Pickwickian Syndrome

Acquired obesity-associated sleep apnea, cyanosis, somnolence, muscle twitching, and periodic breathing.

Obesity-Hypoventilation Syndrome; Syndrome de Pickwick (French appellation).

Named after the fat boy Joe, in Charles Dickens's Pickwick Papers. This disorder is characterized by morbid obesity, cyanosis, somnolence, muscular twitching, and periodic breathing.

In the United States, it is observed in 20-27% of obese children and adolescents. Higher mortality and morbidity is reported in this group of patients. During the second decade of life, females are more affected than males; 80% of teenagers with obesity will remain affected in adulthood.

Reduction in lung volumes including expiratory reserve volume, vital capacity, and functional residual capacity. Closing capacity is increased, leading to airway closure in the dependent areas of the lung and V/Q mismatch, reduced chest and diaphragmatic excursions, decreased alveolar ventilation, and diminished sensitivity of the respiratory center to hypoxia and hypercarbia—all contributing to hypoxia and hypercarbia. Intermittent upper airway obstruction and hypoxia during sleep with resultant chronic sleep deprivation and daytime somnolence; severe and chronic hypoxia leading to polycythemia, pulmonary hypertension, right ventricular hypertrophy, and failure.

Clinical features; biochemical (polycythemia, hypoxia, hypercarbia); lung function tests (reduced lung volumes including total lung capacity, functional residual capacity, vital capacity, and expiratory reserve volume); ECG (right axis deviation); chest radiography or echocardiography (cardiomegaly); sleep studies (obstructive sleep apnea).

Morbidly obese, lethargy, drowsiness, headache, and muscle twitching; may develop mental retardation; exertional dyspnea, cyanosis, and periodic breathing, particularly marked during sleep, enuresis; hypertension and later signs of chronic cor pulmonale (distended neck veins, enlarged heart and liver, peripheral edema). Major improvement is usual following nasal continuous positive airway pressure at night: daytime sleepiness and behavioral problems regress, and a better quality of sleep allows enhanced physical activity and favors weight loss.

Detailed preoperative cardiac and respiratory assessment is required; some weight loss might be advisable prior to elective surgery.

Difficulty in maintaining patent airway during mask ventilation and difficult tracheal intubations common; arterial desaturation usually rapid because of reduced functional residual capacity; intraoperative hypertension, arrhythmias and heart failure may occur; tolerates hypovolemia poorly because of reduced blood volume per unit body weight; reliable indirect blood pressure monitoring is difficult to achieve because of large arm size; difficult venous access; identification of landmarks for regional blocks and invasive lines difficult; increased incidence of postoperative respiratory complications; supine position is associated with a drop in PaO2 and is to be avoided postoperatively; nasal continuous positive airway pressure or continuous positive airway pressure mask recommended for obstructive sleep apnea; polycythemia may predispose to deep venous thrombosis, although pulmonary embolism is extremely rare in children.

Use of prophylaxis against gastric aspiration recommended; require lower drug doses on a per kilogram basis; increased sensitivity to respiratory depressants, including opioids.

Prader-Labhart-Willi Syndrome: Disorder characterized by morbid obesity, cyanosis, excessive daytime sleepiness, shortness of breath, elevated arterial partial pressure of carbon dioxide, flushed face, high blood pressure, polycythemic, muscular twitching, and periodic breathing. Most patients present with sleep apnea syndrome.