Experimental model of laryngotracheal stenosis in infants: effects of different high-frequency jet ventilation patterns on pulmonary parameters

Abstract

Supraglottic high-frequency jet ventilation (HFJV) in laryngotracheal surgery in infants with modified jet laryngoscopes offers the surgeon an unimpaired operating field. However, supraglottic HFJV is associated with the development of high airway pressures, inadvertent positive end-expiratory pressure (PEEP) levels, and barotrauma. We investigated the total lung volumes (TLV) and tidal volume variations at peak inspiratory pressure levels (PIP) and at PEEP levels along with the pulmonary pressures (PIP and PEEP) during two conventional methods of supraglottic HFJV in an infant trachea-lung model without stenosis and with different degrees of stenosis. With augmentation of the driving pressure in the experiment without stenosis, the TLV plus the pulmonary pressures increased. With narrowing of the stenosis, TLV reduced at PIP level and increased at PEEP level. Volume shifts were significantly higher during superimposed HFJV compared with monofrequent HFJV at equivalent stenosis diameter (P < 0.05) except for the setting with 0.3 bar driving pressure (P > 0.05). The pulmonary PIP was in none of the test series higher than 20 mbar, and the pulmonary PEEP did not exceed 14 mbar. The results from our experimental model support the safe and effective clinical use of supraglottic HFJV in infants with tracheal stenosis. Moderate driving pressures provide acceptable pulmonary pressures in normal compliant lungs.