3D Electrical Impedance Tomography of Regional Ventilation During Jet Ventilation: A Pilot Study

Low-frequency jet ventilation (LFJV) is commonly used in laryngotracheal surgery when intubation is not feasible. However, limited understanding of regional ventilation and distal airway pressures raises safety concerns and restricts broader adoption. This study employed electrical impedance tomography (EIT) to quantify tidal volumes and regional ventilation patterns in patients undergoing airway surgery with LFJV.

Adult patients undergoing microlaryngeal surgery for subglottic stenosis were prospectively recruited from the Laryngology Clinic. A standardized anesthesia protocol was followed. EIT was used to measure tidal volumes and assess regional ventilation during bag-mask ventilation, laryngeal mask airway (LMA) ventilation, LFJV before and after dilation, and during recovery. Linear mixed-effects models were applied to compare LFJV with LMA ventilation, accounting for repeated measures within subjects.

Six patients underwent surgery with EIT monitoring, of whom four had complete datasets for analysis. LFJV preferentially ventilated apical lung regions, while basal regions were consistently under-ventilated. Apical-to-basal volume ratios were consistently higher during LFJV compared with LMA (> 100% higher). Similar differences were observed in the global inhomogeneity index (24% higher), left-to-right ratio (21% higher), and anterior-to-posterior ratio (9.5% higher).

This is the first study to apply EIT to assess ventilation distribution during LFJV for microlaryngeal surgery. LFJV was associated with relative hypoventilation of basal and dorsal lung regions and increased ventilation inhomogeneity compared with LMA ventilation. Larger studies are warranted to validate these results and inform optimization of LFJV in clinical practice.

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