By Dr. Kenny Peter Pang, Ear Nose Throat / Sleep Specialist, Asia Sleep Centre, Paragon, Singapore author of Advanced Surgical Techniques in Snoring and Obstructive Sleep Apnea available in March 2013.
Contrary to popular belief, the throat and the upper airway has major impact on one’s sleep pattern and quality. The patency and size of one’s upper airway can affect the sleep quality and affect one’s health and quality of life. Due to a narrowed and/or congested throat (airway), the resistance to breathing can be very high, making breathing during sleep very difficult and laboured. This is more pronounced during sleep, as one’s muscles are completely relaxed and flaccid (soft), resulting in collapse and closure of the throat; hence, no breathing during sleep. This is known as Obstructive Sleep Apnea (OSA).
In Singapore, the incidence of Obstructive Sleep Apnea is estimated to be about 15%.
The Evolution of the Airway.
It is well accepted that for most mammals, the airway is the most important conduit for the passage of air into the lungs, for gaseous exchange and the intake of oxygen. From the four-legged crawling canines to the two-legged standing gorillas, the airway is structurally within the cranio-facial skeleton (solid hard box/skull) of the animal.
Based on Darwin’s theory of evolution, it is well known that as the four-legged animal evolved and stood up, many changes took place in the upper body, namely, his upper limbs (arms/hands) got shorter, the spine became stronger, firmer and upright, the brain evolved bigger and, most crucially, the facial shape also changed.
Darwin’s Theory of Evolution
The face shaped changed and became shorter from front to back, the face grew longer, the upper head expanded (as the brain grew bigger), and his neck development also increased, the neck gradually grew longer, with the airway conduit no longer being protected by the cranio-facial skeleton.
The evolutionary changes are evident when examining the cross sections of the canine model, to the gorilla model to the human model. The facial morphology has changed to shorten the cranio-facial section of the airway in the skull, enlarge the cranium (brain), increase neck length and with most of the airway unprotected in the neck.
The unprotected airway in the neck is no longer protected by the cranio-facial skeleton, it is surrounded by skin, muscles and soft tissues; the airway is hence, more vulnerable, prone to collapse, injury and trauma.
This therefore leads to a much higher incidence of snoring and obstructive sleep apnea in humans compared to animals.
God gave us the nose to breathe through it, warm the air we breathe, and filter dust particles. The nose is pivotal in the breathing apparatus of the human. Any swelling/obstruction in the nose would result in turbulent airflow and difficulty breathing; resulting in more negative pressure required to inhale air into the lungs, this results in a more negative pressure in the throat (creating a vacuum effect), causing collapse of the throat muscles and structures. (see diagram)
Hence, the nose is pivotal in the management of obstructive sleep apnea, however, numerous studies/research have shown that OSA is a disorder of a multilevel system in the throat (including the palate, the tonsils and/or the tongue) that collapses during sleep. Therefore, treating the nose alone is inadequate in the treatment of OSA.
The throat in the airway comprises of the palate (soft tissue structure containing mainly muscles), the side walls of the throat (mainly muscles and fat), the left and right tonsils (mainly lymphoid tissue), and the tongue (see diagram). The throat is a dynamic structure that “acts” as a soft air conduit, to channel air into the lungs from the external environment. Any enlarged or swollen structure/s in this air conduit would narrow the space and result in obstruction during breathing. In the same vein, any form of negative pressure or vacuum effect would “suck” the structures inward and result in airway obstruction. With turbulent airflow in this soft air conduit, vibration ensues resulting in snoring. Snoring implies an increased resistance to the inflow of air during breathing at the level of the upper airways.
Some patients may have adeno-tonsillar hypertrophy with a crowded upper airway with very little space for airflow, while obese patients frequently have a thick and fatty soft palate and side walls in the throat. It is the vibration of these soft tissues during sleep that results in snoring.
The average human spends about 6 to 8 hours per day sleeping. Hence, we spend about one third of the day sleeping, and therefore, one third of our life time sleeping, yet so many of us take sleep for granted.
For the average Singaporean that lives up to about 80 years old (current life expectancy), hence, we sleep for a total of 26 years of our life!
It is well accepted that dream sleep (25% of sleep) is the most important element in the sleep process, for well being, memory re-building, rejuvenation and mental alertness. Hence, dream sleep is vital to the human mind and body. Simplistically, dream sleep is a highly active brain in a “paralyzed” body. This is a perfection made by our divine maker, so as to prevent us from acting out our dreams (i.e. if one was dreaming that one was playing soccer, one does not actually kick and act it out in bed, endangering one’s bed partner). This however, works against the patient with an already narrowed airway (narrow throat or air conduit), as this already narrowed airway will lose its tone (complete relaxation) during dream sleep and collapse, leading to upper airway obstruction, cessation of breathing and lack of oxygen. Therefore, this leads to stress on the heart, brain and other organs in the body. This condition is called obstructive sleep apnea (OSA).
This very important dream sleep component of sleep, that is crucial for memory rebuilding, rejuvenation and well being, will not be able to take place if the body is deprived of the fundamental basic need for oxygen, due to stoppages of breathing, resulting from a blocked airway (usually multilevel). This results in interrupted sleep, sleep fragmentation and poor sleep quality.
During the day, the patient is excessively sleepy, has poor concentration, poor memory and becomes irritable/moody. Common patient complaints include early morning tiredness and morning headaches. Other symptoms include forgetfulness, depression, irritability and, less commonly, impotence.
During the night, patients may complain of frequent awakenings with a choking and gasping sensation, nocturia (frequent passing urine at night), or nightmares. Many bed partners have witnessed their partners choking and holding their breaths (apneas) during their sleep.
Long term health consequences include high blood pressure, heart disease, strokes and sudden death during sleep.
Captain (NS) Jimmy Ang, has Ankylosing Spondylitis, high blood pressure and severe obstructive sleep apnea. He had been snoring loudly, and feeling very tired during the day for the past few years. Every morning he would not feel refreshed despite sleeping adequate hours at night. His wife would observe him choking and gasping for breath during the night while he slept.
Mr. Ang says that his “wake up” call came a few months before the surgery as he fell asleep whilst driving in the afternoon and hit another vehicle in front. He had nose, palate and tongue surgery after undergoing the home based wrist worn sleep test that showed he had severe obstructive sleep apnea, in August 2009. Mr. Ang reveals that “since the surgery, my life has changed for the better. My nose passages feel opened, breathing is very smooth and I don’t snore anymore. It has been over 3 years since the surgery, I am able to breathe without difficulty in my sleep and feel refreshed in the mornings. My blood pressure is also very well controlled now, after the surgery. I am so happy that I also sent my son for the same sinus surgery.”