Introduction

The CO2 laser is the most resourceful laser in the management of cutaneous lesions. It is the gold standard amongst all ablative lasers. Potential applications of this laser in day to day dermatological practice are boundless. Advances in both power and delivery have made CO2 laser a flexible device, which is progressively more effective in dermatology and aesthetic practice. It has found use in both incisional and excisional procedures along with fractional resurfacing. This article gives a brief overview of the laser physics and its limitless indications in dermatology.

Laser physics:

The CO2 laser emits invisible far infrared light at 10,600nm either in a continuous wave or/ pulsed/ superpulsed /ultrapulsed mode. The laser light energy is absorbed within 20-500µm in the soft tissue and 90% of it is selectively absorbed by water which is its target chromophore. Based on the principle of selective thermolysis the absorption of this energy results in rapid heating and tissue vaporisation. Use of CO2 laser requires alertness of the power distribution within the impact spot, referred to as transverse electromagnetic mode (TEM).  The most basic (TEM₀) represents normal distribution i.e. 86% of power within the spot of impact. This TEM highlights the significance of adjoining thermal damage zones and importance of laser setting to avoid tissue injury.

The parameter setting for the CO2 laser relies on its delivery mode whether pulsed or continuous. For continuous mode power is the primary setting.

Excision /cutting mode:

A higher irradiance is required for tissue excision. Irradiance /Power density (W/cm²) = Power output / impact spot size. Hence the beam is focussed to a small diameter (0.1-0.2 mm) with high output (1-30 W) in order to achieve a higher irradiance (between 50,000 – 1, 00, 000W/cm²). Additionally the hand piece can be operated in a focused mode, yielding high irradiance and excellent cutting properties or it may be used in a defocused mode, yielding lower irradiance and better coagulative properties.

Indications

CO2 laser has found its use in limitless indications(benign and malignant lesions) in dermatology , when used  individually or in combination with other procedures(Table1).With the advent of the fractional CO2 laser the results in aesthetic practice have been impressive.

Table1 : Common, uncommon and CO2 laser assisted indications

Contraindications:

History of keloid or hypertrophic scar, active bacterial or viral infection? Use of isotretinoin in the last 6 months, collagen vascular disease, atrophic hairless scars of burns and trauma.

Pre operative Procedures:

Informed consent: Proper Informed consent to be obtained , specifically mentioning the possible appearance of the post treated area , including possible pigmentory changes and need for post operative care.

Anaesthesia: Co2 laser being ablative laser anaesthesia is a pre requirement. Depending on the type of lesion these can range from topical anaesthetics i.e. EMLA(eutectic mixture of local anaesthesia) to local infiltration and ring or field blocks. Superficial epidermal lesions can be treated under topical anaesthetics   with minimal discomfort. Care should be taken to avoid lignocaine with adrenaline while locally infiltrating areas with end arteries including ear lobes, fingers, toes, nose and penis.

Intraoperative:

Being ablativeCo2 lasers pose a fire hazard. Presence of oxygen further increases the risk. Hair sprays and alcohol based gels are highly inflammable and hence moistened towels and sponges should be used to drape the perimeter of laser treatment areas. It produces plume of smoke due to thermal interaction with human tissue that may contain chemicals, portions of intact DNA, bacteria and viruses. Mechanical smoke evacuator system with a high-efficiency particulate air (HEPA) or an ultra-low penetration air (ULPA) filter should be used to capture the plume, nozzle of which should be placed possibly within 1-2 cm of the lasing site. Patient’s eye should be protected with an eye shield or wet gauze.

Postoperative:

It is vital to discuss postoperative care with the patient at initial consultation to establish if he /she are amenable and thus a candidate for laser: Post operative care includes:

·         Topical antibiotics for a week for superficial epidermal lesions post procedure.

·         Instructions to avoid picking the scabs.

·         Sun protection for lesions treated on face and neck.

·         Occlusive dressing in case of deeper lesions.

Complications:

Minor complications include, post inflammatory hyper and hypopigmentation,  erythema,  acne and rosacea  exacerbations. More serious complication include, hypertrophic scarring, delayed healing and ectropion formation.

Conclusion: Co2 laser has satisfactory outcomes with minimal side effects in various aesthetic and dermatology procedures. It is one of the most resourceful tools in dermatology practice.

References:

1. Krupa Shankar D, Chakravarthi M, Shilpakar R. Carbon dioxide laser guidelines. J Cutan Aesthet Surg.2009;2:72–80

2. Savant S. Textbook of dermatosurgery and cosmetology. 2nd ed. India: ASCAD-Mumbai; 2008. The carbon dioxide (CO₂) and erbium: YAG (Er: YAG) lasers; pp. 462–76.

3. Hruza GJ. Laser treatment of epidermal and dermal lesions. Dermatol Clin. 2002;20:147–64.