An assessment of the validity of enteral aspirate pH measurements made with commercial pH strips

Abstract

Summary Background & aims Clinicians must ensure that enteral feeding tubes are in the correct position prior to use. Malposition of enteral feeding tubes into the trachea resulting in respiratory distress or death has been described in the literature. pH strips can be used to determine tube position; however, commercially available pH strips are industrial in nature and not intended for clinical use. Therefore, institutions have a requirement for clinically validated pH strips. The aim of this study is to compare the accuracy of commercially available pH strips ranges 0–6 and 2–9 (Merck Serono, UK) to a calibrated pH meter (pH 211 Microprocessor, Hanna Instruments) for the assessment of enteral aspirate. Methods Forty-eight patients were included in the study; some patients had an aspirate taken on more than one occasion. A total of 60 measurements were attempted. In 6 cases the investigators failed to obtain an aspirate, therefore 54 aspirates were analysed in total. Each aspirate obtained was analysed by both pH strips and a calibrated pH meter. Results These data show a high correlation between the pH strips (both 0–6 and 2–9) and the pH meter, with r-values (Pearson's correlation) approaching 1 in all cases. Conclusions We conclude that Merck Serono pH strips accurately reflect the actual pH of enteral aspirate when compared to a calibrated pH meter. They may therefore be useful in the placement of feeding tubes and in the determination of feeding tube position in the stomach and small bowel.