title: [Water-cooled laser sealing of lung tissue in an ex-vivo ventilated porcine lung model].
abstract: BACKGROUND
  Laser resections of lung metastases are followed by air leaks from the parenchymal defect. Large surfaces after metastasectomy are closed by sutures or sealants while smaller areas are frequently sealed thermally by cautery or laser. In this study two different techniques of thermal sealing of lung tissue with laser light are investigated.
  
  
  OBJECTIVE
  Carbonisation of lung tissue during thermal sealing appears at temperatures higher than 180 °C. Hypothetically this is contraproductive to haemo- as well as to pneumostasis. In this experimental study thermal laser sealing with and without carbonisation is investigated. In one series tissue temperatures higher than 100 °C are avoided by water dropping from the tip of the light guide onto the parenchymal leak. In the other series carbonisation appeared because the laser light was applied in the non-contact mode without tissue cooling. The characteristics of the laser were 40 W, 1350 nm continuous mode. Air leaks (Vt) were measured with a simple and fast technique with high precision. The sealing effect of either series was defined as S = (1-Vt/V0) and the difference of S was statistically examined.
  
  
  RESULTS
  The basic values V0 before sealing were about the same in both series. The air leaks Vt after 15, 30 and 45 s of sealing varied significantly in both series (p = 0.03). During simultaneous cooling the sealing effect was increasing with the duration of laser application, while it became worse in the series without cooling. Histological examination of the sealing zone showed only coagulation of the tissue, while ruptured alveolae could be seen more often in the non-cooled sealing area.
  
  
  CONCLUSIONS
  It could be shown in the ex-vivo lung model that laser sealing of parenchymal leaks is improved by simultaneous cooling during laser application. Non cooled laser sealing seems to heat up the tissue abruptly and create carbonisation followed by multiple ruptures of alveola and small airways. In accordance with our clinical experience this experimental study confirms that laser sealing for pneumostasis after metastasectomy can be improved by simultaneously cooling the resection area when treated with the laser.
authors.affiliation: Thoraxchirurgie, Klinikum Bremen Ost, Deutschland.
authors.forename: T
authors.initials: T
authors.lastname: Tonoyan
authors.affiliation: Thoraxchirurgie, Klinikum Bremen Ost, Deutschland.
authors.forename: G
authors.initials: G
authors.lastname: Prisadov
authors.affiliation: Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Universitätsmedizin, Greifswald, Deutschland.
authors.forename: P
authors.initials: P
authors.lastname: Menges
authors.affiliation: Zentrum für Pathologie, Klinikum Bremen Mitte, Bremen, Deutschland.
authors.forename: K
authors.initials: K
authors.lastname: Herrmann
authors.affiliation: Institut für Statistik, Universität Bremen, Deutschland.
authors.forename: P
authors.initials: P
authors.lastname: Bobrov
authors.affiliation: Thoraxchirurgie, Klinikum Bremen Ost, Deutschland.
authors.forename: A
authors.initials: A
authors.lastname: Linder
mesh_terms: D000818:Animals; D006488:Hemostasis, Surgical / Q000295:instrumentation*; D066298:In Vitro Techniques; D017075:Laser Coagulation / Q000295:instrumentation*; D008168:Lung / Q000601:surgery*; D008955:Models, Cardiovascular; D012086:Reoperation; D013552:Swine