Key Points
- To derive dynamic mathematical relations describing respiratory sinus arrhythmia using computer simulation.
- Analogue computer simulation fed with a signal proportional to thorax circumference.
- Calculated heart rate changes in real time using nonlinear differential equations.
- Compared predicted heart rate changes to actual heart rates during various breathing modes.
- Close correspondence between predicted and actual heart rate changes across different individuals and breathing modes.
- Identified two separate reflexes producing biphasic heart rate transients related to respiration.
- Demonstrated that stretch receptors, not hemodynamic or central nervous factors, initiate heart rate changes.
Structured PICO
PPopulationDifferent individuals (human subjects) and an analogue computer simulation model
IInterventionAnalogue computer simulation using nonlinear differential equations fed with a signal proportional to thorax circumference
CComparatorActual heart rate changes in real time
OOutcomeCorrespondence of predicted and actual changes of heart rate
Mathematical modeling and analogue computer simulation revealed that respiratory sinus arrhythmia is driven by stretch receptors initiating two separate reflexes, rather than hemodynamic or central nervous factors.