Page 476 - Clinical Small Animal Internal Medicine

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444 Section 5 Critical Care Medicine

cardiotoxicity secondary to local anesthetic administra- 0.05 mL/kg/h for up to 24 hours can be considered for
VetBooks.ir tion in humans. The proposed mechanism of action patients who remain severely symptomatic. Utilizing a
“lowest effective dose” approach is recommended due to
involved overriding the local anesthetic‐induced inhibi-
tion of myocardial carnitine acylcarnitine translocase,
of IVLE therapy in veterinary patients.
potentially by mass effect or competitive inhibition, the general lack of information regarding adverse effects
allowing fatty acids to reach the mitochondria and be Reported side‐effects in human medicine include
used for energy production. infection due to contamination of the lipid product,
Since its initial introduction into the arsenal of available anaphylactoid reactions, and allergic reaction to the egg
medical treatments, IVLE therapy has proven beneficial in or soybean component of the IVLE. A syndrome known
the treatment of lipophilic toxins other than local anes- as “fat overload syndrome” (FOS) has been observed in
thetics. Many of these lipophilic toxins cause dysfunction humans. FOS is associated with fat embolism, liver
to organs other than the heart, yet their effects may still be dysfunction, or coagulation system dysfunction (throm-
reversed by IVLE administration, suggesting that IVLE bocytopenia and prolonged clotting times). These side‐
treatment has a different or additional mechanism of effects have not yet been reported in clinical veterinary
action beyond improved free fatty acid availability or patients, but the use of IVLE as a treatment for lipophilic
intracellular calcium accumulation. The most widely toxins is still somewhat new in veterinary medicine.
proposed mechanism of action for the beneficial effects of When considering IVLE administration, the clinician
IVLE treatment of patients poisoned by liphophilic sub- must carefully weigh the severity and duration of toxic
stances is the “lipid sink” theory. This theory states that symptoms against the cost and potential complications
increasing the plasma lipid content “sequesters” lipophilic associated with this intervention.
toxins within the plasma, decreasing movement out of the
bloodstream and into target organs such as the brain.
Anecdotal and published reports describe successful Conclusion
IVLE use in the treatment of a wide variety of toxins
ranging from local anesthetics (bupivacaine) and vaso- Small animal veterinarians commonly encounter acute
active drugs (amlodipine, propranolol) to antiparasitic poisoning. A sound, comprehensive approach to patient
drugs (ivermectin, moxidectin) and antidepressant medi- care (building on the fundamentals of a good history,
cations (bupropion, etc.). IV lipid emulsions are available physical exam, and diagnostic work‐up) is important for
as 20% formulations. The optimal dose is unclear at this diagnosing toxic exposure. A solid understanding of
time, but recommendations have been extrapolated from common toxins and appropriate utilization of available
available human literature, animal research, and veteri- resources such as poison control hotlines help the
nary case reports. Current guidelines suggest 1.5–4 mL/ clinician to establish the treatment plan most likely to
kg IV bolus be given over one minute and followed by a result in a successful outcome. Exciting new therapies
constant rate infusion (CRI) of 0.25 mL/kg/min over such as hemoperfusion and IVLE administration con-
30–60 minutes. Patients who fail to respond to this pro- tinue to evolve, making it important for the practicing
tocol may require additional boluses of 1.5 mL/kg every small animal clinician to remain up to date on the most
4–6 hours for 24 hours. Continued CRI doses of up to current available treatments.