Chae Yongseok, Protsenko Dmitriy, Holden Paul K, Chlebicki Cara, Wong Brian J F
The Beckman Laser Institute, 1002 Health Sciences Rd East, Irvine, California 92697, USA.
Lasers Surg Med. 2008 Oct;40(8):550-61. doi: 10.1002/lsm.20666.
Trauma, emergent tracheostomy, and prolonged intubation are common causes of severe deformation and narrowing of the trachea. Laser technology may be used to reshape tracheal cartilage using minimally invasive methods. The objectives of this study were to determine: (1) the dependence of tracheal cartilage shape change on temperature and laser dosimetry using heated saline bath immersion and laser irradiation, respectively, (2) the effect of temperature on the mechanical behavior of cartilage, and (3) tissue viability as a function of laser dosimetry.
Ex vivo rabbit trachea cartilage specimens were bent and secured around a cylinder (6 mm), and then immersed in a saline bath (45 and 72 degrees C) for 5-100 seconds. In separate experiments, tracheal specimens were irradiated with a diode laser (lambda = 1.45 microm, 220-400 J/cm(2)). Mechanical analysis was then used to determine the elastic modulus in tension after irradiation. Fluorescent viability assays combined with laser scanning confocal microscopy (LSCM) were employed to image and identify thermal injury regions.
Shape change transition zones, between 62 and 66 degrees C in the saline heating bath and above power densities of 350 J/cm(2) (peak temperatures 65+/-10 degrees C) for laser irradiation were identified. Above these zones, the elastic moduli were higher (8.2+/-4 MPa) than at lower temperatures (4.5+/-3 MPa). LSCM identified significant loss of viable chondrocytes within the laser-irradiation zones.
Our results indicate a change in mechanical properties occurs with laser irradiation and further demonstrates that significant thermal damage is concurrent with clinically relevant shape change in the elastic cartilage tissues of the rabbit trachea using the present laser and dosimetry parameters.
创伤、紧急气管切开术和长时间插管是气管严重变形和狭窄的常见原因。激光技术可用于通过微创方法重塑气管软骨。本研究的目的是确定：（1）分别使用热盐水浴浸泡和激光照射时气管软骨形状变化对温度和激光剂量的依赖性，（2）温度对软骨力学行为的影响，以及（3）作为激光剂量函数的组织活力。
将离体兔气管软骨标本弯曲并固定在一个圆柱体（6毫米）周围，然后浸入盐水浴（45和72摄氏度）中5至100秒。在单独的实验中，用二极管激光（波长=1.45微米，220 - 400 J/cm²）照射气管标本。然后进行力学分析以确定照射后拉伸时的弹性模量。采用荧光活力测定法结合激光扫描共聚焦显微镜（LSCM）对热损伤区域进行成像和识别。
确定了盐水加热浴中62至66摄氏度以及激光照射功率密度高于350 J/cm²（峰值温度65±10摄氏度）时的形状变化过渡区。在这些区域之上，弹性模量（8.2±4 MPa）高于较低温度时（4.5±3 MPa）。LSCM识别出激光照射区域内活软骨细胞有显著损失。
我们的结果表明激光照射会导致力学性能发生变化，并进一步证明使用当前的激光和剂量参数，在兔气管弹性软骨组织中，显著的热损伤与临床相关的形状变化同时发生。
