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Obstructive Sleep Apnea Perioperative Implications
From Mechanisms to Risk Modification
Satya Krishna Ramachandran MD FRCAAssistant Professor of Anesthesiology
University of Michigan Medical School, Ann [email protected]
Disclosures
• Paid scientific advisory consultant – Galleon Pharmaceuticals– Merck, Sharp & Dohme
• Funding – PSA with MSD for 2014– MiCHR CTSA PGP UL1TR000433 for 2014
The material of this talk is independent of these disclosures
This is a confidential Quality Improvement and Assurance/peer review document of the University of Michigan Hospitals and Health Centers. Unauthorized disclosure or duplication is absolutely prohibited. This document is protected from disclosure pursuant to the provisions of MCL
333.20175; MCL 333.21515; MCL 331.531; MCL 331.533 or such other statutes that may be applicable
Goals & Objectives
• To describe the relationship between OSA and early postoperative respiratory failure
• To review mechanisms of unanticipated early postoperative respiratory failure
• To critically evaluate methods of risk-modification of early postoperative respiratory failure
Evidence in the surgical population
• Retrospective studies: associations– Gupta – more complications, ICU admissions– Hwang – more morbidity– Memtsoudis – independent increase in morbidity– Mokhlesi – Increased respiratory failure
• Prospective evidence: associations– Chung – more postoperative desaturation episodes– Gali – more morbidity with postoperative episodic desat.
• Sudden death – case reportsGupta. Mayo Clin Proc. 2001;76:897-905
Hwang. Chest. 2008;133:1128-34Memtsoudis. Anesth Analg. 2011;112:113-21
Gali B. Anesthesiology 2009;110:869-77Ostermeier. Anesth Analg. 1997;85:452-60
If they are prone to sudden death during sleep, is the risk of
postoperative sudden death increased
in patients with OSA?
0
2
4
6
8
10
12
06:00-11:59 12:00-17:59 18:00-23:59 00:00-05:59
Time of day (24 hour clock)..
Num
ber o
f cas
es (n
=32)
...
Irreversible
Reversible
Nocturnal Variation In Outcome Of ARE
Ramachandran SK. J Clin Anesth 2011;23:207-13
Postoperative ARE from RM database
35 cases – 5 deaths / 6 years
History or known risk factors for OSA present in ~40% cases
Mechanisms of Perioperative AE?• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
Somers et al. Circulation. 2008;118:1080-1111
Mechanisms of Perioperative AE?• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
Hypoxia and Arrhythmia/Conduction
• Nocturnal ventricular arrhythmias – Min SpO2<60%– AHI >65.hr-1
• QRS prolongation– Min SpO2<90%– AHI >30.hr-1
• Heart Block– Min SpO2<90%– Obesity
Sheppard. Chest. 1985 Sep;88(3):335-40Valencia-Flores. Obes Res. 2000 May;8(3):262-9.
Ramachandran – unpublished data
Mechanisms of Perioperative AE?• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
Mechanisms of Perioperative AE?
• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
Intrathoracic Pressure Changes
• Repeated Mueller maneuvers during OSA– Intrathoracic pressures approach -65 mmHg
• ?Increased risk of postoperative pulmonary edema
• Increased transmural gradient across atria and ventricles– Increased wall stress and afterload– Diastolic dysfunction– Atrial remodeling
Mechanisms of Perioperative AE?
• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
OSA and Inflammation• Selective activation of inflammatory pathways
– Hypoxemia – Sleep deprivation/fragmentation
• Increased levels in OSA– Cytokines, adhesion molecules, serum amyloid– C-reactive protein - ?obesity related– TNF
• May influence postoperative mortality and morbidity
Mechanisms of Perioperative AE?• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
Unanticipated Postoperative Respiratory Failure
• Prediction model in 222,094 patients from the NSQIP dataset.
• Overall, 49.4% unanticipated tracheal intubations occurred within first three days after surgery.
• The incidence of unanticipated early postoperative intubation (UEPI) was 0.83-0.9%
Ramachandran SK et al. Anesthesiology 2011;115:44-53
UEPI Independent Predictors
• Surgical Type• Current Ethanol Use • Current Smoker • Dyspnea • COPD• Diabetes Mellitus• Active Congestive Heart
Failure
• Hypertension Requiring Medication
• Abnormal Liver Function • Cancer • Prolonged Hospitalization • Recent Weight Loss • Body Mass Index < 18.5 Or
≥ 40 Kg/m2 • Sepsis
Ramachandran SK et al. Anesthesiology 2011;115:44-53
UEPI Independent Predictors
• Surgical Type• Current Ethanol Use • Current Smoker • Dyspnea • COPD• Diabetes Mellitus• Active Congestive Heart
Failure
• Hypertension Requiring Medication
• Abnormal Liver Function • Cancer • Prolonged Hospitalization • Recent Weight Loss • Body Mass Index < 18.5 Or
≥ 40 Kg/m2 • Sepsis
Ramachandran SK et al. Anesthesiology 2011;115:44-53
Mechanisms of Perioperative AE?• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity
OSA and chemoreceptor sensitivity• Limited adult data• Postoperative ARE outcomes unrelated to dose• Opioid consumption lower in patients who died
Ramachandran SK et al. J Clin Anesth 2011;23:207-13
Baseline Risk Reduction Strategies
• Preoperative CPAP• Opioid sparing techniques
– Regional anesthesia/analgesia– Non-opioid adjuncts– Minimal access surgery
• Continuous pulse oximetry monitoring• Postoperative CPAP
Expert Opinion
PREoperative CPAP• No RCT guided evidence of perioperative benefit• Possible mechanisms:
– Less severe nocturnal desaturation– More dependable postoperative CPAP usage
• Challenges:– Majority of patients are undiagnosed– Adherence with therapy is low– Timely preoperative testing/fitting
CPAP and QTc Dispersion
• Longitudinal 6-month study of CPAP• 12-lead ECG data analysis
Dursunoglu et al. Sleep Medicine 2007;8:478–483
MSQC study
• Introduced a new concept – Preoperative PAP treatment for OSA– Implies diagnosis of OSA– Compliance generally ~50%
• MSQC nurse abstractors collect data from 56 hospitals in Michigan– Risk adjusted for surgery, comorbid conditions and
intraoperative characteristics
Frequency TablesEntire Cohort
Sleep Apnea Freq. (%)None 32,148 90.91
Untreated 1,769 5Treated 1,446 4.09
Total 35,363 100
General SurgerySleep Apnea Freq. (%)
None 20,873 90.31Untreated 1,226 5.3
Treated 1,013 4.38Total 23,112 100
MSQC AnalysisEntire Cohort
Adjusted Odds Ratio p Value [95% Conf. Interval]
Morbidity
Sleep ApneaNone 1.00 (ref)Untreated 1.26 0.008 1.06- 1.50Treated 0.87 0.115 0.72- 1.04
Pulmonary Occurence
Sleep ApneaNone 1.00 (ref)Untreated 1.14 0.334 0.87- 1.48Treated 0.60 0.007 0.42- 0.87
Mortality
Sleep ApneaNone 1.00 (ref)Untreated 1.11 0.692 0.66- 1.86Treated 0.69 0.237 0.37- 1.28
Multivariate AnalysisEntire Cohort
Adjusted Odds Ratio p Value [95% Conf. Interval]
Morbidity
Sleep ApneaNone 1.00 (ref)Untreated 1.26 0.008 1.06- 1.50Treated 0.87 0.115 0.72- 1.04
Pulmonary Occurence
Sleep ApneaNone 1.00 (ref)Untreated 1.14 0.334 0.87- 1.48Treated 0.60 0.007 0.42- 0.87
Mortality
Sleep ApneaNone 1.00 (ref)Untreated 1.11 0.692 0.66- 1.86Treated 0.69 0.237 0.37- 1.28
Baseline Risk Reduction Strategies
• Preoperative CPAP• Opioid sparing techniques
– Regional anesthesia/analgesia– Non-opioid adjuncts– Minimal access surgery
• Continuous pulse oximetry monitoring• Postoperative CPAP
Expert Opinion
Baseline Risk Reduction Caveats• Opioid sparing techniques
– Reduce opioid consumption – May not modify respiratory risk
Blake et al. Anesthes Int Care. 2009;37:720-725
Baseline Risk Reduction Strategies
• Preoperative CPAP• Opioid sparing techniques
– Regional anesthesia/analgesia– Non-opioid adjuncts– Minimal access surgery
• Postoperative CPAP• Continuous pulse oximetry monitoring
Expert Opinion
Risk Modification – Postop CPAP
• Robust evidence for early treatment of hypoxia– Randomized Controlled Trial of CPAP vs. O2 – Major elective abdominal surgery
• CPAP associated with – lower intubation rate (1% vs 10%)– lower occurrence rate of pneumonia (2% vs 10%), infection
(3% vs 10%), and sepsis (2% vs 9%).
• No RCT evidence of benefit of postoperative CPAP in OSA patients
Squadrone V. JAMA 2005;293:589-595
Baseline Risk Reduction Strategies
• Preoperative CPAP• Opioid sparing techniques
– Regional anesthesia/analgesia– Non-opioid adjuncts– Minimal access surgery
• Postoperative CPAP• Continuous pulse oximetry monitoring
Expert Opinion
Postoperative Monitoring Overview
• Outcome studies – monitoring success is limited to recent, small single center studies, majority evidence points to no benefit.
• Limitations of current state of alarm technology
• Why universal monitoring may be a problem
Outcome Studies
• 3 tiers of monitoring conceptually:– Spot monitoring– Continuous bedside monitoring– Integrated monitoring /surveillance systems
• Largest studies are of bedside devices• Majority of current evidence around IM/SS• Direct comparative effectiveness trials are
impossible in the current climate
Unanswered Questions
• What were the monitoring signatures of “MET/RRT events”?
• What were the sensitivity and positive predictive value of the system?
• Did the treatment change the outcome?
Integrated Monitoring System
• An IMS (BioSign; OBS Medical, Carmel, Indiana) used heart rate, blood pressure, respiratory rate, and peripheral oxygen saturation by pulse oximetry to develop a single neural networked signal, or BioSign INDEX (BSI)
• Data were analyzed for cardiorespiratory instability according to BSI trigger value and local MET activation criteria.
Unanswered Questions
• What were the monitoring signatures of “MET/RRT events”?
• What is the sensitivity and positive predictive value of IMS/SS?
• Did the treatment change the outcome?
Unanswered Questions
• What were the monitoring signatures of “MET/RRT events”?
• What is the sensitivity and positive predictive value of IMS/SS?
• Did the treatment change the outcome? – NNT/NNP– NNH
Does Monitoring Change Outcomes?
• For outcome modification, two things need to happen:– The IMS event changes treatment– The treatment changes the outcome
• Neither was tested in Hravnak’s or Taenzer’s study
• Both studies used MET/RRT as escalation step
Relationship Between Desaturation & Unanticipated Respiratory Failure
Preop Night 1 Night 30
10
20
30
40
50
60
70
80
90
100
AHILowest SaO2(%)
Relationship Between Desaturation & Unanticipated Respiratory Failure
Preop Night 1 Night 30
10
20
30
40
50
60
70
80
90
100
Unplanned intubationAHILowest SaO2(%)
Summary
• It is possible to predict need for MET/RRT fairly accurately using advanced monitoring
• MET/RRT intervention does not change mortality risk
• Risk periods for desaturation and unplanned intubation are not congruent
• Postoperative monitoring is associated with increased technological intensification, alarm fatigue and risk of harm in CURRENT STATE
Future State of Monitoring
• Can only be effective in pathology that is responsive to treatment
• Shift away from threshold based event recognition
• Identification of “state change” from healthy to at-risk state
• Needs to address poor PPV and sensitivity