Dynamic cooling of human skin using a nontoxic cryogen with no ozone depletion and minimal global warming potential

Abstract

A method and apparatus for performing a laser treatment of a patient includes applying a positive pressure impulse on a predetermined target site on the patient with sufficient positive pressure arising from the momentum flux of sprayed material incident on the target site to momentarily lessen pain sensation during irradiation during or proximate in time to irradiation of the target site. The predetermined target site is cooled by applying a predetermined amount of coolant or cryogen onto the target site. The target site is radiated with energy to produce heat in tissue at the target site while leaving a superficial part of the target site substantially undamaged due to dynamic cooling of the superficial part of the target site by the coolant. Mediation of the pain sensation arising from the radiation is at least partially masked or lessened by the positive pressure impulse and / or by the temperature of the coolant.

Description

[0001]The present application is a continuation-in-part application of copending U.S. patent application Ser. No. 11 / 845,503, filed on Aug. 27, 2007, which in turn is related to U.S. Provisional Patent Application Ser. No. 60 / 840,867, filed on Aug. 28, 2006, both of which are incorporated herein by reference and to which priority is claimed pursuant to 35 USC 120.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to the field of therapeutic treatment of skin or tissue by exposure to light or other electromagnetic radiation in combination with cryogen cooling of the irradiated tissue.[0004]2. Description of the Prior Art[0005]An important issue in laser treatment of cutaneous lesions is to protect the epidermis from thermal damage. This heating, which is primarily caused by light absorption in the melanosomes, can easily bring the temperature of the basal layer above the threshold damage value of 65-70° C. Precooling of the epidermal basal layer fro...

AI Technical Summary

Benefits of technology

Liquid carbon dioxide effectively reduces pain and thermal damage during laser treatments by providing efficient cooling with a low global warming potential, reducing the risk of ignition and skin damage, while allowing for precise control of cooling patterns and pain management.

Problems solved by technology

An important issue in laser treatment of cutaneous lesions is to protect the epidermis from thermal damage.

Potential non-flammable candidates for cryogen spray cooling could be carbon dioxide (CO2, R-744) or nitrous oxide (N2O, R-744a) but, unfortunately, these compounds do not form boiling liquids at atmospheric pressure.

Liquid CO2 results in dry-ice formation immediately after leaving the outlet nozzle.

However, the evaporation loss is high, and the cryogenic equipment for delivering liquid cryogen spurts in the 100 ms range might be technically very cumbersome.

Thus, the combined use of flammable cryogen and high laser energy might induce burns to the skin.

Port wine stain is a congenital lesion with a frequency of one in two hundred births, often resulting in a high psychological burden for the child.

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