lec 3

• Phlebotomy involves cutting into or making an incision into a vein for blood collection.
• Venipuncture is the act of puncturing a vein to gain access for blood collection.
• A phlebotomist is a person who collects blood samples.
• Key considerations include restraint of the animal, knowledge of anatomical location, and confidence.
• Aseptic technique is an important consideration.
• Alcohol is adequate for cleaning the skin unless placing a catheter; use a sterile syringe and needle.
• Alcohol should dampen the fur, not sterilize the skin.
• Collection tubes have different colored tops to indicate different additives and uses; the order of draw matters.
• Always follow the volume requirement on the collection tube.

Collection Tube Options

• EDTA (purple top) is used for CBC, TP, and PCV.
• Sodium Citrate (blue top) is used for coagulation testing.
• Serum tubes (red or tiger top) are used for serum chemistry.
• Diatomaceous Earth tubes (grey top) are used for activated clotting time.
• Heparin tubes (green top) are used for tests requiring plasma or whole blood, like TP/PCV.

Vacutainer System

• Vacutainer systems are not commonly used in small animals.
• This system is most useful for large animals or lab animals, or when needing to fill several tubes.
• Flow is fast; be careful of overfilling; have good control.

Needle Sizes

• For dogs and cats, a 22G needle is typically used.
• For jugular samples in large animals, use an 18G needle.
• Use a 20G needle for bovine tail vein samples.
• Using too small of a needle can cause hemolysis.

Cephalic Veins

• Cephalic veins are peripheral and located on the medial aspect of the forearm.
• Some veins are more superficial than others.
• Insertion through the skin is the most painful part of the procedure.

Jugular Vein

• There are both right and left central jugular veins.
• The jugular vein is the best option when a larger volume of blood is needed.
• Avoid overextending the head during collection.
• Insert the needle almost parallel to the skin.

Lateral Saphenous Vein

• The lateral saphenous vein is rarely used in cats.
• This is a peripheral vein that runs diagonally across the lateral surface of the distal tibia.
• Described as a "wiggly" vein.

Medial Saphenous Vein

• The medial saphenous vein is a peripheral vein.
• This is a great option for cats and also suitable for dogs.
• This vein is also known as the femoral vein.
• Located on the medial aspect of the pelvic limbs.
• Delicate vessel.

Marginal Ear Vein

• The marginal ear vein is suitable for collecting a small drop of blood.
• It is often used for blood glucose monitoring.
• A warm compress may help.
• Use a 25G needle to prick the vessel, massage out a drop of blood, and apply pressure to stop bleeding.

Required Supplies

• Vacutainers
• Collection system
• Alcohol
• Hemostasis materials
• Gauze
• Vetwrap

Step-by-Step Blood Collection

• Occlude vein.
• Restrain the animal or phlebotomist (jugular and tourniquet).
• Apply 70% alcohol to the site.
• Insert needle with bevel up at a 15-25 degree angle or a smaller angle for the jugular.
• Slowly draw back on the syringe plunger to collect blood.
• Have the restrainer maintain occlusion of the vein.
• When blood is collected, have the restrainer release pressure before removing the needle.
• Perform hemostasis (by restrainer) with digital pressure using gauze for 30-60 seconds; use gauze/wrap.
• Transfer blood into vial(s) and follow the correct order.
• Avoid pushing blood through the vial septum; instead, remove the cap or use the needle to allow negative suction to transfer the blood.
• Gently invert the vial 5-10 times if it contains an additive, such as an anticoagulant or clot activator.
• Dispose of the needle in sharps and the syringe in biohazard/garbage.
• With the vacutainer system, insert blood collection tubes into the sleeve to fill.

Additional Steps for Vacutainer

• Follow the appropriate order of draw.
• Gently invert the vial 5-10 times if it contains an additive.
• Remove the last vial from the needle before removing the needle from the animal.
• Perform hemostasis.
• Detach the needle from the plastic sleeve and discard it in sharps.
• When working with peripheral veins, start low (distal aspect of the vein).
• If unsuccessful, try again more proximally.

IV Injections

• Similar to taking a blood sample.
• For cats and dogs, use a peripheral vein (cephalic, saphenous).
• Apply alcohol to the site.
• Stabilize the vessel.
• Use a 22 gauge needle (consider 25G for tiny or severely hypovolemic patients).
• Have the restrainer occlude the vein.
• Insert the needle bevel up through the skin and wall of the vein.
• Aspirate a small volume of blood.
• Have the restrainer unocclude the vein.
• Inject contents.
• Perform hemostasis.
• Discard the needle and syringe appropriately.

Medication Extravasation

• Notify the DVM.
• Infuse saline subcutaneously around the extravasated site to dilute medications/effects and apply a warm compression for approximately 10 minutes.

Routes for Fluid Therapy

• IV (Intravenous) is the route of choice for most situations.
• IO (Intraosseous) involves fluid administered into the bone marrow, requires aseptic technique using sterile supplies.
• SQ (Subcutaneous) is administered under the skin, typically near the neck scruff along the shoulders.
• PO (Per Os) is oral administration, easy but contraindicated if the patient is vomiting.
• IP (Intraperitoneal) is administered to lab animals and neonates using careful injection technique.

Pros/Cons of Fluid Administration Routes

• PO: Inexpensive and can be done at home, but cannot be used if the patient is vomiting.
• SQ: Decreased cost, can be done on an outpatient basis or at home, and can be repeated, but only isotonic solutions and non-irritating substances can be used, as irritating substances may cause tissue necrosis.
• IP: Can be used to deliver medications to very small or exotic patients, but there is a risk of injury to abdominal organs and peritonitis, and absorption into systemic circulation is slow.
• IV: Many types of fluid options are available and delivered directly into the circulatory system, but requires hospitalization and increased time and cost.

When Fluids are Needed

• Correct electrolyte imbalances.
• Diuresis (e.g., renal disease, FLUTD, drugs).
• Medication delivery.
• Cardiovascular support.
• Transfusion due to blood loss.
• During anesthesia.

Fluid Compartments

• The body is divided into compartments affecting the concentration of solutes and H2O.
• Osmosis is the movement of a solvent (e.g., H2O) from an area of low solute concentration to an area of high solute concentration.
• Intracellular (ICF) is the fluid within cells.
• Extracellular (ECF) is the fluid outside of cells.
• Interstitial fluid is the space between blood vessels and surrounding tissues.
• Intravascular fluid is within blood vessels.
• Body = 60% water
• ICF: 2/3 water (inside the cells)
• ECF: 1/3 water (outside the cells)
• ¾ of ECF is interstitial (surrounding tissues).
• ¼ of ECF is intravascular (blood vessels).

Dehydration vs. Hypovolemia

• Dehydration is fluid loss from interstitial space and extravascular cells, primarily water loss.
• Hypovolemia is fluid loss from intravascular space, which may reduce RBC fluid volume.
• Symptoms of hypovolemia include decreased BP, cool extremities, tachycardia, and weak pulse.

Clinical Signs of Dehydration

• Hydration parameters include mucous membrane moisture, skin tent, eye output, and urine output.
• PCV/TP may be normal or increased, depending on the severity of dehydration.

Fluid Classification

• Crystalloids are aqueous solutions of small, water-soluble molecules that easily pass through cell membranes.
• Isotonic solutions, such as 0.9% NaCl and Lactated Ringer's Solution (LRS).
• Hypotonic solutions are lower in solute (Na) concentration relative to plasma.
• Hypertonic solutions have a higher solute (salt) concentration relative to plasma.
• Colloids are large molecules that attract water into the intravascular space and are retained in the IV space for an extended period.
• Synthetic colloids include Dextran and Hetastarch.
• Natural colloids include plasma and albumin.
• Dehydration is typically corrected with isotonic fluids (e.g., LRS).
• Hypovolemia is best corrected with colloids or a combination of crystalloids and colloids if fluid volume is an issue.

Fluid Therapy Plan

• Considerations include past events causing fluid loss (dehydration), maintenance loss (e.g., due to breathing, sweating, salivation), and ongoing loss (e.g., V/D).
• Evaluate the animal's condition and its ability to tolerate increased volumes of fluid.
• Fluid additives include electrolytes, potassium, dextrose, and medications.

Identifying Fluid Overload

• Signs of overload include restlessness, respiratory distress, tachypnea, coughing, nasal discharge, peripheral edema (e.g., paws), significant weight gain in a short period, and a drop in PCV/TP levels.
• Utilize fluid pumps for controlled delivery with alarms for set volume infused and occlusion to overload.
• Ensures accurate volume is delivered at the correct rate.
• Fluid pumps deliver fluid at a constant rate.
• Gravity flow relies on passive flow rate monitored according to the position of the patient and IV catheter, without alarms.