Validation of the RightSpot™ device for determination of gastric pH during nasogastric tube placement

BACKGROUND The RightSpotpH™ indicator is a new device designed to facilitate pH-based confirmation of nasogastric tube placement while minimizing exposure of the operator to nasogastric contents. STUDY OBJECTIVES In vivo and in vitro validation of the RightSpotpH™ indicator. FINDINGS Patients (23) undergoing general anesthesia had placement of a nasogastric tube and gastric pH electrode catheter following endotracheal intubation. Direct intragastric pH was recorded simultaneously with gastric aspirate pH using the RightSpotpH™ indicator as well as an external pH electrode. In vitro validation of the RightSpotpH™ indicator was performed using standard buffer solutions. Electrode catheter-determined intragastric pH was compared to the RightSpotpH™ indicator result (pH greater or less than 4.5) as was aspirate pH using an external pH electrode. The positive predictive value for the RightSpotpH™ indicator was 0.92 (95% CI 0.62-0.99) and negative predictive value was 1.0 (95% CI 0.48-1.0) when compared to the direct catheter intragastric pH determination. This corresponds to a sensitivity of 1.0 and specificity of 0.83. The positive predictive value for the RightSpotpH™ indicator was 1.0 (95% CI 0.29-0.99) and negative predictive value was 0.75 (95% CI 0.19-0.99) when compared to the external pH electrode determination of aspirate. This corresponds to a sensitivity of 0.91 and specificity of 1.0. Blinded in vitro testing of 46 buffer solution samples of pH 2-7 yielded sensitivity and specificity for correct pH discrimination of 1.0 and 1.0. CONCLUSIONS The RightSpotpH™ indicator is sensitive and specific for determination of intragastric pH determination as less than or greater than 4.5 as commonly used for nasogastric tube placement.