激光皮肤科手术中单次及多次喷射冷冻剂时皮肤模型表面温度。

Ramirez-San-Juan Julio C, Aguilar Guillermo, Tuqan Alia T, Kelly Kristen M, Nelson J Stuart

Beckman Laser Institute and Medical Clinic, University of California, Irvine, California 92612, USA.

Lasers Surg Med. 2005 Feb;36(2):141-6. doi: 10.1002/lsm.20124.

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 degrees C (sub-zero time, Deltat(s)) and -26 degrees C (residence time, Deltat(r)) during the application of single (SCS) and multiple (MCS) cryogen spurts. Two initial HSP substrate temperatures were studied, T(i): 23 and 70 degrees C.

STUDY DESIGN/MATERIALS AND METHODS: An epoxy-based HSP was constructed to measure T(min), t(Tmin), Deltat(s), and Deltat(r), for 17 spray patterns: 1 SCS with a total cryo-delivery time (Deltat(c)) of 40 milliseconds; 8 MCS patterns with identical Deltat(c), but with a total cooling time (Deltat(total)) varying from 50 to 280 milliseconds; and 8 SCS patterns that matched the Deltat(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 Deltat(total) </= 110 milliseconds, the differences between SCS and MCS patterns with the same Deltat(total) for all variables (T(min), t(Tmin), Deltat(s), Deltat(r)) are negligible. Most importantly, all these variables show a remarkable linear dependence with Deltat(total). In the interval 110 milliseconds < Deltat(total) < 280 milliseconds, T(min) and t(Tmin) are similar for SCS and MCS, while Deltat(s) and Deltat(r) show more pronounced differences between the two spray patterns. In this interval, the values of T(min) and Deltat(s) for MCS remain invariant and similar to the corresponding values for Deltat(total) = 110 milliseconds.

CONCLUSIONS

These results suggest that: (1) similar epidermal protection may be attained with SCS and MCS for Deltat(total) </= 110 milliseconds; and (2) for 110 milliseconds < Deltat(total) </= 280 milliseconds, MCS help to maintain Deltat(s) similar to that of SCS at Deltat(total) = 100 milliseconds, which may be beneficial to prevent cryo-injury.

背景

尽管在激光皮肤科手术中使用冷冻喷雾冷却（CSC）来将表皮损伤风险降至最低，但有人担心CSC可能会导致冷冻损伤。为了解决这一担忧，有必要评估人体皮肤模型（HSP）长时间暴露于CSC的影响。

目的

测量单次（SCS）和多次（MCS）冷冻剂喷射过程中HSP表面的最低温度（T(min)）及其出现的时间（t(Tmin)），并确定喷射的HSP表面温度保持在0摄氏度以下的时间（零下时间，Deltat(s)）以及-26摄氏度的时间（停留时间，Deltat(r)）。研究了两种初始HSP底物温度，T(i)：23和70摄氏度。

研究设计/材料与方法：构建了一种基于环氧树脂的HSP，用于测量17种喷雾模式下的T(min)、t(Tmin)、Deltat(s)和Deltat(r)：1次总冷冻剂输送时间（Deltat(c)）为40毫秒的SCS；8种Deltat(c)相同但总冷却时间（Deltat(total)）从50到280毫秒不等的MCS模式；以及8种与MCS模式的Deltat(total)相匹配的SCS模式。

结果

对于两种T(i)，我们的结果表明可以区分两种不同的冷却状态。对于Deltat(total)≤110毫秒，所有变量（T(min)、t(Tmin)、Deltat(s)、Deltat(r)）在Deltat(total)相同的SCS和MCS模式之间的差异可以忽略不计。最重要的是，所有这些变量都与Deltat(total)呈现出显著的线性关系。在110毫秒<Deltat(total)<280毫秒的区间内，SCS和MCS的T(min)和t(Tmin)相似，而两种喷雾模式下的Deltat(s)和Deltat(r)差异更为明显。在此区间内，MCS的T(min)和Deltat(s)值保持不变，且与Deltat(total)=110毫秒时的相应值相似。

结论

这些结果表明：（1）对于Deltat(total)≤110毫秒，SCS和MCS可能实现相似的表皮保护；（2）对于110毫秒<Deltat(total)≤280毫秒，MCS有助于将Deltat(s)维持在与Deltat(total)=100毫秒时SCS的Deltat(s)相似的水平，这可能有利于预防冷冻损伤。