Influence of Tracheal Obstruction on the Efficacy of Superimposed High-frequency Jet Ventilation and Single-frequency Jet Ventilation

• Published in: Anesthesiology (Philadelphia) 2015, Vol.123 (10), p.799
• Main Authors: Sütterlin, Robert, Frykholm, Peter, Lo Mauro, Antonella, Gandolfi, Stefano, Priori, Rita, Larsson, Anders, Aliverti, Andrea
• Format: Article
• Language: English
• Subjects: airway obstruction; Anaesthesiology and Intensive Care; Anestesiologi och intensivvård; HFJV; jet ventilation; SHFJV; tracheal stenosis
• ISSN: 0003-3022; 1528-1175

Background Superimposed high frequency jet ventilation (SHFJV) has been used successfully in selected patients with severe central airway obstruction undergoing airway interventions. We sought to systematically describe the efficacy of SHFJV in relation to obstruction and the high frequency component (f HF ) in a model of tracheal stenosis. Methods Ten anesthetized animals (25-31.5kg) were alternately ventilated with SHFJV (low frequency 16min -1 , random f HF ) at a set of different f HF from 50-600min -1 . Tracheal obstruction was created using exchangeable stents with different inner diameter (2, 4, 6, 8mm) that were inserted into the trachea. Chest wall volume was measured using optoelectronic plethysmography, airway pressures were recorded and blood gases were analyzed repeatedly. Results Stent ID reduction from 8 to 2mm resulted in an increase of ∆EEV CW by up to 3x ( e.g. 323 [255 - 410] ml vs 106 [81 - 138] ml at f HF =100 min -1 ). At the same time, V T decreased by up to 4.2x ( e.g. 477 [434 – 524] ml vs 114 [79 – 165] ml). P a O 2 and p a CO 2 remained at acceptable levels for 4-8 mm stent ID but CO 2 removal became suddenly impaired at 2mm stent ID (p a CO 2 >12 kPa). Pre-stenotic airway pressure monitoring was accurate at 8mm stent ID, but overestimation of peak inspiratory pressure (PIP) up to 2x and underestimation of PEEP up to 19x was observed at 2mm stent ID. Conclusion SHFJV was able to maintain oxygenation and carbon dioxide removal over a wide range of obstructions, despite decreasing V T and successive air trapping. At 2 mm stent ID, only carbon dioxide removal became insufficient.