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Apnea after normocapnic mechanical ventilation during NREM sleep
A M Leevers1, P M Simon, J A Dempsey
1John Rankin Laboratory of Pulmonary Medicine, Department of Preventive Medicine, University of Wisconsin, Madison 53705.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1994
Summary
High tidal volume (VT) and breathing frequency (f) mechanical ventilation during sleep inhibits inspiratory effort. This leads to prolonged apnea, suggesting neuromechanical inhibitory effects during controlled breathing.
Area of Science:
- Respiratory Physiology
- Sleep Medicine
- Neuromuscular Control
Background:
- Mechanical ventilation is used to support breathing during sleep.
- The effects of high tidal volume and breathing frequency on inspiratory effort during sleep are not fully understood.
Purpose of the Study:
- To investigate if normocapnic mechanical ventilation with high tidal volume (VT) and breathing frequency (f) during non-rapid-eye-movement (NREM) sleep induces apnea.
- To examine the neuromechanical inhibitory effects of mechanical ventilation on inspiratory motor output.
Main Methods:
- Seven healthy subjects underwent mechanical ventilation during NREM sleep.
- Tidal volume was increased to 2.1 times eupneic levels, followed by an increase in breathing frequency.
- Normocapnia was maintained throughout the experiment.
Main Results:
- Inspiratory effort was completely inhibited during and after mechanical ventilation.
- Apnea occurred immediately after cessation of ventilation, lasting significantly longer than normal expiratory durations.
- The duration of apnea was approximately 7.1 times the eupneic expiratory duration.
Conclusions:
- Normocapnic mechanical ventilation at high VT and f during NREM sleep inhibits inspiratory motor output.
- These neuromechanical inhibitory effects likely initiate and prolong apnea.
- Findings suggest a mechanism for apnea induction during controlled ventilation in sleep.