Confirming nasogastric tube position with electromagnetic tracking versus pH or X-ray and tube radio-opacity

Abstract

Recent evidence suggests official statistics greatly underestimate the occurrence of complications from misplaced nasogastric (NG) tubes, even when detected. Current methods of confirming tube position do not provide adequate protection from misplacement. In addition, some tubes are inadequately radio-opaque. We prospectively audited placement of Cortrak polyurethane tubes (PUTs) to determine: accuracy of the electromagnetic (EM) trace in confirming tube position, radio-opacity of PUTs compared with previously placed polyvinylchloride (PVC) Ryles tubes and whether 12 French PUTs can be used to aspirate gastric residual volumes (GRVs). A total of 127 PUTs were placed in 113 patients. EM traces accurately confirmed tube position compared with X-ray (100% agreement). A 'gastric' EM trace has been defined for future use by other operators. PUTs were adequately radio-opaque with good agreement between interpreters (>98%) whereas PVC Ryles tubes were insufficiently radio-opaque (57-73%), invisible in 23% of cases and with poor agreement between interpreters leaving risk of error. The alternative of using pH confirmation was not possible in 44%. In these cases subsequent X-ray incurred a 2-hour delay to feed and medicines. In addition, neither post-placement pH testing nor X-ray warn of lung placement and potential trauma, whereas the EM trace warned of lung placement prior to damage in 7% of placements. 12 French, single-port PUTs appear adequate to aspirate large GRVs. EM tracing may be considered a standalone method of confirming NG tube position. Corflo (Cortrak) PUTs are adequately radio-opaque. Use of PVC Ryles and other inadequately radio-opaque tubes should stop.