In-vivo-and in-vitro evaluation of the 5 French neonatal gastric tonometer
type: CreativeWork
description: Introduction - Gastrointestinal tonometry has been widely used in adult practice for the early detection of shock and multi-organ failure. Its application in paediatrics has been limited by unsuitably large tonometers and doubt about the accuracy of measurements when saline is used as a tonometric fluid / vehicle for carbon dioxide (CO₂) equilibration. Objective - To evaluate the accuracy and reliability of the newly developed saline 5 French (5F) neonatal gastric tonometer. Study Design - (a) Direct in-vivo comparison of the 5F 0.9%saline tonometer (NST) with the recirculating gas tonometer (RGT) [the current reference standard in adult practice] in 10 Paediatric intensive care unit (PICU) patients, measuring tonometric PCO₂ (PtCO₂) and gastric intramucosal PCO₂ (PiCO₂). (b) In-vivo comparison of PiCO₂ measurements from two 5F tonometers in 10 PICU patients in unfed and fed state. (c) In-vitro comparison of reference PCO₂ to PtCO₂ values obtained using 0.9%saline and phosphate buffered saline in SF tonometers, and the RGT. Results - (a) Comparing the SF NST to RGT in 50 paired simultaneous measurements over PtCO₂ range 3.0 - 9.7kPa, the mean bias was -1.44kPa; limits of agreements (LOA) ±1.45kPa. The mean values of PtCO₂- derived gastric intramucosal pH (pHi) and PiCO₂-PaCO₂ difference differed significantly by -.11 and + 1.1kPa respectively (p<0.0001). (b) 100 paired 5F NST measurements (50 fed/ 50 unfed) over PtCO₂ range 2.48-11.1kPa were assessed. No significant difference was observed in PtCO₂: mean difference (standard deviation) - unfed 0.05kPa (0.36) (p=0.36); fed 0.05kPa (0.42) (p=0.43). (c) 20 consecutive measurements of PtCO₂ were obtained from the 5F NST, 5F phosphate buffered saline tonometer (PBST) and RGT at constant reference PCOi's of 2.5, 5.0, 7.5, 10.0kPa. The 5F NST underestimated the reference PCO₂ by a mean bias of 58% (LOA ±20%); the 5F PBST by 6% (LOA ±26%); while the RGT performed best with a mean bias of 5.7% and tight LOA ±1.5%. Conclusion…
abstract: Introduction - Gastrointestinal tonometry has been widely used in adult practice for the early detection of shock and multi-organ failure. Its application in paediatrics has been limited by unsuitably large tonometers and doubt about the accuracy of measurements when saline is used as a tonometric fluid / vehicle for carbon dioxide (CO₂) equilibration. Objective - To evaluate the accuracy and reliability of the newly developed saline 5 French (5F) neonatal gastric tonometer. Study Design - (a) Direct in-vivo comparison of the 5F 0.9%saline tonometer (NST) with the recirculating gas tonometer (RGT) [the current reference standard in adult practice] in 10 Paediatric intensive care unit (PICU) patients, measuring tonometric PCO₂ (PtCO₂) and gastric intramucosal PCO₂ (PiCO₂). (b) In-vivo comparison of PiCO₂ measurements from two 5F tonometers in 10 PICU patients in unfed and fed state. (c) In-vitro comparison of reference PCO₂ to PtCO₂ values obtained using 0.9%saline and phosphate buffered saline in SF tonometers, and the RGT. Results - (a) Comparing the SF NST to RGT in 50 paired simultaneous measurements over PtCO₂ range 3.0 - 9.7kPa, the mean bias was -1.44kPa; limits of agreements (LOA) ±1.45kPa. The mean values of PtCO₂- derived gastric intramucosal pH (pHi) and PiCO₂-PaCO₂ difference differed significantly by -.11 and + 1.1kPa respectively (p<0.0001). (b) 100 paired 5F NST measurements (50 fed/ 50 unfed) over PtCO₂ range 2.48-11.1kPa were assessed. No significant difference was observed in PtCO₂: mean difference (standard deviation) - unfed 0.05kPa (0.36) (p=0.36); fed 0.05kPa (0.42) (p=0.43). (c) 20 consecutive measurements of PtCO₂ were obtained from the 5F NST, 5F phosphate buffered saline tonometer (PBST) and RGT at constant reference PCOi's of 2.5, 5.0, 7.5, 10.0kPa. The 5F NST underestimated the reference PCO₂ by a mean bias of 58% (LOA ±20%); the 5F PBST by 6% (LOA ±26%); while the RGT performed best with a mean bias of 5.7% and tight LOA ±1.5%. Conclusion…
author: Thorburn, Kentigern
language: eng
date published: 1999
date modified: 2026-07-22T22:23:00Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Paediatrics and Child Health

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/26488