Sleep Disordered Breathing, commonly called SDB, is a variety of sleep problems that involve the respiratory system. The most common form of this is called Obstructive Sleep Apnea (OSA), followed by Central Sleep Apnea (CSA), and Complex Sleep Apnea Syndrome which is a combination of both Obstructive and Central Sleep Apnea. Apnea is a word that means one stops breathing – another word common in sleep medicine is Hypopnea – this means that the flow of air into the lungs is greatly reduced. The diagnosis of OSA or CSA is by using a measurement called the AHI – which stands for the Apnea/Hypopnea Index. This is expressed in the number of episodes of apnea or hypopnea per hour. In other words, how many times each hour, while you sleep, do you either stop breathing or take very shallow breaths.
Obstructive Sleep Apnea is caused by the upper airway partially or totally collapsing during sleep. It is estimated that approximately 4% of middle-aged males and 2% of middle-aged females have this disorder. It is related to the amount of tissue and fat in the upper airway and during certain stages of deep sleep this tissue/fat tends to slide down the airway and blocks off the flow of air. Central Sleep Apnea issues are related to the respiratory drive located in the brain – for reasons not totally understood – the signal to breath during certain sleep stages fails to happen. In both conditions, the lack of air into the lungs results in a decrease in the amount of oxygen in the blood. When the oxygen levels get too low, the person tends to “startle awake” gasping for air. It is also quite common that obstructive sleep apnea (OSA) people tend to snore loudly – but this is not always the case.
There are two distinct types of sleep:
- rapid-eye-movement sleep (REM),
- non-REM sleep commonly shown as NREM.
REM sleep is the period of time that most dreaming occurs. The largest amount of REM normally takes place about one hour before awakening. Most people only spend 15 -20% of sleep time in REM, thus, non-REM sleep makes up 80 – 85% of sleep time. During non-REM sleep your heart rate, breathing, and blood pressure all drop to levels below those that occur while you are awake. This is normally the time for rest and recuperation for the cardiac system. Whereas, during REM sleep, both your blood pressure and heart rate can go up and down. Any time you wake up from sleep (even briefly) both your blood pressure and heart rate increases. One can understand that SDB can take a negative toll on your heart from repetitive waking up throughout the sleep cycle. People with serious SDB problems can wake up 20 – 40 times an hour or hundreds of awakenings a night. These awakenings are often so short that the person is unaware of any interruption in sleep during the night. These awakenings, also known as arousals, can prevent an individual from reaching the restorative stages of sleep and, in most cases, cause one to feel un-rested after a full night of sleep.
SDB and Hypertension – hypertension is high blood pressure. Approximately 80% of people with drug-resistant hypertension have SDB. SDB produces prolonged cardiovascular stress, leading to high blood pressure both night and day. Some investigators believe that hypertension can be caused by SDB. Hypertension is a known risk factor for the development of other forms of cardiovascular disease such as heart attack, heart failure, and stroke.
SDB and Coronary Artery Disease (CAD) – approximately 30% of CAD patients have SDB. Treatment of SDB is associated with a decrease in the occurrence of new cardiovascular events.
SDB and Atrial Fibrillation (AF) – SDB affects approximately 50% of all AF patients. AF patients on effective treatment for SDB have a lower risk of AF recurrence than those with untreated SDB.
SDB and Congestive Heart Failure (CHF) – Various articles have estimated that anywhere from 50 – 70% of all CHF patients have SDB. SDB is common in moderate and severe heart failure patients. It contributes to CHF disease progression and worsening of outcomes, including increased mortality. Studies have proven that effective SDB treatment leads to improved heart function and a reduction in enlarged heart dimensions.
The Anderson Hospital Sleep Center is able to test people for suspected SDB and help develop treatment options with you and your physician. Below is a survey tool called STOP-BANG. It is fairly accurate in determining the risk of having a form of SDB. Please take a minute to answer these 8 simple questions – you might want to ask your bed partner to assist in answering some of these questions. If a person answers three (3) or more questions with a yes answer – they may want to consider talking to their primary care physician about possibly having a sleep test performed. The medical data seems to show clearly that untreated SDB will lead to heart disease.
- Snoring – do you snore loudly (louder than talking or loud enough to be heard through a closed door)?
- Tired – Do you often feel tired, fatigues, or sleepy during the daytime?
- Observed – has anyone observed you stop breathing during your sleep? This is sometime noticeable by multiple pauses between snores during episodes of snoring.
- Blood Pressure – Do you have or are you being treated for high blood pressure?
- BMI – BMI more than 35 (BMI is body mass index) – if you are overweight by 20 pounds or more then – yes. BMI is a measurement that uses your height and weight to calculate it.
- Age – is your age over 50 years old?
- Neck Circumference – greater than 40 centimeters? (16 – 17 inches) – About a size 18 neck in men
- Gender – are you a male
This article has highlighted the issues related to cardiac disease and SDB. There are a multitude of other health and mental/cognitive issues related to SDB.