In a patient with a confirmed local anesthetic allergy, can a neuraxial block be performed and what precautions are recommended?

Neuraxial Block in Local Anesthetic Allergy

Yes, neuraxial blocks can be safely performed in patients with suspected local anesthetic allergy because true allergy to amide local anesthetics is extremely rare, and these drugs are likely to be safe even in patients with a history of adverse reactions during anesthesia. 1

Evidence Supporting Safety of Amide Local Anesthetics

Allergy to amide local anesthetics (lidocaine, bupivacaine, ropivacaine) is exceedingly rare:

• True allergic reactions to amide local anesthetics represent less than 1% of all adverse local anesthetic reactions 2
• In a 20-year study of 208 patients with alleged local anesthetic allergy, only 4 patients (1.9%) had true immediate allergic reactions 3
• Another study of 28 patients with adverse reaction history found that rapid spontaneous recovery was the rule, suggesting immediate allergic reactions were unlikely 4
• Guideline consensus states that drugs used in local and regional anesthesia are likely to be safe, as allergy to amide local anesthetic drugs is extremely rare 1

Most "Allergic" Reactions Are Not True Allergy

The vast majority of reported local anesthetic "allergies" are actually:

• Vasovagal syncope 5
• Epinephrine-related reactions (tachycardia, anxiety) 5
• Toxic overdose from intravascular injection 2
• Reactions to preservatives (methylparaben, metabisulfite) rather than the local anesthetic itself 6, 3
• Psychogenic reactions 2

Recommended Approach for Neuraxial Block

1. Obtain Detailed History

• Determine the exact nature of the previous reaction (timing, symptoms, drugs administered) 1
• Review previous anesthetic records if available 1
• Identify whether preservatives or additives were present in the previous local anesthetic solution 6, 3

2. Proceed with Preservative-Free Amide Local Anesthetic

• Use preservative-free preparations of amide local anesthetics (bupivacaine, ropivacaine, or lidocaine) for the neuraxial block 6, 3
• This eliminates reactions to preservatives, which account for many "allergic" reactions 6
• Avoid chlorhexidine preparations if possible, as chlorhexidine allergy is more common than local anesthetic allergy 1

3. Ensure Latex-Free Environment

• Provide a latex-free environment, as latex allergy is far more common than local anesthetic allergy and can present similarly 1
• Approximately 1.4% of the population exhibits latex allergy versus the extremely rare incidence of true amide local anesthetic allergy 1

4. Have Resuscitation Equipment Available

• Keep full resuscitation equipment immediately available 7, 8
• Monitor blood pressure and electrocardiogram continuously 7, 8
• Have medications for anaphylaxis treatment readily accessible 1

When to Consider Allergy Testing

Formal allergy testing is only necessary if:

• The patient has a documented history of immediate-type hypersensitivity reaction (urticaria, angioedema, bronchospasm, cardiovascular collapse) occurring within minutes of local anesthetic administration 2
• Previous records clearly document an anaphylactic reaction temporally related to local anesthetic administration 1

However, skin testing has significant limitations:

• Results are very technique-dependent and require specialist training 1
• Approximately 10% of the general population exhibits skin reactivity to neuromuscular blockers without clinical allergy 9
• Negative testing does not guarantee safety if pretest probability is very low 1

Alternative if True Allergy Confirmed

If true amide local anesthetic allergy is definitively confirmed through proper allergy testing:

• Consider using an ester local anesthetic (chloroprocaine) if cross-reactivity testing is negative 5
• Ester and amide local anesthetics have different chemical structures and do not cross-react 5
• Alternatively, 1% diphenhydramine with epinephrine has been used as a local anesthetic substitute, though this is off-label 5

Critical Pitfalls to Avoid

• Do not avoid neuraxial anesthesia based solely on patient-reported "allergy" without investigating the nature of the previous reaction 3
• Do not assume all local anesthetics cross-react—amide and ester classes are chemically distinct 5
• Do not overlook preservatives as the culprit—always use preservative-free preparations when allergy is suspected 6, 3
• Do not forget latex allergy—this is a more common cause of perioperative anaphylaxis than local anesthetic allergy 1