Abstract
Background: This study assessed the responses of Blood Pressure (BP) and Heart Rate (HR) to change of posture, Sustained Handgrip (SH),deep breathing(DB) and Valsalva manoeuvre (VM) in order to determining the normal limits and pattern of Autonomic Cardiovascular Indices (ACI) among healthy young adults. Methods: Two hundred and four volunteer (98 men and 106 women) aged 18- 40 years (mean, 22.45 ± 4.86 years) participated in the study. After excluding systemic diseases by clinical evaluation, each participant performed five non-invasive cardiac autonomic function tests in series. Differences in supine and erect systolic BPs were assessed by sphygmomanometry, diastolic BP responses to SH were determined by dynamometry while HR variability in response to VM, DB and postural change were assessed by continuous electrocardiogram. Normal limits of ACI were determined at 5th and 95th percentiles. Results: The mean (normal limits) for SBP response to change of posture (mmHg); DBP response to sustained handgrip (mmHg); Valsalva ratio; heart rate response to deep breathing (beats per minute); PTI; tachycardia ratio; bradycardia ratio and RHR(beats per minute) respectively were: -4.26 ± 9.17(-19.00-11.00); 20.14 ± 17.35(0.00-54.00); 1.55 ± 0.40(1.10-2.40); 31.82 ± 10.81(13.0048.75); 1.41 ± 0.31(1.08-1.84); 0.80 ± 0.12(0.58-1.00); 1.21 ± 0.20(0.95-1.60) and 70.61 ± 12.23(53.00-93.00). During Valsalva maneouvre, Post-Strain Pause (PSP) which ranged from 1.2812.76s was observed in 14(6.86%) of the participants. PSP occurred more frequently in women (9.43%) than men (4.08%). No significant gender difference in the duration of post-strain pause (t=-1.628, p=0.105). In majority of the participants (67.6%), an elevation of SBP occurred within 2minutes of rising from supine to erect position. Immediate Post-Standing Pause (IPSP) occurred among 139 (68.14%) participants. Conclusion: Non-invasive assessment of cardiac autonomic function is feasible in Nigeria. Increase rather than decrease in systolic blood pressure response occurred more frequently upon a change from supine to erect posture. IPSP was a unique pattern of cardiac autonomic functions in study population.
Highlights
This study assessed the responses of Blood Pressure (BP) and Heart Rate (HR) to change of posture, Sustained Handgrip (SH),deep breathing(DB) and Valsalva manoeuvre (VM) in order to determining the normal limits and pattern of Autonomic Cardiovascular Indices (ACI) among healthy young adults
The study group consisted of 204 young adults (98 men, 106 women) between the ages of 18 and 40 years
The systolic blood pressure response to postural change had been classified into two categories; increase SBP response and decrease SBP response
Summary
This study assessed the responses of Blood Pressure (BP) and Heart Rate (HR) to change of posture, Sustained Handgrip (SH),deep breathing(DB) and Valsalva manoeuvre (VM) in order to determining the normal limits and pattern of Autonomic Cardiovascular Indices (ACI) among healthy young adults. The autonomic nervous system (ANS) is one of the main divisions of the nervous system. It is responsible for the regulation of visceral functions and maintenance of homeostasis of the internal milieu [1,2,3]. An abnormality of cardiac autonomic nervous system is referred to as cardiac autonomic dysfunction (CAD) or neuropathy (CAN) It is a serious complication of many diseases. CAD carries approximately five-fold risk of mortality in patient with diseases affecting the cardiac autonomic nervous system especially diabetes mellitus [5,6,7,8,9,10,11]. CAD may occur in a diversity of diseases such as diabetes mellitus, alcoholism, Parkinsonism, malnutrition, vitamin deficiencies, heavy metal poisoning, rheumatic arthritis and kidney disorders [12,13]
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