Acquired obesity-associated sleep apnea, cyanosis,
somnolence, muscle twitching, and periodic breathing.
Obesity-Hypoventilation Syndrome; Syndrome de Pickwick
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 ...