Abstract 19770: Timely Modulation of Cardiac Output by a Pacemaker Can Stabilize Induced Periodic Breathing
Background: Periodic breathing (PB) is characterised by oscillations in end-tidal CO2 (et-CO2) that drive oscillations in ventilation, and is common in heart failure where it is associated with increased morbidity and mortality. Using cardiac pacemakers it is possible to manipulate cardiac output, generating shifts in arterial CO2 concentration and consequent ventilatory changes. We aimed to alter the magnitude of et-CO2 and ventilatory oscillations via cardiac pacemaker in a cyclic CO2 model of PB.
Methods and Results: Fourteen patients with cardiac pacemakers (5 with heart failure (EF 27.6 ±13.9) and 9 with normal systolic function) inhaled exogenous CO2 that cycled from 0 to 4.25 ± 1.8% every thirty seconds producing oscillations in ventilation and end-tidal CO2 (PB). When cardiac output was oscillated from low to high every thirty seconds to coincide with peak ventilation, the degree of induced oscillation in et-CO2 was reduced by 43% (sd/mean et-CO2 untreated = 0.08±0.02 versus sd/mean et-CO2 treated with pacemakers = 0.05±0.02, p<0.001). By reducing the degree of oscillation in et-CO2, the degree of induced ventilatory oscillation was reduced by 55% (sd/mean ventilation untreated= 0.13±0.06 versus sd/mean treated with pacemaker= 0.09±0.05, p<0.01). Increasing cardiac output just prior to trough ventilation caused a 10% increase in the size of induced oscillations in end-tidal CO2 from sd/mean = 0.08±0.02 kPa during application of CO2 alone versus 0.09±0.02 kPa, p=0.05.
Conclusion: Oscillation of cardiac output using a cardiac pacemaker can be used to deliberately oscillate the respiratory gases and ventilation. This may be of therapeutic use in ventilatory conditions characterised by their oscillatory nature such as PB or central sleep apnoea, whereby counter-oscillating ventilation via a pacemaker may stabilise et-CO2 and ventilation.
- © 2010 by American Heart Association, Inc.