apnea, sleep

Obstructive sleep apnea (OSA) is the apnea (abnormal, temporary cessation of respiration) caused by intermittent physical obstruction of the upper airway of the nose and pharynx (basically the area of the throat from the voicebox to the rear openings of the nasal passages) due to chronic adenoidal or tonsillar enlargement or due to neurological or muscular problems of the area of the soft palate and tissues of the pharynx. In children it is most often associated with chronic adenoidal enlargement and/or obesity; older children and adults with sleep apnea are more likely to have neuromuscular problems or to be obese.

The upper airway region (nose, mouth, and throat above the larynx) is collapsible to enable us to talk and swallow. More than than 30 pairs of muscles control the degree of openness of the airway in a process of balancing the natural tendency to collapse with the need to maintain an open airway. Certain structural abnormalities - enlarged adenoids or tonsils, abnormalities of facial bone structure, or obesity can disrupt this balance in the direction of more easy obstruction of the airway. Severe disruptions produce significant airway blockage in the night during sleep, causing the symptoms and complications of obstructive sleep apnea.

Our instinctive drive to breath decreases during sleep, and breathing patterns change during the different phases of sleep. During deeper, non-REM sleep (when we are not dreaming), breathing is regular but more shallow. There is marked relaxation of the muscles in the upper airway region. This relaxation and subsequent narrowing of the upper airway causes increased resistance to airflow as the tissues fall together into a more relaxed postion. When we dream, the the muscles of the upper airway relax even more. Breathing becomes more erratic with regard to rate and depth. There are frequent pauses.

If this natural state of sort of borderline ventilation is disturbed by any additional obstruction, significant respiratory impairment can result. Oxygen (O2) levels fall and carbon dioxide (CO2) levels rise in the lungs and bloodstream as a natural result of reduced air movement into and out of the lungs.

At a minimum, sleep apnea interferes with the ability to get a good night's sleep by disturbing REM sleep (Rapid Eye Movement - dream sleep). The child must constantly arouse to the point where muscle tone in the upper airway increases enough to allow breathing to resume. This can happen literally hundreds of times a night, making normal rest impossible.

More disturbing potential complications of sleep apnea arise from the fact that as mentioned, when air movement into and out of the lungs is restricted, oxygen (O2) levels fall and carbon dioxide (CO2) levels rise in the lungs and bloodstream. Over time, these disturbed levels of blood gases cause abnormal constriction of the vessels in the lungs and other direct toxic effects on the body.

The potential complications of obstructive sleep apnea include

  • neurologic - caused by chronic brain oxygen deprivation at night
    • developmental delay
    • learning problems
    • hyperactivity and attention problems
    • daytime sleepiness - I have seen children who repeatedly fell soundly asleep in class due to sleep apnea at night
    • morning headaches
    • seizures (rare)
  • cardiac
    • pulmonary hypertension - constriction of the arteries of the lung due to low oxygen and high carbon dioxide at night
    • cor pulmonale - right heart enlargement from the strain of pumping against chronically increased resistance in the lungs
    • heart failure
    • sytemic high blood pressure (hypertension)
  • poor growth (failure to thrive)
  • bedwetting
  • sudden death (rare)

Obstructive sleep apnea is suspected by parents and physicians when the child snores loudly and then abruptly stops for variable periods. At the end of the apnea period, the child will gasp and resume breathing. I often tell parents to tape record the snoring pattern and take the recording with them when they see the specialist. The child may actually turn blue during a severe apnea episode. He may sleep in an abnormal position, unconsciously arching the neck in an attempt to open the airway a bit more. The parents may allow the child to sleep with them, for fear that he will stop breathing in the night, or to arouse him when he does.

While the child's history may be more or less diagnostic, in many cases the diagnosis of significant sleep apnea is not certain from parental reports. Physical examination during the day is helpful but again of limited value in many instances, since the absolute size of the tonsils and adenoids does not reliably indicate sleep apnea - many kids with huge tonsils breathe just fine at night. The best study method available is polysomnography, or the sleep study. A number of physiologic functions are measured simultaneously during sleep. These studies can sometimes be done in an abbreviated or limited fashion at home, but if the study is normal, an overnight study in a hospital sleep laboratory may still be needed.

Treatment of sleep apnea begins with tonsillectomy and adenoidectomy, essentially for all cases. If that fails, treatment might include nighttime nasal "CPAP" (Continuous Positive Airway Pressure - "SEE-pap"). Weight loss is helpful for obese children. Uvulopharyngopalatoplasty (UVPP - removal of the uvula, tonsils, and floppy soft palate tissue) is widely done in adults with OSA syndrome, but is rarely done in children, and then usually in those with neuromuscular problems such as cerebral palsy or Down syndrome.

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