HFSA ePoster Library

Background:. Assessment of cardiovascular hemodynamics during exercise enables unique clinical insight into physiopathology. However, there are challenges performing more invasive measures in many clinical settings and thus several non-invasive measures have emerged such as: breathing soluble gases, bioimpedance, thoracic bioreactance, modeling of arterial pressure wave forms and transthoracic echocardiography. Another type of noninvasive technology is based on Systolic Timing Intervals (PEP/LVEP) and captures signals from a combination of a single lead ECG and 2 standard pulse oximeters, one placed on the head and the other, finger (FloWave®, Cardiac Profiles, Inc., Franklin, TN). The combination and configuration enable direct measures of Pre-Ejection Period, Left Ventricular Ejection Period (Systolic Timing Intervals), Diastolic Filling Time, Central and Peripheral Pulse Transit Time, and Pulse Wave Velocity; with subsequent calculation of Stroke Volume, Cardiac Output and Ejection Fraction.
Purpose: To determine whether the Systolic Timing Interval (STICO) method of quantifying Cardiac Output and Stroke Volume (originally designed for resting measures) are comparable to those obtained using a validated soluble gas (OpCircCO) method or calculation based on VO₂ (VO₂CO) during exercise.
Methods: For the present study, 14 healthy subjects (male: n=12, female: n= 2; age=36±12yrs; Ht=177.4±7.8cm; Wt=80.1±13.2kg; BMI=25.5±3.9kg/m²) performed incremental exercise on a recumbent cycle ergometer (Lode Corival, Groningen, Netherlands). Workloads (WL) consisted of 5 stages (0, 40, 80, 120, 160W) with the wattage increased every 5min. At rest and during exercise, CO was obtained via the STICO method using a standard GE/Marquette soft tip finger oximeter, standard Masimo E1 ear oximeter and a single lead ECG continuously while the OpenCircCO and VO₂CO measures were obtained the last minute of each workload.
Results: Out of 14 subjects, 3 subjects stopped exercise at the end of 80W, 1 stopped at the end of 120W and 9 completed all exercise stages. At the highest WL, subjects reached a VO₂ of 1.96±0.48 L/min and a HR of 140±22 bpm. For STICO, OpCircCO and VO₂CO, subjects reached CO values of 13.52±2.86, 15.05±1.85 and 15.51±.1.65 L/min, respectively and a stroke volume of 91.44±20.25, 102.60±21.83 and 107.21±17.82 ml, respectively (p>0.05). When we performed regression with all subjects and all measures of CO at all WL, between STICO and OpenCircCO, there was a good relationship (r=0.748, p<0.001) with a Bland and Altman agreement analysis demonstrating a -1.41 difference (95% CI: -6.4-3.5). Between STICO and VO₂CO, we observed an r=0.879 (p<0.001) and a Bland and Altman agreement analysis with a -0.94 difference (95% CI: -4.5-2.7).
Conclusions: A novel exploitation of cardiac hemodynamics using systolic timing intervals may allow relatively good assessment of cardiac output during exercise in healthy adults.