Oxygen Supplementation in a Model of a Ventilator-Dependent Tracheostomized Child

Abstract

Background: Pediatric patients receiving chronic mechanical ventilation via tracheostomy have variable needs for oxygenation. Supplemental oxygen can be supplied either through the ventilator or at the tracheostomy site. In this study we compared tracheal FIO₂ achieved through 2 different methods in a model of pediatric mechanical ventilation via tracheostomy. We hypothesize that administering oxygen through the tracheostomy would provide a higher FIO₂.

Methods: An in-vitro model of pediatric ventilation via tracheostomy was utilized with a home ventilator (Breas Vivo 65) which was connected in series to a single-limb heated wire passive ventilator circuit (Fisher & Paykel RT219, internal diameter 30 mm), a tracheostomy ring (t-ring) adapter, 4.0 pediatric tracheostomy tube with cuff inflated (Bivona TTS), t-piece with oxygen analyzer (trachea), filter, and an infant test lung (20% leak, resistance Rp50 and compliance 2 mL/mbar). Ventilator settings were PC-SIMV, RR 30, PC 30, I-time 0.6, PEEP 5 and PS 15. Oxygen was administered through the ventilator’s designated oxygen inlet and through the t-ring at different flows and the resultant FIO₂ was measured at the tracheal level. Measurements were done in quadruplicate after 5 minutes of continuous operation. A T-test was used to compared tracheal FIO₂ obtained with different connections.

Results: See Table.

Conclusions: In an in-vitro model of pediatric ventilation via tracheostomy, delivering supplemental oxygen through the t-ring provided a higher FIO₂ than using the ventilator port when oxygen flows were ≥ 3 L/min. However, the use of a t-ring could potentially affect the monitored tidal volume.