Obstructive Sleep Apnea Perioperative Implications From Mechanisms to Risk Modification Satya Krishna Ramachandran MD FRCA Assistant Professor of Anesthesiology

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]

mailto:[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

Obstructive Sleep Apnea and 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

AHI and outcome

Gami. N Engl J Med. 2005;352:1206-14.

Nocturnal pattern in sudden death

Gami. N Engl J Med. 2005;352:1206-14.

Severity of OSA and

nocturnal variation in

sudden death

Gami. N Engl J Med. 2005;352:1206-14.

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


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


MSNA and OSA

Somers et al. J Clin Invest. 1995;96:1897-904

MSNA and Sleep Stage


MSNA In Awake State


Mechanisms of Perioperative AE?

• Hypoxia• Sympathetic activation• Cardiovascular variability• Inflammation• Comorbid disease • Chemoceptor hypersensitivity

Cardiovascular variability

Narkiewicz et al. Circulation. 1998;98:1071-1077

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


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


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



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

Metabolic Disease and RD?

RISK MODIFICATION

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

Preop CPAP Benefit - MSNA, MAP


CPAP and QTc Dispersion

• Longitudinal 6-month study of CPAP• 12-lead ECG data analysis

Dursunoglu et al. Sleep Medicine 2007;8:478–483

Ryan et al. Thorax 2005;60:781–785

CPAP and Arrhythmia in CHF

Cessation of CPAP and MSNA


UM Model for Fast Track PSG

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


Mortality


Multivariate AnalysisEntire Cohort

Adjusted Odds Ratio p Value [95% Conf. Interval]

Morbidity


Pulmonary Occurence


Mortality





• 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




• Postoperative CPAP• Continuous pulse oximetry monitoring

Expert Opinion

UM model for Postop CPAP

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




• 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

Surveillance Systems

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.

Does IMS Prevent Instability?

Does IMS Reduce Frequencyof Instability Events?

Does IMS Reduce Duration of Instability?



• What is the sensitivity and positive predictive value of IMS/SS?

• Did the treatment change the outcome?

What is the Sensitivity of EWS?



• 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

Are we monitoring the right patient at the right time?

Relationship Between Desaturation & Unanticipated Respiratory Failure

Preop Night 1 Night 30

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90

100

AHILowest SaO2(%)

Relationship Between Desaturation & Unanticipated Respiratory Failure

Preop Night 1 Night 30

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20

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100

Unplanned intubationAHILowest SaO2(%)

Can Monitoring Harm?

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

Conclusions

• OSA is associated with increased risk of early postoperative respiratory failure

• PREoperative CPAP is associated with significant physiological benefit– Compliant PAP therapy is associated with outcome

benefit• Postoperative monitoring is of unknown value

in OSA patients

Documents

Obstructive Sleep Apnea Perioperative Implications From Mechanisms to Risk Modification Satya Krishna Ramachandran MD FRCA Assistant Professor of Anesthesiology