Obstructive Sleep Apnea

Cory M. Furse, MD, MPH

Disclosure Multiple photographs used

in this presentation have been obtained from GOOGLE.

I have no financial relationships to disclose.

I will be referring to most researchers by first name and/or nickname as if I actually know them.

Objectives

• Review the pathophysiology of obstructive sleep apnea

• Review current recommendations concerning the patient with obstructive sleep apnea for outpatient surgery

Alae nasi

Tensor palatini

Genioglossis

Geniohyoid

Thyrohyoid

Sternohyoid

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Normal State

Polysomnography• Electroencephalogram• Electrooculogram• Electromyogram of respiratory muscles• Airflow at the nose or mouth via thermistor• End-tidal CO2

• Impedance plethysmography for chest/abdomen movement

• EKG, NIBP, and SpO2

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Polysomnography

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Sleep Apnea Event

Symptoms of OSA Loud snoring

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Sleep Apnea Event Altered body position

Decreased pharyngeal muscle tone

Respiratory drive depression- MV 16%- SPO2 2%- PaCO2 4-6mmHg

Depression of protective respiratory reflexes during normal Non-REM sleep

DefinitionsOSA: 15 or more apneas/hypopneas per hour during

sleep, caused by collapse of the upper airwayApnea: 10s or more without airflowHypopnea: 50% reduction in thoracoabdominal movement

lasting for 10s

Levitsky – LSU Adv Physiol Educ 32: 196–202, 2008

Curr Opin Anaesthesiol 22:405–411

Epidemiology ~24% of middle-aged men ~9% of middle-aged women ~5% of 3-5yr old children Prevalence of OSA increases with age and

body weight An estimated 85% of people with OSA are

undiagnosed!

Chung – Toronto Western Hospital

Lanphier EH – SUNY at Buffalo J Appl Physiol 18: 471-477, 1963

Lanphier EH – SUNY at Buffalo J Appl Physiol 18: 471-477, 1963

Lanphier EH – SUNY at Buffalo J Appl Physiol 18: 471-477, 1963

Lanphier EH – SUNY at Buffalo J Appl Physiol 18: 471-477, 1963

Symptoms of OSA Loud snoring Hypersomnolence Depressed mentation

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Levitsky – LSU Adv Physiol Educ 32: 196–202, 2008

Levitsky – LSU Adv Physiol Educ 32: 196–202, 2008

Symptoms of OSA Loud snoring Hypersomnolence and Depressed mentation

– Interference with normal sleep architecture, esp. REM sleep

– Increases risk of motor vehicle accidents Morning Headaches

– Repeated dialation of cerebral blood vessels

Adv Physiol Educ 32: 196–202, 2008Levitsky – LSU

Somers – Iowa J. Clin. Invest. 1995. 96:1897-1904.

Signs of OSA Systemic hypertension

- Chronic recurrent sympathetic stimulation- Increase in endothelin, a potent, long lasting

vasoconstrictor Heart failure

- Right heart 2° to pulmonary HTN- Left heart 2° to systemic HTN

Arrhythmias- Atrial fibrillation

Ann Intern Med. 2005;142:187-197.Caples – Mayo Clinic

Signs of OSA Polycythemia

- Chronic hypoxic episodes stimulate renal release of renin

- Increase in blood viscosity further exacerbating heart failure if present

Metabolic alkalosis- Respiratory acidosis while asleep with renal

retention of bicarbonate ions and excretion of H+

Ann Intern Med. 2005;142:187-197.Caples – Mayo Clinic

Obstructive Sleep Apnea

Signs Systemic HTN Heart Failure Arrhythmias Polycythemia Metabolic Alkalosis

Symptoms Loud Snoring Hypersomnolence Depressed Mentation Morning Headaches Nocturia

Why do we care?• Difficult Intubation

– If GA is employed

• Difficult Sedation– If MAC/Regional is employed

• Postoperative Pain Control– May increase the severity of

their OSA

• Liability?– If a patient with OSA has an

adverse event at home

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Endorsed- American Academy of Sleep Medicine- American Academy of Otorhinolaryngology – Head and Neck Surgery

“Affirmation of Value” - American Academy of Pediatrics

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Chung – Toronto Western Hospital Curr Opin Anaesthesiol 22:405–411

Identification of Patients with OSA

Identification of Perioperative Risk

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Preoperative Preparation

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Recommendations- Initiation of CPAP- Use of mandibular advancement devices- Preoperative weight loss

Prior corrective surgery for OSA- Assume these patients are still at risk, unless they

have a normal sleep study Beware of the difficult airway

Liang – MGH Anesthesiology 2008; 108:998–1003

Liang – MGH Anesthesiology 2008; 108:998–1003

Intraoperative Management

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Recommendations- Intraoperative medications should be selected

with consideration of the potential for postoperative respiratory compromise

- If moderate sedation is used, consider using the patients CPAP or oral appliance

- Awake extubation- Extubation and recovery in the lateral,

semiupright, or other nonsupine position

Postoperative Management

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Recommendations- Regional > Neuraxial > Oral Opioids > Parental

Opioids - Supplemental O2 until at baseline SPO2 on RA- CPAP when feasible- Nonsupine positions- Continuous monitoring of SPO2 when hospitalized

Outpatient Surgery?

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Discharge Criteria

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

Recommendations- SPO2 should return to baseline on RA- Patients should be monitored a median of 3hr

longer then their non-OSA counterparts- Monitoring should continue for a median of 7hr

after last episode of obstruction or hypoxemia while breathing RA in an unstimulating environment

Appendix:

Gross – Farmington, CT Anesthesiology 2006; 104:1081–93

A median of 10% of outpatients would need to be inpatients if these guidelines were followed

73% indicate that sensitivity of the criteria for detecting patients previously undiagnosed with OSA is “about right”

82% indicate that the scoring system for assessing perioperative risk is “about right”

Chung – University of Toronto Anesthesiology 2008; 108:812–21

STOP BANG

S – Snoring, loudly, heard through a closed doorT – Tiredness, during daytimeO – Observed, witnessed apneic episodesP – Pressure, hypertension

B – BMI, > 35A – Age, > 50 yrN – Neck Circumference, > 40 cmG – Gender, Male

Chung – University of Toronto Anesthesiology 2008; 108:812–21

STOP BANG vs. ASA guidelines

Sensitivity AHI >5 AHI >15 AHI >30

STOP-BANG 83.6 92.9 100

ASA Guidelines 72.1 78.6 87.2

Advantage of STOP-BANG is the markedly decreased amount of time required to administer the questionnaire as compared to ASA guideline checklist

Chung – University of Toronto Anesthesiology 2008; 108:822–830

QUESTIONS?