Tuberc Respir Dis.  1988 Jun;35(2):73-87. 10.4046/trd.1988.35.2.73.

An Experimental Study on Safety and Efficacy of Nd-YAG Laser Irradiation in Tracheobronchial Tree

• KMID: 2528608
• DOI: http://doi.org/10.4046/trd.1988.35.2.73

Abstract

Nd-YAG Laser photoresection is an effective treatment modality in malignant airway obstruction but is not without complications. The major reported complications were perforation of airway, massive bleeding, asphyxia and cardiovascular complications. Most perforations and bleedings were due to an excess in the irradiated dosage. There have been some suggestions for safe dosage according to clinical experience but none are based on experimental data. The large airway is composed of two different section of histology, i.e., the anterior cartilaginous section and the posterior membranous section; the thickness of wall becomes thinner in the main bronchus than in the trachea. It is expected that the safe dosage may be different in the various sections of the tracheobronchial tree. We performed an in vitro study using 50 porcine a irway and an in vivo study in 5 dogs to determine the safe dosage in various sections of the airways in Nd-YAG laser photoresection. In the porcine airway, the safe dosage was 40-60 J in trachea and 30-40 J in main bronchus. There was no difference in anterior and posterior section due to anatomic characteristics of the porcine tracheobronchial tree The tissue injury was more severe with higher energy and shorter irradiation time than with lower energy and longer time with same irradiation dosage. Tissue injury was also more extensive at non-irradiated adventitial site than at irradiated mucosal site. In the in vivo study using canine trachea, tissue damage was definitely more severe in the posterior section of trachea than in the anterior section. Cartilage was a barrier for blocking further tissue damage. The safe dosage was 60-80 J for the anterior section, 40-60 J in posterior section in trachea and 30-40 J in main bronchus respectively. After laser irradiation, there was no delayed type tissue injury and healing process supervened.