Recent evidence and guidelines of periop management of obstructive sleep apnea (OSA).

http://youtu.be/8h6n5rNB9_A

Articles discussed:

1. Chest. 2013 May;143(5):1284-93. doi: 10.1378/chest.12-1132.

Serum bicarbonate level improves specificity of STOP-bang screening for
obstructive sleep apnea.

Chung F, Chau E, Yang Y, Liao P, Hall R, Mokhlesi B.

Department of Anesthesia, Toronto Western Hospital, University Health Network,
University of Toronto, Toronto, ON, Canada. frances.chung@uhn.ca

BACKGROUND: The STOP-Bang questionnaire is a validated screening tool for the
identification of surgical patients with obstructive sleep apnea (OSA). A
STOP-Bang score ≥ 3 is highly sensitive but only moderately specific.
Apnea/hypopnea during sleep can lead to intermittent hypercapnia and may result
in serum bicarbonate (HCO₃⁻) retention. The addition of serum HCO₃⁻ level to the 
STOP-Bang questionnaire may improve its specificity.
METHODS: Four thousand seventy-seven preoperative patients were approached for
consent and screened by the STOP-Bang questionnaire. Polysomnography was
performed and preoperative HCO₃⁻ level was collected in 384 patients. Study
participants were randomly assigned to a derivation or validation cohort.
Predictive parameters (sensitivity, specificity, positive and negative predictive
values) for STOP-Bang score and serum HCO₃⁻ level were calculated.
RESULTS: In the derivation cohort, with a STOP-Bang score ≥ 3, the specificity
for all OSA, moderate/severe OSA, and severe OSA was 37.0%, 30.4%, and 27.7%,
respectively. HCO₃⁻ level of 28 mmol/L was selected as a cutoff for analysis.
With the addition of HCO₃⁻ level ≥ 28 mmol/L to the STOP-Bang score ≥ 3, the
specificity for all OSA, moderate/severe OSA, and severe OSA improved to 85.2%,
81.7%, and 79.7%, respectively. Similar improvement was observed in the
validation cohort.
CONCLUSION: Serum HCO₃⁻ level increases the specificity of STOP-Bang screening in
predicting moderate/severe OSA. We propose a two-step screening process. The
first step uses a STOP-Bang score to screen patients, and the second step uses
serum HCO₃⁻ level in those with a STOP-Bang score ≥ 3 for increased specificity.

PMID: 23238577  [PubMed - in process]

2. Anesth Analg. 2012 Nov;115(5):1060-8. doi: 10.1213/ANE.0b013e318269cfd7. Epub
2012 Aug 10.

Society for Ambulatory Anesthesia consensus statement on preoperative selection
of adult patients with obstructive sleep apnea scheduled for ambulatory surgery.

Joshi GP, Ankichetty SP, Gan TJ, Chung F.

Department of Anesthesiology and Pain Management, University of Texas
Southwestern Medical Center, Dallas, TX 75390-9068, USA.
girish.joshi@utsouthwestern.edu

The suitability of ambulatory surgery for a patient with obstructive sleep apnea 
(OSA) remains controversial because of concerns of increased perioperative
complications including postdischarge death. Therefore, a Society for Ambulatory 
Anesthesia task force on practice guidelines developed a consensus statement for 
the selection of patients with OSA scheduled for ambulatory surgery. A systematic
review of the literature was conducted according to the Preferred Reporting Items
for Systematic Reviews and Meta-Analyses guidelines. Although the studies
evaluating perioperative outcome in OSA patients undergoing ambulatory surgery
are sparse and of limited quality, they do provide useful information that can
guide clinical practice. Patients with a known diagnosis of OSA and optimized
comorbid medical conditions can be considered for ambulatory surgery, if they are
able to use a continuous positive airway pressure device in the postoperative
period. Patients with a presumed diagnosis of OSA, based on screening tools such 
as the STOP-Bang questionnaire, and with optimized comorbid conditions, can be
considered for ambulatory surgery, if postoperative pain can be managed
predominantly with nonopioid analgesic techniques. On the other hand, OSA
patients with nonoptimized comorbid medical conditions may not be good candidates
for ambulatory surgery. What other guidelines are available on this topic? The
American Society of Anesthesiologists (ASA) practice guidelines for management of
surgical patients with OSA published in 2006. Why was this guideline developed?
The ASA guidelines are outdated because several recent studies provide new
information such as validated screening tools for clinical diagnosis of OSA and
safety of ambulatory laparoscopic bariatric surgery in OSA patients. Therefore,
an update on the selection of patients with OSA undergoing ambulatory surgery is 
warranted. How does this guideline differ from existing guidelines? Unlike the
ASA guidelines, this consensus statement recommends the use of the STOP-Bang
criteria for preoperative OSA screening and considers patients' comorbid
conditions in the patient selection process. Also, current literature does not
support the ASA recommendations that upper abdominal procedures are not
appropriate for ambulatory surgery. Why does this guideline differ from existing 
guidelines? This consensus statement differs from existing ASA guidelines because
of the availability of new evidence.

PMID: 22886843  [PubMed - indexed for MEDLINE]

3. N Engl J Med. 2013 Jun 20;368(25):2352-3. doi: 10.1056/NEJMp1302941.

A rude awakening--the perioperative sleep apnea epidemic.

Memtsoudis SG, Besculides MC, Mazumdar M.

Department of Anesthesiology, Hospital for Special Surgery, Weill Medical College
of Cornell University, New York, USA.

PMID: 23782177  [PubMed - in process]

4. Reg Anesth Pain Med. 2013 Jul-Aug;38(4):274-81. doi:
10.1097/AAP.0b013e31828d0173.

Sleep Apnea and Total Joint Arthroplasty under Various Types of Anesthesia: A
Population-Based Study of Perioperative Outcomes.

Memtsoudis SG, Stundner O, Rasul R, Sun X, Chiu YL, Fleischut P, Danninger T,
Mazumdar M.

From the *Department of Anesthesiology, Hospital for Special Surgery, †Division
of Biostatistics and Epidemiology, Department of Public Health; and ‡Department
of Anesthesiology, New York-Presbyterian Hospital, Weill Medical College of
Cornell University, New York, NY.

BACKGROUND AND OBJECTIVES: The presence of sleep apnea (SA) among surgical
patients has been associated with significantly increased risk of perioperative
complications. Although regional anesthesia has been suggested as a means to
reduce complication rates among SA patients undergoing surgery, no data are
available to support this association. We studied the association of the type of 
anesthesia and perioperative outcomes in patients with SA undergoing joint
arthroplasty.
METHODS: Drawing on a large administrative database (Premier Inc), we analyzed
data from approximately 400 hospitals in the United States. Patients with a
diagnosis of SA who underwent primary hip or knee arthroplasty between 2006 and
2010 were identified. Perioperative outcomes were compared between patients
receiving general, neuraxial, or combined neuraxial-general anesthesia.
RESULTS: We identified 40,316 entries for unique patients with a diagnosis for SA
undergoing primary hip or knee arthroplasty. Of those, 30,024 (74%) had
anesthesia-type information available. Approximately 11% of cases were performed 
under neuraxial, 15% under combined neuraxial and general, and 74% under general 
anesthesia. Patients undergoing their procedure under neuraxial anesthesia had
significantly lower rates of major complications than did patients who received
combined neuraxial and general or general anesthesia (16.0%, 17.2%, and 18.1%,
respectively; P = 0.0177). Adjusted risk of major complications for those
undergoing surgery under neuraxial or combined neuraxial-general anesthesia
compared with general anesthesia was also lower (odds ratio, 0.83 [95% confidence
interval, 0.74-0.93; P = 0.001] vs odds ratio, 0.90 [95% confidence interval,
0.82-0.99; P = 0.03]).
CONCLUSIONS: Barring contraindications, neuraxial anesthesia may convey benefits 
in the perioperative outcome of SA patients undergoing joint arthroplasty.
Further research is needed to enhance an understanding of the mechanisms by which
neuraxial anesthesia may exert comparatively beneficial effects.

PMID: 23558371  [PubMed - in process]

5. Anesthesiology. 2012 Jul;117(1):188-205. doi: 10.1097/ALN.0b013e31825add60.

Obesity hypoventilation syndrome: a review of epidemiology, pathophysiology, and 
perioperative considerations.

Chau EH, Lam D, Wong J, Mokhlesi B, Chung F.

Department of Anesthesiology, Toronto Western Hospital, University Health
Network, University of Toronto, Toronto, Ontario, Canada.

Obesity hypoventilation syndrome (OHS) is defined by the triad of obesity,
daytime hypoventilation, and sleep-disordered breathing without an alternative
neuromuscular, mechanical, or metabolic cause of hypoventilation. It is a disease
entity distinct from simple obesity and obstructive sleep apnea. OHS is often
undiagnosed but its prevalence is estimated to be 10-20% in obese patients with
obstructive sleep apnea and 0.15-0.3% in the general adult population. Compared
with eucapnic obese patients, those with OHS present with severe upper airway
obstruction, restrictive chest physiology, blunted central respiratory drive,
pulmonary hypertension, and increased mortality. The mainstay of therapy is
noninvasive positive airway pressure. Currently, information regarding OHS is
extremely limited in the anesthesiology literature. This review will examine the 
epidemiology, pathophysiology, clinical characteristics, screening, and treatment
of OHS. Perioperative management of OHS will be discussed last.

PMID: 22614131  [PubMed - in process]