A Study of Autonomic Modulations with Short Term Heart Rate Variability in Bronchial Asthma Patients And It’s Correlation with Pulmonary Function Tests

BACKGROUND: Asthma is a chronic inflammatory disease characterized by airway hyper-responsiveness, chronic wheezing, cough and chest tightness. Bronchial asthma is associated with positive family history hence the genetic history is predisposing factor in development of asthma. The previous studies showed that there was an imbalance favoring the parasympathetic system in the asthmatic airways. This study was done to compare the autonomic modulation between asthmatic patients and normal subjects based on short term heart rate variability. METHODS: This cross sectional study involved 30 asthmatic patients and 30 normal subjects in an age group of 20 to 45 years. Spiropalm digital airflow spirometry was used to assess the pulmonary functions. Neviqure digital electrocardiography recorder was used to study 5 minutes HRV and Finland software was used for analysis of HRV. Data was analyzed by SPSS software using independent student t test, Chi square test and Pearson correlation analysis. RESULTS: The time domains measures SDNN, RMSSD, NN50, and pNN50% are significantly decreased in asthmatics compared to the normal subjects. The frequency domain measures VLF and LF are decreased while HF is increased significantly in asthmatic patients. The Chi square test between bronchial asthma and positive family history shows that the person with positive family history of bronchial asthma has 45 times more chance of getting the disease. The Pearson correlation analysis shows HF has significant negative correlation with FEV1%. CONCLUSION: There is a significant increase in central vagal outflow and concomitant low sympathetic outflow in asthmatic patients. There is in an increased parasympathetic activity with increase in the severity of bronchial asthma. Low beat to beat variability is observed in asthmatics which is a predictor of cardiac mortality and morbidity. 90% of bronchial patients have positive family history