Volume not guaranteed: closed endotracheal suction compromises ventilation in volume-targeted mode

Closed endotracheal suction interferes with mechanical ventilation received by infants, but the change to ventilation may be different when ventilator modes that target expired tidal volume (VT(e)) are used.

To measure airway pressure and tidal volume distal to the endotracheal tube (ETT) during and after closed suction in a volume-targeted ventilation mode with the Dräger Babylog 8000+, and to determine the time until VT(e) returns to the baseline level.

In this benchtop study, closed suction was performed on 2.5- to 4.0-mm ETTs connected to a test lung. 5-8 French suction catheters were used at suction pressures of 80-200 mm Hg during tidal-volume-targeted ventilation.

During catheter insertion and suction, circuit inflating pressure increased and tidal volume was maintained, except when a large catheter relative to the ETT was used, in which case tidal volume decreased. End-expiratory pressure distal to the ETT was reduced during suction by up to 75 cm H(2)O while circuit end-expiratory pressure was unchanged. Reduction in end-expiratory pressure distal to the ETT was greatest with large catheters and high suction pressures. Following suction, circuit and tracheal inflating pressures increased and tidal volume increased before returning to baseline in 8-12 s.

Closed endotracheal suction interferes with ventilator function in volume-targeted mode, with substantially negative intratracheal pressure during suction, and the potential for high airway pressures and tidal volumes following the procedure. These effects should be considered and pressure limits set appropriately whenever using volume-targeted ventilation.