Page 383 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Technical Aspects of Fluid Therapy 373

If the animal is prone to peripheral edema, a limb bandage obstruction with a clot. Continuous infusion of central
may be extended distally to the paw. However, this is not venous and arterial catheters with solutions containing
routinely necessary in an ambulatory animal with a prop- 1 U/mL of heparin prolongs the life of those catheters
erly applied catheter bandage. A heavy full limb bandage in human patients. 17,38,67 In contrast, the value of inter-
may be used (with or without a rigid splint) if the indwell- mittent flushing of catheters with heparin solutions is less
ing catheter crosses a joint. Immobilization of the joint in clear, with some recent studies showing that use of hepa-
this setting helps reduce endothelial trauma and may help rinized saline prolongs catheter patency and others
prevent venous thrombosis secondary to mechanical showing no benefit from intermittent heparin solutions
injury by the catheter. compared with saline alone. 54,66,67 These discrepancies
may be partly because of study differences in training
CATHETER MAINTENANCE nursing staff to properly flush catheters (Figure 15-8)
or disparities in data analysis. 71 No objective studies have
The need for an intravenous catheter should be reviewed addressed this issue in veterinary patients. Based on
daily and the catheter removed when it is no longer ther- human practice and observations of veterinary patients,
apeutically necessary. Until then, the vein and the limb or catheters that are not being used may be filled once daily
face should be examined at least twice daily for evidence with concentrated heparin (100 to 1000 U/mL).
of infection or edema. Regional lymph nodes should be Catheters used only for intermittent administration of
palpated for signs of swelling or tenderness. If any drugs should be flushed with sterile saline (with or
evidence of inflammation or thrombosis is found, the without heparin) and locked with a more concentrated
catheter should be removed. If the bandage is too tight, heparin solution immediately after drug administration.
it should be loosened or completely replaced. When distal Frequent flushing with higher concentrations of heparin
edema is evident, the culprit is usually white tape that was in cats and small dogs may produce systemic
applied too tightly. anticoagulation and should be avoided.
Although increasing duration of catheterization does Sterility of the infusion system must be maintained.
not necessarily increase the rate of bacterial coloniza- Only new sterile administration sets should be
tion, 47,48 catheters (especially over-the-needle designs) attached to a new catheter (unless it is used for just a
should be routinely considered for removal by 72 to 96 few hours [e.g., for intraoperative fluid therapy]), and
hours, especially if there is palpable evidence of thrombo- disconnections are made only when essential. Hands
sis or phlebitis. The dressing covering a through-the-nee- should be washed and disposable gloves worn for setting
dle catheter should be routinely replaced at 48 hours or up a new system, making disconnections, injecting
more frequently if it appears wet or soiled. At this time, medications, or withdrawing blood. When fluids are to
the skin and vein are examined and palpated for evidence be administered, a “T” piece or needleless connection
of inflammation or thrombosis. If either is suspected device should be used at the catheter, and locking Luer
consider removing the catheter. If the catheter and vein connections should be used between the administration
appear in good condition, the skin surrounding the entry set, extension sets (if used), and the patient catheter.
site is cleansed with an antiseptic scrub and cotton balls. Needleless connection devices that allow blood with-
Disruption of the entry wound or any in-and-out drawal, intravenous administration set disconnections,
movement of the catheter through the wound is avoided. and drug administration minimize contamination of
The skin is allowed to dry completely; fresh antiseptic catheter connection when compared with opening the
5
ointment on sterile gauze is applied; and the catheter is tubing system to attach a syringe directly. The patient’s
rewrapped. end of fluid administration tubing must be anchored to
Removal of percutaneously inserted through-the-nee- the catheter bandage with a piece of white tape to relieve
dle catheters is also routinely considered after 4 days; traction on the catheter connector (“T” piece or similar
however, they may be safely left in place for much longer device) and prevent separation. If the animal needs to
periods if they were inserted using a long subcutaneous be moved, avoid disconnecting the fluid line whenever
tunnel and are carefully maintained. 48 If intravenous ther- possible. If a needleless connector is not used, the fluid
apy is to be continued, a new catheter is inserted before line should be clamped at the “T” piece and the fluid
the old one is removed whenever possible. Intraosseous bag and line carried with the patient.
catheters are removed when they are no longer needed, All intravenous tubing and containers are changed
when fluid begins leaking into surrounding tissue or by every 72 hours or sooner if contamination is suspected.
48 hours, whichever comes first. Surgically inserted Injection ports and needleless connection devices should
catheters made of inert materials and with long subcuta- be cleaned carefully with 70% isopropanol before needle
neous tunnels may be left in place for days to months. puncture. Injection port caps are replaced if they are
Catheters in use for continuous fluid therapy probably observed to leak or if they have been penetrated more
do not need to be flushed periodically to prevent catheter than approximately 20 times.