What is Transient Nocturnal Desaturation?

transient nocturnal desaturation, tnd, copdTransient nocturnal desaturation, also known as nocturnal hypoxemia, is defined as a temporary drop in oxygen saturation during sleep. The condition is a significant problem in COPD, affecting a relatively large number of COPD patients. In fact, one study suggests that 27-70% of COPD patients with daytime oxygen saturation levels of 90-95% experience substantial desaturation at night, particularly during a period of sleep known as rapid eye movement (REM) sleep. In people with severe COPD, desaturation during sleep is even more profound than desaturation during exercise, which is also common.[1]

Causes of Nocturnal Hypoxemia and Desaturation

The primary causes of transient nocturnal desaturation are underlying lung disease and congestive heart failure. These conditions can cause the following conditions, which typically are the cause of nocturnal oxygen desaturation:[2][3]

  • Hypoventilation – defined as abnormally slow breathing; a common condition found in people with COPD. Often leads to hypoxemia (low blood oxygen levels) and hypercapnia (high blood carbon dioxide levels).
  • Ventilation/perfusion (VQ) mismatch – also common in COPD; occurs when ventilation (the exchange of air between your lungs and the environment) and perfusion (the passage of blood through the lungs) are not equal. V/Q mismatch also leads to hypoxemia and hypercapnia in COPD patients.

Risk Factors and Predictors of Nocturnal Desaturation

There are a variety of potential predictors and risk factors when it comes to nocturnal oxygen desaturation. One study suggests that the only predictor of transient nocturnal desaturation is daytime oxygen saturation levels of less than or equal to 93%.[2] Another study suggests that the best predictor of transient nocturnal desaturation is daytime carbon dioxide levels.[4] Another study found several statistically significant predictors of nocturnal oxygen desaturation in moderate to very severe COPD patients with a normal concentration of oxygen in the blood. These predictors included desaturation during a 6-minute walk test, right atrial/right ventricle dilation on echocardiography and positive c-reactive protein levels, which indicate presence of systemic inflammation, all of which pointed to likely nocturnal hypoxemia in these patients.[5]

Though further study is warranted, there seem to be many predictors and risk factors that can help doctors determine whether a patient should be tested for nocturnal oxygen desaturation.

Diagnosis of Nocturnal Hypoxemia and Desaturation

First, most COPD patients should be screened for daytime predictors of nocturnal oxygen desaturation if they report signs of nocturnal hypoxemia, including fast and shallow breathing, headaches upon waking, insomnia, excessive daytime sleepiness, rapid heart rate and nightmares.[5] From there, your doctor or a sleep specialist will perform a number of tests while you sleep to determine whether or not you are experiencing nocturnal oxygen desaturation.

To be diagnosed with transient nocturnal desaturation, your normal, daytime oxygen saturation level must drop at least 4% during sleep for at least 5 minutes. Monitoring your oxygen saturation levels at night involves using overnight continuous pulse oximetry.  This is a reliable, cost effective tool that automatically monitors and records information about your saturation levels while you sleep.1  Nocturnal oximetry is recommended to evaluate gas exchange during sleep in COPD patients.[4]

Treatment of Nocturnal Oxygen Desaturation

Although it’s been well-established that daytime hypoxemia is treated with long-term oxygen therapy (LTOT), treatment for transient nocturnal desaturation varies among physicians.[7] Developing a clear understanding of how prevalent nocturnal desaturation is in COPD – in the absence of other respiratory conditions – is an important step towards managing it in a standardized way.[7] Therefore, it is suggested that in the absence of obstructive sleep apnea, supplemental oxygen can be prescribed and patients should then be assessed for improvement in symptoms like quality of sleep, and energy, concentration and focus during the day. As always, supplemental oxygen should be used at the minimum therapeutic level to provide benefits and help prevent nocturnal desaturation.[1]

Nocturnal-Only Oxygen Therapy (aka Oxygen Therapy During Sleep)

At present, there are two groups of COPD patients that may benefit from the use of oxygen therapy during sleep:

  • Patients who normally require oxygen therapy during the day because of daytime hypoxemia who experience nocturnal oxygen desaturation during sleep.
  • Patients who do not have daytime hypoxemia or use oxygen therapy during the day, but who experience a drop in their oxygen saturations when they sleep.

Supplemental oxygen therapy can provide myriad benefits for these groups experiencing nocturnal hypoxemia and oxygen desaturation, and Inogen oxygen concentrators can help increase those benefits. For patients using oxygen therapy at night, there are a number of factors to consider for the treatment to be as successful as possible. Patients should discuss the convenience of their oxygen delivery device, including whether they can travel with it, as well as the sound level when in operation and the mode of oxygen delivery (i.e. pulse dose versus continuous flow dosing). With an oxygen concentrator from Inogen, you get a product rooted in innovation and designed to help improve your life. 

Inogen oxygen concentrators are made to be incredibly quiet, so they will not disturb you or a partner as you settle down to rest or while you sleep. All Inogen oxygen concentrators run at a noise level of 40 decibels or less, which is about the noise level of a library.[8] Additionally, because each of our oxygen concentrators is designed to be small and easy to take with you, you can bring your Inogen oxygen concentrator with you, even when you travel, so you will not have to worry about sleeping away from home.

Finally, Inogen offers portable oxygen concentrators with Intelligent Delivery Technology® to help ensure that you get the right oxygen dose for you at the right time. Intelligent Delivery Technology adjusts to your breathing rate, delivering the correct bolus dose for your nocturnal breathing pattern. If your doctor determines that you need continuous flow oxygen, our home oxygen concentrators offer continuous flow dosing to meet your needs.

Learn How Inogen Can Help Treat Your Nocturnal Desaturation

If you believe you may have nocturnal hypoxemia and oxygen desaturation, you should see your doctor right away. Transient nocturnal desaturation can cause serious problems and, like any hypoxemic condition, can affect your health over time. You may ultimately experience negative changes in your blood vessels, blood pressure, brain health, cardiac function and pulmonary function. Nocturnal desaturation can also be an indication that a chronic health condition, like COPD or pulmonary hypertension, is worsening. If you wake up feeling unusually fatigued and unrefreshed, even after a full night’s sleep, it is time to seek medical attention.[9][10] 

You will need to be tested for transient nocturnal oxygen desaturation via home oximetry, but your doctor may also request that you undergo a sleep study and an arterial blood gas study to get a complete understanding of the severity of your nocturnal hypoxemia and oxygen desaturation. Even after beginning treatment, you will still undergo some of these tests to continue to monitor your oxygen saturation and to ensure that you do not experience hypercapnia, or a buildup of carbon dioxide in your blood. 

If your doctor prescribes nocturnal oxygen therapy for you, ask about whether an Inogen oxygen concentrator meets your oxygen needs at night. Because we offer both Intelligent Delivery Technology pulse dosing in our portable oxygen concentrator units and continuous flow dosing in our home oxygen concentrator unit, you have several Inogen options to choose from to help you combat nocturnal hypoxemia and oxygen desaturation effectively. Find out what kind of oxygen delivery device your doctor recommends for you, then contact Inogen today to find out how we can meet your needs. We look forward to helping you improve your freedom, mobility and independence by helping you treat your nocturnal desaturation. Oxygen. Anytime. Anywhere.

NOTE: Medicare will cover nocturnal-only oxygen therapy under certain circumstances. To read more about this and to see if you qualify, read Medicare’s Home Oxygen Therapy Guide.


[1] Owens, R. L. “Supplemental Oxygen Needs During Sleep. Who Benefits?” Respiratory Care, vol. 58, no. 1, 1 Jan. 2013, pp. 32–47., doi:10.4187/respcare.01988.

[2] Zanchet, Renata Claudia, and Carlos Alberto de Assis Viegas. “Dessaturação Noturna: Preditores e Influência No Padrão Do Sono De Pacientes Portadores De Doença Pulmonar Obstrutiva Crônica Com Hipoxemia Leve Em Vigília.” Jornal Brasileiro De Pneumologia, SciElo, 2006, www.scielo.br/scielo.php?pid=S1806-37132006000300006&script=sci_abstract&tlng=en.

[3] Peters, Brandon. “What Oxygen Desaturation Index (ODI) Means on a Sleep Study Report.” Verywell Health, Verywell Health, 3 Jan. 2020, www.verywellhealth.com/oxygen-desaturation-index-3015362.

[4] Plywaczewski, Robert, et al. “Incidence of Nocturnal Desaturation While Breathing Oxygen in COPD Patients Undergoing Long-Term Oxygen Therapy.” Chest, vol. 117, no. 3, Mar. 2000, pp. 679–683., doi:10.1378/chest.117.3.679.

[5] R, Jackin Moses, and Karthik Narayanan P. “Predictors of Nocturnal Oxygen Desaturation in Normoxemic Patients with Moderate to Very Severe Chronic Obstructive Pulmonary Disease.” International Journal of Contemporary Medical Research [IJCMR], vol. 6, no. 10, Oct. 2019, pp. J1–J5., doi:10.21276/ijcmr.2019.6.10.41.

[6] Fanfulla, F, et al. “Sleep Disordered Breathing in Patients With Chronic Obstructive Pulmonary Disease.” Minerva Medica, U.S. National Library of Medicine, Aug. 2004, pubmed.ncbi.nlm.nih.gov/15334044/.

[7] Lacasse, Yves, et al. “Evaluating Nocturnal Oxygen Desaturation in COPD–Revised.” Respiratory Medicine, U.S. National Library of Medicine, 10 May 2011, pubmed.ncbi.nlm.nih.gov/21561753/.

[8] “Noise Sources and Their Effects.” Noise Comparisons, Purdue.edu, 23 May 2020, www.chem.purdue.edu/chemsafety/Training/PPETrain/dblevels.htm.

[9] “Sleep-Related Hypoxemia – Causes, Diagnosis, Treatment.” Tuck Sleep, Tuck Sleep LLC, 22 Apr. 2020, www.tuck.com/sleep-disorders/sleep-related-hypoxemia/.

[10] Leader, Deborah. “COPD Can Make Your Oxygen Levels Drop at Night.” Verywell Health, Verywell Health, 29 Jan. 2020, www.verywellhealth.com/transient-nocturnal-desaturation-914932.

Additional sources:

El-Sorougi, Waleedmohamed, et al. “Role of Oxygen and Continuous Positive Airway Pressure Therapy in Chronic Obstructive Pulmonary Disease Patients with Nocturnal Oxygen Desaturation.” Egyptian Journal of Bronchology, vol. 10, no. 3, 9 Nov. 2016, pp. 266–273., doi:10.4103/1687-8426.193637.

Rafanan, Albert L., et al. “Nocturnal Hypoxemia Is Common in Primary Pulmonary Hypertension.” Chest, Elsevier, 28 Dec. 2015, www.sciencedirect.com/science/article/abs/pii/S0012369215501736.

Scott, Adrienne S, et al. “Oxygen Desaturation during a 6 Min Walk Test Is a Sign of Nocturnal Hypoxemia.” Canadian Respiratory Journal, Pulsus Group Inc, 2011, www.ncbi.nlm.nih.gov/pmc/articles/PMC3267623/.


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