Page 382 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

372 FLUID THERAPY

obstructed with a “core” of cortical bone. This may 5. A t-port, syringe, or fluid administration set (Figure 15-
sometimes be expelled by forceful injection of saline 7, E) can be attached for administration of emergency
with a 1-mL syringe. If no marrow elements are drugs, and crystalloid or colloid solutions.
aspirated, try rotating the needle 90 degrees, or Solutions can be administered at rates similar to those
advance it a bit further. used intravenously but may be slower in smaller
6. Flush the needle with a small amount of the saline patients. Drug dosages for IO administration are the
solution. Only modest resistance to injection is same as intravenous dosages. Pain may be associated
encountered unless the bone is very small. Fluid deliv- with high rates of fluid infusion and this may be
ered by gravity flow should flow freely (although more reduced by the infusion of lidocaine (1 to 2 mg/kg
slowly than through a venous catheter). Begin the of a 2% solution).
fluid infusion, and frequently palpate the surrounding
tissue for any evidence of fluid leakage from the bone. BANDAGING
Leakage usually occurs when the needle has penetrated
the opposite cortex and the tip is outside the bone or All intravenous catheters must be adequately secured to
when excessive rocking motion was used during inser- the body. Catheters left in place in unattended animals
tion, leaving a large hole in the cortical bone should be covered with a sterile dressing and a bandage
surrounding the needle through which fluid escapes. that provides protection against traction, damage, and
7. If the needle is to remain in place for more than a few contamination. The bandage should be heavy enough
minutes, anchor it by passing a suture through the to protect the catheter but should not be completely
periosteum and tying it to the hub of the needle or occlusive so that moisture can evaporate from the skin
to a tape butterfly secured to the hub. and dressing. The point of entry should be covered with
8. If the animal needs to be moved and repositioned with povidone-iodine ointment on a sterile gauze sponge.
the catheter in place, cover the entry site with antiseptic Single-dose packets of ointment are preferred over jars
ointment. A “doughnut” of limb stocking material can that become contaminated with repeated use, and
be placed around the needle to provide enough povidone-iodine is preferred over triple antibiotic
padding to protect the needle from contact with the ointments, which support growth of fungi and resistant
examination table or cage floor. It should be at least bacteria. 55,88 Catheters used for short procedures may
thick enough to be level with the top of the needle be dressed with a small amount of ointment at the entry
hub. Secure this padding to the patient with bandaging site and secured to the neck or limb with white tape. White
material. tape is inelastic and must be wrapped loosely (with the
neck or limb held in a natural position) to prevent bind-
Procedure for Using the EZ-IO Device 46 ing, venous occlusion, and edema. Additional stability is
1. The patient is placed in lateral recumbency and the achieved by suturing the catheter hub to the skin before
greater tubercle of the humerus is identified. wrapping. The catheter should be anchored securely
2. If time allows, shave and aseptically prepare the ana- enough to minimize any in-and-out movement through
tomic site. Infiltrate the skin, subcutis, and periosteum the skin; this allows the skin to close around the catheter
with approximately 0.25 to 0.5 mL of 2% lidocaine and form a natural barrier to bacterial migration.
and make a small stab incision. In some emergency Interestingly, there is little evidence from human
cases, such as cardiopulmonary cerebral resuscitation patients that any type of dressing reduces the incidence
(CPCR), local anesthetic infiltration and the stab inci- of catheter infection compared with catheters left exposed
sion are skipped. and kept clean and dry. 58 Transparent “breathable”
3. The intraosseous catheter is loaded onto the power dressings appear to offer little advantage for human
driver and the tip of the needle is pushed through patients over gauze dressings 28 unless impregnated
the skin and into the periosteum of the greater tuber- with chlorhexidine 34 (e.g., Tegaderm CHG Chlorhexi-
cle. Forward pressure is applied to make sure the dine Gluconate IV Securement Dressing, 3M Corp.,
needle does not slip off the cortical bone. The power Minneapolis) and do not adhere as well to animal skin.
button of the drill is depressed and the catheter is If the catheter is to remain in place for longer periods,
drilled until it is seated in the bone. a layer of cast padding thick enough to provide some
4. Oncethecatheterisproperlypositioned,thehubshould physical support to the entire bandage is applied. A layer
be firmly implanted and you should be able to move the of stretch gauze may be wrapped around the padding; this
leg with the hub of the catheter. The stylet is then should be applied snugly enough to create a firm unit of
removed (Figure 15-7, C), and correct placement can material but not tightly enough to occlude venous return.
be confirmed by aspiration of bone marrow through The outermost layer may be an adhesive or coadhesive
the catheter (Figure 15-7, D). Aspiration may cause bandaging material. This material is also wrapped on
some minor discomfort and the patient may react. snugly but not tightly enough to occlude venous return.