Skin model surface temperatures during single and multiple cryogen spurts used in laser dermatologic surgery
✍ Scribed by Julio C. Ramirez-San-Juan; Guillermo Aguilar; Alia T. Tuqan; Kristen M. Kelly; J. Stuart Nelson
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 121 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0196-8092
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Background
Although cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during laser dermatologic surgery, concern has been expressed that CSC may induce cryo‐injury. In order to address this concern, it is necessary to evaluate the effects of prolonged exposure of human skin phantoms (HSP) to CSC.
Objective
To measure the minimum surface temperature (T~min~) and the time at which it occurs (t~Tmin~) as well as determine the time the sprayed HSP surface remains below 0°C (sub‐zero time, Δ__t__~s~) and −26°C (residence time, Δ__t__~r~) during the application of single (SCS) and multiple (MCS) cryogen spurts. Two initial HSP substrate temperatures were studied, T~i~: 23 and 70°C.
Study Design/Materials and Methods
An epoxy‐based HSP was constructed to measure T~min~, t~Tmin~, Δ__t__~s~, and Δ__t__~r~, for 17 spray patterns: 1 SCS with a total cryo‐delivery time (Δ__t~c~) of 40 milliseconds; 8 MCS patterns with identical Δ__t~c~, but with a total cooling time (Δ__t__~total~) varying from 50 to 280 milliseconds; and 8 SCS patterns that matched the Δ__t__~total~ of the MCS patterns.
Results
For both T~i~, our results show that it is possible to distinguish between two different cooling regimes. For Δ__t__~total~ ≤ 110 milliseconds, the differences between SCS and MCS patterns with the same Δ__t__~total~ for all variables (T~min~, t~Tmin~, Δ__t__~s~, Δ__t__~r~) are negligible. Most importantly, all these variables show a remarkable linear dependence with Δ__t__~total~. In the interval 110 milliseconds < Δ__t__~total~ < 280 milliseconds, T~min~ and t~Tmin~ are similar for SCS and MCS, while Δ__t__~s~ and Δ__t__~r~ show more pronounced differences between the two spray patterns. In this interval, the values of T~min~ and Δ__t__~s~ for MCS remain invariant and similar to the corresponding values for Δ__t__~total~ = 110 milliseconds.
Conclusions
These results suggest that: (1) similar epidermal protection may be attained with SCS and MCS for Δ__t__~total~ ≤ 110 milliseconds; and (2) for 110 milliseconds < Δ__t__~total~ ≤ 280 milliseconds, MCS help to maintain Δ__t__~s~ similar to that of SCS at Δ__t__~total~ = 100 milliseconds, which may be beneficial to prevent cryo‐injury. Lasers Surg. Med. 36:141–146, 2005. © 2005 Wiley‐Liss, Inc.