title: Thermoforming of tracheal cartilage: viability, shape change, and mechanical behavior.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: The Beckman Laser Institute, 1002 Health Sciences Rd East, Irvine, California 92697, USA. ychae@uci.edu
authors.forename: Yongseok
authors.initials: Y
authors.lastname: Chae
authors.forename: Dmitriy
authors.initials: D
authors.lastname: Protsenko
authors.forename: Paul K
authors.initials: PK
authors.lastname: Holden
authors.forename: Cara
authors.initials: C
authors.lastname: Chlebicki
authors.forename: Brian J F
authors.initials: BJ
authors.lastname: Wong
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002356:Cartilage / Q000033:anatomy & histology* / Q000601:surgery*; D053685:Laser Therapy; D054023:Lasers, Semiconductor / Q000627:therapeutic use*; D011817:Rabbits; D014132:Trachea / Q000033:anatomy & histology* / Q000601:surgery*; D014135:Tracheal Stenosis / Q000601:surgery
references.citation: Photochem Photobiol. 2000 Feb;71(2):218-24
references.pmid: 10687397
references.citation: Ann Otol Rhinol Laryngol. 1996 Mar;105(3):176-81
references.pmid: 8615580
references.citation: Lasers Surg Med. 2003;32(4):271-8
references.pmid: 12696094
references.citation: Arch Facial Plast Surg. 1999 Oct-Dec;1(4):282-7
references.pmid: 10937116
references.citation: J Biomech. 1997 Aug;30(8):813-7
references.pmid: 9239566
references.citation: Lasers Med Sci. 2003;18(3):148-53
references.pmid: 14505198
references.citation: J Appl Physiol (1985). 1994 Jul;77(1):441-51
references.pmid: 7961268
references.citation: Arch Facial Plast Surg. 2006 Mar-Apr;8(2):105-16
references.pmid: 16549737
references.citation: J Appl Physiol (1985). 1992 Jan;72(1):219-25
references.pmid: 1537717
references.citation: Arthroscopy. 2003 Mar;19(3):310-3
references.pmid: 12627157
references.citation: Am J Dis Child. 1985 Jun;139(6):618-20
references.pmid: 4003367
references.citation: J Thorac Cardiovasc Surg. 1994 Jun;107(6):1476-80
references.pmid: 8196392
references.citation: Chest. 1996 Mar;109(3):626-9
references.pmid: 8617068
references.citation: J Bone Joint Surg Am. 2001 Apr;83(4):566-71
references.pmid: 11315786
references.citation: Lasers Surg Med. 2001;29(2):160-4
references.pmid: 11553905
references.citation: Lasers Surg Med. 2005 Sep;37(3):201-9
references.pmid: 16127702
references.citation: Am J Vet Res. 2006 Aug;67(8):1280-5
references.pmid: 16881837
references.citation: J Cosmet Laser Ther. 2002 Mar;4(1):9-14
references.pmid: 12079631
references.citation: Semin Thorac Cardiovasc Surg. 2004 Fall;16(3):220-4
references.pmid: 15619189
references.citation: Lasers Surg Med. 2007 Jun;39(5):451-7
references.pmid: 17565732
references.citation: J Drugs Dermatol. 2006 Sep;5(8):740-4
references.pmid: 16989188
references.citation: J Appl Physiol (1985). 1994 Jun;76(6):2627-35
references.pmid: 7928893
references.citation: Laryngoscope. 1993 Nov;103(11 Pt 1):1273-83
references.pmid: 8231582
references.citation: Am J Vet Res. 1998 Jan;59(1):18-22
references.pmid: 9442237
references.citation: Acta Otorhinolaryngol Belg. 1995;49(4):383-7
references.pmid: 8525837
references.citation: J Appl Physiol (1985). 2003 Jul;95(1):265-71
references.pmid: 12794098
references.citation: Interact Cardiovasc Thorac Surg. 2004 Jun;3(2):349-51
references.pmid: 17670257
references.citation: Laryngoscope. 2003 Aug;113(8):1418-22
references.pmid: 12897569
references.citation: Lasers Surg Med. 2004;34(4):315-22
references.pmid: 15083492
references.citation: Pediatr Surg Int. 2006 Nov;22(11):887-90
references.pmid: 16932914
references.citation: Lasers Surg Med. 2001;28(5):427-34
references.pmid: 11413554
references.citation: Pediatr Res. 1989 Nov;26(5):429-33
references.pmid: 2812893
references.citation: Otolaryngol Head Neck Surg. 1980 Jul-Aug;88(4):409-11
references.pmid: 6821424
references.citation: Connect Tissue Res. 1999;40(4):259-72
references.pmid: 10757114
references.citation: Arch Facial Plast Surg. 2002 Jul-Sep;4(3):180-5
references.pmid: 12167077
references.citation: Biotechnol Genet Eng Rev. 2000;17:553-78
references.pmid: 11255681
references.citation: Arthroscopy. 2001 Feb;17(2):117-23
references.pmid: 11172239
references.citation: Anesth Analg. 2004 May;98(5):1451-3, table of contents
references.pmid: 15105229
references.citation: Curr Probl Surg. 1998 Jun;35(6):453-542
references.pmid: 9630833
references.citation: Am J Vet Res. 2006 Oct;67(10):1708-12
references.pmid: 17014320
references.citation: J Biomech. 1998 Jan;31(1):81-6
references.pmid: 9596542
references.citation: Am Rev Respir Dis. 1973 Feb;107(2):274-9
references.pmid: 4683585