CLT Cooling & Pain Management 3 — Questions and Answers
Question 1: Methemoglobinemia is a rare but serious adverse effect associated with which topical anesthetic?
- Lidocaine only
- Tetracaine only
- Prilocaine and benzocaine (Correct answer)
- Cocaine hydrochloride
Correct answer: Prilocaine and benzocaine
Prilocaine and benzocaine can oxidize hemoglobin to methemoglobin, reducing oxygen-carrying capacity; this risk is elevated in infants and with large application areas.
Question 2: The 'pre-cooling, parallel cooling, post-cooling' sequence refers to:
- Applying ice before, during, and after each treatment session
- Cooling the skin before, during, and after each laser pulse to maximize epidermal protection (Correct answer)
- Three separate appointments spaced weeks apart
- A three-pass laser technique to improve outcomes
Correct answer: Cooling the skin before, during, and after each laser pulse to maximize epidermal protection
This sequence describes a comprehensive cooling strategy where epidermal protection is maintained before the pulse (pre), during the pulse (parallel), and immediately after (post) to minimize thermal injury.
Question 3: What distinguishes nerve blocks from topical anesthetics in the context of laser procedures?
- Nerve blocks require no licensed provider
- Nerve blocks anesthetize entire anatomic regions and have longer duration than topical agents (Correct answer)
- Nerve blocks are applied to the skin surface 60 minutes before treatment
- Nerve blocks are only used for post-treatment pain management
Correct answer: Nerve blocks anesthetize entire anatomic regions and have longer duration than topical agents
Nerve blocks (regional anesthesia) anesthetize larger anatomic territories and last longer than topical agents but must be administered by qualified medical personnel.
Question 4: Which parameter determines the thermal relaxation time of the epidermis, which cooling systems are designed to exploit?
- Melanin concentration in the basal layer
- Epidermal thickness and thermal diffusivity (Correct answer)
- Sebaceous gland density
- Stratum corneum water content
Correct answer: Epidermal thickness and thermal diffusivity
The thermal relaxation time of the epidermis depends on its thickness (~60–100 µm) and thermal diffusivity, which cooling devices use to selectively remove heat before it damages epidermal cells.
Question 5: A patient with a sulfa drug allergy asks about topical anesthetics. Which agent should be used with caution or avoided?
- Lidocaine
- Prilocaine
- Benzocaine (Correct answer)
- Tetracaine
Correct answer: Benzocaine
Benzocaine is a para-aminobenzoic acid (PABA) ester with cross-reactivity potential in patients allergic to sulfonamides; lidocaine and prilocaine are amides with no sulfa cross-reactivity.
Question 6: Post-treatment pain from ablative resurfacing is best managed in the first 24 hours with:
- Topical steroid cream applied heavily
- Cool saline compresses, oral analgesics, and keeping the area moist (Correct answer)
- Vigorous ice application directly to the wound
- Occlusive petroleum gauze only, no analgesics
Correct answer: Cool saline compresses, oral analgesics, and keeping the area moist
Cool saline compresses soothe acute inflammation, oral analgesics manage pain systemically, and moist wound care supports healing without the risks of direct ice or steroids on open wounds.
Question 7: Which cooling device type delivers cooling ONLY to the epidermis without affecting the target chromophore below?
- Cryogen spray device (Correct answer)
- Chilled water bath
- Ice pack compression
- Refrigerated gel electrode
Correct answer: Cryogen spray device
Cryogen spray cools only the superficial epidermis in milliseconds, leaving the deeper dermal chromophores (e.g., hair follicles, vessels) at ambient temperature and responsive to laser energy.
CLT Cooling & Pain Management 3
Methemoglobinemia is a rare but serious adverse effect associated with which topical anesthetic?