The intestine Is a complex structure that is involved not only in the absorption of nutrients, but also acts as a barrier between the individual and the outside world. As such, the intestine plays a pivotal role in immunosurveillance and protection from enteric pathogens. Investigating gut physiology and immunology commonly employs the intestinal loops as an experimental model.
Many of these loop models are non recovery surgical procedures that study short-term changes in the intestine. We previously created a recovery gut loop model to specifically measure long-term immunological changes in the gut of sheep following exposure to vaccines, adjuvants and viruses. A significant drawback with this method is a single window of opportunity to administer agents to the loop at the time of surgery.
Similarly, samples of both the intestinal mucosa and numeral content can only be taken at determination of the project. We have therefore modified our gut model by inserting long-term catheters into the intestine. These are instruments involved in intestinal surgery, DO'S forceps, also known as intestinal.
Clamps are important instruments that ensure the intestine is not injured during surgery. The catheters in the experiment are labeled with black marks using a permanent marker and are then sterilized. Orbital ointment is inserted inside the end of each catheter or basil is a non-antibiotic barrier ointment.
The stereo strip drape is cut with the scalpel blade. The skin and muscle are in size using electrocautery if needed. A surgical scalpel blade could be used for the same procedure, however, tissue bleeding becomes more pronounced.
A single stab incision with a scalpel blade forms a small hole allowing Metzenbaum scissors to open the peritoneum. The secum is located in the lower right quadrant of the abdomen and is used as a landmark. Dium is cranial attached to the secum, and both the ileum And seum are highlighted here.
The seum is Then placed back into the abdomen. A precut piece of silk suture is used to measure the length of the intestinal segment within which 15 centimeter long loops will be established in this surgery. The intestinal segment consists of approximately 85 centimeters of ileum.
The ends of the intestinal segment are clamped with doin forceps on the non loop side and with large Kelley forceps on the loop side of the ileum. The ium is then cut between the clamps. This is repeated on the other side.
The intestinal segment is flushed twice with 60 milliliters of sterile saline. 60 milliliters of a broad spectrum antibiotic solution is then introduced into the intestinal segment, distributed as evenly as possible throughout the length of the segment and left for 30 minutes. The incised ends of the ileum are joined in an anastomosis two stay.
Sutures aligned the ends of the ileum together and a simple continuous suture pattern. Using an absorbable two zero Vicryl suture connects the lateral side of the intestine to the other. The ileum is then flipped and the suturing is repeated on the other Side.
Five milliliters of sterile saline is injected At the anastomosis site to check for leaks.Here. The end of the needle drivers are gently passed into the ileum at the anastomosis site to ensure the lumen is large and patent. The broad spectrum antibiotic solution is gently removed from the intestinal segment.
The blunt ends Of the intestinal segment are sealed with a two layer closure. Each end of the intestinal segment is closed with a simple continuous suture pattern using absorbable two zero vicral suture, followed by an inverting suture pattern. The loops are formed by liening the intestinal segment with two zero silk sutures.
The first ligature is placed five centimeter coddly to the blunt end of the intestinal Segment. The intestinal segment is remeasured to ensure it's of sufficient length to support all loops. To create the first loop.
A silk suture ligature is placed 15 centimeters coddly to the first suture, thereby establishing the loop. It is important to note that the ends of the ligature sutures are left long as these will be used to secure the catheter to the loop wall. A small incision is made into the wall of each loop.
A yellow disposable vessel dilator enlarges the hole allowing the catheter to be introduced into the lumen Of the loop. The silicone bead on the catheter helps prevent the catheter from slipping outta the loop. A purse stringing suture pattern is used to tightly close the incision.
The Catheter is further secured to the loop wall by tying the catheter with the ligature sutures used previously To delineate the loop, the catheter is well secured and the catheterized loop is highlighted in this image. All three catheterized loops are highlighted here. Note, the loops appear pink, healthy and viable, demonstrating that the blood flow has not been compromised by the surgical procedure.
Again, the loops Appear healthy. A stab incision is placed near the original abdominal incision. Catheters are exteriorized through the incision and the catheterized loops are placed back into the abdominal cavity.
The Abdominal wall is sutured using a size three absorbable gut suture in a single interrupted pattern. The Skin is closed with an interrupted horizontal mattress suture pattern using non-absorbable two zero nylon suture. A stainless steel hollow Tube is used to tunnel catheters under the skin.
The tube is inserted near the abdominal incision and travels under the skin and exit the skin near the base of the neck and between the shoulders. This exit location is necessary to protect the catheters from subsequent damage. The catheters are inserted into the tube and pushed forward for At least 50%of the tube length.
The tube with the catheters is then pulled from the skin at the exit site. The skin incision is suture close using non-absorbable two zero nylon suture. The catheters are labeled and placed in a poach until needed.
This Image shows a sheep five days post-surgery and the animal appears bright, alert and responsive and has resumed her normal diet. In this Procedure, we were able to introduce long-term catheters into intestinal loops established within the ileum of sheep. This allows us to measure physiological and immunological changes following various treatments within these distinct intestinal compartments.
The salient features of this surgical procedure are intestinal segment establishment within the ileum removal of esta from the intestinal segment by flushing with sterile saline, introduction of broad spectrum antibiotics into the intestinal segment, anastomosis of the ileum, removal of antibiotics from the intestinal segment, blunt enclosure of the intestinal segment, termini loop establishment within the intestinal segment, catheter insertion into loops, stabilization of catheters within the loops catheter exterior. This drawing shows a schematic representation of the catheterized intestinal leap procedure described in this video. Note, the three 15 centimeter long catheterized loops, the two 15 centimeter long non catheterized interspaces established between the loops and the two five centimeter terminal segments all established within an 85 centimeter long intestinal segment of the sheep ileum.
