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Skin model surface temperatures during single and multiple cryogen spurts used in laser dermatologic surgery
Author(s) -
RamirezSanJuan Julio C.,
Aguilar Guillermo,
Tuqan Alia T.,
Kelly Kristen M.,
Nelson J. Stuart
Publication year - 2005
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.20124
Subject(s) - millisecond , residence time (fluid dynamics) , materials science , biomedical engineering , nuclear medicine , analytical chemistry (journal) , chemistry , medicine , chromatography , physics , geotechnical engineering , astronomy , engineering
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.