300 Section - Heart rate variability as a predictor of peak cough flow in patients with subacute stroke

Long-term disabilities can stem from stroke, and respiratory issues can worsen the overall prognosis and increase the risk of death. Effective peak cough flow (PCF) has the ability to clear the airway; however, in patients with stroke, it is significantly lowered, thereby increasing the risk of aspiration pneumonia and extending the average length of hospital stay. Heart rate variability (HRV) indicates autonomic function, which is necessary for controlling the cardiovascular and respiratory systems. Autonomic dysfunction is associated with a poor stroke prognosis; however, the interaction between HRV and PCF requires further research.

 

Design:

Subjects were included if within 1 month of stroke and had 24-hour Holter monitoring and PCF measurements. The relationships between the PCF and HRV parameters were assessed using Pearson’s correlation coefficient. Stepwise multiple linear regression was used to test the hypothesis that HRV measurements could be used to estimate PCF.

Results:

Positive correlations were found between the very low frequency (VLF) HRV parameter and peak expiratory flow (PEF; r=0.694, p=0.001) as well as with the forced expiratory volume in one second (FEV-1; r=0.505, p=0.001). From multiple linear regression analysis, VLF was shown to significantly predict PEF (β=0.694, p< 0.001) and FEV-1 (β=0.467, p< 0.001). Additionally, low frequency and standard deviation of normal-to-normal intervals also predicted FEV-1 and were statistically significant (p< 0.001). These results suggest that the respiratory functions of stroke patients are likely to be associated, at least in part, with some parameters of HRV, most notably the VLF and SDNN.

Conclusion:

HRV and PCF in patients with subacute stroke are interrelated, indicating that HRV may be useful for the early diagnosis of autonomic dysfunction, improving respiratory function, and minimizing bronchopulmonary complications. Investigating the impact of HRV on autonomic dysfunction may provide useful insights into autonomic systems and their respiratory functions.