Graded carbon dioxide laser-induced subglottic injury in the rabbit model.
OBJECTIVE
To conduct an endoscopic and histologic analysis of the subglottic effects of various carbon dioxide laser-induced injuries in the rabbit model.


METHODS
Animals were assigned to either a control (cricothyroidotomy only) group or 4 (cricothyroidotomy and posterior subglottic laser) groups that were injured using varying systematically controlled carbon dioxide laser power exposures (5 W, 8 W, and 12 W), with durations of 2 or 4 seconds, and surface area exposures (25% or 40%).


METHODS
Twenty-seven New Zealand white rabbits.


METHODS
The subglottis was approached via cricothyroidotomy. Control airways were immediately closed, while injured airways were subjected to graded carbon dioxide laser exposures prior to closure. Airways were endoscopically monitored preoperatively, immediately postoperatively, and on postoperative days 1, 7, 14, and 21, after which the animals were humanely killed and subglottic tissue harvested for histological evaluation.


RESULTS
Clinical observation revealed no significantly obstructive (acute) stenosis during the duration of the study. Endoscopic visualization revealed the formation of posterior subglottic scarring. Histological analysis of the mucosa revealed that use of carbon dioxide laser resulted in a statistically significant (unpaired, 2-tailed t test, P<.05) proportional thickening of the lamina propria layer, without significant changes in the epithelial and cartilaginous layers. In addition, mucosal blood vessel size increased proportional to the power of the laser delivered to the area (P<.05).


CONCLUSIONS
Carbon dioxide laser-induced injury to the subglottis caused localized scarring, lamina propria thickening, and increased vascularity, which resolved with time and was not associated with significant airway obstruction. This model describes a systematic, controlled, and reproducible method of investigating subglottic injury.
Chafin
J Brett
JB
Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, PA, USA.
Sandulache
Vlad C
VC
Dunklebarger
Joshua L
JL
Otteson
Todd D
TD
Hoffmann
Paul J
PJ
Hoffmann
Paul A
PA
Hebda
Patricia A
PA
Dohar
Joseph E
JE
D000818:Animals; D002245:Carbon Dioxide; D005931:Glottis / Q000293:injuries*; D007091:Image Processing, Computer-Assisted; D007828:Laryngoscopy; D053685:Laser Therapy / Q000009:adverse effects*; D011817:Rabbits; D015203:Reproducibility of Results; D014945:Wound Healing / Q000502:physiology
D002245:Carbon Dioxide