Evaluating a Case of Sleep Apnoea

Dr J.M. JoshiProfessor and HeadDepartment of Pulmonary MedicineT.N. Medical CollegeB.Y.L. Nair HospitalMumbai

SAS

• Sleep apnoea syndromes (SAS) represent a group of conditions with abnormal respiration during sleep

• 3 forms of sleep apnea: OSA, CompSAS and CSA constitute 84% 15% and 0.4%, of cases respectively

• Obstructive sleep apnea syndrome-OSAS (objective sleeping respiratory disturbance with daytime sleepiness)

• Nasal continuous positive airway pressure (CPAP) is the most effective treatment for patients with moderate to severe OSAS

Obstructive Apnoea• Obstructive Apnoea when complete

closure of the upper airway

• The respiratory efforts continue

airflow chest abdomen

Central Apnoea

• Central Apnoea complete cessation of effort to breathe

• Airway still open but no respiratory drive, hence no respiratory muscle activity

airflow chest abdomen

CLINICAL FEATURES

Snoring is the cardinal symptom, cyclical with periods of loud snoring exceeding 100 decibels or snoring alternating with quieter intervals of apnoeas

Diagnosis of OSA

A) EDS

B) 2 of the following • Snoring • Witnessed apnoeas• Unrefreshing sleep• Daytime fatigue• Poor concentrationAnd

c) Sleep Study showing AHI > 5

Ref: PSG Task Force, ASDA. Sleep 1997;20:406-22.

Polysomnography (PSG)Neurological• EEG • EOG• EMGCardio-Respiratory• Snoring • Thoraco-abdominal

movements • Airflow• Oximetry

Type 3

Type 4

Ref: Clinical guidelines for unattended PM in the diagnosis of OSA in adult patients. J Clin Sleep Med 2007; 3:737–747

Type 1,2

PSG Before and After CPAP

Severity Grading of OSAS

•Mild: 5–15 events/hour of sleep

•Moderate: 15–30 events/hour of sleep and

•Severe: more than 30 events/hour of sleep

Conventional Diagnostic Therapeutic Approach

• Full polysomnography (PSG) is currently the “gold standard’’ for the diagnosis of OSAS and titration of effective continuous positive airway pressure (CPAP)

• Technicians should titrate CPAP pressures overnight until most of the apnoeas and arousals are abolished, as monitored by PSG

Alternative Ambulatory Diagnostic Therapeutic

Approach• Urgent need to evaluate approaches to

management that did not unduly rely on sleep laboratory–based PSG studies led to

• Diagnostic-therapeutic approach using home

based limited PSG (cardio-respiratory variables only) or oximetry with ambulatory CPAP titration

Clinical Probability of OSAS• Ambulatory diagnostic-therapeutic approach

requires accurate identification of probable cases of OSAS

• Sleepy snorer by Epworth Sleepiness Score

• Sleep Apnea Clinical Score (SACS) based on snoring, witnessed episodes of apnea, neck circumference, and systemic hypertension

Epworth Sleepiness Score

Clinical Probability of OSAS• “Sleepy Snorer” by Epworth Sleepiness Score• Sleep Apnea Clinical Score (SACS)

Ref: Likelihood ratios for a sleep apnea clinical

prediction rule. AJRCCM 1994;150:1279-85.

Summary

• Magnitude of OSA and paucity of sleep labs needs simplified approaches for physicians

• Enough evidence now exists that simple ambulatory diagnostic–therapeutic strategies have equivalent clinical outcome in cases with high pretest probability

• Patients who have a low probability, have co-morbidities or have difficulties during ambulatory management should be referred to a sleep centre for detailed evaluation/in-laboratory attended full PSG and further management