Firing patterns of muscle sympathetic neurons during short-term use of continuous positive airway pressure in healthy subjects and in chronic heart failure patients.

The current study tested the hypothesis that modification in central hemodynamics during short-term continuous positive airway pressure (CPAP) application was accompanied by altered firing patterns of sympathetic nerve activity in CHF patients and healthy subjects. Muscle sympathetic nerve activity (MSNA), hemodynamic and ventilatory parameters were obtained from 8 healthy middle aged subjects and 7 CHF patients. Action potentials (APs) were extracted from MSNA neurograms, quantified as AP frequency and classified into different sized clusters. While on CPAP at 10cm H2O, multi-unit MSNA, AP frequency and mean burst area/min increased in healthy middle aged subjects (p<0.05) whereas CPAP had no effect on these variables in CHF patients. In conclusion, the impact of CPAP on central hemodynamics in healthy individuals elicited a moderate activation of sympathetic neurons through increased AP firing frequency, whereas in CHF patients both hemodynamics and MSNA remained unaltered.