Perioperative management of the sleep apnea patient
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Perioperative Management of the Sleep Apnea Patient. Grand Rounds June 6, 2007 Richard Browning, M.D. Goals. Review Incidence Define OSA & OSH Learn how to diagnose Understand the pathophysiology Develop a plan for pre-, intra- and post-op management. Incidence.

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Perioperative management of the sleep apnea patient

Perioperative Management of the Sleep Apnea Patient

Grand Rounds

June 6, 2007

Richard Browning, M.D.


Goals
Goals

  • Review Incidence

  • Define OSA & OSH

  • Learn how to diagnose

  • Understand the pathophysiology

  • Develop a plan for pre-, intra- and post-op management


Incidence
Incidence

  • Among middle-aged adults –

    4% of men & 2% of women

  • Estimated that 80-95% are undiagnosed

  • Testing increasing 124% every 3 years

  • Therefore, diagnosis of OSA will increase 5 to 10-fold over next decade.


Causes risk factors
Causes / Risk Factors

  • Obesity, Obesity, Obesity

  • Increasing age

  • Male gender

  • Structural abnormalties

  • Tonsillar hypertrophy, nasal pathology

  • Alcohol, smoking and family history


Causes risk factors1
Causes / Risk Factors

  • Up to 90% of adult patients with OSA are obese

  • OSA parallels the obesity epidemic


Table 1 distribution by age of categorical levels of ahi ahi apneas hypopneas hour of sleep
Table 1. Distribution by Age of Categorical Levels of AHI*(AHI=Apneas + Hypopneas/Hour of Sleep)

Habitual

Snoring AHI > 5 AHI > 10 AHI > 15

Age (Yrs) (%) (%) (%) (%)

<25 14 10 2 0

26-50 41 26 15 0

>50 46 61 50 36

AHI = Apnea Hypopnea Index


Definition of osa
Definition of OSA

  • OSA is defined as a cessation of airflow for more than 10 seconds despite continuing ventilatory effort, 5 or more times per hour of sleep and a decrease of more than 4% in SaO2.


Definition of osh
Definition of OSH

  • OSH is defined as a decrease in airflow of >50% for >10 seconds, 15 or more times/hour of sleep, and often with i in SaO2.


Anatomy of the Obstructed Airway

Exam: Tonsillar Hypertrophy

Oropharynx With

Tonsillar Hypertrophy

Normal Oropharynx


Pediatric sleep apnea
Pediatric Sleep Apnea

Sleep with Sleep Apnea

Child’s Enlarged Palatine & Adenoidal Tonsils


Exam oropharynx
Exam: Oropharynx

Patient With the Crowded Oropharynx


Physical exam
Physical Exam

Structural Abnormalities

Guilleminault C et al. Sleep Apnea Syndromes. New York: Alan R. Liss, 1978.


Airway anatomy
Airway Anatomy

  • 3 collapsible pharyngeal segments

  • Nasopharynx, posterior pharynx to soft pallate

  • Retroglossal pharynx, uvula to epiglottis

  • Retroepiglottal pharynx



Patency
Patency

  • Depends on pharyngeal dilator muscles which stiffen and distend the airway during inspiration.


Patency1
Patency

  • 3 segments are controlled by:

    • A. Tensor palatini

    • B. Genioglossus*

    • C. Hyoid bone muscles

      *Most important


Genioglossus muscle
Genioglossus Muscle

  • Activity is phasic with inspiration

  • Activity decreases with sleep

  • Almost ceases with REM sleep

  • Abolished in OSA at onset of APNEA

  • Increases with arousal


What happens with normal sleep

What Happens with Normal Sleep?


Normal sleep
Normal Sleep

  • 4 to 6 cycles of N-REM sleep followed by REM sleep

  • 4 stages of N-REM with progressive slowing of EEG


Normal sleep1
Normal Sleep

  • Stage 3 and 4 N-REM and REM are very deep levels of sleep

  • Progressive generalized loss of muscle tone

  • Restorative periods of sleep


Normal sleep2
Normal Sleep

  • Progressive decrease in muscle activity and resultant increase in upper airway resistance.



Airway collapse
Airway Collapse

  • Occurs with loss of muscle activity

  • Increased subatmospheric pharyngeal pressure

  • MRI reveal anterior and lateral wall collapse


Obesity effects airway anatomy adversely
Obesity Effects Airway Anatomy Adversely

  • Inverse relationship between obesity and pharyngeal area

  • Fat deposits in the uvula, tongue, tonsillor pillars, aryepiglottic folds and lateral pharyngeal walls.


Obesity effects airway anatomy adversely1
Obesity Effects Airway Anatomy Adversely

  • Increase fat deposits change shape of pharynx

  • Decreases efficiency of normal muscle function

  • Increase extra-mural pressure

  • All conspire to increase propensity for collapse


Obesity effects airway anatomy adversely2
Obesity Effects Airway Anatomy Adversely

  • Therefore, neck obesity is more important than generalized obesity in determining risk of OSA.



Pathophysiology of sleep apnea
Pathophysiology of Sleep Apnea

Awake: Small airway + neuromuscular compensation

Sleep Onset

Hyperventilate: correct hypoxia & hypercapnia

Loss of neuromuscular compensation

+

Decreased pharyngeal muscle activity

Airway opens

Pharyngeal muscle activity restored

Airway collapses

Arousal from sleep

Apnea

Increased ventilatory effort

Hypoxia & Hypercapnia


Clinical consequences
Clinical Consequences

Sleep Apnea

Sleep Fragmentation

Hypoxia/ Hypercapnia

Cardiovascular Complications

Excessive Daytime Sleepiness

Morbidity

Mortality


Diagnosis of osa
Diagnosis of OSA

  • Clinical

    • A. Obesity BMI >30 Kg/M2

    • B. Snoring / Apnea / Arousal

    • C. Daytime Sleepiness

    • D. Increased Neck Circumference >42 cm


Diagnosis of osa1
Diagnosis of OSA

  • Gold Standard is a sleep study

  • EEG, EOG, Airflow sensors, ETCO2 esophageal pressure, chest and abdomen movement, submental EMG, oximetry, BP, EKG


AHI

  • APNEA – Hypopnea Index

  • 6-20, 21-50, >50 per hour Mild, Moderate, Severe

  • O2SAT usually reported


Anesthesia effect
Anesthesia Effect

  • Propofol, Thiopental, Opioids, Benzodiazepines, NMBs, Inhalational Anesthestics cause pharyngeal collapse

  • First 3 days are greatest risk for apnea from drug-induced sleep


Surgical effects
Surgical Effects

  • Sleep architecture is disturbed first 3 days

  • Days 4-6, patients experience REM sleep rebound

  • Apnea risk increased for 1 week post-op


Surgical effects1
Surgical Effects

  • REM sleep disturbance is surgical stress related and proportional to magnitude of surgery

  • REM rebound may contribute to poor hemodynamic outcomes from profound sympathetic activation


Osa risk conclusions
OSA Risk Conclusions

  • Perioperative complications increase with severity

  • Anethestic drugs and surgical stress exacerbate baseline problem

  • May play significant role in unexplained MIs, stroke or death


Perioperative management
Perioperative Management

  • Make diagnosis and grade severity

  • Thorough airway assessment and plan for intubation to extubation

  • Plan for pain management

  • Plan for post-op monitoring


Osa severity
OSA Severity

  • Inpatient vs. Outpatient

  • Regional vs. General

  • Pre-op Nasal CPAP


Airway assessment
Airway Assessment

  • OSA independent factor for difficult intubation may be as high as 5%

  • Limited jaw protrusion, abnormal neck anatomy, obesity, moderate to severe OSA consider awake intubation

  • Good topicalization, limit sedatives

  • Be prepared


Pain management
Pain Management

  • Regional or local anesthetic technique

  • NSAID

  • Clonidine / Dex

  • IV narcotic, no basal infusion


Extubation
Extubation

  • High risk, 5% post-extubation obstruction

  • Fully reversed, fully awake

  • Semi-upright position

  • Oral or nasal airway

  • Be prepared


Monitoring
Monitoring

  • O2SAT and close observation post-op in PACU, resume N-CPAP

  • Inpatients continuous pulse oximetry monitoring until stable

  • Outpatients may be discharged if they meet discharge criteria and the surgical acuity dictates


Conclusions
Conclusions

  • Increased # and severity

  • Diagnostic challenge

  • Airway management risk

  • Post-op challenge for pain, monitoring and resource management


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