Evaluation of Hydration Status by Bioelectrical Impedance Vector Analysis in Patients with Ischemic Heart Disease Undergoing Exercise Stress Test

Our protocol aims to clinically demonstrate the utility of evaluating hydration status using biological impedance analysis in patients with ischemic heart disease, and how the hydration status can be compared with cardiopulmonary response, evaluated by exercise stress test. Recently, hydration status has been proposed as a factor linked to plasma volume, able to modify blood flow and viscosity, impacting systolic volume, heart rate, and arteriovenous oxygen difference, which are determinants of oxygen uptake. Considering the less explored fields of hydration status, balance, and cardiopulmonary response in patients with ischemic heart disease, the applications of alternative methods, like bioelectrical impedance analysis in evaluating hydration status become relevant.

According to our results, the relevance of understanding the complex role of altered hydration status related to an empiric cardiopulmonary response and physical performance could compromise disease prognosis in patients with ischemic heart disease. Demonstrating the procedure will be Pablo Zermeno-Ugalde and Alexandra Rodriguez-Guillen, Master of Science Students, and Hugo Radillo-Alba, a highly specialized cardiologist in cardio rehabilitation for my laboratory. To begin, explain the procedure to the patient, and collect information about gender, age, weight, and height.

Instruct the patient to remove any metal objects, such as watches, rings, bracelets, necklaces, shoes, and socks. Place the patient in a supine position on a stretcher bed. Ensure that arms and legs maintain an angular separation of 30 to 45 degrees, and the palms of the hands face upwards.

Clean the area using a pad soaked with 70%ethyl alcohol. To place the proximal electrodes on the hand, first place one electrode on the wrist, just between the lunate-scaphoid carpal joint and the ulna-radius joint. Then place another electrode on the middle finger, just behind the metacarpophalangeal joint.

Ensure a distance of at least five to 10 centimeters between the electrodes to avoid electrode-electrode interaction. Next place the distal electrodes on the foot, one electrode on the ankle at the joint between the internal and external malleoli and astragalus, and another electrode between the metatarsal-phalangeal joints of the third finger, while keeping the electrodes at a distance from each other. First, connect the circular outlet of the leads to the back of the device.

Attach the hand guide leads by connecting the red clip on the wrist and the black clip on the middle finger. Then connect the foot guide leads of the distal electrodes by placing the red clip on the ankle and the black clip on the third finger. Verify that all clips are placed on the edge of the skin electrode.

Turn on the device by pressing the on button. Observe the values on the screen immediately and wait 30 to 60 seconds for resistance and reactance data to stabilize. Then register the resistance and reactance values.

Turn off the device by pressing the off button. Once the measurement is done, remove the red and black clips for the hand and the foot. Then carefully remove the skin electrodes and discard them.

Download and open the BIVA software. In the RXE population sheet, select the complete line, according to the population to be evaluated. Copy the selected data and paste them into the second row.

Click the subjects sheet and fill in the information located in the second row, such as patient ID in column one. In column two, the value for Seq should always be one. In columns three and four, indicate the surname and name of the patient.

Indicate the sex of the patient in column five. Add values of resistance and reactance in columns six and seven. Insert the height of the patient in column eight and the weight in column nine.

In column 10, population code, indicate a value, between one to 13, that appears in the first column of the reference population sheet. In column 11, group code, add a value between one to 10 to select the patient to be evaluated. Next, indicate the age of the patient in column 12.

Click the complement option in the main menu and click calculate to obtain the resistance and reactance values, adjusted by height in columns 13 and 14. Then click the point graph sheet and the resistance reactance graph will be displayed. In the dialogue box named Select Groups, select the group option and click OK.Interpret the hydration status from the plot.

Before the experiment, ensure that the patient complies with the prerequisites of the test and ask the patient to wear comfortable clothing. Explain the EST protocol to the patient, and register the gender, age, weight, and height into the EST system. Next, fix a size-fit EST mask to the patient's face.

Wait for the EST equipment gas analysis elements to calibrate automatically, ensuring the environmental CO2 does not exceed 1, 200 PPM. To connect the 12-lead electrocardiographic electrodes on the patient's chest, first place four electrodes on the arms, one on the right arm over the acromion bone, one on the left arm over the acromion bone, one on the right costal margin, and one on the left costal margin. Then place six electrodes on the chest, V1 on the second intercostal space and over the right border of the sternum, V2 on the second intercostal space and the left border of the sternum.

Place V4 on the fourth intercostal space, crossing with the left midclavicular line, V3 between V2 and V4, V5 on the fifth intercostal space, at the level of the left anterior axillary line, and V6 six on the sixth intercostal space at the level of the left middle axillary line. Perform a resting spirometry by instructing the patient to inhale deeply as much as possible. Then indicate to exhale as fast and forcefully as possible, trying to maintain at least six seconds in the breath-out effort.

Evaluate the forced expiratory volume in one second and the forced vital capacity parameters provided in the EST system and choose the best values achieved by the patient. Evaluate the cardiac conditions, such as baseline electrocardiogram, heart rate, and blood pressure to ensure the patient does not present limiting factors before starting the EST, and observe the patient's gait, making sure that they do not present a walking disorder. Monitor and evaluate the EST with attention to blood pressure, heart rate, and electrocardiographic trace changes every three minutes.

Continue monitoring the perception of any symptoms and the perceived physical effort by the Borg scale. After EST is finished, monitor the patient's blood pressure, heart rate, and EKG during the recovery period. Ensure these parameters return to baseline values.

Extract and register cardiopulmonary data, such as metabolic equivalents, oxygen uptake, and heart rate oxygen pulse from the EST software. Resistance reactance graph obtained using this protocol was used to classify hydration status as euhydration, hyperhydration, and hypohydration. Representative impedance data from two patients classified their hydration status as hyperhydration and hypohydration.

EST values for these patients suggest that abnormal hydration status may induce a lower cardiopulmonary response, shown by lower values of metabolic equivalents, oxygen uptake, and heart rate oxygen pulse. Bioelectrical impedance analysis is a practical, non-invasive, and cost-effective method that can be used to estimate body composition within a clinical setting. But it has also been proposed as an alternative method to evaluate hydration status, showing advantages over other methods, such as biomarker test or isotope dilution.

Our representative results suggest that abnormal hydration status may induce a lower cardiopulmonary response, as was observed in oxygen uptake, especially when hyperhydration occurs. Although hydration status can be closely related to cardiopulmonary response in patients with ischemic heart disease, using bioelectrical impedance analysis to evaluate hydration status represent a reliable and standardized method in clinical research.