A New Echocardiographic Tool for Cardiac Output Evaluation: An Experimental Study

Area of Science:

• Cardiovascular Physiology
• Medical Imaging
• Critical Care Medicine

Background:

• Cardiac output (CO) assessment via echocardiography and thermodilution (COth) shows variable correlation.
• A novel transthoracic echocardiography (TTE) tool enables automatic calculation of subaortic velocity time index (VTIauto) and CO (COauto).

Purpose of the Study:

• To evaluate the correlation between COth and COauto in a piglet hemorrhagic shock (HS) model.
• To compare COth with CO derived from manual VTI measurements and assess VTIvaresp preload-dependency.

Main Methods:

• Eighteen piglets underwent controlled hemorrhage to a mean arterial pressure of 40 mm Hg, maintained for 30 minutes.
• CO was measured using Pulse index Contour Cardiac Output thermodilution (COth).
• Transthoracic echocardiography (TTE) was used for manual (VTIave, VTImax, VTImin) and automatic (VTIauto) measurements to calculate CO (COave, COmax, COmin, COauto).

Main Results:

• The automated TTE tool achieved a 60% success rate (122/204 measures), compared to 97% for manual methods.
• COauto demonstrated a strong correlation with COth (r=0.83, P<0.01).
• Manual TTE CO measurements showed weaker correlations with COth (r=0.54 to 0.43, P<0.01).

Conclusions:

• In an experimental HS model, the automated TTE tool (COauto) exhibits superior correlation with COth compared to manual echocardiographic CO estimations.
• This automated ultrasound technology presents a promising advancement for accurate CO monitoring in critical settings.