Risk Factors for Transient Nocturnal Desaturation
Some studies conclude that daytime oxygen saturation levels of less than or equal to 93% have been found to be a predictor of transient nocturnal desaturation in people who have normal oxygen levels or are or mildly hypoxic who also have stable COPD.
Causes of Transient Nocturnal Desaturation
Transient nocturnal desaturation is primarily caused by a decreased rate of breathing (hypoventilation) and to a lesser degree, a ventilation/perfusion mismatch.
Hypoventilation may lead to alterations in arterial blood gases such as hypercapnia and hypoxemia in COPD patients, especially during REM sleep. These alterations may lead to increased episodes of arousal and sleep disruption, pulmonary hypertension and a higher mortality rate. Additionally, having other sleep disorders such as sleep apnea may further increase problems and symptoms associated with transient nocturnal desaturation.
Screening Considerations for Transient Nocturnal Desaturation
In people with moderate to severe COPD who are suspected to have transient nocturnal desaturation, home oximetry is an effective tool in screening for this condition. Overnight home oximeters measure oxygen saturation levels during sleep and are equipped with alarms that sound when oxygen saturation falls below a certain level. They also record your oxygen saturation levels so that your health care provider can better evaluate you for transient nocturnal desaturation.
Another tool that is useful in identifying transient nocturnal desaturation and other sleep disorders is overnight polysomnography (PSG,) commonly referred to as a sleep study. A sleep study can be a helpful tool in diagnosing sleep disturbances and is beneficial to the practice of sleep medicine.
PSG is performed in a controlled environment, preferably a sleep center and is monitored by a trained technician. It simultaneously records various physiological parameters that are related to sleep and wakefulness, including breathing, heart rate, oxygen levels, muscle activity and eye movements.
Treatment of Transient Nocturnal Desaturation
Patients who have severe transient nocturnal desaturation would clearly benefit from prolonged oxygen therapy, particularly if there is evidence of daytime hypoxemia. Additionally, if you are using oxygen during the day, you should talk to your health care provider about the possibility of needing more oxygen during sleep to prevent further desaturation during the night. People with COPD may also find that they get a better night's sleep using oxygen only at night, but, the benefit of this remains unclear.
For more information, read 10 Tips for Getting a Good Night's Sleep With COPD and talk with your health care provider.
Source:
Fanfulla F, Cascone L, Taurino AE.Minerva Med. Sleep disordered breathing in patients with chronic obstructive pulmonary disease. 2004 Aug;95(4):307-21.
Lacasse Y et. al. Evaluating nocturnal oxygen desaturation in COPD - revised. Respir Med. 2011 May 9.
Marrone O, Salvaggio A, Insalaco G. Int J Chron Obstruct Pulmon Dis. Respiratory disorders during sleep in chronic obstructive pulmonary disease. 2006;1(4):363-72.
Weitzenblum E, Chaouat A, Charpentier C, Krieger J. Sleep and COPD. Rev Prat. 1995 May 15;45(10):1257-60.
