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OSA Screening

Screening for obstructive sleep apnea before surgery: why is it important?

Simply ,Patients with OSA are at higher risk for post-operative respiratory arrest (1)

The gold standard for diagnosis is an overnight sleep study, or polysomnography, which is both expensive and resource-intensive.
The results of polysomnography are reported as the apnea/hypopnea index (AHI).

The AHI is derived from the total number of episodes of apnea and hypopnea divided by the total sleep time.

The American Academy of Sleep Medicine classifies the disease as follows:

Mild OSA = AHI of 5 to 15 events per hour
Moderate OSA = of 15 to 30 events per hour
Severe OSA = AHI of greater than 30 events per hour.

The STOP questionnaire was first published in Anesthesiology in 2008, where it was validated in surgical patients at preoperative clinics as a screening tool.(2)

The STOP questionnaire queried patients on:

(S) Snoring: Do you snore loudly (loud enough to be heard through closed doors?”
(T) Tired: Do you often feel tired, fatigued, or sleepy during daytime?
(O) Observed: Has anyone observed you stop breathing during sleep?
(P) Blood Pressure: Do you have high blood pressure?

 patient with a STOP score of 2 out of 4 was considered at high risk for OSA.

In the same study, the STOP questionnaire was expanded into a STOP-BANG questionnaire, which also queried patients on:

(B) Body mass index>35 kg/m2?
(A) Age>50?
(N) Neck circumference >40 cm (15 ¾ inches)?
(G) Gender=male?

With the added four questions, a patient with a score of 3 out of the possible 8 was considered at high risk for OSA.

With STOP-BANG, sensitivities in identifying patients with an AHI greater than 5, greater than 15, and greater than 30 were increased to 83.6, 92.9, and 100%.

Thus STOP-BANG has been validated as a tool with high sensitivity that can be used to screen patients for moderate and severe OSA.

(1)Cullen DJ: Obstructive sleep apnea and postoperative analgesia—a potentially dangerous combination. J Clin Anesth 2001; 13:83).

(2) (Chung F, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology. 2008 May;108(5):812-21).
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