Aesthetic Dermatology MCQ - Fractionated carbon dioxide (CO2) laser

A 60-year-old man with Fitzpatrick skin type II and severe photodamage, deep rhytides, and actinic keratoses desires full-face skin resurfacing. He is prepared for a longer recovery period for optimal results. Which of the following fractionated ablative lasers combines significant tissue ablation with coagulative thermal damage to promote robust neocollagenesis, and what is its primary chromophore?

A) Fractionated carbon dioxide (CO2) laser; water
B) Fractionated erbium:YAG (Er:YAG) laser; water
C) Fractionated 1550 nm erbium-doped fiber laser; water
D) Q-switched Nd:YAG laser; pigment
E) Pulsed dye laser; hemoglobin

Correct Answer: A) Fractionated carbon dioxide (CO2) laser; water

Explanation

This question addresses the use of fractionated ablative lasers, specifically for severe photodamage and deep rhytides.

Key Features of Fractionated Ablative CO2 Laser:

• Mechanism: The fractionated CO2 laser (10,600 nm) delivers microscopic columns of ablative energy that vaporize tissue, creating controlled wounds. It also produces significant coagulative thermal damage in the surrounding dermis, which stimulates robust neocollagenesis and tissue remodeling.

• Chromophore: Water is the primary chromophore for CO2 lasers, as water molecules strongly absorb light at 10,600 nm.

• Indications: Severe photodamage, deep rhytides, actinic keratoses, and scars.

• Advantages: Deeper penetration and greater thermal effects than non-ablative or Er:YAG lasers, leading to more dramatic results.

• Recovery: Typically 7-10 days of re-epithelialization with erythema, edema, and serous exudate.

Why the Fractionated CO2 Laser is Best for This Case:

The patient has severe photodamage and deep rhytides and is prepared for a longer recovery. The fractionated CO2 laser offers the most significant improvement for these concerns due to its ablative and coagulative effects.

Why Not the Other Options?

• (B) Fractionated Er:YAG laser (2940 nm): Also targets water and provides ablation, but it has less coagulative thermal damage than CO2. It is better for mild to moderate photodamage or patients wanting a shorter recovery (5-7 days).

• (C) Fractionated 1550 nm erbium-doped fiber laser: This is a non-ablative device that creates microthermal zones without vaporizing tissue. It targets water but is used for mild photodamage and requires multiple sessions. Recovery is faster (1-2 days of erythema).

• (D) Q-switched Nd:YAG laser (1064 nm): Targets pigment (e.g., melanin, tattoo ink) and is used for pigmented lesions and tattoos, not skin resurfacing.

• (E) Pulsed dye laser (585-595 nm): Targets hemoglobin and is used for vascular lesions (e.g., port-wine stains, rosacea). It is not for resurfacing.

Management Considerations:

• Preoperative: Assess skin type (higher risk of dyspigmentation in types III+), avoid isotretinoin for 6-12 months.

• Postoperative: Meticulous wound care with ointments, strict sun protection, and pain management.

Prognosis:
Excellent for severe photodamage and rhytides, with results lasting years. Risks include dyspigmentation, scarring, and infection.

Note: Fractionated ablative CO2 lasers are the gold standard for significant skin rejuvenation in patients accepting longer downtime. The key is the balance between ablation (vaporization) and coagulation (thermal damage) for optimal neocollagenesis. Always match the laser type to the patient's severity of concerns and downtime tolerance.