Section 8: Fluid Administration and Monitoring

Top Three Takeaways

1. Using skilled veterinary technicians to administer and monitor fluid therapy allows the veterinarian to focus on the tasks they alone must perform (i.e., diagnosing, prescribing—including the fluid therapy prescription—prognosing, and surgery), leading to increased efficiency and oversight of patients.
2. Monitoring during IV fluid therapy is critical to prevent fluid overload. When patient monitoring or referral to a hospital that provides monitoring is not available, consider an alternate route of delivery.
3. Infusion pumps are frequently used; however, they may not always be the optimal method for fluid administration.

Fluid Administration

IV infusion pumps are most commonly used but are not always the ideal mode of administration. For example, a large dog who needs a rapid crystalloid infusion may need an infusion rate that exceeds the 1–2 L/hr that standard pumps provide. In this case, a pressure bag would be the preferred method to deliver the large fluid volume in a short time. For animals receiving a small volume of fluids, a syringe pump may be more accurate than a standard infusion pump that does not have micro settings (Table 16).

The IV administration set is another consideration in choosing equipment. Smaller animals may benefit from a micro drip set (60 drops/mL), which provides more precise fluid delivery. This can be especially helpful when using the gravity method to deliver fluids in small patients. Macro drip sets come in a variety of drip factors; those most used in veterinary medicine are 10 drops/mL and 15 drops/mL. Fluid pumps are also usually designed for use with a specific type or size of tubing, so it is important to match these to ensure adequate fluid delivery (Table 16).

Use a new IV line and bag for each patient148 (see Table 17 for IV catheter care and placement). Prime IV lines with the fluid to be infused before use to avoid air embolism. A T-port can ease medication administration, and a Y-port can be used when administering more than one compatible infusion.

IV fluid bags should not be used for saline flushes because of the risk of contamination. Commercially prefilled syringes are preferred to decrease the chances of introducing bacterial contamination that could lead to infection.^1,2,3

If IV access is not achievable, consider IO catheters early in treatment to avoid fluid resuscitation delays. IO devices are able to quickly drill through the bone but require training. When no device is available, needles or peripheral IV catheters can be used (see https://www.youtube.com/watch?v=10twNYP1pB0 for instructions on placing an IO catheter).

gtt, drop; s, second

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1. Reddick AD, et al. Intravenous fluid resuscitation: was Poiseuille right? Emerg Med J. 2011;28(3):201-2.
2. Webster J, Osborne S, Rickard CM, Marsh N. Clinically-indicated replacement versus routine replacement of peripheral venous catheters. Cochrane Database Syst Rev. 2019;1(1):CD007798.

Download Table 17 PDF

Fluid Monitoring

Trained nursing staff should continually monitor IV fluid administration (Table 18). Without adequate monitoring, severe consequences can occur and compromise patient care. Use multiparameter monitoring to gain a broad picture of the patient’s volume and hydration status and avoid fluid-related complications (Table 19).

Monitor patients at high risk for fluid overload at least every 2 hr (see Tables 19 and 20 for methods). Weigh these patients 2–3 times a day, check their respiratory rate every 1–2 hr, measure fluid inputs and urine output, and watch for signs of edema. If available, perform focused ultrasonography for fluid responsiveness, which includes scanning for cavity effusion and B-lines in the lungs and evaluating the vena cava. For patients at risk of recurrence of hypovolemic shock, evaluating the inferior vena cava may be a better indicator of recurrence than other more commonly monitored parameters such as heart rate and blood pressure.⁴

In smaller patients, especially pediatrics, keep in mind that serial blood draws can decrease blood volume.

Fully utilizing veterinary technicians, who can not only set up and run fluid therapy but also identify the signs of fluid-related complications, allows the veterinarian to delegate this nursing task after  prescribing fluid therapy orders. The stronger a veterinary technician’s understanding of the “why” of fluid therapy, something that is addressed in veterinary technology and nursing programs, the more they can be optimized to their fullest potential, allowing for higher efficiency of the veterinary team.

Many veterinary practices are either unable to provide 24 hr care or geographically unable to refer patients to a 24 hr facility. When continual patient monitoring is not possible, the task force recommends giving IV fluids during the clinic’s open hours and SC fluids before leaving for the night. A slightly higher IV fluid rate can be used during the day unless contraindicated because of the patient’s disease state. Patient monitoring must be provided whenever administering IV fluids.

TVI, total volume infused; VTBI, volume to be infused

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* Reprinted from Davis H, Jensen T, Johnson A, et al. 2013 AAHA/AAFP fluid therapy guidelines for dogs and cats. J Am Anim Hosp Assoc. 2013;49(3):149-59.

** Including cardiac auscultation to identify new murmurs

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Download Table 20 PDF