Confirmation of endotracheal intubation over a jet stylet: in vitro studies

An accepted method of tracheal reintubation is to pass an endotracheal tube (ETT) over a jet stylet (JS). It is desirable to confirm tracheal reintubation prior to removing the JS from its known intratracheal location. The purpose of this study was to determine the functional size equivalent of the annular space between the JS and ETT for all combinations of variously sized ETTs and JSs and to determine whether this annular space will permit detection of exhaled carbon dioxide (CO2). Our experiment consisted of two parts. One model measured the airflow resistance of variously sized test catheters (14- to 18-gauge intravenous catheters and ETT sizes 2.5-9.0 mm inside diameter (ID)) and all of the possible combinations of small, medium, and large Sheridan JSs within 4.9-9.0-mm ID ETTs (ETT/JS) by determining pressure versus annular space flow curves. The other model measured the times to first detection of CO2, to 70% maximum (max) [CO2] detection, and from first detection to 70% max [CO2] through empty 4.0- to 9.0-mm ID ETTs and through the annular space between all possible ETT/JS combinations at lung driving pressures of 5-10 mm Hg. The resistance of the catheters and ETT/JS combinations increased as the flow rate increased and/or the net conducting area of the conduit decreased. Some ETT/JS had an annular space < a 4.0 mm ID ETT. All three CO2 detection times increased with decreasing size of the net conducting area and with decreasing driving pressure.(ABSTRACT TRUNCATED AT 250 WORDS)