Being able to administer fluids to veterinary patients is an important part of providing optimal care. It is crucial that
technicians understand why fluids are essential, the different types of fluids available, and how to provide them. This article
focuses on how to administer the fluids. For information on other aspects of fluid therapy, see "Fluid therapy: Calculating the rate and choosing the correct solution."
Catheter placement and care
The veterinarian will determine which fluids to deliver and at what rate in ml/kg/day, ml/kg/hr, or ml/hr. The technician
can then start administering the fluids, usually through an intravenous (IV) catheter. IV catheters are most commonly placed
in one of three veins: cephalic, saphenous, and jugular—the cephalic vein being the most common in small animals. For details
on how to place a cephalic catheter, see "Cephalic catheter placement."
Practitioners use several types and sizes of IV catheters. In most patients, a peripheral catheter is indicated. Packaging
for these catheters lists a gauge number that correlates to the inside diameter of the IV catheter. The larger the gauge number,
the smaller the catheter's diameter (i.e. a 22-ga catheter has a smaller internal diameter than an 18-ga catheter). The largest-diameter (smallest-gauge) catheter
possible should be used when placing an IV catheter. The wider the catheter's diameter, the less resistance to the fluid flow,
allowing for a fluid bolus to be administered more quickly.
Daily IV catheter care is extremely important. If an IV catheter is placed but fluids are not started, flush the catheter
with heparinized saline solution every four hours to prevent clotting. It is important to remove the IV catheter's wrap so
the insertion site can be visualized to ensure there is no redness, swelling, or discharge from around the insertion site.
Check the patient's leg for any swelling above or below the catheter. If there is swelling, remove the catheter and place
a new one in a different location. If catheter care is not provided, the vein may develop thrombophlebitis in which the vein
becomes inflamed (phlebitis) and a thrombus (clot) is formed on the vessel walls. If left untreated, the vein may completely
thrombose, causing a severe clotting in the vessel that will render the vein unusable and increase the risk of infection at
the catheter site.
Before administering a solution through a fluid line port or directly into the catheter, swab the port with alcohol. When
disconnecting a patient from fluids, always cap off the IV catheter and place a fresh capped needle on the end of the fluid
line. Be sure to keep the connection between the IV catheter and the IV line sterile.
IV fluid pump and drip lines
Most veterinary hospitals have IV fluid pumps that provide a set amount of fluids per hour. The use of IV fluid pumps is the
safest and most accurate way to deliver fluids to a patient. If your practice does not have IV fluid pumps, IV fluids can
still be administered by using IV drip lines, either via micro-drips or macro-drips. The micro-drip sets deliver 60 drops/ml,
while the macro-drip sets deliver 10 or 15 drops/ml. The number of drops/ml can vary by manufacturer, so check the packaging
to determine the number of drops/ml. Calculate the drip rate for the patient based on the drops/ml and the amount of fluids
to be provided by using the formula above.
When providing fluids to a patient via a drip set, monitor the amount of fluid in the bag to ensure the patient is receiving
the prescribed amount. Note that the patient's position can greatly impact the amount of fluids received. For instance, when
a cat lies down and tucks its legs underneath itself, the fluids can stop flowing; but when the cat is moving, it may receive
a large fluid amount in a short period. To help monitor the amount of fluids a patient is receiving, put a piece of tape beside
the numbers on the side of the bag and note the amount of fluids left. Write at the top when the bag was started, and then
mark off where the fluid should be at every hour after that.