Page 371 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Technical Aspects of Fluid Therapy 361

THROUGH-THE-NEEDLE If the animal has abundant loose skin on the neck,
INTERMEDIATE-STYLE CATHETERS elevating the nose tenses the skin and facilitates iden-
Materials Needed for Placement in the tification of the vein. It is helpful to experiment with
External Jugular Vein different head and nose positions until the optimal
position is found. If you are right handed, occlude
1. Appropriate catheter: the ideal length will result in
the vein at the thoracic inlet with the thumb of the left
the tip of the catheter within the anterior vena cava
hand, and use your left index finger to palpate the
just anterior to the right atrium.
vein. The patient’s right external jugular vein is pre-
2. Two clean latex examination gloves ferred because it may be easier to advance the catheter
3. 00 or 000 monofilament nylon, needle holders, into the cranial vena cava from this side. The puncture
suture scissors site should be 1 to 2 cm (about 0.5 to 0.75 inch)
4. 22-gauge needle lateral to the vein and in the cranial half of the neck.
5. One roll each 1 inch (2.54 cm) waterproof white tape 4. As with over-the-needle catheters, a small skin inci-
and porous white tape
sion facilitates insertion of large-gauge catheters
6. One roll each of appropriately sized stretch gauze,
and eases access through tough skin (Figure 15-4,
cast padding, and adhesive (Elastikon, Johnson &
B). The techniques for direct and indirect insertion
Johnson, New Brunswick, N.J.) or coadhesive are the same as noted previously. Indirect insertion
(Vetrap. 3M, St. Paul, Minn.) wrap
is strongly preferred because this forms a subcuta-
7. One catheter injection cap, catheter “T” piece, or
neous tunnel between the point of entry through
needleless connection device
the skin and the point of entry through the vein that
8. Syringe with heparinized saline solution, 1 to serves as a barrier to bacterial migration. Never
2 U/mL touch the skin at the point of insertion, and never
9. Sterile gauze sponges touch the needle/catheter shaft.
10. Single dose of povidone-iodine ointment
5. Fully retract the catheter into the sterile sheath so
11. Tube of cyanoacrylate adhesive (DURO superglue,
that it is not visible at the needle bevel. Grasp the
Loctite Corp., Cleveland) (optional)
device firmly at the hub of the needle, and penetrate
All materials are arranged ready for use on a clean tray the skin with the bevel of the needle facing away from
or Mayo stand: the skin surface. When possible, advance the needle
1. Antiseptic ointment applied onto a gauze sponge subcutaneously parallel to the vein for at least 2 cm
2. “T” piece, injection cap, or needleless connection
(0.75 inch) before introducing it into the vein
device purged with saline solution
(Figure 15-4, C). Penetration of the vein is usually
3. Catheter opened and ready for use heralded by a distinct pop as the needle punctures
4. Tape strips made as needed
the tough wall of the vessel. A flashback of blood
entering the needle hub is usually, but not always,
Procedure seen (Figure 15-4, D). The catheter may then be
1. Prepare the venipuncture site as described previously. manipulated through the sterile sheath and advanced
2. Wash your hands, apply germicidal lotion (if not through the needle.
already done), and put on clean examination gloves. 6. If you suspect successful venipuncture but do not see
3. Proper positioning is critical for successful cannula- a flashback, try advancing the catheter through the
tion of the external jugular vein. In animals with thin needle. If the catheter is not easily advanced, it is likely
skin and large, easily distended veins, the procedure is that the catheter has entered subcutaneous tissue. In
easily accomplished with the animal restrained in lat- that case, withdraw the entire assembly in unison. Do
eral recumbency. In this position, the external jugular not pull the catheter back through the needle until
vein is usually located directly lateral to the trachea. the needle is withdrawn because of the risk of shear-
Sternal recumbency or a sitting position is preferred ing on the needle bevel. Inspect the needle and
in animals that resist being restrained on their side catheter for damage; if none is present, it may be used
and in those with thick skin or small, poorly distensi- for another attempt. Any subsequent attempts can be
ble veins. In both the sternal and sitting positions, made through the original skin wound.
the animal should be held with its pelvic limbs 7. Because the needle forms a hole in the vessel wall that
directed away from the side chosen for venipuncture is larger in diameter than the catheter, postcathe-
(Figure 15-4, A). This maneuver makes the neck terization hemorrhage is occasionally a problem.
more convex on that side and reduces the depth of This can be minimized by holding the venipuncture
the jugular furrow. An assistant elevates the head, site above the level of the heart to reduce venous
and the nose should be initially held in a horizontal pressure, such as by performing jugular vein cannu-
position and directed away from the intended site lation with the animal in a sitting position. Accurate
at a 30- to 45-degree angle with the median plane. needle positioning minimizes laceration of the vein,