Patient Safety Tip of the Week
October 11, 2016
New Guideline on Preop Screening and Assessment
for OSA
Our regular readers
are well aware of the numerous controversies and limited evidence base
regarding perioperative issues in patients with known obstructive sleep apnea (OSA)
or those suspected as being at high risk for OSA (see the list of prior columns
at the end of today’s column).
The Society of Anesthesia and Sleep Medicine has just
published “Guidelines on Preoperative Screening and Assessment of Adult
Patients with Obstructive Sleep Apnea”
(Chung
2016). This is a most thorough evaluation of the evidence base regarding
multiple issues related to OSA in patients about to undergo surgery. One is
struck by the lack of strong evidence for almost all the recommendations in the
guideline, though we are not surprised since we’ve previously discussed most of
the controversial issues. Yet this consensus guideline uses common sense and is
very practical and appropriately balances concerns for patient safety with
utilization of resources and concerns over timing of surgery.
Below is their executive summary of the recommendations:
- Patients with obstructive
sleep apnea (OSA) undergoing procedures under anesthesia are at increased
risk for perioperative complications compared with patients without the
disease diagnosis. Identifying patients at high risk for OSA before surgery
for targeted perioperative precautions and interventions may help to
reduce perioperative patient complications.
- Screening tools help to
risk stratify patients with suspected OSA with reasonable accuracy.
Practice groups should consider making OSA screening part of standard preanesthetic evaluation.
- There is insufficient
evidence in the current literature to support canceling or delaying
surgery for a formal diagnosis (laboratory or home polysomnography) in
patients with suspected OSA, unless there is evidence of an associated
significant or uncontrolled systemic disease or additional problems with
ventilation or gas exchange.
- The patient and the health
care team should be aware that both diagnosed OSA (whether treated,
partially treated, or untreated) and suspected OSA may be associated with
increased postoperative morbidity.
- If available,
consideration should be given to obtaining results of the sleep study and,
where applicable, the patient’s recommended positive airway pressure (PAP)
setting before surgery.
- If resources allow,
facilities should consider having PAP equipment for perioperative use or
have patients bring their own PAP equipment with them to the surgical
facility.
- Additional evaluation to
allow preoperative cardiopulmonary optimization should be considered in
patients with diagnosed, partially treated/untreated, and suspected OSA
where there is indication of an associated significant or uncontrolled
systemic disease or additional problems with ventilation or gas exchange
such as: (i) hypoventilation syndromes, (ii)
severe pulmonary hypertension, and (iii) resting hypoxemia in the absence
of other cardiopulmonary disease.
- Where management of
comorbid conditions has been optimized, patients with diagnosed, partially
treated/untreated OSA, or suspected OSA may proceed to surgery provided
strategies for mitigation of postoperative complications are implemented.
- The risks and benefits of
the decision to proceed with or delay surgery include consultation and
discussion with the surgeon and the patient.
- The use of PAP therapy in
previously undiagnosed but suspected OSA patients should be considered
case by case. Because of the lack of evidence from randomized controlled
trials, we cannot recommend its routine use.
- Continued use of PAP
therapy at previously prescribed settings is recommended during periods of
sleep while hospitalized, both preoperatively and postoperatively.
Adjustments may need to be made to the settings to account for
perioperative changes such as facial swelling, upper airway edema, fluid
shifts, pharmacotherapy, and respiratory function.
Though this guideline deals primarily with the preoperative
issues and does not delve into the many intra- and post-operative issues in
patients with known or suspected OSA, this is a valuable document with lots of
great references. Note also that a podcast
about the guideline is available via the Anesthesia &Analgesia website as
well.
A new meta-analysis confirms the utility of the pre-op
STOP-Bang questionnaire in predicting complications following surgery (Nagappa
2016). From studies in the literature they found 11 qualified
studies with over 20,000 adult patients who underwent surgery. Compared to
those with a pre-op STOP-Bang score of 0-2, those with a score of 3 or more had
an almost 4 times higher risk of complications (OR = 3.83). But, while OSA may
be responsible for many of those complications, don’t forget that many of the
STOP-Bang items by themselves (high BMI, hypertension, large neck
circumference, age >50) may be associated with higher risks of surgical
complications. Nevertheless, just knowing that such patients are at greater
risk for complications should make staff more vigilant after surgery. They
should be especially vigilant for signs of OSA and, as noted in the new Society
of Anesthesia and Sleep Medicine guideline above, PAP therapy should be
considered on a case-by-case basis even though the jury is still out on routine
use of PAP in patients with undiagnosed but suspected OSA.
Our June 7, 2016
Patient Safety Tip of the Week “CPAP
for Hospitalized Patients at High Risk for OSA” highlighted a study (Sharma
2016) which used the STOP tool to
screen obese patients (BMI ≥ 30 kg/m2) admitted to select medical
(non-surgical) services and sorted them into high- and low-risk for OSA groups.
They found that rapid response system (RRS) activations were significantly more
frequent in those patients in the high-risk group. But high-risk patients who
were put on PAP (CPAP, BiPAP, or APAP) and were
compliant with PAP were significantly less likely to have RRS activations than
those high-risk patients not compliant with PAP or not receiving PAP. The study
also implies (but does not actually include the data) that those patients
compliant with PAP had lower mean LOS.
But perhaps the most important message is that patients identified
at higher risk by the STOP-Bang questionnaire need closer postoperative
monitoring. And, as we’ve emphasized in numerous columns, just using pulse
oximetry and respiratory rate monitoring is not sufficient. Capnography has now become the gold standard
for monitoring patients. A recent review (Geralemou 2016)
highlights the evidence base that capnography predicts impending respiratory
depression earlier than does either pulse oximetry or respiratory rate. That is
especially true in patients who are receiving supplemental oxygen. And we’ve
noted numerous times how in patients with OSA a nurse or respiratory therapist
may respond to a pulse oximetry alarm only to find a patient now awake and
breathing normally with a normal oxygen saturation. Then the patient goes back
to sleep and develops airway obstruction.
Geralemou et al. note some of the
concerns regarding this technology including consistent appropriate positioning
of the end-tidal CO2 monitoring device in awake extubated patients, patient
comfort, and less familiarity with this device compared to pulse oximetry by
nursing staff.
But many hospitals have not yet adopted routine capnographic monitoring because of concerns over cost. Geralemou et al. point to a study which showed
postoperative respiratory failure added approximately 9 hospital days to
hospital length of stay, greater than $53,000 to hospital costs, and an almost
22% increase in mortality (Zhan 2003).
The Canadian Agency for Drugs and Technologies in Health (CADTH) in 2016 did an
analysis of end-tidal CO2 monitoring in the hospital setting (CADTH
2016). Though admitting that high level evidence of efficacy is limited,
they performed an exploratory analysis which concluded that for patients in
serious or critical condition and for patients with obstructive sleep apnea or
receiving high doses of opioids in post-operative care, use of end-tidal CO2
monitoring is likely less costly and more effective than standard monitoring.
In addition, a business case has been made for the cost
effectiveness of capnographic monitoring for
procedural sedation for gastrointestinal endoscopy (Saunders
2016). Those authors found that the addition of capnography resulted in a
27.2 % and 18.0 % reduction in the proportion of patients
experiencing an adverse event during deep and moderate procedural
sedation/analgesia, respectively. The reduction in adverse events resulted in
cost savings that accounted for the additional upfront purchase cost.
Capnography was estimated to reduce the cost per procedure by $85 (deep) or $35
(moderate).
All these articles reinforce 2 best practices we feel need
universal adoption:
- Use of the STOP-Bang questionnaire to screen
for patients at risk of OSA preoperatively in all patients. (We also think
it should be used to screen any hospitalized patient who might be given
opioids or sedation).
- Use of capnography in monitoring any
patient in whom the possibility of respiratory compromise is considered.
Our prior columns on
obstructive sleep apnea in the perioperative period:
June 10, 2008 “Monitoring
the Postoperative COPD Patient”
August 18, 2009 “Obstructive
Sleep Apnea in the Perioperative Period”
August 17, 2010 “Preoperative
Consultation – Time to Change”
July 2010 “Obstructive
Sleep Apnea in the General Inpatient Population”
July 13, 2010 “Postoperative
Opioid-Induced Respiratory Depression”
November 2010 “More
on Preoperative Screening for Obstructive Sleep Apnea”
February 22, 2011 “Rethinking
Alarms”
November 22, 2011 “Perioperative
Management of Sleep Apnea Disappointing”
March 2012
“Postoperative
Complications with Obstructive Sleep Apnea”
May 22, 2012 “Update
on Preoperative Screening for Sleep Apnea”
February 12, 2013 “CDPH:
Lessons Learned from PCA Incident”
February 19, 2013 “Practical
Postoperative Pain Management”
March 26, 2013 “Failure
to Recognize Sleep Apnea Before Surgery”
June 2013 “Anesthesia
Choice for TJR in Sleep Apnea Patients”
September 24, 2013 “Perioperative
Use of CPAP in OSA”
May 13, 2014 “Perioperative
Sleep Apnea: Human and Financial Impact”
March 3, 2015 “Factors
Related to Postoperative Respiratory Depression”
August 18, 2015 “Missing
Obstructive Sleep Apnea”
June 7, 2016 “CPAP
for Hospitalized Patients at High Risk for OSA”
References:
Chung F, Memtsoudis SG,
Ramachandran SK, et al. Society of Anesthesia and Sleep Medicine Guidelines on
Preoperative Screening and Assessment of Adult Patients with Obstructive Sleep
Apnea. Anesthesia & Analgesia 2016; 123(2): 452-473, August 2016
Podcast: Article of the Month – August 2016 – Christine Park
and Frances Chung
Creator: OpenAnesthesia
Interviewer: Christine Park
Interviewee: Frances Chung
Duration: 29:31
Anesthesia & Analgesia August 2016, Volume 123, Issue 2;
http://journals.lww.com/anesthesia-analgesia/pages/currenttoc.aspx
Nagappa M, Chung F. Perioperative
Complications & Stopbang Scores. A
Metaanalysis. 2016 annual meeting
of the Canadian Anesthesiologists’ Society (abstract 152726) as discussed in: Vlessides M. STOP-Bang Questionnaire Ably Identifies Risks
for Perioperative Complications. Anesthesiology News 2016; October 3, 2016
Sharma S, Chowdhury A, Tang L, et al. Hospitalized Patients
at High Risk for Obstructive Sleep Apnea Have More Rapid Response System Events
and Intervention Is Associated with Reduced Events. PLOS One 2016; Published:
May 11, 2016
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153790
Geralemou S, Probst S, Gan TJ. The Role of Capnography to Prevent Postoperative
Respiratory Adverse Events. NPSF Newsletter 2016; 31(2): 42-43 October 2016
http://www.apsf.org/newsletters/pdf/Oct2016.pdf
Zhan C, Miller MR: Excess length of stay, charges, and
mortality attributable to medical injuries during hospitalization. JAMA 2003;
290: 1868-1874
http://jamanetwork.com/journals/jama/fullarticle/197442
CADTH (Canadian Agency for Drugs and Technologies in
Health). Capnography for Monitoring End-Tidal CO2 in Hospital and Pre-hospital
Settings: A Health Technology Assessment. Ottawa: CADTH 2016 (CADTH health
technology assessment; no.142); March 2016
https://www.cadth.ca/sites/default/files/pdf/HT0007_End-Tidal_CO2_Review.pdf
Saunders R, Erslon M, Vargo J.Modeling the Costs and
Benefits of Capnorgraphy Monitoring during Procedural
Sedation for Gastrointestinal Endoscopy. Endosc Int Open 2016; 04(03): E340-E351
https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0042-100719
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