Supraglottic combined frequency jet ventilation versus subglottic monofrequent jet ventilation in patients undergoing microlaryngeal surgery

We compared the efficacy of gas exchange during supraglottic combined-frequ ency jet ventilation via a jet ventilation laryngoscope and during monofreq uent jet ventilation via the Mon-Jet catheter (Xomed, Jacksonville, FL). Tw enty-three anesthetized (propofol, fentanyl, vecuronium) patients undergoin g microlaryngeal surgery were prospectively studied and randomly assigned t o one of two groups. The patients' lungs were ventilated with combined-freq uency jet ventilation (10 min, 15 and 600 breaths/min, inspiration/expirati on time ratio = 1, driving pressure 750-1500 mm Hg), monofrequent (low-freq uency group: 15 breaths/min; high-frequency group: 600 breaths/min) jet ven tilation (20 min), and again combined-frequency jet ventilation (15 min). P aO2 PaCO2 and the inspiratory oxygen fraction (FIO2) were measured. Wilcoxo n's signed rank test was applied. During monofrequent jet ventilation, PaCO 2 increased and the PaO2/FIO2 decreased significantly (P < 0.05) as compare d with combined-frequency jet ventilation (low-frequency group: PaCO2 from 39.4 +/- 3.3 to 50.8 +/- 8.0 mm Hg, PaO2/FIO2 from 306 +/- 100 to 225 +/- 9 4 mm Hg; high-frequency group: PaCO2 from 36.7 +/- 7.2 to 60.3 +/- 6.1 mm H g, PaO2/FIO2 from 429 +/- 87 to 190 +/- 51 mm Hg; mean +/- SD). After switc hing back to combined-frequency jet ventilation, PaCO2 decreased and PaO2/F IO2 increased to baseline levels. We conclude that gas exchange during micr olaryngeal surgery can be more easily maintained with supraglottic combined -frequency jet ventilation than with subglottic monofrequent jet ventilatio n via the Mon-Jet catheter. implications: This study demonstrates that the combination of high- and low-frequency supraglottic jet ventilation via a j et ventilation laryngoscope provides a better pulmonary gas exchange and al lows more accurate airway pressure monitoring during microlaryngeal surgery than subglottic monofrequent jet ventilation via an endotracheal catheter.