Key Points
- To identify the mechanisms driving the persistence of respiratory sinus arrhythmia during central apnea.
- Monitored instantaneous heart rate in awake dogs (N=5) during baseline mechanical ventilation and during central apneas induced by stopping ventilation.
- Fitted fundamental and first-harmonic sine waves to heart rate data across 10 control ventilator cycles and during subsequent apneic cycles.
- Control ventilator cycles demonstrated significant coupling with heart rate variability, showing a mean curve fit r² of 0.57 ± 0.07.
- Ventilator-linked respiratory sinus arrhythmia persisted after stopping ventilation, with goodness-of-fit decreasing significantly only by the third phantom cycle (P < 0.02).
- Heart rate variability reappeared toward the end of central apnea, displaying characteristic respiratory sinus arrhythmia periodicity and rhythm profile in 81% of cases.
Structured PICO
IInterventionCentral apneas produced by cessation of mechanical ventilation
CComparatorConstant mechanical ventilation
OOutcomeHeart rate variability and persistence of respiratory sinus arrhythmia (RSA)surrogate
The persistence of ventilator-linked respiratory sinus arrhythmia at the onset of central apnea supports the concept of a 'memory' in the respiratory system.