Obesity is the main risk factor for several sleep breathing disorders, including obstructive sleep apnea syndrome (OSAS), either alone or associated with chronic obstructive pulmonary disease (COPD), and alveolar obesity-hypoventilation syndrome (AOHS). In several of these conditions, the indicated treatment includes the use of non-invasive ventilation during sleep, such as the use of continuous positive airway pressure (continuous positive airway pressure or CPAP) and two-level pressure (BIPAP, bi-level positive airway pressure). In this chapter, a brief review is made of what the most recent studies say regarding the treatment of SOHA with non-invasive ventilation (NIV), comparing different ventilation modes and/or treatments.
TopAlveolar Obesity-Hypoventilation Syndrome: Definition
Obesity is one of the biggest public health problems in the developed world and has therefore been dubbed the “global epidemic of the 21st century” (López-Jiménez et al., 2016). This metabolic disease, recognised by the World Health Organisation as a serious health, social and economic problem, is associated with high morbidity and mortality rates (Ojeda Castillejo et al., 2015).
In addition to a pathology in its own right, obesity is a risk factor for the development of other chronic diseases, since it leads to significant changes in the physiology of the respiratory system that can lead to a wide spectrum of clinical manifestations, ranging from secondary dyspnea and restrictive ventilatory defect to hypercapnic respiratory failure, characteristic of Hypoventilation-Alveolar Obesity Syndrome (AOHS) (Ojeda Castillejo et al., 2015).
The Obesity-Alveolar Hypoventilation Syndrome (AOHS), or Pickwick Syndrome, or Obesity Hypoventilation Syndrome, or Obesity Hypoventilation Syndrome (OHS), which consists of the lack of effectiveness of the respiratory system in maintaining adequate gas exchange (Silva, 2006), was first described in 1956 and, is currently known as a condition characterized by obesity, hypercapnia and respiratory alterations during sleep, namely episodes of apnea and hypoventilation, in the absence of any other cause/disease that explains respiratory failure (López-Jiménez et al., 2016).
In 1999, AOHS was defined by the American Academy of Medicine of SONO (AAMS) as the association of obesity (BMI - Body Mass Index > 30 Kg/m2), chronic daytime hypercapnia (PaCO2 > 45 mmHg) and sleep breathing disorders, excluding all other causes of alveolar hypoventilation, such as severe obstruction or restrictive pulmonary diseases, chest wall disorders or neuromuscular diseases (Orfanos et al., 2017). Individuals may have symptoms such as daytime drowsiness, fatigue or morning headaches (Jacqueline et al., 2018).
In addition, AOHS is characterized by mild hypoxemia in wakefulness, associated with extreme oxygen desaturations during REM (Rapid Eye Movement) sleep and concomitant acute and repeated increases in PaCO2. Its importance today is due, in most cases, to the increased prevalence of obesity and the discovery of obstructive sleep apnea and hypopnea syndrome (OSAS) as a determining factor of symptoms - individuals with AOHS are more severely affected by cardiovascular diseases, compared to obese eukápnic individuals, with a mortality rate of 23% versus 9% (Nowbar et al., 2004).
Obstructive Sleep Apnea/Hypopnea Syndrome (OSAS), more commonly known as Obstructive Sleep Apnea Syndrome (OSAS), is a condition characterized by repeated partial narrowing (hypopnea) or total collapse (apnea) of the upper airways during sleep, resulting from an imbalance between the mechanisms that maintain airway permeability and the forces that promote its closure, with consequent hypoxemia and hypercapnia, associated with sleep fragmentation, pronounced snoring and excessive daytime sleepiness due to frequent nocturnal awakenings (Esquinas, 2011).