DIFFICULTY FALLING OR STAYING ASLEEP: BREATHING DISORDERS – SPECIFIC FORMS OF CSA
Other specific forms of CSA include alveolar hypoventilation, which occurs during sleep when the breathing rate or the amount of air inhaled decreases. In some cases hypoventilation is a result of obesity; excess body weight prevents the lungs from expanding to their full capacity. In other patients the problem may be related to specific disorders of the muscles, nerves, or bones, or it may be due to some basic malfunctioning of the respiratory centers located in the brain stem. Yet another variety of CSA is Cheyne-Stokes breathing, the name given to the dyspnea (breathing difficulty) that afflicts patients with left ventricular failure. When heart failure occurs, possibly as a result of some disruption in the nerves, circulation is slowed, the oxygen level of the blood drops, and the level of acids and other toxins increases, giving rise to alternating periods of apnea (breathing cessation) and hyperpnea (gasping, panting breathing).
Victims of CSA are often unaware that the problem exists, because they breathe normally during the day. One clue may be that the patient snores at night; generally, however, snoring is more likely to be a symptom of obstructive apnea. CSA is usually worst during REM sleep because the system that responds to elevated levels of carbon dioxide in the blood is suspended during
REM sleep. Consequently, interruptions in breathing last longer, and the level of oxygen falls to a lower point than during NREM stages. Alcohol, which suppresses the central respiratory drive, only makes the problem worse. Patients with heart disease may experience arrhythmias or increased blood pressure, although these risks are even greater in cases of OSA.
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