[TOC]
- Obese patient (BMI >30) + PaCO₂ >45 mmHg while awake not due to other causes
- Concomitant obstructive sleep apnea
- Many have pulmonary hypertension and right heart failure
- Implications on pulmonary function tests
- Lower functional residual capacity and expiratory reserve volume
- decreased total lung capacity, functional vital capacity, FEV1, maximum voluntary ventilation
- Worse in supine position
- Airway closure during exhalation
- Worsens V/Q mismatch and increased work of breathing
- Increased upper airway resistance
- Increased respiratory rate and decreased tidal volume is the pattern of breathing