Intravenous Catheter Placement in Small Mammals

Video

Video produced by Dr. M. Scott Echols and narrated by Dr. Marla Lichtenberger.

 

Introduction

Intravenous or IV catheters are commonly placed in ferrets and rabbits to administer fluids and medications, induce anesthesia, and for delivery of analgesic drugs during and after surgery. Intravenous catheters are also placed with growing frequency in chinchillas, guinea pigs and other exotic companion mammals (Fig 1).

Precaution or risk

Nevertheless the risk of catheter placement can outweigh the benefits in moribund patients. In these individuals it may be prudent to administer warm subcutaneous fluids while gently warming the patient (Fig 2).

Equipment needed

To reduce patient stress, gather supplies needed for catheterization before removing the patient from its cage (Box 1).

Box 1. Equipment needed for intravenous catheter placement
Appropriately sized indwelling catheter Pre-warmed surgical scrub and sterile saline Gauze sponges Heparinized saline Pediatric T-port or intermittent infusion plug White porous tape Elastic wrap Clippers Optional: Topical anesthetic cream (e.g. EMLA cream)

Veins commonly selected for intravenous catheter placement

Popular IV catheter sites include the cephalic vein, the lateral saphenous and, in rabbits, the marginal ear vein (Fig 3).

Cephalic vein

1. To place a catheter in the cephalic vein, restrain the patient in sternal recumbency on a non-slip surface.
2. Shave the forelimb, and aseptically prepare the site.
3. The skin in ferrets and some rabbits can be thick and difficult to penetrate. It can help to create a relief hole using a 20 to 25-gauge hypodermic needle (Fig 4).
   

   Figure 4. Use a hypodermic needle to create a relief or burr hole in thick-skinned patients. Click image to enlarge. Click on image to enlarge

4. Once the vessel is stabilized, insert and advance the catheter into place.
5. Then flush the catheter with a small volume of heparinized saline.
6. Secure the catheter in place, taking care not to apply too much tape. This will make the catheter so heavy it will be more likely to slide out (Fig 5).
   

   Figure 5. Avoid the temptation to apply excessive amounts of tape as this will make the catheter so heavy that it will slide out.

7. Lightly cover the catheter with elastic wrap.

 

Marginal ear vein

The auricular veins run along the outermost portion of the pinna (Fig 6). The auricular artery runs through the center of the pinna. It may be tempting to place a catheter into the ear artery since it is much larger, but fluids and medication should never be inserted into the central ear artery.

• Shave and aseptically prepare the ear.
• Stabilize the ear by placing a hand around the base of the pinna.
• Hold off the ear vein with either the thumb or index finger.
• Create a relief hole as needed (see cephalic vein above).
• Then insert and advance the catheter (Fig 7).
  

  Figure 7. Shown here, a catheter is advanced into the marginal ear vein while the ear is held off at the base of the pinna. Click image to enlarge.

• Taping can be awkward due to the shape and size of the ear, however securing the pinna to a roll of gauze or syringe case can make it easier to stabilize the catheter (Fig 8). Once the gauze or syringe case is in place, secure the catheter in a normal manner.

Daily fluid requirements

Administer IV fluids by constant rate infusion or divide calculated daily fluid requirements into two or four boluses. A fluid or syringe pump is the safest, most accurate way to deliver intravenous fluids to a small patient. A burette may also be used.

 

Catheter maintenance

If the catheter is not removed during the postoperative period, remove the elastic wrap at least once daily and gently clean the area. If the catheter site is red, warm, swollen or painful, then the catheter should be pulled and placed in another site.

 

Patient monitoring

It extremely important to closely monitor small patients for evidence of overhydration (Box 2).

Box 2. Signs of overhydration
Early water access	Advanced overhydration
Serous nasal discharge Tachypnea	Pulmonary edema Subcutaneous edema Jugular venous extension

Signs of early water excess can include serous nasal discharge and tachypnea. (Fig. 9) If left unchecked, the patient develops pulmonary edema, subcutaneous edema and jugular venous distension.

References