Determinants of Age Related Breathing Instability During Non-Rapid-Eye-Movement (NREM) Sleep
Condition: Sleep Apnea; Age
MeSH terms: Sleep Apnea Syndromes
Study type: Interventional

Summary: 
      The purpose for this research protocol was to examine the role of breathing control
      mechanisms that determine the development of sleep-disordered breathing in the elderly. This
      proposal focused on key factors that contribute to the control of ventilation in elderly
      adults during sleep. The investigators studied the age-specific changes in ventilatory
      control in older and young adults during NREM sleep.
    

Detailed description: 
      Sleep apnea-hypopnea syndrome (SAS) is a relatively common disorder in the US population with
      significant adverse health consequences. Despite the high prevalence of SAS in elderly
      individuals, the underlying mechanisms have remained elusive. Specifically, the investigators
      do not know whether the high prevalence of sleep apnea in older adults is due to increased
      central breathing instability. This proposal focused on investigating age-specific
      differences in the susceptibility to central breathing instability in adults.

      This project had the following specific objectives:

        -  To determine age-specific changes in the hypocapnic apneic threshold during NREM sleep
           in elderly vs young individuals.

        -  To determine age-specific changes in long-term facilitation during sleep in elderly
           versus young individuals.

      Procedure: The investigators determined the susceptibility to central breathing instability
      by mechanically ventilating the subjects during NREM sleep using non-invasive pressure
      support ventilation. The investigators compared the hypocapnic apneic threshold in old
      (age>60 years) and young (age 18-50 years) individuals who were healthy. The investigators
      also measured the parameters over a continuum of age from 18 to 89 years.

      - The investigators investigated whether there was a difference in the susceptibility to long
      term facilitation of ventilation between young and old healthy individuals in response to
      episodic hypoxia, while maintaining isocapnia.

      Sleep apnea is very common in older Veterans and is associated with significant
      cardiovascular complications. Greater insight into the pathogenesis will have a positive
      impact on the health of Veterans suffering from this condition. This study furthers the
      understanding of the pathogenesis of breathing instability leading to sleep-disordered
      breathing during sleep. The investigators anticipate findings will provide a basis for new
      approaches to prevention and management of SAS in Veterans.
    

Intervention name(s): 1) hyperventilation via noninvasive positive pressure ventilation 2) multiple trials of episodic hypoxia
Intervention type(s): Other
Intervention description(s): 1) noninvasive hyperventilation to determine apneic threshold; 2) episodic hypoxia to determine ventilatory long term facilitation
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: apneic threshold; central apnea; intermittent hypoxia; aging; ventilation; chemoresponsiveness; carbon-dioxide reserve