Thermodilution, pressure-volume loop catheters, and contrast ventriculography are reliable and accurate methods for determining cardiac physiology such as stroke volume and cardiac output in a laboratory setting in swine.
Swine are frequently used in medical research given their similar cardiac physiology to that of humans. Measuring cardiac parameters such as stroke volume and cardiac output are essential in this type of research. Contrast ventriculography, thermodilution, and pressure-volume loop (PV-loop) catheters can be used to accurately obtain cardiac performance data depending on which resources and expertise are available. For this study,five Yorkshire swine were anesthetized and intubated. Central venous and arterial access was obtained to place the necessary measurement instruments.A temperature probe was placed in the aortic root. A cold saline bolus was delivered to the right atrium and temperature deflection curve was recorded. Integration of the area under the curve allowed for the calculation of the current cardiac output.A pigtail catheter was percutaneously placed in the left ventricle and 30 mL of iodinated contrast was power injected over 2 seconds. Digital subtraction angiography images were uploaded to volumetric analysis software to calculate the stroke volume and cardiac output. A pressure volume-loop catheter was placed into the left ventricle (LV) and provided continuous pressure and volume data of the LV, which allowed the calculation of both stroke volume and cardiac output.All three methods demonstrated good correlation with each other. The PV-loop catheter and thermodilution exhibited the best correlation with a 3% error and a Pearson coefficient of 0.99, with 95% CI=0.97 to 1.1, (p=0.002). The PV-loop catheter against ventriculography also showed good correlation with a 6% error and a Pearson coefficient of 0.95, 95% CI=0.96 to 1.1 (p=0.01). Finally, thermodilution against ventriculography had a 2% error with r=0.95, 95% CI=0.93 to 1.11, (p=0.01). In conclusion, we state that the PV-loop catheter, contrast ventriculography, and thermodilution each offer certain advantages depending on the researcher’s requirements. Each method is reliable and accurate for measuring various cardiac parameters in swine such as the stroke volume and cardiac output.
Swine are frequently used in hemorrhage control and resuscitation research due to their similar physiology to humans. Integral to resuscitation research is continuous cardiac output monitoring to assess the physiological response to interventions. Several clinical systems exist such as pulmonary artery (PA) catheters and pulse contour analysis-based systems1. Additionally, echocardiography (echo), computed tomography (CT) and magnetic resonance imaging (MRI) can all be used to capture hemodynamic data. Images obtained during end-diastole and systole can be used to determine the volume of blood ejected during that cardiac cycle. While these techniques are minimally invasive, they only present data acquired at the time of imaging and do not provide continuous measures2. They are also either largely operator dependent (echo) or require advanced, expensive equipment (CT and MRI). Given different laboratories’ capabilities and resources, there are various alternative methods to measure the cardiac output optimally in each instance.
Thermodilution is a common method of measuring cardiac output in the clinical setting using a Swan-Ganz catheter3. This method can be recreated in a laboratory setting in swine to directly measure the cardiac output. Contrast ventriculography can also be utilized if the fluoroscopic capability is readily available4. Finally, pressure-volume loop catheters offer a means of directly measuring the ventricular pressure and volume on a beat-to-beat basis and can generate more nuanced data5. This method utilizes electrical admittance and Wei’s equation to measure the chamber volume. Compared to older conductance-based catheters, admittance catheters eliminate the parallel conductance phenomenon between the blood and the cardiac muscle, thereby producing more accurate measurements without requiring repeated calibration6.
The aim of this study is to validate the accuracy of these three methods against each other in terms of measuring cardiac stroke volume and output in a healthy swine model. Ultimately, each investigator can choose which approach suits their needs the best, depending on their study requirements and what resources are available to them.
This study details a standardized method of three different ways to accurately measure cardiac output in swine. Swine has analogous cardiovascular anatomy and physiology to humans and is commonly used as a model for human cardiac physiology, specifically for pre-clinical evaluations of surgical and interventional processes10. This allows swine to serve as the primary model for cardiovascular physiology, pathology, and emerging biotechnology11. In order to assess these …
The authors have nothing to disclose.
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0.9% sodium chloride injection | Hospira | 0409-4888-50 | |
7 Fr Introducer Kit | Terumo | RCFW-5.0-35 | |
Anesthesia Machine | Drager | Fabius Tiro | |
Contrast Power Injector | GEHealthcare | E8004N | |
Fluoroscope | GEHealthcare | OEC 9800 | |
Heating/Cooling T/pump | Gaymar | Tp-700 | |
Isoflurane | Baxter | 10019-360-40 | |
Jackie catheter | Terumo | 40-5023 | |
Omnipaque | GEHealthcare | 559289 | |
PowerChart | ADinstruments | ML866/P | Software |
PowerLab | ADinstruments | PL3516 | |
PV-loop catheter | Transonic | Prefer pigtail tip to straight tip | |
PV-loop module | Transonic | FFS-097-A004 | |
Surgical suture, black braided silk, 3.0 | Surgical Speciaties Corp. | ||
Thermocouple probe | ADinstruments | MLT1401 | |
Ultrasound probe | Philips | L12-4 | |
Various-sized syringes | |||
ViewPlus | Sanders Data Systems | Software |
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