Morphological changes induced by extensive endobronchial electrocautery

Due to recent improvements of safety conditions for therapeutic devices, electrocautery is being considered with renewed interest in the field of therapeutic bronchoscopy. The efficiency of this technique for destructing intraluminal tumours is well documented and makes it an attractive alternative to Yttrium aluminium garnet (YAG) laser photo-coagulation. Little is known, however, about the morphologic changes induced by electrocautery within the bronchial wall structures. This information is, however, important since electrocautery has been proposed as an alternative to other techniques to treat superficial tumours of the bronchial wall. Soft coagulation, with autostop, using two different power setting (40 and 120 W), produced by a new generation of high frequency voltage regulated generators was applied circumferentially to the trachea or left main bronchus, in a series of 52 piglets. Early (48 h) and late effects (6 weeks) were assessed through gross examination (bronchoscopy and autopsy) and light microscopy. Early effects of electrocautery included coagulation necrosis of the mucosa only and intense acute inflammation extending deep into the bronchial structure. The inflammatory phase progressively resolved while extensive transmural fibrosis and deterioration of the cartilage plates developed. The nature and extent of these lesions did not depend upon the energy delivered (40 W versus 120 W). Retractile scar formation and loss of cartilaginous support then produced iatrogenic secondary stenoses. These results do not question the use of electrocautery to palliate endoluminal tumours but should make operators careful when treating extensive infiltration of the bronchial wall.