Management of Poisonings and Intoxications

Abstract

Poisoning occurs after exposure to any of a number of substances, including medicines, which can result in severe toxicity including death. The nephrologist may be involved in poisonings that cause kidney disease and for targeted treatments. The overall approach to the poisoned patient involves the initial acute resuscitation and performing a risk assessment, whereby the exposure is considered in terms of the anticipated severity and in the context of the patient's status and treatments that may be required. Time-critical interventions such as gastrointestinal decontamination (e.g., activated charcoal) and antidotes are administered when indicated. The nephrologist is usually involved when elimination enhancement techniques are required, such as urine alkalinization or extracorporeal treatments. There is increasing data to guide decision making for the use of extracorporeal treatments in the poisoned patient. Principles to consider are clinical indications such as whether severe toxicity is present, anticipated, and/or will persist and whether the poison will be significantly removed by the extracorporeal treatment. Extracorporeal clearance is maximized for low–molecular weight drugs that are water soluble with minimal protein binding (<80%) and low endogenous clearance and volume of distribution. The dosage of some antidotes (e.g., N-acetylcysteine, ethanol, fomepizole) should be increased to maintain therapeutic concentrations once the extracorporeal treatment is initiated. To maximize the effect of an extracorporeal treatment, blood and effluent flows should be optimized, the filter with the largest surface area selected, and duration tailored to remove enough poison to reduce toxicity. Intermittent hemodialysis is recommended in most cases when an extracorporeal treatment is required because it is the most efficient, and continuous kidney replacement therapy is prescribed in some circumstances, particularly if intermittent hemodialysis is not readily available.

Continuous renal replacement therapy for lithium toxicity: A worthy treatment to avoid intradialytic hypotension and vasopressors

“…Lithium toxicity directly affects muscle and nerve cells, which include cardiomyocytes. Clinical manifestations include decreased level of consciousness, seizures, fatal arrhythmias, and impaired kidney function 7 . Our patient's reading of “above 6 mEq/L” placed her well into the category of severe toxicity, which is seen at levels above 3.5 mEq/L 7 .…”

“…While lithium toxicity has a risk of cardiovascular collapse, intermittent hemodialysis also has a risk of hypotension, especially due to its maximum clearance of 240 mL/min, as opposed to CCRT's maximal clearance of 80 mL/min 7 . Our patient's level of lithium toxicity was high enough to precipitate hypotension with the added stress of intermittent hemodialysis.…”

“… 7 Our patient's reading of “above 6 mEq/L” placed her well into the category of severe toxicity, which is seen at levels above 3.5 mEq/L. 7 Furthermore, while our patient was only intermittently confused, her improvement in creatinine by more than 0.3 mg/dL after the clearance of her lithium levels indicated that the patient had acute kidney injury despite not knowing a prior baseline. 8 Even more concerning was her prolonged QTc, which raised concern for the developing EKG signs of lithium toxicity that include bradycardia, flattened or inverted T waves, heart block, and sick sinus syndrome.…”

“…Clinical manifestations include decreased level of consciousness, seizures, fatal arrhythmias, and impaired kidney function 7 . Our patient's reading of “above 6 mEq/L” placed her well into the category of severe toxicity, which is seen at levels above 3.5 mEq/L 7 . Furthermore, while our patient was only intermittently confused, her improvement in creatinine by more than 0.3 mg/dL after the clearance of her lithium levels indicated that the patient had acute kidney injury despite not knowing a prior baseline 8 .…”

“…While normal saline is often used to help enhance urinary excretion, her renal impairment combined with her lithium levels greater than 5 mEq/L were indications to consider extracorporeal treatment, of which hemodialysis is the most favored choice 7 . Lithium has a small size of 74 Da, is rapidly absorbed and is not protein bound, making it easily diffusible through any modern filter 6,7 . Intermittent hemodialysis (HD) is preferred and is the most effective method of removal, influencing the multidisciplinary team's consideration of resuming this modality 5 .…”