Patient Safety Tip of the Week
May 13, 2014
Perioperative Sleep Apnea:
Human and Financial Impact
Our numerous columns on the obstructive sleep apnea (OSA) in
the perioperative period (see the list at the end of todays column) have
emphasized that most cases of OSA are unrecognized and that such patients are
at risk for complications and even death following surgery. In parallel with
the obesity epidemic, the prevalence of OSA has been steadily increasing.
A new study sought to quantify outcomes and resource
utilization in patients with known sleep apnea who underwent total hip or knee arthorplasty (Memtsoudis
2014). The authors reviewed data on over 500,000 patients from 2006
to 2010 in a large database. The prevalence of diagnosed sleep apnea was 8.4%.
This actually increased from 6.2% to 10.3% over the course of the study period.
Compared to those patients without sleep apnea diagnoses, patients with sleep
apnea had a higher incidence of post-op complications, including a 47% increased risk of major postoperative morbidity. They
also more frequently used critical care, telemetry, stepdown
services, mechanical ventilation and noninvasive ventilator support, though
they had less frequent blood transfusions. Patients with sleep apnea also had
longer lengths of stay and consumed more
economic resources (about 14% higher). Keep in mind that these were
patients with diagnosed sleep apnea. As weve noted previously the vast
majority of patients with sleep apnea are undiagnosed at the time they have
surgery. It therefore is very likely that the impact of sleep apnea on both
outcomes and resource utilization is actually much more substantial.
Interestingly, compared to other studies showing increased
in-hospital mortality this study and some other recent ones have failed to
demonstrate increased mortality in those patients with OSA undergoing surgery. In
an accompanying editorial Chung and Mokhlesi (Chung
2014) speculate about this mortality issue. They suggest that the obesity
paradox or ischemic preconditioning might play a protective role or that
patients with known OSA simply have impending respiratory failure recognized
and managed earlier. They stress that CPAP can be effective in the
perioperative period, though compliance with CPAP is suboptimal (see our September 24, 2013 Patient Safety Tip of the
Week Perioperative
Use of CPAP in OSA).
Speaking of
mortality and sleep apnea, a recent study has demonstrated an association
between OSA and maternal mortality in pregnancy (Louis 2014).
Because of a recent trend in increasing rates of severe maternal
morbidity and mortality despite quality improvements, the authors sought to see
if obstructive sleep apnea (OSA) in pregnant women was impacting pregnancy-related
morbidities and in-hospital maternal mortality.
They looked at a nationally representative sample of 55,781,965
pregnancy-related inpatient hospital discharges from 1998-2009. The rate of OSA
increased from 0.7 in 1998 to 7.3 in 2009, an average annual increase of 24%.
After controlling for obesity and other potential confounders, OSA was
associated with increased odds of preeclampsia, eclampsia,
cardiomyopathy, and pulmonary embolism. Women
with OSA experienced a more than fivefold increased odds of in-hospital
mortality. The adverse effects of OSA on selected outcomes were exacerbated
by obesity.
Back to OSA and surgery, another very interesting study
provides some insight into sleep-disordered breathing in patients undergoing
surgery (Roggenbach 2014). The authors looked at breathing patterns
in 37 patients undergoing major surgery who had not already been diagnosed with
OSA. They did polygraphic recordings on these
patients the pre-op night and 6 consecutive nights following surgery. They did
not have full polysomnograms. Rather, O2-saturation,
pulse, nasal air flow and snoring were monitored. 59% of the patients had
abnormal nocturnal breathing patterns (AHI = 5 or higher) on the pre-op night,
with 22% having AHIs of 15 or higher. The median apnea-hypopnea index (AHI)
was 6.0 for the group as a whole on the pre-op night. The AHI increased on the
6 nights following surgery, with the increases
on the third through sixth nights being significant (median AHIs being
16.9, 11.6, 15.2, and 22.5 respectively for those subsequent nights). Previous
observations had demonstrated a delayed increase in OSA after surgery, usually
in conjunction with the return of REM sleep on the second or third post-op day.
But this appears to be the first study to monitor for a longer duration and it
shows a substantial increase in the risk of OSA in the late post-op period.
Those authors speculate that the surgery itself may have a
modulating effect on nocturnal breathing patterns. Their patients underwent
major prostate or abdominal surgeries. They note that such surgeries are
regularly associated with substantial fluid accumulation and speculate that peripharyngeal soft tissue edema might contribute to
reduced airway patency. They also speculate that some of the cytokines
typically released with surgery may lead to the early REM suppression seen
after surgery, with the subsequent REM rebound appearing later.
Overall, their findings would certainly have implications
about the duration of monitoring of patients with suspected OSA
post-operatively. It would also seem to challenge performance of surgery in the
ambulatory setting. But keep in mind that these were cases of major surgery. It
would probably not be appropriate to generalize these findings to cases of more
minor surgery. Note that Society for Ambulatory Anesthesia Consensus Statement
on Preoperative Selection of Adult Patients with Obstructive Sleep Apnea
Scheduled for Ambulatory Surgery (Joshi
2012) emphasizes the need for opioids and control of comorbidities as the most
important considerations in deciding whether someone with suspected OSA should
have their surgery as an inpatient or outpatient. But even that consensus
statement emphasizes to patients and their families that the risks related to
OSA persist for several days after surgery.
Reggenbach and colleagues also
found little difference in self-reported snoring or daytime drowsiness in their
patients who had sleep-disordered breathing compared to those who did not, but
the small number of cases makes that difficult to interpret. While the small
numbers would not suggest we need to stop using screening tools such as the
STOP-Bang questionnaire, the observation does warn us that some patients will
have abnormal AHIs in the post-op period even in the absence of pre-existing
symptoms. They also surprisingly found no correlation between AHI values and
daily opioid dosing but, again, the numbers were small.
Speaking of screening tools, another recent study found a
screening tool for OSA to be of little value in children (Wild
2014). The authors found that, though identifying 85% of children with
moderate to severe OSA, the American Society of Anesthesiologists screening
tool for moderate to severe OSA (MSOSA) had a 78% false positive rate.
And, speaking of children, dont forget that the recent
warnings about use of codeine in children first originated after deaths of
pediatric patients receiving codeine after adenotonsillectomy
for OSA (see our Whats New in the
Patient Safety World columns for September 2012 FDA
Warning on Codeine Use in Children Following Tonsillectomy and March 2013 Further
Warning on Codeine in Children Following Tonsillectomy and our May 2014 Pediatric
Codeine Prescriptions in the ER). And a study done last year focusing on
death and neurological injuries following tonsillectomy (Cote
2013) concluded that at
least 16 children could have been rescued had respiratory monitoring been
continued throughout first- and second-stage recovery, as well as on the ward
during the first postoperative night. Those authors also stress the need for a validated
pediatric-specific risk assessment scoring system to assist with identifying
children at risk for OSA. That might help determine which children are not
appropriate to be cared for on an outpatient basis.
Our prior columns on obstructive
sleep apnea in the perioperative period:
Patient Safety Tips of the Week:
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 13, 2010 Postoperative
Opioid-Induced Respiratory Depression
February 22, 2011 Rethinking
Alarms
November 22, 2011 Perioperative
Management of Sleep Apnea Disappointing
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
September 24, 2013 Perioperative
Use of CPAP in OSA
Whats New in the Patient Safety World columns:
July 2010 Obstructive
Sleep Apnea in the General Inpatient Population
November 2010 More
on Preoperative Screening for Obstructive Sleep Apnea
March 2012
Postoperative
Complications with Obstructive Sleep Apnea
June 2013 Anesthesia
Choice for TJR in Sleep Apnea Patients
References:
Memtsoudis SG, Stundner
O, Rasul
R, et al. The Impact of Sleep Apnea on Postoperative Utilization of Resources
and Adverse Outcomes. Anesth Analg
2014; 118: 407-418
Chung F, Mokhlesi B. Postoperative
complications associated with obstructive sleep apnea: time to wake up! Anesth Analg 2014; 118: 251253
Louis JM, Mogos MF, Salemi JL, et al.
Obstructive sleep apnea and severe maternal-infant morbidity/mortality in the
United States, 1998-2009. Sleep 2014; 37(5): 843-849
http://www.journalsleep.org/ViewAbstract.aspx?pid=29449
Roggenbach
J, Saur P, Hofer S, et al. Incidence of
perioperative sleep-disordered breathing in patients undergoing major surgery:
a prospective cohort study. Patient Safety in Surgery 2014; 8: 13
http://www.pssjournal.com/content/8/1/13
Joshi GP, Ankichetty SP, Gan TJ, Chung F. Society for Ambulatory Anesthesia
Consensus Statement on Preoperative Selection of Adult Patients with Obstructive
Sleep Apnea Scheduled for Ambulatory Surgery. Anesthesia & Analgesia 2012;
115(5): 1060-1068
Wild D. OSA Screener
of Limited Clinical Use in Children, Study Finds. Anesthesiology News 2014;
40:4 April 2014
http://www.anesthesiologynews.com/ViewArticle.aspx?d=PRN&d_id=21&i=April+2014&i_id=1050&a_id=26233
Cote CJ, Posner KL, Domino KB. Death or Neurologic Injury After Tonsillectomy in Children with a Focus on Obstructive
Sleep Apnea: Houston, We Have a Problem! Anesth Analg 2013; Published Ahead-of-Print 10 July 2013
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