Pickwickian Syndrome

Synonyms: Obesity-Hypoventilation Syndrome, Pickwick Syndrome

"The object that presented itself to the eyes of the astonished clerk, was a boy - a wonderfully fat boy - habited as a serving lad, standing upright on the mat, with his eyes closed as if in sleep."¹

The term Pickwickian Syndrome was first coined by Dr C.S. Burwood and colleagues who described the case of a businessman, weighing in at over 260 pounds with a height of 5ft 5 inches.² The classic triad of features is extreme obesity, somnolence and obstructive apnoea

Controversy surrounds the pathophysiology, some authors believing that the basic problem relates to the way the ventilatory drive reacts to hypoxia and hypercapnoea. Others consider that fat distribution, hormones, and upper airway size are involved.
Upper airways obstruction is certainly known to play a prominent role. It may be associated with rapid eye movement (REM) atonia, increased fat distrbution around the neck and upward displacement of the diaphragm by abdominal fat.³

In recent years, differentiation has been made between people suffering from sleep apnoea and Pickwickian syndrome in which hypoventilation is also evident whilst they are awake.⁴ Most patients with the syndrome also have sleep apnoea, but some patients do not, suggesting that it is the obesity per se which is causing chronic hypoventilation.⁵

There are no figures available for incidence or prevalence, mainly because the condition has been poorly defined in the past and often confused with obstructive sleep apnoea. Risk factors mirror that for obesity, and the condition is commoner in females. Tonsillar hypertrophy is an aggravating factor in children. The peak ages of presentation are 5-7 years and adolescence.³

History

Symptoms suggestive of the diagnosis may include features of sleep apnoea (witnessed apnoea, snoring enuresis, nightmares, sleep walking), chronic mouth breathing, daytime sleepiness, hyperactivity in children, morning headaches, decreased exercise tolerance, poor school performance, poor memory and poor concentration.

A drug history should be taken to exclude alcohol excess, sedating antihistamines and central nervous system depressants, all of which can aggravate the condition.

Examination

• The typical patient will be clinically obese, with marked fat deposition around the chin and abdomen. Thoracic kyphosis is often a feature.
• The head, ears, nose and throat should be examined to exclude facial dysmorphologies or ENT abnormalities that may cause upper airway obstruction such as macroglossia, micrognathia, retrognathia or high-arched palate. The tonsils should be examined to exclude hypertrophy and the nasal passages to exclude polyps, cysts or swollen nasal turbinates.
• Examination of the chest may reveal signs of cor pulmonare (loud second heart sound, displaced cardiac impulse).Acquired pes excavatum may result from overuse of the respiratory muscles overcoming extrathoracic obstruction.

Pickwickian syndrome cannot be diagnosed on history and examination alone, but requires the demonstration of daytime hypercapnoea.⁵

• Sleep apnoea and other sleep-related breathing disorders
• Prader-Willi syndrome (a genetic condition causing obesity, hypotonia, mental retardation, short stature, hypogonadotropic hypogonadism, strabismus, and small hands and feet)
• Beckwith-Wiedemann Syndrome (omphalocoele with macroglossia - thought to be genetic related)
• Narcolepsy
• Use/abuse of sedatives and antihistamines
• Sleep deprivation.

• Arterial blood gases - these are needed to confirm daytime hypercapnoea and hypoxaemia.
• Nocturnal oximetry should be carried out to determine whether sleep apnoea is also present (about one-fifth of sleep apnoeic patients will have Pickwickian syndrome). Formal polysomnography may be required in borderline cases.
• Chest Xray - may show chest wall deformities, or signs of cardiomegaly or congestive failure.
• Echocardiogram - may show right ventricular hypertrophy.
• ECG - arrhythmias and right bundle branch block have been recorded.
• Pulmonary function tests:
  • Flow volume loop - expiratory volume as measured by spirometry is plotted in a continuous curve against flow rate. may show a 'sawtooth' pattern associated wtih upper airways obstruction.⁶
  • Forced vital capacity and expiratory reserve volume may be reduced and airways resistance increased.
• Overnight polysomnography may confirm hypoventilation, hypoxia, and hypercapnoea during sleep, especially in children and adolescents.

A return to normal body weight is the mainstay of treatment. Unfortunately, although they may lose weight initially, many patients are non-compliant with dietary restriction in the long term. They are furthermore restricted from increasing their physical activity due to pulmonary symptoms. Barometric surgery may be required in severe cases. Continuous positive airways pressure (CPAP) is helpful, and may need to be supplemented by oxygen.

If the patient fails to lose weight, there is a high risk of pumonary hypertension, cor pulmonale, and early mortality.