Obesity Hypoventilation Syndrome

Pickwickian Syndrome Obstructive sleep apnea was called the Pickwickian syndrome in the past because Joe the Fat Boy who was described by Charles Dickens in the Pickwick papers had typical features with snoring, obesity, sleepiness and “dropsy”.

OHS: Definition Obesity (BMI 30 kg/m2) Hypercapnia (PaCO2  45 mmHg) Sleep-disordered breathing Thomas Nast, The Pickwick Papers

OHS: Clinical Presentation Middle-aged 2:1 male-to-female Extremely obese Significant sleep-disordered breathing (fatigue, hypersomnolence, snoring, AM headache)

OHS: Epidemiology Prevalence among OSA: 10-20% No clear ethnic or racial predominance In USA, prevalence of OSAS among middle-aged men and women were 4% and 2% (Young et al)

OHS: Hypercapnia Increased CO2 production Decreased respiratory drive (will not breathe) Respiratory pump malfunction or increased airway compliance (cannot breathe) Inefficient gas exchange

Obesity Chronic hypercapnia OSA Upper airway resistance Increased mechanical load and weak respiratory muscles Leptin resistance Acute hypercapnia during sleep Blunted ventilatory response Increased serum bicarbonate Chronic hypercapnia Mokhlesi, B et al., Recent Advances in Obesity Hypoventilation Syndrome, Chest

OHS: Lung Volumes TLC TLC TV TV   RV RV

OHS: Lung Volumes Volume TLC Lungs TLC Chest Wall FRC FRC   RV Pressure

Mechanism of OSAS The upper airway dilating muscles,like all striated muscles-normally relax during sleep. In OSAS, the dilating muscles can no longer successfully oppose negative pressure in the airway during inspiration. Apneas and hypopneas are caused by the airway being sucked and closed on inspiration during sleep.

Anatomy of OSA NORMAL SNORING SLEEP APNEA

Symptoms of OSA,OHS Night time Snoring Witnessed apnoea Frequent nocturnal awakenings Waking up choking or gasping for air Unrefreshed sleep Restless sleep nocturia Dry mouth decreased libido

Symptoms of OSA,OHS Daytime Early morning headaches Fatigue Daytime sleepiness Poor memory, concentration or motivation Unproductive at work Falling asleep during driving Depression

Symptoms of Sleep Apnea Syndrome

Features of Excessive Sleepiness Motor vehicle crashes Work related accidents Impaired school or work performance Marital problems Memory and concentration difficulties Depression Impaired quality of life

OHS,OSA & Cardiovascular Diseases Uncontrolled HTN- 83% have OSAH; activation of sympathetic drive. Acute coronary syndrome- 40-50% has OSA Cardiac arrhythmias mostly Af Heart Failure Sudden cardiac death Stroke

OSA,OHS and DM Patients from the sleep clinic with AHI>10 are much more likely to have impaired glucose tolerance and diabetes (Meslier et al Eur Respir J 2003)

Diagnosis A good sleep history Assessment of obesity, oral cavity Assessment of possible predisposing causes: HTN, hypothyroidism, acromegaly and Polysomnography: gold standard tool

Polysomnography EOG - Electrooculogram EEG - Electroencephalogram EMG - Electromyogram EKG - Electrocardiogram Tracheal noise Nasal and oral airflow Thoracic and abdominal respiratory effort Pulse oximetry

Overnight PSG

Apnea-Hypopnea Index Apnoea-hypopnoea index (AHI)= number of apnea/hypopnea per hour of sleep AHI<5 Normal AHI 5-15 Mild OSA AHI 15-30 Moderate OSA AHI >30 Severe OSA

OHS: Treatment PAP (CPAP or BiPAP) Oxygen therapy Surgery No standard protocol for titration Oxygen therapy Surgery Tracheostomy Weight reduction Pharmacotherapy Medroxyprogesterone Acetazolamide

Behavioral Treatments Attain an ideal body weight Sleep on the side Avoid sedative medication before sleep Avoid being sleep deprived Avoid alcohol before sleep Elevate the head of the bed Promptly treat colds and allergies Avoid large meals before bedtime Stop smoking

Body Position Strategies- Raise HOB Avoid supine position Tennis ball in pajamas Backpacks

CPAP Therapy Works as a pneumatic Splint 1st choice of treatment in moderate to severe OSAHS Success rate 95-100% Long term compliance 60-70% Retitrate pressure if needed

Oral Appliances MAD □ Not as effective as CPAP, TRD □ Not yet available in Iran □ Appropriate first-line treatment for Mild OSA, primary snoring, upper airway resistance syndrome ( UARS ) □ Not as effective as CPAP, 52% OSA have AHI<10% □ Young, non-obese □ Second line therapy for moderate-severe OSA □ Patient’s choice - Not tolerating / refuse to use CPAP, or are not surgical candidates MAD TRD

Medical Treatments Weight loss Pharmacological Oxygen therapy Nasopharynegeal intubation Nasal CPAP BiLevel CPAP Automatic CPAP Oral Appliances Atrial Pacing

Oxygen Therapy Improves oxygen saturation during sleep May prolong apneic episodes Reduces cardiac arrythmias Useful additive treatment with CPAP Rarely reduces apneic episodes Can improve daytime sleepiness May cause CO2 retention

Pharmacological Therapy Protriptyline Medroxyprogesterone Fluoxetine Antihistamines Nasal Steroids Theophylline Acetazolamide Modafinil Magalang UJ et al, 2003

Conclusion With the increasing problem of obesity, the impact of undetected OHS & OSAS as a public health burden cannot be undermined among our population, It merits appropriate preventive and treatment strategies.

references Mokhlesi, B., Tulaimat, A. (2007), “Recent Advances in Obesity Hypoventilation Syndrome”, Chest 132 (4),1322-1332. Weinberger, S.E., Drazen, J.M., “Disturbances in Respiratory Function”, in Kasper et al (eds), Harrison’s Principles of Internal Medicine (16th Edition), New York: McGraw-Hill, pp. 1498-1505. Guyton, A.C., Hall, J.E. (2000), Textbook of Medical Physiology (10th edition), Philadelphia: W.B. Saunders.