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THE ANESTHESIA CONSULTANT

Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group

Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
emailrjnov@yahoo.com

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Airway obstruction at the base of the tongue in a patient with obstructive sleep apnea

Clinical Case for Discussion: You’re the anesthesiologist for a 51-year-old man scheduled for arthroscopic rotator cuff surgery at a freestanding surgery center.  His wife volunteers that the patient is a loud snorer.  The patient denies ever being diagnosed with obstructive sleep apnea.  Should you proceed with the surgery?  Can the patient safely be discharged home after surgery at a freestanding facility ?  What would you do?

You discuss the case with an anesthesia colleague.  She recommends you utilize a STOP-BANG questionnaire on the patient.  What is she talking about?

Discussion: Frequent snoring is present in 34% of men and women over the age of 40. (Baldwin, et al, Sleep disturbances, quality of life, and ethnicity: the sleep heart health study, J Clin Sleep Med. 2010 Apr 15;6(2):176-83).  Does any physician ever cancel a surgery at a freestanding surgery center because the patient is a snorer?  Should we?  Is there any data?

STOP-BANG may sound like a title from the next James Bond movie, but it has nothing to do with spies, guns, or crime.  STOP-BANG is a tool for diagnosing obstructive sleep apnea.

Obstructive sleep apnea (OSA) is a common comorbidity in surgical populations. It’s estimated that approximately 4% of men and 2% of women, 18 million Americans overall, have OSA (Miller’s Anesthesia, 2010, p 2776). An estimated 82% of men and 92% of women with moderate or severe sleep apnea have not been diagnosed (Chung F, Elsaid H, Screening for obstructive sleep apnea before surgery: why is it important? Curr Opin Anaesthesiol. 2009 Jun;22(3):405-11). Patients with OSA are at higher risk for post-operative respiratory arrest (Cullen DJ: Obstructive sleep apnea and postoperative analgesia—a potentially dangerous combination. J Clin Anesth  2001; 13:83).

OSA is defined as complete cessation of airflow during breathing lasting 10 seconds or longer despite maintenance of neuromuscular ventilatory effort, and occurring five or more times per hour of sleep, accompanied by a decrease of at least 4% in Sao2. (Miller’s Anesthesia, 2010, p 2092). 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. (Chung F, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology. 2008 May;108(5):812-21).

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?

A patient with a STOP score of 2 out of 4 was considered at high risk for OSA.  Patients’ scores from the STOP questionnaire were evaluated versus his or her AHI total from polysomnography. In Chung’s study, the STOP questionnaire was given to 2,467 patients, and 211 of these patients underwent polysomnography. The sensitivities of the STOP questionnaire in identifying patients with an AHI greater than 5, greater than 15, and greater than 30 were 65.6, 74.3, and 79.5%, respectively.

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%.

In a recent study, (Ong TH, et al, Simplifying STOP-BANG: use of a simple questionnaire to screen for OSA in an Asian population. Sleep Breath. 2010 Apr 26), 348 patients undergoing polysomnography were asked to fill in the 8-question STOP-BANG questionnaire. The sensitivities of the STOP-BANG screening tool for an AHI of >5, >15, and >30 were 86.1%, 92.8%, and 95.6%, respectively.

Thus STOP-BANG has been validated as a tool with high sensitivity that can be used to screen patients for moderate and severe OSA.  As a clinician, what do you do with the STOP-BANG information?

You ask your shoulder arthroscopy patient the 8 STOP-GANG questions, and he scores 1 point for snoring, 1 point for age>50, and 1 point for male gender.  These results qualify him for a possible diagnosis of OSA.  Will you still anesthetize him for this outpatient surgery?

The most useful reference to answer this question is the ASA Practice Guidelines for the Perioperative Management of Patients with Obstructive Sleep Apnea (Anesthesiology 2006; 104:1081–93).  If a sleep study is available, the Practice Guidelines feature an OSA Scoring System which scores on three criteria:  (A) the severity of sleep apnea, (B) the invasiveness of the surgery and anesthesia, and (C) the requirement for post-operative opioids.  Per this OSA Scoring System, our shoulder arthroscopy patient scores (A) 2 points for presumed moderate OSA, (B)  2 points for peripheral surgery with general anesthesia, and (C) 2 points for possible high doses of oral or parenteral opioids post-op.  His OSA Score is the total of (A) and the higher of (B) or (C), or 2 + 2 = 4 points.  The Practice Guidelines state that, “Patients with a score of 4 may be at increased perioperative risk from OSA.”

The Practice Guidelines state that for “minor orthopedic surgery/general anesthesia” on patients suspected of having OSA, the decision to discharge the patient home after outpatient surgery is “equivocal,” as there is no convincing data advising one way or another.  The Practice Guidelines also state that “these patients should not be discharged from the recovery area to an unmonitored setting (i.e., home or unmonitored hospital bed) until they are no longer at risk for postoperative respiratory depression, . . . and may require a longer stay as compared with non-OSA patients undergoing similar procedures.”

The Practice Guidelines suggest regional techniques rather than systemic post-operative opioids, in an attempt to reduce the likelihood of adverse outcomes in patients at increased perioperative risk from OSA.

So what do you do?

You go ahead and anesthetize the patient.  If you’re comfortable with upper extremity regional blocks, you may utilize this technique in your anesthetic.  In any case, you’ll use your excellent judgment to delay discharge until the patient looks safe to be discharged home.  If his oxygen saturation, airway status, or opioid requirements are unsatisfactory, you’ll transfer him to a hospital for overnight stay.

With STOP-BANG or without STOP-BANG, your clinical judgment . . . based on your training . . . will still be your most valuable tool.

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Published in September 2017:  The second edition of THE DOCTOR AND MR. DYLAN, Dr. Novak’s debut novel, a medical-legal mystery which blends the science and practice of anesthesiology with unforgettable characters, a page-turning plot, and the legacy of Nobel Prize winner Bob Dylan.

KIRKUS REVIEW

In this debut thriller, tragedies strike an anesthesiologist as he tries to start a new life with his son.

Dr. Nico Antone, an anesthesiologist at Stanford University, is married to Alexandra, a high-powered real estate agent obsessed with money. Their son, Johnny, an 11th-grader with immense potential, struggles to get the grades he’ll need to attend an Ivy League college. After a screaming match with Alexandra, Nico moves himself and Johnny from Palo Alto, California, to his frozen childhood home of Hibbing, Minnesota. The move should help Johnny improve his grades and thus seem more attractive to universities, but Nico loves the freedom from his wife, too. Hibbing also happens to be the hometown of music icon Bob Dylan. Joining the hospital staff, Nico runs afoul of a grouchy nurse anesthetist calling himself Bobby Dylan, who plays Dylan songs twice a week in a bar called Heaven’s Door. As Nico and Johnny settle in, their lives turn around; they even start dating the gorgeous mother/daughter pair of Lena and Echo Johnson. However, when Johnny accidentally impregnates Echo, the lives of the Hibbing transplants start to implode. In true page-turner fashion, first-time novelist Novak gets started by killing soulless Alexandra, which accelerates the downfall of his underdog protagonist now accused of murder. Dialogue is pitch-perfect, and the insults hurled between Nico and his wife are as hilarious as they are hurtful: “Are you my husband, Nico? Or my dependent?” The author’s medical expertise proves central to the plot, and there are a few grisly moments, as when “dark blood percolated” from a patient’s nostrils “like coffee grounds.” Bob Dylan details add quirkiness to what might otherwise be a chilly revenge tale; we’re told, for instance, that Dylan taught “every singer with a less-than-perfect voice…how to sneer and twist off syllables.” Courtroom scenes toward the end crackle with energy, though one scene involving a snowmobile ties up a certain plot thread too neatly. By the end, Nico has rolled with a great many punches.

Nuanced characterization and crafty details help this debut soar.

Click on the image below to reach the Amazon link to The Doctor and Mr. Dylan: