The minilink breathing system: resistance and suitability for spontaneous ventilation

The Portex infant breathing/ventilation systems with 8.5 mm and 15 mm internal diameter connectors were compared with a standard T-piece which had a 15 mm connector and 22 mm internal diameter tubing. The differential pressures across each system were measured at constant fresh gas flows up to 30 l.min-1 dry air. Resistance was calculated at flows compatible with quiet respiration and peak inspiratory flow. Flow resistance of the 3.0 mm internal diameter tracheal tube in conjunction with the minilink breathing systems were similar to those previously reported for tracheal tubes alone. However, the minilink breathing system assumed a greater influence on resistance when tracheal tubes of larger internal diameter were used. It added considerably more resistance than the standard tubing. This may have a deleterious effect during spontaneous ventilation in older children.