title: Tubeless combined high-frequency jet ventilation for laryngotracheal laser surgery in paediatric anaesthesia.
abstract: BACKGROUND
  High-frequency jet ventilation (HFJV) is an alternative ventilatory approach in airway surgery and for facilitating gas exchange in patients with pulmonary insufficiency. We have developed a new technique of combined HFJV utilising two superimposed jet streams. In this study we describe the application of tubeless supralaryngeal HFJV during laryngotracheal laser surgery in infants and children.
  
  
  METHODS
  Tubeless combined HFJV characterised by the simultaneous supralaryngeal application of a low-frequency (LF) and a high-frequency (HF) jet stream was evaluated in a clinical study in 10 children undergoing elective laryngotracheal CO2 laser surgery. Additionally, pressure and flow characteristics were determined with the use of a paediatric test lung. HFJV was applied by means of a modified Kleinsasser laryngoscope with integrated metal injectors. In addition to pulse oximetry, monitoring of ECG, heart rate and blood pressure, supraglottic airway pressure was measured and arterial blood gases were analysed.
  
  
  RESULTS
  Tubeless combined HFJV was used in 10 infants and children (mean age 4.6 yr, range 2 months-10 years) undergoing 17 consecutive endoscopic procedures with CO2 laser microsurgery of the larynx or the trachea under general anaesthesia. The mean duration of supralaryngeal HFJV was 46 min (range 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 test 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, respectively.
  
  
  CONCLUSIONS
  The application of the combined double frequency HFJV was effective in maintaining gas exchange in the presence of laryngeal or tracheal stenoses. It provided good visibility of anatomical structures and offered space for surgical manipulation, avoiding the use of combustible material inside the larynx or trachea.
authors.affiliation: Department of Anaesthesiology and General Intensive Care, University of Vienna, Austria. gerald.ihra@univie.ac.at
authors.forename: G
authors.initials: G
authors.lastname: Ihra
authors.forename: C
authors.initials: C
authors.lastname: Hieber
authors.forename: S
authors.initials: S
authors.lastname: Adel
authors.forename: A
authors.initials: A
authors.lastname: Kashanipour
authors.forename: A
authors.initials: A
authors.lastname: Aloy
mesh_terms: D000771:Anesthesia, Intravenous; D002648:Child; D002675:Child, Preschool; D006611:High-Frequency Jet Ventilation / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007223:Infant; D007828:Laryngoscopy; D007830:Larynx / Q000601:surgery*; D053685:Laser Therapy; D014132:Trachea / Q000601:surgery*