Welcome to the Sleep Investigation Unit
Sleep Unit staff will provide you with a tour of the Sleep Unit upon your arrival from the Pre-admissions centre on Level 4. Please feel free to ask any questions you may have. This booklet has been designed to provide you with further information regarding your stay with us. We hope it not only confirms information provided to you upon your arrival but answers questions you may not have thought to ask.
What is a CPAP Pressure Determination?
A CPAP (pronounced see-pap) Pressure Determination (CPAP PD) study is performed in order to treat your obstructive sleep apnoea (OSA). It is conducted in a very similar manner to the diagnostic sleep study you have probably already undergone. All wires and bands are applied once more. However, in this instance, instead of the nasal prongs (that were used to measure your nasal airflow), you will be expertly fitted with a nasal mask. The mask will be connected to a CPAP machine via a length of tubing. Overnight, your breathing, oxygen levels, brain waves and muscle activity will again be monitored while you sleep. But on this occasion, trained staff will gently adjust the pressure being delivered by the machine to:
- eliminate episodes of OSA (and therefore your snoring)
- keep your oxygen levels as high as possible
- help you achieve a normal solid nights sleep
We know that achieving each of these goals has the potential to improve both your quality and quantity of life by minimising risks such as heart disease, high blood pressure and stroke. Your daily functioning in all spheres of life may also improve because you are less fatigued.
What is going to happen to me?
This evening 4 processes or procedures will take place.
1. The Set-Up (approximately 40 to 60 minutes)
Once you have been admitted by the staff an evening meal will arrive a short time after. After dinner you will be asked to change into your pyjamas and you will be seated on a chair in your room. While you are seated, a qualified nurse or sleep technician will apply a number of small sensors to your face, under your chin, on the top of your head, on your chest, your waist and your leg. These sensors will measure your muscle activity, heart rate or brain waves. The application of the sensors is a time consuming process (usually 40 to 60 minutes), as measurements have to be taken with a tape measure to ensure correct placement of the sensors. Application of the sensors is painless. Once the sensors are attached to your head and body, the loose wires will either be gathered together and taped to your pyjamas on your shoulder or placed in a small bag that can be carried with you. You will be free to walk around the Sleep Unit, watch television, go to the toilet or sit and read. In addition to the application of the sensors, your height, weight and blood pressure measurements will be taken and recorded.
2. CPAP Education and Mask Fitting (approximately 30 minutes
Prior to the commencement of the CPAP PD, you will be shown and fitted with a number of masks in an effort to obtain the most comfortable and effective mask for you. Mask fitting is one of the most important factors in CPAP therapy. You will trial the mask initially with a low pressure of air and then later on you will sleep with the mask overnight. It is important that you inform the evening or overnight staff of any problems you may be experiencing so they are able to make the appropriate changes and limit sleep disruption. Pressure requirements will vary depending on the severity of your OSA, and individual anatomical differences.
3. Bed Time Connection (approximately 15 to 30 minutes
Studies will commence sometime between 10.00 – 11:00 pm. Patients are asked to prepare for bed (brush teeth, visit the toilet) before this time. The sensors applied to you earlier must be plugged into the bedside computer module and additional equipment may also need to be applied. This equipment usually includes two Velcro belts applied around your chest and waist. These belts are used to measure your chest effort and diaphragm effort when breathing. A position probe is attached to the chest belt to monitor your position when lying in bed. You will be asked to wear the mask you were fitted with during the evening. The nurse or technician caring for you will wait until you are asleep and your airway begins to obstruct. They will then commence adjusting the pressure of your bedside CPAP machine with a remote control unit. The pressure will only be adjusted to a level that is sufficient to stop your airway from occluding. Another probe (a pulse oximeter probe) will be attached to one of your fingers. This probe measures your oxygen level and pulse rate.
In some instances another probe will be applied to your inner wrist or chest to measure the level of carbon dioxide being emitted through your skin.
When all of the equipment is attached and all of the sensors have been plugged into the bedside computer module, one final test ¾ known as ‘patient calibrations’ ¾ will be performed before lights are turned out.
4. Patient Calibration (approximately 10 minutes)
While you are lying in bed, the nurse or technician responsible for monitoring you overnight will speak to you from the monitoring room over the intercom system. You will be asked to perform a number of simple commands, such as blinking your eyes and pretending to swallow. Calibrations will be completed within 10 minutes. The lights to your room will be turned out, and if you wish, your door will be closed.
Overnight, while you sleep, your breathing, oxygen levels, brain waves and muscle activity will be monitored by qualified staff with the aid of a computer.
The pressure on your CPAP machine will be adjusted by the remote control in an attempt to abolish your obstructions, maintain your oxygen levels as high as possible and to ensure you have a good nights sleep.
Should I take my medications?
Some medications may change your sleep patterns and therefore affect the sleep study result. It is not advisable to change or discontinue any medication prior to your sleep study, without consulting your doctor. Unless advised, you should continue with any prescribed medication.
What if I need help during the night?
There is a call bell located in every room. Please press the button on the intercom located next to right hand side of the bed to summon the nurse or technician caring for you if you are experiencing any problems whatsoever. Please avoid using the general ward nurse call button located on your TV remote control console on the left hand side of the bed. This sends an alarm to the nurses in the general level 6 ward.
When can I leave in the morning and when will I get my results?
Study recording concludes at 6.00 am. The leads take 15 minutes to be removed. You are then able to shower and have a light breakfast which usually arrives at around 6:15am. If you wish to wait for the full breakfast meal service at 7:20am please inform your nurse or technician.
The overnight nurse or technician will provide you with a script indicating your recommended pressure. You will also receive further documentation regarding machine suppliers addresses and phone numbers, rental and purchasing details, and your mask brand, type and size. Any immediate questions you may have can be addressed.
Try before you buy
We recommend you trial or hire a CPAP machine to begin with. You will need to purchase your mask and tubing. These are considered personal items and will not be available for rent. As soon as possible after your CPAP pressure determination, you should contact your chosen CPAP supplier to arrange a rental or trial unit. Take your script into them (or have them come to you) and they will fit you out with the correct equipment. Should you wish to discuss you results with you doctor prior to hiring a CPAP unit, make an appointment as soon as possible. You will generally be eligible for a rebate from your private health fund only after the CPAP unit is purchased. It is a good idea to contact your health fund to determine your rebate entitlements for CPAP equipment.
You will need to see your Sleep Physician 2 to 4 weeks after commencing CPAP. Please contact your referring Physician’s rooms to make a follow-up appointment.