A Study of Cardiac Parameters using Impedance Plethysmography (IPG) in Healthy Volunteers

Impedance plethysmography is non – invasive technique to measure blood flow in any part of the body like heart (Impedance Cardiography), arteries or veins. As only heart rate and blood pressure is not sufficient to access a person’s hemodynamic status, cardiac output and other cardiac parameters measured by this simple technique will help further to access heart’s functional status with avoidance of all complications associated with previous catheter related invasive techniques. Main aim of the study was to measure cardiac parameters noninvasively in healthy volunteers of all age groups of both sex using impedance cardiography and then compare them between different age groups. Study was done in 5 age groups (16 – 25 yrs, 26 – 35 yrs, 36 – 45 yrs, 46 – 55 yrs and > 55 yrs) and in total 400 subjects. Each group was of 80 healthy volunteers of either sex. It was carried out on Nivomon Series computerized software in Bhavnagar region. Cardiac parameters measured were SV – Stroke Volume, SI - Stroke Volume Index, CO – Cardiac Output, CI – Cardiac Index, LVET – Left Ventricular Ejection Time, SVR – Systemic Vascular Resistance and SVRI - Systemic Vascular Resistance Index. Normative baseline laboratory data obtained from 400 healthy volunteers were as: SV - 65.15 ± 13.18 ml / beat, SI - 38.16 ± 7.64 ml / beat / m², CO - 4.94 ± 1.09 lit. / min, CI - 2.91 ± 0.51 lit. / min / m², LVET - 357.35 ± 46.32 msecs, SVR - 1500.95 ± 305.45 dyne•sec / cm5 and SVRI - 2507.75 ± 441.63 dyne•sec / cm5 / m². These values were found to be consistent with normal reference range. So now these baseline normative data will be helpful in many future research studies related to heart function in Bhavnagar region for this novel instrument. Significant differences were found for all parameters between different age groups. LVET and SVR were found on higher side in later ages due to atherosclerosis and other age related changes. Positive correlation was found between BSA and SV, CO. Negative was the case for BSA and SVR. In case of gender difference in last age group, Zo was found to be extremely higher in females due to higher fat proportion. Also SV was significantly lower and SVR was higher in females but no difference was there for CO and LVET. Overall, cardiac parameters were measured with this impedance technique accurately. Although there were some limitations, this technique was found to be simple, cheap and effective. If this technique is further validated and established, than it can be used widely for many physiological and pharmacological studies on human heart. Further, it can be used in ICU, in clinical set up for many heart disease patients, and also in CCU or in emergency trauma centres for other critically ill patients.