What is used for numbing?

Local Anesthetics for Numbing in Medical Procedures

For numbing procedures, lidocaine is the most widely used local anesthetic, available in various formulations including topical creams, gels, injections, and combination products, with specific options selected based on the procedure type and tissue involved. 1

Topical Anesthetics for Intact Skin

• EMLA cream (2.5% lidocaine/2.5% prilocaine) requires 60 minutes under occlusion for full effectiveness on intact skin 1, 2
• Liposomal lidocaine 4% (LMX-4) reaches full effectiveness in 30 minutes 1
• Heated lidocaine preparations become effective in approximately 20 minutes 1
• Maximum strength lidocaine creams (4%) with menthol (1%) are available over-the-counter for pain relief 3

Anesthetics for Open Wounds

• LET solution/gel (lidocaine, epinephrine, tetracaine) is recommended for open wounds, providing anesthesia in 10-20 minutes 1, 2
• For patients >17 kg: apply 3 mL of LET solution directly to the wound and cover with an occlusive dressing 1
• For patients <17 kg: use weight-based dosing of 0.175 mL/kg of LET solution 1
• Allow LET to remain in contact with the wound for 10-20 minutes or until wound edges appear blanched 1, 2

Injectable Local Anesthetics

• Lidocaine 1-2% is most commonly used for infiltration anesthesia 1
• Bupivacaine 0.25% provides longer-lasting anesthesia (up to 8 hours) compared to lidocaine (1-2 hours) 1
• Ropivacaine 0.2% offers prolonged anesthesia with less cardiotoxicity than bupivacaine 1, 4
• Mepivacaine has an intermediate duration of action and is useful when epinephrine is contraindicated 5

Techniques to Reduce Pain of Administration

• Buffer lidocaine with sodium bicarbonate to reduce injection pain 1
• Warm the anesthetic solution to body temperature before injection 1, 6
• Use the smallest gauge needle possible and inject slowly 1
• Apply manual pressure to injection sites to reduce discomfort 1

Special Considerations for Different Procedures

For IUD Placement

• Topical options include 4-5g EMLA cream applied to the cervix 1
• Intracervical block with 2mL 1% lidocaine immediately prior to tenaculum placement 1
• Paracervical block with buffered 1% lidocaine at the 4 and 8 o'clock positions at the cervicovaginal junction 1

For Pediatric Procedures

• For neonates and infants <6 months: 2mL of 25% sucrose solution administered orally 2 minutes before painful procedures provides analgesic effects 1
• Use pacifiers in conjunction with sucrose for enhanced effect 1
• For children, topical anesthetics should be placed at multiple potential IV sites to improve success rates 1

For Regional Nerve Blocks

• Bupivacaine 0.25%: 0.2-0.5 mL/kg for peripheral nerve blocks 1
• Ropivacaine 0.2%: 0.2-0.5 mL/kg for peripheral nerve blocks 1
• Preservative-free clonidine (1-2 mcg/kg) can be added to enhance and prolong analgesia 1

Safety Considerations and Precautions

• Calculate maximum doses based on patient weight to prevent toxicity 5, 7
• Avoid using multiple forms of lidocaine simultaneously to prevent potential toxicity 2, 8
• Monitor for signs of systemic absorption: dizziness, confusion, tinnitus, or bradycardia 5, 9
• Use caution in patients with hepatic or renal disease due to altered metabolism and clearance 5, 7
• Contraindications include allergy to amide anesthetics and grossly contaminated wounds for topical applications 1

Common Pitfalls to Avoid

• Insufficient contact time for topical anesthetics (10-20 minutes for LET, 60 minutes for EMLA) results in inadequate anesthesia 1, 2
• Applying lidocaine products to grossly contaminated wounds reduces effectiveness and increases infection risk 1
• Using multiple lidocaine-containing products simultaneously increases the risk of systemic toxicity 2, 8
• Failure to buffer lidocaine with bicarbonate when injecting increases pain of administration 1