Managing patients with obstructive sleep apnea (OSA)

Michael Allison, MD
26th Nov 2020

What is the prevalence of obstructive sleep apnea?

Obstructive sleep apnea (OSA) is estimated to affect 3–10% of individuals under the age of 50 and 9–17% of those older than 50 years of age—making this a common problem clinicians will face. 

Man and women under fifty and man and women over fifty with prevalence of obstructive sleep apnea. Illustration.

Figure 1. The prevalence of obstructive sleep apnea (OSA). It is estimated that 3–10% of individuals under the age of 50 and 9–17% of those older than 50 years of age will be affected by OSA.


What are the risk factors for OSA?

There are eight main risk factors that would lead to an evaluation for OSA:

  1. Snoring
  2. Daytime somnolence
  3. Unrefreshed sleep
  4. Sedentary fatigue 
  5. Nocturia
  6. Morning headaches
  7. High body mass index (BMI)
  8. Increased neck circumference

Women with eight symptoms of obstructive sleep apnea. Cartoon.

Figure 2. The eight main risk factors for obstructive sleep apnea (OSA) are snoring, daytime somnolence, unrefreshed sleep, sedentary fatigue, nocturia, morning headaches, a high body mass index (BMI), and increased neck circumference.


How is OSA diagnosed?

The diagnosis of obstructive sleep apnea is made with polysomnography to determine the number of apneas and hypopneas per hour. 


How is OSA treated?

The collapse of the upper airway that causes obstruction and apnea during sleep is reversed with the application of positive-pressure ventilation. This is most commonly delivered as continuous positive airway pressure (CPAP).

How should I titrate CPAP for my patient with OSA?

Laboratory titration

Initial titration of CPAP is typically done in the laboratory setting (during sleep) and is adjusted to reduce the number of obstructive events. Typically, CPAP is started at 4 cmH2O and can be adjusted in fixed increments to a maximum of 20 cmH2O. 

Patient in bed in sleep lab and scale of pressure titration for CPAP. Illustration.

Figure 3. Continuous positive airway pressure (CPAP) ventilation treatment for obstructive sleep apnea (OSA) is typically titrated in a sleep lab with settings starting at 4 cmH2O and increased incrementally to 20 cmH2O.

Automated titration

Newer evidence suggests that automated CPAP titration—where titration is done by the machine itself—appears as effective as sleep lab titration for initiating CPAP.

Though typically sleep apnea is treated at home, patients with sleep apnea often have other medical problems and may become hospitalized. CPAP should be continued in the hospital for patients with sleep apnea, but a common problem is that many patients don’t know or can’t recall what their home settings are. In these situations, automated titration of CPAP is convenient and sets reliable pressures to improve the patient’s apnea. So, if available on your hospital’s CPAP machines, automated titration is the ideal choice.

What do you do if you don't have an automated titrate CPAP machine? Use BMI-based settings.

Setting a CPAP machine based on BMI has been evaluated and results in settings similar to those set by polysomnography. Start with a pressure of 8 cmH2O for patients with a BMI of less than 30. Use 10 cmH20 if the BMI is 30 through 35, and 12 cmH2O if the BMI is greater than 35.

Three women with increasing body mass index and respective pressure setting for CPAP. Illustration

Figure 4. The initial pressure setting for continuous positive airway pressure (CPAP) ventilation treatment for obstructive sleep apnea (OSA) can be determined according to the patient’s body mass index (BMI): 8 cmH2O for  BMI < 30, 10 cmH2O for BMI 30–35, and 12 cmH2O for BMI > 35.

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Recommended reading

  • Hukins, CA. 2005. Arbitrary-pressure continuous positive airway pressure for obstructive sleep apnea syndrome. Am J Respir Crit Care Med. 171: 500–505. PMID: 15563637
  • Veasey, SC and Rosen, IM. 2019. Obstructive sleep apnea in adults. N Engl J Med. 380: 1442–1449. PMID: 30970189