Cadaveric Porcine Spines as a Model for the Human Epidural Space.

Most patients who undergo epidural anesthesia are pregnant and thus a protected population, which has limited investigations of the human epidural space. Among the several species studied as models for the human spine, the porcine spine has been used as a model for spine instrumentation. Although the spread of colored dye within the porcine epidural space has been investigated, no model has demonstrated in situ spread by using radiopaque contrast dye. To this end, we here used 10 Yorkshire swine cadavers through an approved tissue sharing agreement. Epidural catheters were placed by using a landmark-based loss-of-resistance technique; placement was confirmed through radiography. The catheters were connected to epidural infusion pumps to ensure consistent dosing, 2-mL boluses of contrast dye were injected into the space, and radiographs were taken and recorded after each bolus. The total spread of the contrast dye was analyzed. We demonstrated consistent and reliable spread of fluid in the epidural space among the animals used, with low variability between animals of different weights. Our results support the use of the epidural space of cadaveric swine as a model for the human epidural space. Furthermore, the technique for epidural administration by using the landmark-based loss-of-resistance demonstrated in this model was validated, thus supporting future investigations of medication delivery into the epidural space.

A Pilot Study of Four Intraosseous Blood Transfusion Strategies.

BACKGROUND: Intraosseous (IO) access is used by military first responders administering fluids, blood, and medications. Current IO transfusion strategies include gravity, pressure bags, rapid transfusion devices, and manual push-pull through a three-way stopcock. In a swine model of hemorrhagic shock, we compared flow rates among four different IO blood transfusion strategies. METHODS: Nine Yorkshire swine were placed under general anesthesia. We removed 20 to 25mL/kg of each animal's estimated blood volume using flow of gravity. IO access was obtained in the proximal humerus. We then autologously infused 10 to 15mL/kg of the animal's estimated blood volume through one of four randomly assigned treatment arms. RESULTS: The average weight of the swine was 77.3kg (interquartile range, 72.7kg-88.8kg). Infusion rates were as follows: gravity, 5mL/min; Belmont rapid infuser, 31mL/min; single-site pressure bag, 78mL/min; double-site pressure bag, 103mL/min; and push-pull technique, 109mL/min. No pulmonary arterial fat emboli were noted. CONCLUSION: The optimal IO transfusion strategy for injured Servicemembers appears to be single-site transfusion with a 10mL to 20mL flush of normal saline, followed immediately by transfusion under a pressure bag. Further study, powered to detect differences in flow rate and clinical complications. is required.

Antibody production in rabbits administered Freund's complete adjuvant and carprofen concurrently.

Freund's complete adjuvant (FCA) is a commonly used immunopotentiator that can boost polyclonal antibody production in animal models such as rabbits, but FCA is also known to cause inflammation and pain. It is important to balance the welfare of animals with the goal of efficiently producing antibodies, but little is known about how common treatments for pain and inflammation, such as non-steroidal anti-inflammatory drugs (NSAIDs), affect the production of polyclonal antibodies. The purpose of this study was to measure polyclonal antibody production in rabbits that were administered FCA either with or without a concurrent treatment of a NSAID, carprofen. Rabbits were divided into two groups and were administered identical treatments of an antigen with adjuvant, and the treatment group also received carprofen injections at different stages of the study. Carprofen treatment did not significantly affect polyclonal antibody production, which suggests that carprofen and other NSAIDs can be used alongside FCA in rabbits to achieve desired levels of antibody production while minimizing pain and distress associated with the use of FCA.