Assessment Of Examination Stress And HRV in Adolescents.

Objective.The present study was designed to define and evaluate examination stress among ,adolescents in the age group of 12–18 years in relation to heart rate variability (HRV), an index of sympathovagal interplay, one of the sensitive neurophysiological axes to be influenced initially, when an individual is exposed to any stressor.Methods. Hari’s stress inventory for students was used to qualify examination stress was collected on 69 healthy school students, free from any acute or chronic ailment, one month and seven days before the start of final examinations along with acquisition of short – term HRV to profile the sympathovagal interplay, a sensitive index of both physical and mental stress. Results. The stress inventory depicted that the sample population was under an enhanced mental stress 7 days before the examination as compared to that observed 1 month before the ratios of HRV 1month and 7 days before the final examination. Significant appreciable difference could also be appreciated in the values of SDANN in time domain and amplitude of the waveforms in HF, LF on the frequency domain of HRV.Conclusion. An enhanced sympathetic outflow as discerned through increase in LF/HF ratio and LF power with a concomitant decrease in HF power along with significant decrease in SDANN values profiling a decreased vagal outflow of the student population denotes an autonomic neurophysiological status that needs a specialist attention in terms of proper and adequate guidance and counselling.

Spectral analysis of heart rate variability in bronchial asthma patients.

The study was carried in the Departments of Physiology and Medicine at S.M.S. Medical College, Jaipur. Thirty patients of bronchial asthma, aged 20-30 years attending outpatient clinics of S.M.S. Hospital and thirty healthy volunteers were recruited in the present study for spectral analysis of Heart Rate Variability (HRV) using impedance peripheral pulse in the right forearm. Two spectral components were recorded namely high frequency (HF) component (0.15–0.4 Hz), an indicator of vagal efferent activity and low frequency (LF) component (0.04–0.15 Hz), replicator of composite sympatho-vagal interplay. These components were analyzed as LF nu (Low Frequency normalized unit), HF nu (High Frequency normalized unit) and LF/HF ratio. Low frequency component in absolute units of the asthmatic patients differed insignificantly (P>0.05) from LF of the subjects, whereas the same calculated as normalized units was found to be significantly low in the patient group (P<0.01), as compared to that of the control group. The High Frequency (in absolute units) index of HRV was significantly high in asthmatics (P<0.01) as compared to the HF (absolute units) of controls. Similar trend was observed in the normalized units of HF (P<0.01). LF/HF ratio was not significantly different in patient and control groups (P>0.05). It was concluded that a significantly raised central vagal outflow and a concomitant significantly low central sympathetic efferent could be appreciated in asymptomatic asthmatic patients as compared to that in the control group. This deranged sympathovagal interplay with parasympathetic dominance could be a plausible pathophysiological mechanism leading to airway obstruction, the hallmark of bronchial asthma.