title: Supraglottic combined frequency jet ventilation versus subglottic monofrequent jet ventilation in patients undergoing microlaryngeal surgery.
abstract: We compared the efficacy of gas exchange during supraglottic combined-frequency jet ventilation via a jet ventilation laryngoscope and during monofrequent jet ventilation via the Mon-Jet catheter (Xomed, Jacksonville, FL). Twenty-three anesthetized (propofol, fentanyl, vecuronium) patients undergoing microlaryngeal surgery were prospectively studied and randomly assigned to one of two groups. The patients' lungs were ventilated with combined-frequency jet ventilation (10 min, 15 and 600 breaths/min, inspiration/expiration time ratio = 1, driving pressure 750-1500 mm Hg), monofrequent (low-frequency group: 15 breaths/min; high-frequency group: 600 breaths/min) jet ventilation (20 min), and again combined-frequency jet ventilation (15 min). PaO(2), PaCO(2), and the inspiratory oxygen fraction (FIO(2)) were measured. Wilcoxon's signed rank test was applied. During monofrequent jet ventilation, PaCO(2) increased and the PaO(2)/FIO(2) decreased significantly (P < 0.05) as compared with combined-frequency jet ventilation (low-frequency group: PaCO(2) from 39.4 +/- 3.3 to 50. 8 +/- 8.0 mm Hg, PaO(2)/FIO(2) from 306 +/- 100 to 225 +/- 94 mm Hg; high-frequency group: PaCO(2) from 36.7 +/- 7.2 to 60.3 +/- 6.1 mm Hg, PaO(2)/FIO(2) from 429 +/- 87 to 190 +/- 51 mm Hg; mean +/- SD). After switching back to combined-frequency jet ventilation, PaCO(2) decreased and PaO(2)/FIO(2) increased to baseline levels. We conclude that gas exchange during microlaryngeal surgery can be more easily maintained with supraglottic combined-frequency jet ventilation than with subglottic monofrequent jet ventilation via the Mon-Jet catheter.
  
  
  CONCLUSIONS
  This study demonstrates that the combination of high- and low-frequency supraglottic jet ventilation via a jet ventilation laryngoscope provides a better pulmonary gas exchange and allows more accurate airway pressure monitoring during microlaryngeal surgery than subglottic monofrequent jet ventilation via an endotracheal catheter.
authors.affiliation: Department of Anesthesiology and General Intensive Care, University of Vienna, Austria. andreas.bacher@univie.ac.at
authors.forename: A
authors.initials: A
authors.lastname: Bacher
authors.forename: K
authors.initials: K
authors.lastname: Pichler
authors.forename: A
authors.initials: A
authors.lastname: Aloy
mesh_terms: D000328:Adult; D000399:Air Pressure; D000769:Anesthesia, Inhalation; D001784:Blood Gas Analysis; D003198:Computer Simulation; D005931:Glottis / Q000033:anatomy & histology*; D006611:High-Frequency Jet Ventilation; D006801:Humans; D007830:Larynx / Q000601:surgery*; D008168:Lung / Q000502:physiology; D008365:Manometry; D008866:Microsurgery; D008953:Models, Anatomic; D011446:Prospective Studies; D012121:Respiration, Artificial