volume administration and hemodynamic assessment in adult porcine and piglet models

Investigating Physiological Responses to Acute Volume Overload in Porcine Models

Acute volume overload, a condition characterized by an abrupt and excessive increase in body fluid volume, is a critical medical concern that warrants comprehensive study1. It is often associated with aggressive and/or inappropriate fluid resuscitation, blood transfusion, and comorbidities such as heart failure and renal failure. It can lead to severe morbidity and an increased likelihood of mortality1,2,3. Despite its clinical significance, the pathophysiology of acute volume overload remains poorly understood3,4. Furthermore, the lack of specific diagnostic criteria and effective monitoring strategies further underscores the need for rigorous scientific investigation. Studying acute volume overload is not only crucial for improving patient outcomes but also for advancing our understanding of human physiology. It provides a unique opportunity to explore the body&#39;s fluid homeostasis mechanisms and their responses to extreme stress1. Studies investigating goal-directed fluid therapy (GDFT) to prevent liberal fluid resuscitation and promote a more goal-directed resuscitation approach have demonstrated improved morbidity and mortality in perioperative settings and in sepsis1,3,4. These studies used a variety of devices to monitor the volume state, including central venous catheters with central venous pressure measurements, ScVO2, arterial line lactate measurements, stroke volume/cardiac output measurements through transesophageal Doppler, lithium dilution cardiac output, arterial pulse contour analysis, thoracic electrical bioimpedance, and transpulmonary thermodilution1,3,4,5. The multiple approaches utilized to assess volume status, each with limitations in accuracy and usability, suggest that there is room for significant improvement in GDFT by enhancing intravascular volume assessment3,4.
Porcine models have emerged as particularly valuable tools in the study of human cardiovascular physiology6. The anatomical and physiological similarities between porcine and human cardiovascular systems, such as heart size, coronary anatomy, and hemodynamic parameters, make pigs ideal models for translational research6. Furthermore, pigs exhibit a comparable response to volume overload as humans, making them excellent models for studying the pathophysiology of acute volume overload and the effectiveness of various therapeutic interventions7,8. The use of porcine models also allows for the collection of high-quality, detailed data points, such as real-time hemodynamic measurements and tissue samples, which are often unattainable in human studies7. This superiority of data points provides a more comprehensive understanding of acute volume overload, which could ultimately contribute to the development of more effective monitoring and prevention strategies.
The use of piglet models in studying acute volume overload is of paramount importance, particularly given the scarcity of pediatric research in this field. Piglets, with their physiological and developmental similarities to human infants, provide an invaluable model, like their adult counterparts, for understanding the pediatric population9,10,11. Despite the high incidence of volume overload conditions in pediatric patients, such as those related to congenital heart diseases or intensive care interventions, research in this area has been markedly limited, especially when it comes to animal models that accurately represent human infants5,12,13. Utilizing piglet models can help bridge this gap, offering insight into the pediatric-specific pathophysiology of acute volume overload and the efficacy of potential therapeutic strategies7,11.
This manuscript describes a method of using a continuous infusion of crystalloid solution directly into the external jugular vein of both adult and pediatric pigs to induce acute volume overload and to study the hemodynamic effects of such volume changes on common peripheral and central data points used in volume status monitoring. This outlined method should serve as a valuable tool to help future scientists investigate the underlying pathophysiological mechanisms of acute volume overload and evaluate potential superior monitoring modalities and innovations.

Author Spotlight: Exploring Venous Waveforms in Porcine Models to Tackle Volume Overload in Medicine

Adult and Pediatric Porcine Model of Acute Volume Overload

Our team's translational research is in how vascular waveforms, specifically the low-frequency venous waveform, change in various volume and respiratory states. We are trying to understand better and improve volume status monitoring. Our research has revealed that the proper analysis of the fundamental frequency and harmonics of the pulse rate, we can sensibly monitor volume status.This novel discovery brings excitement that we may be able to achieve better volume status monitoring in a non-invasive way. Given the novel nature of our research, obtaining venous waveforms in extreme human conditions can be a big challenge. That is why porcine models such as this one are so important to what we do and what we hope to achieve.The significant finding of our research is that waveforms from the venous side, a traditionally ignored field, hold a vast amount of information, specifically the low-frequency spectrum, which is very sensitive to volume status changes. This discovery has given hope that volume monitoring in humans can be improved upon in a non-invasive way. Volume overload is a massive problem in medicine.Little research is being done on how to properly monitor against it. This protocol establishes a reproducible porcine model that can aid future scientists work to tackle this problem.

Volume Administration and Hemodynamic Assessment in Adult Porcine and Piglet Models

After achieving euvolemia on an anesthetized cannulated adult pig, infuse warm Plasma-Lyte crystalloid solution at a rate of 100 milliliters per minute. Confirm the recording of hemodynamic endpoints, such as heart rate, fraction of oxygen saturated hemoglobin, respiratory rate, end-tidal carbon dioxide, CVP, SBP, DBP, MAP, pulse pressure variability or PPV, SPAP, DPAP, and MPAP. Next, measure cardiac output or CO and PCWP after every 500 milliliters of Plasma-Lyte administration until a 15%CO decrease from the previous measurement exists.After total volume administration, perform an arterial blood gas analysis to obtain the partial arterial oxygen pressure, pH, lactate, and base excess of the pig. In the adult pig model, heart rate and MAP displayed a linear relationship during forced hypervolemia, but did not demonstrate statistical significance. In comparison, the CVP, CO, and PCWP showed both linearity and statistical significance.Moreover, the PPV demonstrated a moderate inverse correlation and statistical significance. MAP showed statistical significance, but with an inverse relationship to volume, suggesting volume administration decreased MAP in piglets. No other hemodynamic variable, such as heart rate or PPV demonstrated a linear regression to volume administration or any statistically significant relationship.

volume-administration-hemodynamic-assessment-adult-porcine-piglet

Research

JoVE Journal

Medicine

42 visualizações. Depois de atingir a euvolemia em um porco adulto canulado anestesiado, infundir solução cristalóide Plasma-Lyte quente a uma taxa de 100 mililitros por minuto. Confirme o registro de desfechos hemodinâmicos, como frequência cardíaca, fração de hemoglobina saturada de oxigênio, frequência respiratória, dióxido de carbono expirado, CVP, PAS, PAD, MAP, variabilidade da pressão de pulso ou PPV, SPAP, DPAP e MPAP. Em seguida, meça o débito cardíaco...

Vídeo: Administração de Volume e Avaliação Hemodinâmica em Modelos Adultos de Suínos e Leitões

This protocol describes an acute volume overload porcine model for adult Yorkshire pigs and piglets. Both swine ages undergo general anesthesia, endotracheal intubation, and mechanical ventilation. A central venous catheter and an arterial catheter are placed via surgical cutdown in the external jugular vein and carotid artery, respectively. A pulmonary artery catheter is placed through an introducer sheath of the central venous catheter. PlasmaLyte crystalloid solution is then administered at a rate of 100 mL/min in adult pigs and at 20 mL/kg boluses over 10 min in piglets. Hypervolemia is achieved either at 15% decrease in cardiac output or at 5 L in adult pigs and at 500 mL in piglets. Hemodynamic data, such as heart rate, respiratory rate, end-tidal carbon dioxide, fraction of oxygen-saturated hemoglobin, arterial blood pressure, central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, partial arterial oxygen pressure, lactate, pH, base excess, and pulmonary artery fraction of oxygen-saturated hemoglobin, are monitored during experimentation. Preliminary data observed with this model has demonstrated statistically significant changes and strong linear regressions between central hemodynamic parameters and acute volume overload in adult pigs. Only pulmonary capillary wedge pressure demonstrated both a linear regression and a statistical significance to acute volume overload in piglets. These models can aid scientists in the discovery of age-appropriate therapeutic and monitoring strategies to understand and prevent acute volume overload.

The protocol here shows how continuous administration of crystalloids into the central veins of a euvolemic pig/piglet allows for the appropriate investigation of the physiological effects of acute volume overload.

This protocol describes an acute volume overload porcine model for adult Yorkshire pigs and piglets. Both swine ages undergo general anesthesia, ...

Cannulation and Hemodynamic Monitoring Device Placement in Adult and Piglet Porcine Models

To begin, disinfect the entire anterior neck of an adult anesthetized pig with 2%chlorhexidine scrub, followed by a spray of 5%povidone iodine. Make right-sided vertical incisions immediately lateral to the trachea and extend the incision with monopolar cautery to expose the right external jugular, or EJ, and internal jugular, or IJ veins and internal carotid artery. Employ Kelly tissue scissors and Lahey retractors or tissue forceps to dissect the strap muscles and tract as needed.Expose the bilateral EJ, IJ, and carotid artery. Using a Seldinger technique, place a 4-French arterial line in the right carotid artery, or CA, for invasive blood pressure monitoring. Next place an 8.5 French cannula into the right EJ or IJ.Using blade number 23, make left side vertical incisions immediately lateral to the trachea to expose the left EJ and IJ veins and left carotid artery.Using Kelly tissue scissors and Lahey retractors or tissue forceps dissect the strap muscles and tract as needed. Expose the left EJ, IJ, and carotid artery. Next, cannulate the left EJ or IJ with a 14-French cannula and connect it to a dedicated roller pump tubing primed with Plasma-Lyte solution.Once cannulated, place a 7-French pulmonary artery catheter, or PAC, through the introducer of the right EJ.Monitor the heart rate using telemetry leads. Now connect a pressure transducer attached to a blood pressure amplifier to the CA catheter to monitor the systolic blood pressure, or SBP, diastolic blood pressure, or DBP, and mean arterial pressure, or MAP. Attach a pressure transducer connected to a blood pressure amplifier to the appropriate PAC ports.Monitor the mean pulmonary artery pressure, or MPAP, systolic pulmonary artery pressure, or SPAP, diastolic pulmonary artery pressure, or DPAP, and central venous pressure, or CVP, on the blood pressure amplifier. Administer Plasma-Lyte through the left EJ at approximately 100 milliliters per minute to obtain a starting pulmonary capillary wedge pressure or PCWP, of 8 to 10 millimeters of mercury before the initiation of acute volume overload.