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Mon – Sat 1:00 PM – 09:00 PM
19 CCA, First Floor, DHA Phase 5, Lahore
0311 057 3333
australinapolyclinic@gmail.com
Sleep study or polysomnography is a clinical test which we use to study sleeping pattern and its effects on breathing (snoring, breathing rate, breathing efforts, oxygen saturations), heart (pulse rate, heart rhythm and variation), and any abnormal movements of legs and cheek muscles. Movements of eyes are also recorded which provide help in classifying different stages of sleep.
Sleep stages are divided into two major types: Non-random eye movement and random eye movement sleeps (NREM and REM sleep). NREM sleep is further divided into N1, N2 and N3 types. We spend about 75% of sleep time in NREM sleep. We classify the stages of sleep according to electric activity of brain and eye movements.
We perform level II polysomnogram using 26 channel SomnoTouch PSG system, developed by SOMNOmedics GmbH, Germany. This system provides us high quality data for proper investigations of Sleep Related Breathing Disorders.
People who snore and haveapnoea (cessation of breathing) during sleep will affect their sleep patterns and we can detect these on the EEG (electric recordings of the brain, similar to ECG of heart). Patients who stop their breathing frequently during sleep do not get much deep sleep and due to frequent arousals, their never feel refreshed on waking up. It affects their heart rate which stays higher during sleep and causes higher blood pressure during sleep which in turn increases the risk of heart and brain disease in the long run. We will record their cardiac activity during the sleep study.
Other major features of Sleep Related Breathing Disorders are snoring and apnoea. We measure this by using a plastic tube sensor which is placed across the nose, just like oxygen tubing. It is very sensitive to noise of snoring and air flow, representing breath sounds. In patients with obstructive sleep apnoea, snoring is recorded along with apnoea over time. We get a reading called apnoea hypopnea index which means how many times patients stop or reduce their breathing frequency which leads to reduction in oxygen saturation. Patients whose index is more than 30 have severe sleep apnoea, AHI of 15-30 represent moderate and AHI 5-15 are classified as mild sleep apnoea.
We use two belts, one across the abdomen and other across the chest which not only measure the position in which are sleeping (back, right or left sides) but also effort or muscle activity. It differentiates between obstructive sleep apnoea in which there is strong effort of muscles but no air flow due to collapsed throatversuscentral sleep apnoea when there is no effort at all and hence no air flow. It is important to differentiate between these two types of sleep apnoea which guides proper treatment as treatment of one type can make other type of sleep apnoea worse sometimes.
ECG recording during sleep study provides us information about the pulse rate and rhythm which will be affected by sleep apnoea. We can pick sometime abnormal heart rhythm not related to sleep apnoea which may warrant further investigations.
Leg movements are measured by placing skin electrodes on the calf muscles. In patient with restless leg syndrome, patients move their legs too frequently and too violently which not only will affect their sleep but also their bed partner.
Instructions
Australian Polyclinic,
CCA Phase 5 DHA, Lahore
0311 057 3333
Dr G Sarwar Chaudhry
MBBS (KE), Fellow Royal Australasian College of Physicians (FRACP Australia),
Fellow American College of Chest Physicians (FCCP)
Conjoint Lecturer, University of Newcastle, NSW, Australia
Consultant Pulmonologist and Sleep Physician
Consultant General Physician