Catheterization of the Carotid Artery and Jugular Vein to Perform Hemodynamic Measures, Infusions and Blood Sampling in a Conscious Rat Model

The overall goal of this procedure is to present a technique for implanting catheters into the carotid artery and the common jugular vein To measure hemodynamics, provide fluids, and perform blood sampling in an ambulatory rat. This is accomplished by first putting a catheter into the right jugular vein and then putting a catheter into the left carotid artery. The two catheters are then tunneled under the skin and externalized between the shoulder blades.

Ultimately, the catheters are attached to a tether and swivel setup that allows a rat free movement. While the experimenter can measure pressures, infuse fluids, and take blood samples. Visual demonstration of this method is critical as several of the steps are difficult to learn.

Catheter patency is dependent on precise placement, which is very technique oriented, increasing the importance of seeing how it's done Prior to surgery. All instruments and catheters must be gas sterilized. Check the catheters for leaks using heparinized glycerol by filling each catheter and plugging it with a metal stopper.

Clean the workstation and all surfaces with 70%ethanol. Then cover the operating table with a sterile drape and put an additional drape on the instrument tray. Once the rat is unconscious, shave its neck on the anterior and posterior sides.

Following shaving, apply lubricant to the rat's eyes. Now transfer the animal to the surgical site. Place it over a warm pad to maintain its body temperature.

Then attach a nose cone and deliver 3.5%isof fluorine. Complete the preparations by cleaning the skin with alternating scrubs of Betadine and 70%ethanol. Confirm the rat is unresponsive using a toe pinch.

Then start the surgery first using scissors, make a 0.5 centimeter midline skin incision between the scape. Next, flip the rat to the dorsal position. Then gently restrain its legs to either side with rubber bands and put some rolled up gauze under its neck to improve the surgical site exposure.

Now use a scalpel to make a two centimeter ventral cervical skin incision to the right of the next midline and at the level of the clavicle to catheterize the right jugular vein. First, use a hemostat to bluntly dissect the right jugular vein. Separate out the salivary and lymphatic tissues and isolate a five millimeter section of the jugular.

Then using four zero silk suture, place a loose tie on both the cranial and coddle ends of the jugular vein to maximize its exposure. Next, with microsurgical scissors, make an incision for the catheter lengthwise between the ligatures. Then tie the cranial ligature around the vessel following the incision.

Use the micros dissecting hook and forceps to insert the catheter into the jugular towards the heart until all of the PU three F segment is in the vessel. Then tighten the ligatures at the cranial and coddle ends to secure the catheter. Now catheterize the left carotid artery.

First, use a hemostat to bluntly dissect the oma muscle and expose a five millimeter section of the left carotid artery. Make sure that the vagus nerve is completely separated from the artery. Do not shred or break the nerve.

Next place four zero silk suture with a loose snot on the coddle end of the vessel. Then tie off the cranial end of the vessel and critically, place a bulldog clamp coddly above the suture to stop the blood flow following the incision. Using microsurgical scissors, make a lengthwise incision between the ligatures to pass the catheter.

Then insert the arterial catheter towards the heart using a micro dissecting hook and forceps. Now without locking it, use a small needle holder to tightly hold the part of the catheter in the vessel. Then remove the bulldog clamp.

Then using the forceps, advance the catheter while slowly loosening the needle holder fit the entire PU two F segment into the carotid. This step will require practice to minimize blood loss. Now tighten the coddle ligature around the catheter, but not so tight as to occlude.

To finish, use a straight hemostat to subcutaneously tunnel, a five centimeter tube behind the ear and through the incision between the scape. Then exteriorize the catheters through the tube and remove the tube. Now close the ventricle incision with three stainless steel wound clips while securing the exteriorized catheters.

Then close the dorsal incision using four zero silk suture. Now terminate the anesthesia and let the rat recover in a lateral decubitus position on cellulose bedding postoperatively. Observe the rats every two hours for at least four hours or until they show no signs of pain.

Then check the rats daily. If a rat needs pain, provide ketoprofen every 12 hours in preparation. Pre flush the coil wrapped long catheters with heparin saline.

These catheters are connected to the top of a shoebox cage using a swivel and attach the externalized catheters on the rat, anesthetize a rat as before and provide anesthetic via a nose cone to ensure the rat tolerates the procedure. Now using rubber capped hemostats clamp, the arterial and venous catheters just below the metal plug pins, the rubber is to avoid damaging the catheters. Then use a pair of forceps to remove the metal pin at the end of the catheter and with a blunted needle, attach a one milliliter syringe filled with heparin saline.

In turn, remove the hemostats and withdraw 0.1 milliliters to check that the catheters are patent. Now rec clamp the catheters, remove the needle and attach the longer catheters. Then connect the long catheters to the transducers.

Once completed, let the rat recover in the sternal position on cellulose bedding. To maintain the arterial catheter's patency, flush the lines with 0.05 milliliters of heparin saline every hour coinciding with regular assessments of the animal To take a blood sample. First, attach an empty syringe to the stop cock connected to the arterial catheter.

Withdraw a 0.6 milliliter inline flush. Then attach a sample syringe to the line and take the blood sample. Next, return the inline flush volume and follow it with 0.7 milliliters of heparinized saline.

Meanwhile, MAP and heart rates are recorded in the software and drugs can be administered using an automated system attached to the venous catheter, which maintains physiologic conditions using realtime pressure Data. Changes in vascular pressure are transmitted through the fluid field catheters and converted into electrical signals. The data is represented as hemodynamic wave forms.

Without vascular access, these measurements could not be made. Realtime data streaming allows the experimenter to detect and analyze changes on a beat to beat basis. Compressing the timescale of the waveforms can be done to quantify changes that occur over long time periods.

As expected, this data will correlate to changes in the vasopressor infusion rate Once mastered, this technique can be done in less than 15 minutes if it is performed properly.