Use of heat and moisture exchanging (HME) filters in mechanically ventilated ICU patients: influence on airway flow-resistance.

Objective: To investigate the flow-resistance of a new generation of Heat Moisture Exchanging Filters (HME filters) during 24 h of clinical use.

Design: Before-after trial.

Setting: A general Intensive Care Unit of a university hospital.

Measurement of the flow-resistive properties of double-lumen bronchial tubes in vitro.

This study measures the resistance to gas flow of different double-lumen bronchial tubes used for separate ventilation of each lung in critically ill patients. Different-sized Robertshaw and Carlens' tubes were studied, as well as a new device that consisted of a cuffed bronchial catheter introduced through a standard tracheal tube. The pressure-flow relationship was curvilinear in all cases.