose is then titrated to achieve an SpO₂ of ≥ 90%.
4. Resting Hypoxemia: Patients need continuous oxygen if they have chronic severe resting hypoxemia (SpO₂ ≤ 88% at rest), and should wear it at least 15 hours a day. 
5. Shared Decision-Making for Exertional Hypoxemia: For patients with severe exertional only hypoxemia or nocturnal hypoxemia but no severe resting hypoxemia, the benefits of oxygen therapy are unclear, necessitating a shared decision-making approach between patient and provider.
6. Device Options: stationary concentrators should be prescribed for home/sleep use and portable oxygen (concentrators or tanks) should be prescribed to facilitate ambulation, activities out of the house and exercise. High-flow stationary concentrators can deliver up to 10 LPM. 
7. Portable Oxygen Options: While portable oxygen concentrators (POCs) are lightweight and convenient, they are not suitable for high-flow oxygen needs (their “setting” does NOT equal liter flow!). Most POCs deliver pulse NOT continuous flow. Liquid oxygen is useful for high flow needs, but widely unavailable as of this recording. Tanks should be prescribed for back-up emergencies and travel (tanks come in many sizes and with options to extend the life of a tank with pulse flow with an oxygen conserving device!). Ask patients to bring their portable equipment with them when they come to clinic visits.
8. Travel Considerations: Patients traveling by airplane with supplemental oxygen must plan ahead by selecting an FAA-approved POC, carrying enough battery power for 1.5 times the flight duration, and alerting the airline. Altitude simulation tests estimate hypoxemia at altitude (8000 feet), but aren’t enough to qualify for home oxygen. 
9. Pulmonary rehab is underused and one of the most important interventions we have for chronic lung disease! This is also a great place for people to learn about using their oxygen correctly especially with exercise.

Outpatient Oxygen Therapy – Notes

Intro to outpatient oxygen – Nuts & Bolts

The initial appointment with someone who is being prescribed home long term oxygen therapy (LTOT) for the first time is a big deal. It’s a big life change – especially for someone who needs supplemental oxygen continuously for chronic severe resting hypoxemia. At that initial visit, patient education is paramount, along with correctly documenting the oxygen needs for the prescription and payment by insurance. The provider must also carefully choose which equipment to prescribe for both the home and ambulation/exercise. This will include a discussion about their lifestyle (home size, stairs, interests/hobbies, work/responsibilities, travel, etc.). 

The extent to which such a patient is likely to clinically benefit from supplemental oxygen is important to discuss– benefits in mortality and cognition have been clearly demonstrated in people who have severe chronic resting hypoxemia (NOTT 1980, MRC 1981, Heaton et al 1983). Other potential benefits include improving exercise ability (Davidson et al 1988), breathlessness (Cochrane 2016) and quality of life (Eaton et al 2004).

However a study of those with exertional hypoxemia or moderate resting hypoxemia (SpO2 89-93%) did not demonstrate a mortality or quality of life benefit nor reduction in hospitalizations or anxiety/depression (LOTT Trial 2016). The LOTT study did have slow recruitment which resulted in this composite trial of different types of patients and the experimental group only used 13.6 h/day of oxygen. LTOT for nocturnal oxygen desaturation is similarly low evidence, as a 2020 study demonstrated no difference in COPD exacerbations or quality of life but was underpowered and did not reach full enrollment (Lacasse 2020).

The ATS Clinical Practice Guideline suggests prescribing supplemental oxygen for people with COPD or ILD who have severe exertional room air hypoxemia but the evidence is low-quality (Jacobs 2020). These guidelines also recommend against prescribing long term oxygen therapy for people with COPD who have moderate chronic resting room air hypoxemia (defined as an SpO2 of 89-93%) (Jacobs 2020)– people with ILD and moderate hypoxemia were not addressed due to lack of evidence.

Starting long term oxygen therapy for patients with exertional only hypoxemia or nocturnal hypoxemia is not straightforward and certainly requires shared decision-making considering theoretical benefits including symptom improvement but risking social isolation/loneliness (Suen 2023), fall risk hazards from cables/tubes, cost, logistic issues and potential frustrations of dealing with DME companies. 

Prescribing Oxygen

A patient qualifies for oxygen via any desaturation to 88% or less at rest,  with activity or with sleep (for at least 5 min). A qualifying prescription does not need to be done in a 6 minute walk test– in fact any duration of activity is adequate. After documenting the desaturation, you then need to assess the patient with supplemental oxygen to determine the oxygen “dose” necessary to achieve an SpO₂ ≥ 90%.  The prescription (and documentation) needs to include the diagnosis, the saturation at rest, the saturation with exertion and then sequential saturations with increasing oxygen doses (2 LPM, 4 LPM etc.) up until the patient achieves/maintains an SpO₂ ≥ 90%. At night, they should wear at least the same amount of oxygen at night though further titration could occur during an overnight oxygen study, particularly if the patient has symptoms of hypoxemia (eg am headaches or daytime somnolence). Sleep apnea should be ruled out in this situation. 

Duration of need should be included (usually lifetime or “99 months”). Don’t forget to order portable oxygen (you may need to justify need: eg Patient works 10-12 hours outside of the home and needs sufficient ambulatory oxygen to support). 

Note: Medicare will pay for one portable option (tanks or a portable oxygen concentrator) AND many DME companies will fluctuate in their availability of POCs due to cost to maintain. Many patients like the idea of a portable oxygen concentrator (POC) due to convenience, weight and size, however these are only appropriate for people who can tolerate pulse/on demand oxygen flow and do not require a high liter flow. Note: setting on a POC does NOT equal liter flow. The out of pocket cost for portable oxygen concentrators can range from $2000-4000.

Tanks can be just as portable if the right size is selected (eg A through D tank sizes). Oxygen conserving devices can be ordered with tanks to extend their lifetime (eg converting the tank from continuous to pulse/on demand flow). Patients should also be given big tanks (“E” tanks) in case of an emergency, like a power outage.

How Many Hours a Day Should Oxygen be Worn?

According to the ATS workshop report which aggregated the best evidence to date, supplemental oxygen should be used for a minimum of 15 hours a day (Jacobs 2020). 

Devices

Oxygen ordered via insurance must include a stationary concentrator– patients may not only be prescribed portable/ambulatory oxygen. A stationary concentrator converts concentrated oxygen from ambient air for use directly via cannula. In some instances, the concentrator can fill portable tanks for ambulatory use via a “transfill” system. Low-flow devices will deliver up to 5LPM while high-flow devices can deliver up to 10 LPM. High-flow oxygen orders may need to show desaturations at 4LPM.

Portable options include gaseous oxygen in cylinders, liquid oxygen (very rare/expensive)  and portable oxygen concentrators. A patient’s ambulatory needs will determine what they are “eligible for.” For example, a patient on 5LPM cannot use a portable concentrator and instead will need to use portable, metallic tanks (such as an E or D cylinder) to service their ambulatory needs.

Portable Oxygen Concentrators (POCs): These sound great – and can be great options – with some caveats. These are smaller – purse sized options – that allow for improved mobility. They have settings that are not LPMs!! They often use “pulse-flow” or “on-demand” – this means the patient will get an oxygen bolus every time they trigger the machine with an inspiratory effort. This allows the machine to last longer (i.e. the battery will not drain) but different settings will reduce the amount of oxygen delivered per unit time based on a conserving ratio. This ratio is the “setting” that can often be adjusted when using a portable concentrator in pulse-flow mode. Thus, this is not the flow – which is typically capped at 2 LPM but could be up to 3 LPM, depending on the machine. There are no POCs delivering 5+ LPM even though the settings can be confusing and lead someone to think this is possible! Also, one’s respiratory rate will impact oxygen consumption when using a pulse-flow mode. Bottom line: follow the pulse oximeter and symptoms! Pulse-flow oxygen is almost never used for night time / nocturnal oxygen so if you come across that, be skeptical!

Liquid oxygen tanks: As of this recording, liquid oxygen is widely unavailable. Unfortunately this occurred because of changes to Medicare reimbursement which led to DME companies discontinuing their service for liquid oxygen. The benefits of liquid O2 are that they hold much more oxygen and are lighter and deliver higher flow of oxygen. The ATS workshop guidelines strongly recommend liquid oxygen and legislative advocacy efforts are underway to increase access to this important treatment (Jacobs 2020).

Education

Don’t assume the DME (durable medical equipment) company will do a good job of educating the patient on all-things outpatient oxygen! The dream set up is trained clinical staff who can educate patients before they receive their first oxygen delivery. If you are prescribing supplemental oxygen you should educate yourself on the basics of the devices and therapy so you can pass that on to your patients!

Normal SpO₂ at rest… with exertional hypoxemia. What do we do? What do guidelines & the literature suggest?

Bottom line: The data is not great and guidelines support this via low-quality evidence & low-certainty statements. For practical purposes, a patient without hypoxemia at rest but exertional hypoxemia qualifies for supplemental oxygen BUT mortality benefits has not been demonstrated. Overall, the approach to these patients is more of a shared-decision type approach because the benefits are NOT cut and dry. 

Traveling with Oxygen

Airplanes are pressurized; so while they  typically fly at 30-40,000  feet the cabin is pressurized such that the oxygen tension is more like an altitude of 8,000 feet. Patients with normal physiology may experience a drop in their oxygen saturation, despite pressurization, by 3-4%. However, this is generally clinically irrelevant. Patients with a baseline oxygen requirement are obviously affected in a more clinically significant way due to where they “live” on the oxygen dissociation curve and thus, will need supplemental oxygen. 

Patients who use a certain prescription of oxygen while at home can likely tolerate the same prescription while in the air despite the altitude difference. However, if a patient is either not on supplemental oxygen but close to requiring it and/or they are traveling to an area where the altitude is significantly higher than home, a high altitude simulation test (HAST) could be useful (Dine 2008 et al). In a HAST, the patient breathes in a mixture of gases with an FiO2 of 15.1% simulating a cabin pressure of 8,000 feet. However this test is not accepted by insurance companies as justification for oxygen (though it can be used if people are paying out of pocket to buy or rent a POC).  High altitude simulation tests are also not widely available and we do not recommend their routine use in this situation. 

POCs for travel can be arranged either through the patient’s DME company (if they are already
“on service” with supplemental oxygen) OR through a rental company (eg https://oxygentogo.com/). Plan way in advance! Travelers will need battery power for 1.5x the length of the flight – that’s a standard requirement. 

Links

1. The SOAR Act Overview
2. Pulmonary Fibrosis Foundation Oxygen Education Booklet for patients
3. COPD Foundation Patient Education resources
4. ATS Guideline of Ambulatory Oxygen – One Page Summary
5. ATS Summary for Clinicians: Clinical Practice Guideline on Home Oxygen Therapy for Adults with Chronic Lung Disease (Khor 2021)
6. ATS Full Clinical Practice Guideline on Home Oxygen Therapy for Adults with Chronic Lung Disease (Jacobs 2020).
7. How to use an at-home oxygen concentrator. Basic video guide. (video-link)
8. The seminal NOTT trial (1980): Patients with COPD who are hypoxemic have a significant mortality benefit when placed on continuous oxygen therapy vs nocturnal oxygen therapy (NNT 5). 
9. The MRC Trial (1981): long-term oxygen therapy significantly improves survival in patients with severe chronic obstructive pulmonary disease (COPD) and chronic hypoxemia. The study demonstrated that patients who received continuous oxygen therapy (for at least 15 hours per day) had a better survival rate compared to those who received no oxygen therapy or limited therapy (NNT 5).
10. The LOTT Trial (2016):  Long-term oxygen therapy (LTOT) did not result in a significant improvement in survival or reduction in hospitalizations for patients with moderate chronic obstructive pulmonary disease (COPD) and moderate desaturation (resting SpO2 of 89-93% or exercise-induced desaturation). This trial challenged the routine use of LTOT in patients with less severe hypoxemia, suggesting that oxygen therapy may not be beneficial for those without severe hypoxemia at rest.

Goal

Listeners will develop a nuanced understanding of outpatient oxygen therapy to include the approach to diagnosis, modalities available, and how to approach new diagnoses of persistent hypoxemia in a patient-centered manner. 

Learning objectives

After listening to this episode listeners will…  

1. Define hypoxemia and learn to assess it in a clinical visit, as well in special scenarios such as with ambulation, sleep and travel/altitude.
2. Recognize that the mortality benefits of supplemental oxygen have only been demonstrated in severe chronic hypoxemia at rest, not with ambulation or sleep. 
3. Explore the logistic issues that are critical for providers to understand in prescribing supplemental oxygen, including device types and payment

Disclosures

Susan Jacobs reports no relevant financial disclosures.. The Curbsiders report no relevant financial disclosures. 

Citation

Witt L, Askin C, Jacobs S, Williams PN, Watto MF. “456 Outpatient Oxygen Therapy”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast Final publishing date October 07, 2024.