Pickwickian syndrome: A comprehensive narrative review from historical origins to emerging therapeutic frontiers

Pickwickian syndrome, now formally designated as obesity hypoventilation syndrome (OHS), is a serious cardiorespiratory disorder defined by the triad of obesity (body mass index [BMI] > 30 kg/m²), daytime hypercapnia (arterial PaCO₂ ≥ 45 mmHg), and sleep-disordered breathing, after the exclusion of other causes of alveolar hypoventilation. Its prevalence is estimated between 8% and 12.3% among obese individuals presenting with obstructive sleep apnea (OSA). 
The pathophysiology is multifactorial, encompassing mechanical respiratory load imposed by excess adipose tissue, leptin resistance with blunting of central chemoreceptor drive, altered respiratory mechanics, and systemic inflammation compounded by oxidative stress. Untreated, OHS carries significant morbidity including pulmonary hypertension, cor pulmonale, type 2 respiratory failure, and premature mortality.
Management is multimodal, with non-invasive positive airway pressure therapy - particularly bilevel positive airway pressure (BiPAP) and average volume-assured pressure support (AVAPS), as the cornerstone of treatment alongside weight reduction through lifestyle modification, bariatric surgery, and, most recently, glucagon-like peptide-1 (GLP-1) receptor agonist pharmacotherapy.