A Porcine Model of Acute Respiratory Failure with a Continuous Infusion of Oleic Acid

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 better understand the venous waveform and how the respiratory system influences them. Our research shows that analyzing the fundamental frequencies of respiratory and pulse rates to calculate the RIVA-RI ratio can help in quantitatively monitoring patients'oxygen therapy needs correlating with PA O2.This could lead to a non-invasive tool for triaging patients with acute respiratory insufficiency, worsening asthma, COPD, emphysema, or idiopathic pulmonary fibrosis.

Given the novel nature of our research, obtaining these venous waveforms in humans is a big challenge, and just not practical in a lot of instances. That is why porcine models such as this one are so important to what we would do and what we hope to achieve. The significant findings of our research is that waveforms from the venous side, a traditionally ignored field, hold a vast amount of information.

We have found that these venous signals are very sensitive to changes in both volume status and the respiratory condition. This discovery offers hope for enhancing non-invasive respiratory monitoring in humans. To begin disinfect the entire anterior neck of an anesthetized pig with a 2%chlorhexidine scrub solution, followed by a spray of 5%povidone iodine solution.

With a number 23 blade, make a vertical incision immediately lateral to the trachea on either side of the sternum to expose the right and left external jugular veins and internal carotid arteries. Next, use Kelly tissue scissors and Lahey retractors to dissect the strap muscles and tracked as needed. Expose the common carotid artery, internal jugular, and external jugular veins on both the right and left side.

Using the Seldinger technique, place an arterial line in the right carotid artery for invasive blood pressure monitoring. Monitor heart rate using telemetry leads. Connect a pressure transducer to the carotid artery catheter and monitor the systolic blood pressure, diastolic blood pressure, and mean arterial pressure.

Using the Seldinger technique, place two 8.5 French cannulas into the right and left internal jugular veins. Place two pulmonary artery catheters, one through the right 8.5 French cannula, and the other through the left 8.5 French cannula. Using an independent pressure transducer and amplifier system set up, monitor mean pulmonary artery pressure and central venous pressure.

Prepare 16%oleic acid in normal saline for infusion. Prime the oleic acid into an IV fluid line and add dimethyl sulfoxide to prevent separation. Connect it to the distal port of the left internal jugular pulmonary artery catheter.

Start the oleic acid infusion and mark the start time. Immediately after starting an infusion, adjust ventilator settings to mimic room air conditions. Monitor the heart rate, fraction of oxygen saturated hemoglobin, respiratory rate, and tidal carbon dioxide, central venous pressure, systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse pressure variability, and mean pulmonary artery pressure.

Measure the cardiac output and pulmonary capillary wedge pressure every 30 minutes over the first 60 to 90 minutes, and then every 15 minutes thereafter until the pig is sacrificed. Record peak airway pressure, plateau pressure, and partial arterial oxygen pressure.