Hemoperfusion for acute toxin ingestion

Extracorporeal therapy (ECT) is a method of blood purification performed to remove a pathogenic substance, or solute, from the body. In this procedure, blood is removed from the patient and circulated through an extracorporeal circuit, which purifies the blood before it is returned to the patient.

Hemoperfusion (HP) is a type of extracorporeal blood purification therapy aimed at removing exogenous or endogenous toxins from the bloodstream. Other common types of ECT include renal replacement therapy (hemodialysis [HD], hemofiltration) and therapeutic plasma exchange.¹ Advanced procedures are especially beneficial when traditional decontamination techniques fall short.

Toxicities: Traditional medical management

Acute toxin exposure is a common and potentially life-threatening emergency in dogs and cats. Traditional decontamination techniques include induction of emesis, gastric lavage, activated charcoal, cathartic or intravenous (IV) lipid emulsion (ILE) administration, IV fluid therapy, and antidote administration, if applicable.² Few toxins have a specific antidote available, so therapy is predominantly aimed at decreasing gastrointestinal absorption of the toxin. If the protein is heavily lipophilic, then ILE administration may be considered to reduce clinical signs associated with intoxication and enhance the clearance of the toxin. IV fluid therapy is often employed for patients presenting with acute toxin ingestion, often at high rates, to encourage diuresis and more rapid clearance of the toxin. However, there is limited evidence to support the theory that IV fluid diuresis enhances toxin clearance, and for highly protein-bound toxins such as nonsteroidal anti-inflammatory drugs (NSAIDs), it has minimal positive effects.

Organ damage and life-threatening clinical signs may still develop despite traditional decontamination techniques because of the high ingested dose, rapid absorption of many toxins, and the inherent delay that precedes presentation for veterinary care.² Extracorporeal toxin removal (ECTR) provides a vital bridge whereby the toxin can be removed from the blood after it has undergone partial or complete absorption through the gastrointestinal tract, but often before it has had time to cause significant organ damage.This can reduce the morbidity and mortality related to acute toxin exposure and shorten the time required in the hospital for acute decontamination and monitoring.

The science behind hemoperfusion

During HP, a machine continuously withdraws blood from a dual-lumen dialysis catheter and circulates it through an extracorporeal circuit containing a specialized filter known as an HP column. HP columns contain a large surface area of adsorbent media that can remove various pathogenic solutes. The HP column removes the pathogenic solute from the blood, and the purified blood is returned to the patient. HP columns must remove the pathogenic solute without extracting or affecting standard blood components.³

HP can be performed alone or in series with HD (Figures 1a and 1b). In-series HP/HD is performed in small animal patients using a machine designed for renal replacement therapy in humans. The circuit requires a dialyzer to be placed in series with the HP column. Stand-alone HP is mainly performed using a veterinary-specific machine that does not require a dialyzer in the circuit, such as AimaLojic ReVive.

Figure 1a. Schematic of an in-series HP/HD circuit (Images courtesy of ImmutriX Therapeutics, Inc)

Figure 1b. Schematic of a stand-alone HP circuit

The most common HP columns in veterinary medicine include activated carbon (AimaLojic) and synthetic polymer (CytoSorbents) devices. Activated carbon HP devices contain synthetically derived activated carbon beads that are smooth and uniform (Figures 2a-2d). The carbon beads are activated by superheating them with carbon dioxide, creating many microscopic transport channels within the activated carbon beads, resulting in a massive surface area that is available to bind solute. In contrast, activated charcoal is a naturally derived product that is irregularly shaped with rough edges. Activated charcoal HP columns were previously used for ECTR; however, they have fallen out of favor because of concerns related to hemocompatibility, leaching, and column saturation.

Figure 2a. AimaLojic activated carbon hp column
Figure 2b. Photomicrograph of synthetically derived activated carbon beads
Figure 2c. SEM illustrating smooth surface area and uniformity of activated carbon beads
Figure 2d. Activated carbon bead with surface stripped off, revealing 3000-nm pore size inner structure

Newer activated carbon HP columns have an improved safety profile and increased surface area, offering a far superior option to earlier activated charcoal HP columns. Activated carbon removes solute from the blood via adsorption. During adsorption, atoms, ions, or molecules adhere to the surface of an adsorbent through van der Waals forces, hydrogen bonding, ionic bonding, and covalent bonding. Toxins with a high affinity to bind to activated charcoal will bind to activated carbon.³ The following list includes toxins that can be removed with activated carbon HP¹:

• NSAIDs
• Baclofen
• Amanita toxins
• Cannabinoids
• Barbiturates
• Metaldehyde
• Salicylates
• Serotonin (5-HTP)
• Chemotherapeutics
• Cyclosporine
• Methotrexate
• Paraquat

It is important to note that this list is not exhaustive, and novel toxins have the potential to be successfully removed with activated carbon HP (Figure 3). Knowledge of the toxin characteristics (molecular weight, protein binding, volume of distribution, half-life) is vital in guiding the decision to pursue ECTR.¹ When presented with severe intoxication, the veterinary clinician should research the toxin characteristics to determine whether referral for ECTR should be recommended.

NSAIDs (eg, ibuprofen, carprofen, naproxen, meloxicam) are among the most common toxins accidentally ingested by dogs, according to American Society for the Prevention of Cruelty to Animals Poison Control. NSAIDs can cause gastrointestinal disturbances such as vomiting, diarrhea, and gastrointestinal ulceration; renal disease like acute kidney injury; and central nervous system toxicosis. There are veterinary data⁴ to support that activated carbon HP successfully removes NSAIDs from the bloodstream, greatly enhancing their clearance from the body and reducing the severity of toxicosis. A patient who has recently ingested a renal toxic dose of an NSAID should be offered a referral for ECTR if referral is feasible given the geographic location of the patient, patient characteristics, and pet owner wishes. Asymptomatic patients that undergo ECTR for massive NSAID ingestion are often able to be discharged after 24 to 36 hours, which may be financially comparable if not advantageous to intensive care hospitalization for 72 hours for traditional medical management or prolonged hospitalization due to treatment of acute kidney injury.

Figure 3. Patient undergoes activated carbon hemoperfusion after massive meloxicam ingestion. The patient has a dual-lumen dialysis catheter in the right external jugular vein connected to the AimaLojic ReVive hemoperfusion machine.

When should hemoperfusion be considered for my patient?

If ECTR is promptly initiated, it may prevent, if not minimize, the extent of organ damage experienced secondary to the intoxication. Generally, only a single HP treatment is required for acute toxin removal. Initiating HP early following acute toxin exposure can decrease patient morbidity and mortality and shorten hospitalization time.¹ If your patient meets specific indications, a referral for ECTR should be offered. Indications for ECTR are as follows¹:

• The toxin is likely to result in significant organ dysfunction/injury (eg, acute kidney injury, acute liver failure, respiratory failure) or death.
• Extracorporeal clearance will exceed endogenous clearance.
• A lifesaving antidote is unavailable or ineffective in preventing toxicosis (eg, ethylene glycol).
• The benefits of ECTR exceed the risks.
• The toxin was recently ingested.

It is recommended that you call to consult with your nearest ECTR center before referral to ensure that your patient is a suitable candidate for ECTR and determine the modality of ECT that should be performed. If you are unsure whether a referral is indicated, contact your nearest ECTR center for consultation.

Understanding the risks and contraindications

ECT has been available for small animal patients since the 1970s, and there has been extensive advancement. Although there is minimal risk in a safely prescribed HP treatment, benefits and risks for the individual patient should be considered. Risks associated with HP include the following⁵:

• Periprocedural: hypotension (due to extracorporeal circuit volume, which generally should not exceed 10% to 15% of patient blood volume), hypothermia, hemorrhage (excessive heparin effect), thrombosis (inadequate anticoagulation), allergic reactions (rare, secondary to dialyzer/filter), hypocalcemia (if using citrate anticoagulation), or transfusion reactions (if blood products are required for circuit priming).
• Postprocedural: catheter thrombosis, infection, or hemorrhage (minimal as the catheter is only used for 1 treatment).

In patients with massive and life-threatening intoxications, generally, the most significant risk is the development of organ dysfunction, injury, or death if ECTR is not performed; thus, the benefits far outweigh the risks in most cases. Depending on how quickly the patient is referred for ECTR, there is a variable risk of toxicosis despite ECTR. The sooner the patient is referred for ECTR, the better.

Referring a patient for hemoperfusion

Before proceeding with HP, traditional decontamination techniques (eg, induction of emesis, activated charcoal administration) and baseline diagnostics (eg, baseline renal values for NSAID ingestion cases) should be performed as appropriate for your patient. If referring a patient for ECTR, do not use the jugular veins for venipuncture, as these vessels are required for dialysis catheter placement.

Contact an ECTR center early if HP is a potential treatment for your patient. In the setting of intoxications, early referral is vital for a successful outcome, as there is a time-sensitive window in which HP can help with acute toxin removal. Once you have collected a toxin history (toxin ingested, maximum potential ingested dose, time of ingestion, potential for coingestion, patient comorbidities, etc), assessed your patient, and instituted traditional decontamination techniques where appropriate (eg, activated charcoal administration), it is recommended to promptly contact your nearest extracorporeal center to discuss referral for ECTR.

Takeaway

HP offers an innovative blood purification treatment that helps remove toxins from the bloodstream in animals, particularly following acute toxic exposures. This method reduces the risk of organ damage and the length of hospital stays for affected animals. ACCESS Specialty Animal Hospitals - Los Angeles, in Culver City, California, provides this innovative treatment, which has already successfully supported the recovery of several animals experiencing severe toxic ingestions.

Amanda Spillane, MS, BVSc (Hons), DACVECC, graduated from the University of Queensland, Australia, with a degree in veterinary medicine. After a small animal rotating internship in Queensland, she completed an emergency and critical care residency at the University of Illinois. In 2022, she achieved diplomate status with the American College of Veterinary Emergency and Critical Care. Spillane then completed a fellowship at The Ohio State University in extracorporeal therapies, where she developed a deep passion for nephrology. Currently, she is advancing her specialization as one of the inaugural residents of the American College of Veterinary Nephrology and Urology. In October 2023, Spillane joined ACCESS - Los Angeles, a Thrive Pet Healthcare partner, to lead the nephrology and extracorporeal therapies department.

References

1. Foster JD. Extracorporeal therapies in the emergency room and intensive care unit. Vet Clin North Am Small Anim Pract. 2020;50(6):1215-1236. doi:10.1016/j.cvsm.2020.07.014
2. Groover J, Londoño LA, Tapia-Ruano K, Iacovetta C. Extracorporeal blood purification in acutely intoxicated veterinary patients: a multicenter retrospective study (2011-2018): 54 cases. J Vet Emerg Crit Care (San Antonio). 2022;32(1):34-41. doi:10.1111/vec.13100
3. Barnes J, Cowgill LD, Diaz Auñon J. Activated carbon hemoperfusion and plasma adsorption. Adv Small Anim Care. 2021;2:131-142. doi:10.1016/j.yasa.2021.07.010
4. Her J, Gordon D, Spillane A, Finstad J, Langston C. Outcomes of nonsteroidal anti-inflammatory drug toxicosis treatment with carbon hemoperfusion in dogs. Presented at: International Veterinary Emergency and Critical Care Symposium; September 7-11, 2024; St Louis, MO.
5. Spillane A, Langston C. Extracorporeal Blood Purification. In: Cohn L, Côté E, eds. Cote’s Clinical Veterinary Advisor: Dogs and Cats. 5th ed. 2025.