Report on the development of a procedure to prevent placement of feeding tubes into the lungs using end-tidal CO2 measurements

Abstract

Objective: To determine the accuracy of a technique using capnography to prevent inadvertent placement of small-bore feeding tubes and Salem sump tubes into the lungs.

Setting: Twelve-bed medical intensive care unit (MICU) in a 557-bed teaching hospital.

Patients: A total of 25 ventilated adult MICU patients were studied-5 in phase 1 and 20 in phase 2.

Design: Phase 1 tested the ability of the end-tidal CO2 (ETCO2) monitor to detect flow (and thus accurately detect CO2) through small-bore feeding tubes. A small-bore feeding tube, with stylet in place, was placed 5 cm through the top of the tracheostomy tube ventilator adapter in five consecutive patients. The distal end of the feeding tube was attached to the ETCO2 monitor. The ETCO2 level and waveform were assessed and recorded. Because CO2 waveforms were successfully detected, a convenience sample of 20 adult MICU patients who were having feeding tubes placed (13 Salem sump tubes, 7 small-bore feeding tubes) was then studied. The technique consisted of attaching the ETCO2 monitor to the tubes and observing the ETCO2 waveform throughout placement.

Results: The study hypothesis was supported. Of the seven small-bore feeding tubes tested, all were successfully placed on initial insertion. Placement was confirmed by absence of an ETCO2 waveform and by radiograph. Of the 13 Salem sump tubes, 9 were placed successfully on first attempt and confirmed by absence of CO2 and by air bolus and aspiration of stomach contents. ETCO2 waveforms were detected with insertion of four of the Salem sump tubes; the tubes were immediately withdrawn, and placement was reattempted until successful.

Conclusions: The technique described is a simple, cost-effective method of assuring accurate gastric tube placement in critically ill patients.