Tubeless combined high-frequency jet ventilation for laryngotracheal lasersurgery in paediatric anaesthesia

Background: High-frequency jet ventilation (HFJV) is an alternative ventila tory approach in airway surgery and for facilitating gas exchange in patien ts with pulmonary insufficiency. We have developed a new technique of combi ned HFJV utilising two superimposed jet streams. In this study we describe the application of tubeless supralaryngeal HFJV during laryngotracheal lase r surgery in infants and children. Methods: Tubeless combined HFJV characterised by the simultaneous supralary ngeal application of a low-frequency (LF) and a high-frequency (HF) jet str eam was evaluated in a clinical study in 10 children undergoing elective la ryngotracheal CO2 laser surgery. Additionally, pressure and flow characteri stics were determined with the use of a paediatric test lung. HFJV was appl ied by means of a modified Kleinsasser laryngoscope with integrated metal i njectors. In addition to pulse oximetry, monitoring of EGG, heart rate and blood pressure, supraglottic airway pressure was measured and arterial bloo d gases were analysed. Results: Tubeless combined HFJV was used in 10 infants and children (mean a ge 4.6 yr, range 2 months-10 years) undergoing 17 consecutive endoscopic pr ocedures with CO2 laser microsurgery of the larynx or the trachea under gen eral anaesthesia. The mean duration of supralaryngeal HFJV was 46 min (rang e 15-75 min). Mean driving pressures of the HF and the LF jet streams were 0.75 bar and 0.95 bar, respectively. Inspiratory oxygen ratios were in the range 0.4-1.0. HFJV resulted in mean PaO2 and PaCO2 values of 19.7 kPa and 6.1 kPa, respectively. No complications during HFJV were observed. In the t est lung, combined HFJV applied with driving pressures of 0.7-1.0 bar and 0 .9-1.2 bar for HF and LF jet ventilation, respectively, resulted in maximum peak and baseline distal airway pressures of 17.6 cm H2O and 5.4 cm H2O, r espectively. Conclusion: The application of the combined double frequency HFJV was effec tive in maintaining gas exchange in the presence of laryngeal or tracheal s tenoses. It provided good visibility of anatomical structures and offered s pace for surgical manipulation, avoiding the use of combustible material in side the larynx or trachea. (C) Acta Anaesthesiologica Scandinavica 44 (2000).