All patients who are overweight and obese should begin a controlled weight loss programme. In addition to improving general health, weight loss can improve alveolar ventilation [PaCO2] and arterial oxygen tension [PaO2].
Therapeutic goals for patients with Obesity Hypoventilation Syndrome (OHS) include normalisation of arterial carbon dioxide tension (ie, PaCO2 <45 mmHg) as well as prevention of oxyhemoglobin desaturation during sleep and wakefulness. Therapy goals also include prevention of erythrocytosis, pulmonary hypertension, and cor pulmonale and relief of hypersomnia and altered mentation.
To achieve these goals, all OHS patients need to be managed with nocturnal positive airway pressure. NIV has been widely observed to be an effective treatment for OHS1.
In recent years, NIV used with a leak circuit and a volume-assurance target has been established as a very effective method of reducing PtcCO2. This therapy is particularly effective when compared with pressure-controlled ventilation without any volume assurance1.
ResMed’s Volume Assurance mode, iVAPS (intelligent Volume-Assured Pressure Support) not only secures target volume but also alveolar ventilation, by compensating for dead space ventilation. This is particularly important under changing patient conditions, such as when respiratory drive is impaired during rapid eye movement (REM) sleep or when the patient moves to a supine position.
Storre JH, Seuthe B, Fiechter R, Milioglou S, Dreher M, Sorichter S, Windisch W. Average volume-assured pressure support in obesity hypoventilation: A randomised crossover trial. Chest.2006 Sep;