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[Clinical experiences with the double jet technique superimposed HFJV (high frequency jet ventilation) during
1Klinik für Anästhesiologie und Allgemeine Intensivmedizin, Universität, Wien, Austria. gerald.ihra@univie.ac.at
Objective:
Single-frequency high-frequency jet ventilation (HFJV) is an established ventilatory technique during laryngotracheal surgery. This study describes the clinical use of combined HFJV, characterised by the simultaneous application of a low-frequent (LF) and a high-frequent (HF) jet stream.
Methods:
Two jet streams with different pulsatile frequency (HF approx. 10 Hz, LF 10-30 bpm) and adjustable driving pressures were applied supraglottically by means of a special jet laryngoscope in patients undergoing elective laryngotracheal surgery during total intravenous anaesthesia. HFJV was performed using a pneumatic or electronic jet respirator connected to the central gas supply.
Results:
134 patients were submitted to tubeless HFJV applying the double-jet technique using the jet-laryngoscope. Duration of HFJV was < or = 30 min in 60 patients (45%), between 30 and 60 min in 49 patients (36%), and > or = 60 min in 25 patients (19%). Classification into 3 groups according to weight ((I < 65 kg, II = 65-84 kg, III > or = 85 kg) using driving pressures of 1.52 +/- 0.47 bar, 1.64 +/- 0.78 bar, and 1.69 +/- 0.67 bar for the HF jet and 1.78 +/- 0.54 bar, 1.90 +/- 0.48 bar, and 2.00 +/- 0.49 bar for the NF jet demonstrated differences in paO2 (156 +/- 45 [I] vs 126 +/- 34 [II] vs 96 +/- 18 [III] mm Hg) and paCO2 (42 +/- 9 und 44 +/- 8 vs 48 +/- 8 mm Hg) using comparable FjetO2 (0.6 +/- 0.2). Supraglottic pressures were 11.6 +/- 6.8, 11.5 +/- 7.0, und 12.6 +/- 7.1 cm H2O (I-III). No ventilator-related adverse events were observed.
Conclusion:
Tubeless supraglottic HFJV utilizing two jet streams with low and high frequency was effective in patients during laryngotracheal surgery. The application of two jet streams results in phasic changes of airway pressures between an inspiratory and expiratory pressure level, and facilitates application of enlarged tidal volumes. As demonstrated, oxigenation and ventilation is compromised by increased body weight. Superimposed HFJV (double-jet technique) enables the supraglottic ventilation of heavy patients and/or in the presence of airway stenoses during laryngotracheal surgery without need to use maximum driving pressures.