From the Guidelines
The obesity-related hypoventilation syndrome is called Obesity Hypoventilation Syndrome (OHS). This condition occurs when severely overweight people fail to breathe rapidly or deeply enough, resulting in low blood oxygen levels and high carbon dioxide levels 1. OHS is diagnosed when a person with a body mass index (BMI) greater than 30 kg/m² has daytime hypercapnia (elevated carbon dioxide levels in the blood) without other causes of hypoventilation. The syndrome typically coexists with obstructive sleep apnea in about 90% of cases 1.
Key Characteristics of OHS
- Defined by the combination of obesity, sleep-disordered breathing (SDB), and awake daytime hypercapnia 1
- Leads to serious sequelae, including increased rates of mortality, chronic heart failure, pulmonary hypertension, and hospitalization due to acute-on-chronic hypercapnic respiratory failure 1
- Approximately 90% of patients with OHS have coexistent obstructive sleep apnea (OSA) 1
Diagnosis and Treatment
- Diagnosis requires a sleep study and measurement of arterial blood gases during wakefulness 1
- Treatment usually involves positive airway pressure therapy, either continuous (CPAP) or bilevel (BiPAP), with BiPAP often preferred due to its ability to provide both inspiratory and expiratory support 1
- Weight loss is also a crucial component of treatment, as it addresses the underlying cause, with a suggested weight loss of 25% to 30% of body weight to achieve resolution of OHS 1
Importance of Early Diagnosis and Treatment
If left untreated, OHS can lead to serious complications including pulmonary hypertension, right heart failure, and increased mortality 1. Therefore, early diagnosis and treatment are crucial to improve patient outcomes and reduce morbidity and mortality associated with OHS.
From the Research
Definition and Name of the Syndrome
- The name of the obesity-related hypoventilation syndrome is Obesity Hypoventilation Syndrome (OHS) 2, 3, 4, 5, 6.
- It is also historically described as the Pickwickian syndrome 3, 5.
Characteristics of the Syndrome
- OHS is defined as a combination of obesity, daytime hypercapnia, and sleep-disordered breathing in the absence of other known causes of hypercapnia 2, 3, 4, 6.
- The syndrome is characterized by a triad of obesity, sleep disordered breathing, and chronic hypercapnia during wakefulness 3.
- OHS often remains undiagnosed until late in the course of the disease 3, 4.