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1058 Arterial Blood Sampling and Arterial Catheterization

Arterial Blood Sampling and Arterial Catheterization
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• For animals with increased respiratory effort,
Difficulty level: ♦♦
have supplemental O 2 available. • At a 45-degree angle to the skin, advance the
needle through the skin and into the artery
Synonym (some prefer to keep the bevel of the needle
Arterial phlebotomy Possible Complications and pointing down for arterial puncture).
Common Errors to Avoid • When the artery has been punctured, a
Overview and Goal • Discomfort during placement: consider flashback of blood will be seen, and the
To access a peripheral artery with a needle or lidocaine bleb in the skin where catheter syringe self-fills due to arterial pressure. Fill
catheter for blood sampling or direct arterial will be introduced syringe to approximately 0.5 mL for ABG
blood pressure monitoring • Hemorrhage/hematoma formation during analysis.
attempted placement or if inadequate pres- • Apply direct pressure to the phlebotomy site
Indications sure is applied to the puncture site after until all hemorrhage has stopped (usually 5
• Collection of arterial blood sample for procedure minutes).
analysis (most frequently arterial blood gas • Thrombosis of the vessel (unlikely to cause • Remove any air bubbles from syringe, and
analysis [ABG]) clinically significant ischemia) place open needle into rubber stopper.
• Placement of an arterial catheter for direct • Spasm of the vessel preventing future • Immediately perform ABG, or place syringe
blood pressure measurement (typically in phlebotomy attempts in an ice bath.
critically ill or anesthetized animals) • Infection of the catheter/site Arterial catheter placement:
• Pre-existing hypotension may make vessel • The dorsal metatarsal artery is the most com-
Contraindications identification more challenging. monly used and is described in detail below.
Coagulopathy: recommend coagulation evalu- • Excessive pressure during vessel palpation Femoral, auricular, metacarpal, lingual, and
ation before procedure, assess patient for overt may lessen pulse pressure and limit vessel coccygeal arteries may also be used.
signs of bleeding, question client regarding prior identification. • Restrain, clip, and scrub as above. Clip the
history of bleeding • Obtaining a mixture of venous and arterial dorsal surface of distal hindlimb from hock
blood from adjacent vessels confounds blood to beginning of phalanges.
Equipment, Anesthesia gas analysis. • Have assistant hold limb in extended posi-
Arterial catheter: chemical restraint not typically tion. Do not occlude flow to the vessel (hold
required, although placement is most frequently Procedure off).
done after induction in anesthetized patients. Arterial blood sampling: • Palpate pulse with index and middle fingers
• One to two assistants for restraint • Restrain patient in lateral recumbency with of nondominant hand to convincingly
• Hair clippers vessel to be used exposed, typically dorsal determine the anatomic course of the artery.
• Sterile scrub material metatarsal or femoral artery. The artery lies between the third and fourth
• 6-10 3 × 3 gauze squares • Clip hair in the region of the intended metatarsal bones.
• Arterial catheter (standard over-the-needle puncture site, and sterile scrub site. • Nick the skin only above the intended inser-
IV-type catheter) • Palpate pulse with nondominant hand; tion site using the bevel of a hypodermic
○ Cats, dogs < 10 kg: 24 or 25 gauge use middle and index fingers to assess the needle.
○ Dogs 10-25 kg: 22 gauge anatomic course of the artery. • Over-the-needle IV catheter (IVC) sized
○ Dogs > 25 kg: 20 gauge • Use heparinized syringe with needle size appropriate to patient (see above) is held
• 22-gauge needle to nick skin appropriate to patient (see above). in the dominant hand.
• White tape, 2-cm (1-inch) width
• Heparinized sterile saline flush
• T-port/male adapter
• 3-way stopcock
• Pressure transducer and monitor (if continu-
ously monitoring direct arterial pressure)
For arterial blood sample:
• Hair clippers
• Sterile scrub material
• 1-mL heparinized syringe (commercial or
prepared by coating syringe with heparin
and expelling remaining liquid)
• 20-25–gauge needles (guidelines for size same
as for arterial catheters, above)
• Rubber stopper
• +/− Ice bath
Anticipated Time
• 3-5 minutes (arterial blood sample)
• 10-15 minutes (arterial catheter)
Preparation: Important
Checkpoints ARTERIAL BLOOD SAMPLING AND ARTERIAL CATHETERIZATION Blood sampling from femoral
artery of a dog in left lateral recumbency. Cranial is to lower right. Assistant holds right hindlimb elevated and
• Make sure patient is adequately restrained the prepuce retracted. Phlebotomist identifies course of left femoral artery between middle and index fingers
and all materials are nearby. by palpation of femoral pulse with both fingers and prepares to enter the artery, with the needle bevel down.

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