From the Guidelines
Bupivacaine can be used safely in patients with acute kidney injury (AKI) at standard doses, with careful monitoring for signs of toxicity, as its metabolism is primarily hepatic and not significantly affected by renal function. When considering the use of bupivacaine in AKI patients, it's essential to note that the maximum recommended dose without epinephrine is 1.3 mg/kg, and with epinephrine, it's 3.0 mg/kg, as indicated in the guidelines for local anesthetic agents 1. The duration of action for bupivacaine is between 180-600 minutes, which should be considered when planning the procedure and post-procedure monitoring.
Key considerations for using bupivacaine in AKI patients include:
- Monitoring for signs of toxicity, such as central nervous system toxicity (perioral numbness, metallic taste, confusion, seizures) or cardiovascular toxicity (hypotension, arrhythmias)
- Using proper aspiration technique to avoid intravascular injection
- Considering the use of epinephrine-containing formulations (1:200,000) to reduce systemic absorption when appropriate
- Being aware that acidosis, which often accompanies severe kidney injury, can increase the risk of bupivacaine toxicity
It's also important to note that bupivacaine undergoes extensive hepatic metabolism, with only about 5-6% excreted unchanged in urine, making hepatic function more relevant than renal function for its clearance 1. Therefore, standard adult dosing of 0.25-0.5% bupivacaine solution (maximum 2-3 mg/kg or 175 mg total dose) can generally be maintained in AKI patients, with careful consideration of the patient's overall clinical condition and monitoring for potential toxicity.
From the FDA Drug Label
Various pharmacokinetic parameters of the local anesthetics can be significantly altered by the presence of hepatic or renal disease, addition of epinephrine, factors affecting urinary pH, renal blood flow, the route of drug administration, and the age of the patient. The kidney is the main excretory organ for most local anesthetics and their metabolites. Urinary excretion is affected by urinary perfusion and factors affecting urinary pH. Only 6% of bupivacaine is excreted unchanged in the urine.
The use of bupivacaine in patients with acute kidney injury requires caution, as renal disease can alter the pharmacokinetics of the drug. Key considerations include:
- Renal excretion: Bupivacaine is primarily metabolized in the liver, but its metabolites are excreted by the kidneys.
- Dose adjustment: Patients with acute kidney injury may require dose adjustments to avoid toxicity.
- Monitoring: Close monitoring of the patient's renal function and overall clinical status is necessary when using bupivacaine in this population 2, 2.
From the Research
Safety of Bupivacaine Erector Spinae Block in Acute Kidney Injury
- The use of bupivacaine in patients with acute kidney injury (AKI) requires careful consideration, as AKI can affect the pharmacokinetics and pharmacodynamics of various drugs 3, 4.
- Bupivacaine is a local anesthetic that can be used for erector spinae plane blocks, which have been shown to be effective in managing acute renal colic pain 5.
- However, the safety of bupivacaine in patients with AKI has not been extensively studied, and its use may be associated with an increased risk of toxicity due to impaired renal function 6, 7.
- Medications, including local anesthetics like bupivacaine, can cause AKI through various mechanisms, including direct tubular injury, inflammation, and crystalline precipitation 6, 7.
- To minimize the risk of AKI or exacerbating existing renal impairment, it is essential to use bupivacaine judiciously and monitor patients closely for signs of toxicity or worsening renal function 3, 4.
Considerations for Bupivacaine Use in Acute Kidney Injury
- The dosage and administration of bupivacaine should be carefully adjusted according to the patient's renal function and the severity of AKI 3, 4.
- Alternative analgesic options, such as non-steroidal anti-inflammatory drugs (NSAIDs), may be considered, but their use should also be carefully evaluated in patients with AKI 5.
- Erector spinae plane blocks with bupivacaine may be a viable option for managing acute renal colic pain in patients with AKI, but further studies are needed to confirm their safety and efficacy in this population 5.
- Clinicians should be aware of the potential risks and benefits of using bupivacaine in patients with AKI and take a multidisciplinary approach to manage these patients, including consultation with nephrologists and other specialists as needed 3, 4.