An evaluation of one method of ventilation for laser therapy to the tracheobronchial tree.

Laser therapy has been used extensively for surgery to the respiratory tract since its first application in 1971. At this hospital, the surgeon's preferred technique for laser surgery to the tracheobronchial tree is to use the Nd-YAG laser through a fibreoptic bronchoscope passed through a rigid bronchoscope. General anaesthesia is employed and ventilation is controlled using jet-ventilation by the Sanders technique. Review of the literature failed to locate adequate information on the effect of manoeuvres such as insertion of instruments and the presence of a tracheal obstruction distal to the bronchoscope on the quality of ventilation using this technique. A bench study was undertaken, therefore, in an attempt to mimic such clinical situations and to assess the effect of such manoeuvres on the adequacy and pattern of ventilation. Under all conditions tested 'end-tidal' CO2 concentrations accurately reflected distal 'tracheal' concentrations. The lowest inspired O2 concentration was 50% while entraining air through the bronchoscope. The highest was 86% while entraining oxygen.