What is Pickwickian syndrome, also known as Obesity Hypoventilation Syndrome (OHS)?

From the Guidelines

Pickwickian syndrome, also known as obesity hypoventilation syndrome (OHS), is a life-threatening condition that requires immediate medical attention to prevent serious complications, including increased rates of mortality, chronic heart failure, pulmonary hypertension, and hospitalization due to acute-on-chronic hypercapnic respiratory failure. It is a condition where severely obese individuals have difficulty breathing adequately, particularly during sleep, leading to decreased oxygen levels and increased carbon dioxide retention in the blood 1. The primary symptoms include daytime sleepiness, fatigue, morning headaches, and shortness of breath. Most patients also have obstructive sleep apnea, where breathing repeatedly stops and starts during sleep.

Key Characteristics of Pickwickian Syndrome

• Defined by the combination of obesity (body mass index [BMI] > 30 kg/m2), sleep-disordered breathing (SDB), and awake daytime hypercapnia (awake resting PaCO2 > 45 mm Hg at sea level) 1
• Approximately 90% of patients with OHS have coexistent obstructive sleep apnea (OSA) defined by an apnea–hypopnea index (AHI) >5 events/h, with nearly 70% having severe OSA (AHI > 30 events/h) 1
• Severe obesity is a major risk factor for the development of OHS, with a prevalence of OHS between 8% and 20% in obese patients referred to sleep centers for evaluation of SDB 1

Treatment and Management

• Treatment typically involves weight loss through diet and exercise, with bariatric surgery considered for severe cases 2
• Continuous positive airway pressure (CPAP) therapy, typically starting at pressures of 8-12 cmH2O, is often prescribed to keep airways open during sleep
• Some patients may require bilevel positive airway pressure (BiPAP) therapy instead, with inspiratory pressures of 12-18 cmH2O and expiratory pressures of 6-10 cmH2O
• Supplemental oxygen might be needed if oxygen levels remain low despite these interventions

Importance of Early Intervention

• Untreated OHS can lead to serious complications, including heart failure and pulmonary hypertension, with mortality rates as high as 24% at 1.5–2 years after diagnosis 2
• Early intervention and treatment can significantly improve quality of life and reduce the risk of mortality and morbidity associated with OHS 1, 2

From the Research

Definition of Pickwickian Syndrome

• Pickwickian syndrome is also known as obesity hypoventilation syndrome (OHS) 3, 4, 5, 6
• It is characterized by a combination of sleep-disordered breathing, obesity, and daytime hypercapnia 3
• The condition is a diagnosis of exclusion after every other possible etiology is ruled out 3

Clinical Characteristics

• Patients with Pickwickian syndrome can present with an exacerbation of or a chronic state of progressive dyspnea 3
• The syndrome consists of the triad of obesity, sleep disordered breathing, and chronic hypercapnia during wakefulness in the absence of other known causes of hypercapnia 4
• It is often associated with severe pulmonary hypertension, which can be reversible with appropriate treatment 6

Diagnosis and Treatment

• Diagnosis is based on the presence of obesity, sleep-disordered breathing, and daytime hypercapnia, after ruling out other possible causes 3, 4
• Treatment involves non-invasive ventilatory (NIV) support, weight loss, and supportive management 3, 5
• Early recognition and treatment are important to improve patient outcomes and reduce morbidity and mortality 4