Answer: Pickwick syndrome is a disorder of the respiratory control system of the nervous system, where a person does not breathe as much as they need.
Pickwick syndrome, also called obesity hypoventilation syndrome, is characterized by a combination of symptoms. Generally, it affects obese people, as defined by a body mass index above 30. These people often have a slower respiration rate than normal, where either they do not breathe rapidly or deeply enough. As a result, they may experience hypercapnia (elevated blood levels of carbon dioxide) and hypoxemia (low blood levels of oxygen). Because of these changes in blood oxygen, a person with Pickwick syndrome may have heart problems, and fluid collection in the extremities (edema).
One theory about obesity hypoventilation syndrome (OHS) is related to the neurohormone leptin. Leptin is released by the adipose brown (fatty) tissue in the body, and usually increases respiration. In patients with OHS, this response seems to be blunted.
Another theory is related to the chemoreceptors in the central nervous system, namely the medulla. These receptors are sensitive to the pH level of the cerebrospinal fluid. When the acidity of the CSF rises (pH falls), the body responds by increasing the respiration rate. But, in patients with Pickwick syndrome, this reflex is weakened. ("Recent advances in obesity hypoventilation syndrome")
Pickwick syndrome may result in sleep apnea, a difficulty in staying asleep through the night. This may be a consequence of the poor oxygenation. Therefore, a constant positive airway pressure (CPAP) device may be helpful in relieving the symptoms, and improving daytime functioning.