Sleep Apnea and Commercial Drivers A CLINICAL PERSPECTIVE
Outline 1.
Presentation of OSA
2.
Pathophysiology of OSA
3.
Effects on the Body
4.
Effects on Alertness
5.
Testing for OSA
6.
Outcomes
7.
Summary
Clinical Presentation
Recognizing and Managing Sleep Apnea in Primary Care. Journal of Clinical Psychiatry. 2009; 11 No 6: 330-338
Upper Airway Anatomy- Oropharynx
Composed of numerous muscles and soft tissue but lacks rigid or bony support
Collapsible portion
Ability to change shape and close momentarily for speech and swallowing
Opportunity for collapse at inappropriate times, such as during sleep The Proceedings of the American Thoracic Society, 5:144-153 (2008)
Pathophysiology
What causes OSA? During sleep, generalized decrease of muscle tone of the upper airway Most pronounced in REM In patients with a small airway, repetitive airway collapse can cause numerous dips in oxygen levels Repeated airway collapse can cause numerous brief awakenings which lead to daytime fatigue
Pathophysiology •
Apnea: Complete
•
cessation of airflow
Hypopnea: 30%
reduction in airflow plus at least 4% oxygen desaturation
•
Respiratory Effort-Related Arousal: Mild
airflow reduction which results in an arousal but no desaturation
Patent Upper Airway No obstruction
Partially Blocked Upper Airway Likely snoring •
Hypopnea
•
Respiratory EffortRelated Arousal
Obstructed Upper Airway Apnea •
Possible O2 desaturations
Obstructive Sleep Apnea. NEJM 2006; 334 No 2: 99-104
Outline 1.
Presentation of OSA
2.
Pathophysiology of OSA
3.
Effects on the Body
4.
Effects on Alertness
5.
Testing for OSA
6.
Outcomes
7.
Summary
Sleep Heart Health Study- Hypertension
Sleep Heart Health Study: Sleep Disordered Breathing and Cardiovascular Risk: Cross Sectional Results of the Sleep Heart Health Study AJRCCM. 2001; Vol 163, 19-25
SHHSMortality Compared to those without OSA all-cause OR for mortality in mild OSA was 0.93, 1.17 in moderate OSA, and 1.46 in severe OSA
Sleep Disordered Breathing and Mortality: A Prospective Cohort Study
Tracy Morgan •
Limousine van rear-ended by Wal-Mart driver
•
Driver charged with vehicular homicide
•
Driver had not slept “in excess of 24 hours”
Cognitive impairment from going without sleep for 24 = BAC of 0.10%
Drowsy Driving- Screening
“Obstructive sleep apnea increases the risk of motor vehicle crashes by 500 to 700 percent and raises medical costs. Schneider Trucking recently reported that introduction of a screening and treatment program for obstructive sleep apnea among drivers in its trucking fleet reduced fatiguerelated truck crashes by 30 percent, cut medical costs in treated drivers by 58 percent, and increased its driver retention rate.” Charles Czeisler, MD, professor of sleep medicine division at Harvard Medical School, in a Boston Globe editorial, 2009
Driving Risks for patients with Untreated OSA
The Association between Sleep Apnea and the Risk of Traffic Accidents, NEJM. 1999; 340: 847-51
Driving Risks- Accident Severity
783 patients, 783 matched controls
71% male, average AHI of 22, Epworth 10
Reviewed records for motor vehicle crashes in 3 yrs prior to sleep study
Relative Risk of 2.6 for mild,1.9 for moderate, 2.0 for severe OSA
MVC associated with personal injury, RR: 4.8, 3.0, 4.3
80% of severe MVCs involved patients with OSA Mulgrew et al, Thorax, 2008, 63: 536-541
Outline 1.
Presentation of OSA
2.
Pathophysiology of OSA
3.
Effects on the Body
4.
Effects on Alertness
5.
Testing for OSA
6.
Outcomes
7.
Summary
Testing for OSA Polysomnography • Attended, in-lab • 12-13 channels Home Sleep Testing • 4-8 channels
Polysomnography •
Pros Gold Standard Assess for multiple sleep disorders/abnormalities
Polysomnography •
Cons Expensive- $750-$1900 ‘Unnatural'
Polysomnography Monitors nasal pressure, airflow, heart rate, O2 sat, respiratory effort • Brain wave activity (EEG) • Eye movements (REM sleep) • Leg movements • Muscle tone • (End-tidal CO2 monitoring)
Home Sleep Testing Monitors nasal pressure, airflow, heart rate, O2 sat, respiratory effort • May measure peripheral arterial tone rather than nasal pressure/airflow
Really a sleep apnea test as does not measure ‘sleep’ (no EEG leads)
CleveMed SleepView Home Sleep Testing
•
Traditional HST unit
•
Type III unit
•
8 Channels
•
Chain-of-Custody feature available
WatchPAT 200
Cost Comparison In-lab PSG • $750-$1900 HST •
$200-$400
Polysomnography •
• • •
Allows diagnosis of OSA, CSA, periodic limb movements, nocturnal seizures, parasomnias, +/obesity-hypoventilation syndrome Provides sleep staging Diagnostic and therapeutic capability: able to initiate treatment (PAP, O2) Opportunity for education
Polysomnography With CPAP/BiPAP in place, used to demonstrate resolution of obstructive sleep apnea-hypopnea syndrome • Necessary for DOT certification/re-certification
Home Sleep Testing •
• • •
Allows diagnosis of OSA and CSA Does NOT provide sleep staging Unable to initiate treatment (PAP, O2) Less opportunity for patient education
As cannot verify sleep, may underestimate severity of apnea
Multiple Sleep Latency Test Measure of propensity to fall asleep • Five naps at 2-hr intervals •
Preceded by PSG the night before
• In a quiet, dark room, patient instructed to close eyes and to try to fall asleep • Used to showed resolution of excessive sleepiness following night of treatment with CPAP/BiPAP
Multiple Sleep Latency Test Now has a role in assessing treatment response, i.e. effectiveness of PAP • May be used in place of MWT Mean sleep latency= 10.4 +/- 4.3 min
Maintenance of Wakefulness Test “The MWT is a validated objective measure of the ability to stay awake for a defined period of time.” AASM • Four 40-min trials at 2-hr intervals while seated on bed in dimly lit room • Drug testing in a.m. • Instructions: stay awake as long as possible
Maintenance of Wakefulness Test “The primary purpose of the MWT is to document ability to stay awake following intervention.” AASM • Ideally performed after overnight PSG • Mean sleep latency 30.4 min +/- 11.2 min • Recent guidelines included use of MSLT to document adequate treatment response • No guarantee that results translate to work setting
HST vs. PSG in Diagnosis of OSA for Commercial Motor Vehicle Drivers Clinical •
•
Severe COPD, CHF, uncontrolled arrhythmia- PSG Comorbid sleep disorder- PSG
Regulatory • •
Guidelines indicate PSG to verify sleep Chain-of-Custody issues (changing)
Cost?
Treatment
Mild
Weight loss
Sleeping off your back
Ensuring nasal patency (nasal steroids)
Wedge pillow
Anti-snore shirt
Mandibular re-positioning device
CPAP
Stimulants
Moderate
CPAP
Upper airway surgery
Stimulants (modafanil or methylphenidate) for residual fatigue
Treatment Severe CPAP/BiPAP Maxillomandibular
Advancement surgery Nocturnal supplemental O2 for patients unable to tolerate PAP Stimulants Minimization or avoidance of sedatives/narcotics, especially IV
Treatment Works Evidence shows decreases in mortality •
Protective in patients with AHI>20 CPAP and tracheostomy • Kryger et al, CHEST, 1988 •
•
CPAP decreases CV mortality •
Young et al, SLEEP, 2008
Treatment Works Cochrane Database Review on use of CPAP to treat OSA, 2006 Moderate-severe OSA •
Decreased sleepiness
•
Improved quality of life
Decreased blood pressure
Sleep Heart Health Study- Hypertension
Treatment Works •
Evidence also shows improvements in alertness • Risk of driving accidents normalizes with PAP treatment
MVCs reduced with CPAP 210 patients, mean age of 52 BMI 35.5, AHI 54 3 yrs before/after treatment with CPAP Untreated pts: more MVCs than controls CPAP→ MVCs reduced to level of controls Treated
OSA pts no more accidents than ‘normals’
George CF, Thorax, 2001
MVCs reduced with CPAP 50 2
consecutive patients
36
using CPAP regularly over 2 yrs
yrs after treatment with CPAP
Compliant
Untreated
vs. non-compliant pts
pts: more MVCs than controls CPAP→ MVCs reduced to zero Treated
OSA pts had no accidents
Findley et al, Amer J Resp Crit Care Med, 2000
Summary 1.
Presentation of OSA
2.
Pathophysiology of OSA
3.
Effects on the Body
4.
Effects on Alertness
5.
Testing for OSA
6.
Outcomes
Summary OSA results from upper airway collapse related to anatomical features and, often, obesity 2. OSA causes HTN; increases risk of cardiovascular morbidity; increases all-cause mortality and risk of driving accidents 3. In-lab PSG is recommended test for CMV drivers; growing role for Home Sleep Tests 4. Treatment is effective; compliance is marginal 1.
Summary 1. 2.
Treatment restores alertness to normal levels Most evidence focuses on CPAP
Questions?
