Respiratory efficacy of subglottic low-frequency, subglottic combined-frequency, and supraglottic combined-frequency jet ventilation during microlaryngeal surgery

We tested the respiratory efficacy of different jet ventilation techniques (subglottic low-frequency versus subglottic combined-frequency and subglottic combined frequency versus supraglottic combined frequency) in patients undergoing microlaryngeal surgery. The Pace, and the quotient of arterial oxygen tension (Pao(2)) over FIo(2) were measured. After anesthetic induction (propofol, remifentanil, vecuronium), an endotracheal Mon-Jet catheter (Xomed, Jacksonville, FL) for subglottic jet ventilation and a laryngoscope for supraglottic jet ventilation (Carl Reiner G.m.b.H., Vienna, Austria) were inserted. In Group 1 (n = 18), subglottic low-Frequency (15 breaths/min), combined-frequency (600 and 15 breaths/min), and low-frequency jet ventilation was subsequently performed (15 min each). In Group 2 (n = 19), the sequence was supraglottic, subglottic, and supraglottic combined-frequency jet ventilation. The driving pressures were initially adjusted to achieve normocapnia and were not changed during the entire study period. The FIo(2) was measured endotracheally. The Wilcoxon's signed rank test tvas applied, In Group 1, Paco(2) and Pao(2)/FIo(2) improved significantly after switching from subglottic low-frequency to subglottic combined-frequency jet ventilation (Paco(2) from 46.6 +/- 8.3 to 42.1 +/- 8.1 mm Hg; Pao(2)/FIo(2) from 311 +/- 144 to 361 +/- 141 mm Hg; P < 0.05). In Group 2, Paco(2) increased and Pao(2)/FIo(2) decreased significantly after switching from supraglottic to subglottic combined frequency jet ventilation (Paco(2) from 39.4 +/- 7.1 to 45.9 +/- 7.5 mm Hg; Pao(2)/FIo(2) from 415 +/- 114 to 351 +/- 129 mmHg; P <0.05). We conclude that subglottic combined-frequency jet ventilation is less effective than supraglottic combined-frequency ventilation, but more effective than subglottic low-frequency jet ventilation.