Pickwickian Syndrome (aka Obesity hypoventilation syndrome ...



Pickwickian Syndrome (aka Obesity hypoventilation syndrome (OHS))

Pickwickian syndrome is a disorder that was named after Joe, the fat, red faced boy in Charles Dickens' The Pickwick Papers. This syndrome is defined by extreme obesity and alveolar hypoventilation during wakefulness. In many cases, the coexistence of obstructive sleep apnea (OSA) contributes significantly to the clinical problems seen in this disorder. The sleep apnea is caused in part by the excess amounts of fatty tissue surrounding the chest muscles. When the work of breathing becomes intolerably high, it is more efficient for a person to hypoventilate and tolerate an elevated arterial carbon dioxide tension (PaCO2). This resets the set-point of the central nervous system chemoreceptors to a higher PaCO2, with consequent depression of ventilatory drive. The renal compensation to raise the plasma bicarbonate concentration minimizes the fall in arterial pH in this setting.

Clinical Manifestations:

• Massive obesity (150 percent of their predicted weight)

• Sleep disturbances

• plethoric, florid complexion

• a short, thick neck

• a small oropharynx

• Rales

• Cyanosis

• Pulmonary hypertension, leading to right ventricular failure and peripheral edema

• Dyspnea

• signs of right-sided heart failure, such as elevated jugular venous pressure, hepatomegaly, and pedal edema.

Lab and Diagnostic Data:

• by definition, patients with OHS have alveolar hypoventilation and are therefore hypercapnic (and usually hypoxemic) during wakefulness while breathing room air

• Those patients without airway obstruction (eg, due to chronic obstructive pulmonary disease) can normalize their arterial PCO2 with voluntary hyperventilation, indicating that ventilatory muscle function and chest wall integrity are adequate to reverse the hypercapnia [5].

• hematocrit is elevated in about one-half of patients

• may have high blood pressure

• may have an enlarged liver

• may have an high red blood cell count

• Respiratory studies will show reductions in vital capacity and expiratory reserve volume, and a low maximal voluntary ventilation

• CXR’s frequently reveals an enlarged heart, due to right ventricular hypertrophy, and elevated hemidiaphragms, resulting from increased hydrostatic pressure exerted against the diaphragms by the obese abdomen.

• The electrocardiogram and echocardiogram show right atrial and right ventricular hypertrophy

• Sleep Studies normally show severe hypoxemia during sleep and, in many cases, severe obstructive sleep apnea

Treatment

• Progestins: respiratory stimulants (improvement in awake hypercapnia and hypoxemia)

• Limit ETOH (can increases the apnea frequency in persons with OSA and worsens nocturnal oxyhemoglobin desaturation)

• Treatment of Comorbid Conditions

• Ventilatory Support (BIPAP)

• Oxygen Therapy

• Weight Loss

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