Measuring intramucosal pH in very low birth weight infants
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Published on: August 7, 2017
1Academic Department of Child Health, St. Bartholomew's and the Royal London School of Medicine and Dentistry, Neonatal Unit, Homerton Hospital, London, United Kingdom E9 6SR.
Insights
Intramucosal pH (pH(i)) monitoring in premature infants may predict gastrointestinal complications. Gastric pH(i) and mucosal CO(2) (mCO(2)) measurements offer insights into tissue perfusion and potential risks.
Area of Science:
- Neonatal Medicine
- Gastroenterology
- Critical Care
Background:
- Adequate intestinal perfusion is crucial for mucosal health.
- Existing methods for assessing intestinal perfusion may not reflect mucosal blood flow.
- Intramucosal pH (pH(i)) is a sensitive indicator of tissue oxygenation and perfusion.
Purpose of the Study:
- To investigate the relationship between gastric pH(i), mucosal CO(2) (mCO(2)), and clinical outcomes in low birth weight infants.
- To assess the predictive value of pH(i) and mCO(2) for gastrointestinal complications and mortality.
Main Methods:
- A prospective observational study involving infants weighing <1500 g.
- Gastric pH(i) and mCO(2) were measured using nasogastric tonometry.
- Measurements were taken at multiple time points, correlating with arterial blood gas parameters.
Main Results:
- pH(i) and mCO(2) showed significant correlations with arterial pH (pH(a)), PaCO(2), and base excess.
- Recurrent low pH(i) and elevated mCO(2)/PaCO(2) ratios were associated with increased gastrointestinal complications.
- No significant association was found between these parameters and mortality.
Conclusions:
- Changes in pH gap and CO(2) gap can occur independently of arterial pH.
- Abnormalities in gastric pH(i) may serve as an early predictor of gastrointestinal complications in high-risk infants.
- Tonometry offers a valuable, non-invasive method for monitoring mucosal perfusion in neonates.
Abstract:
Maintenance of adequate perfusion is essential for health of the intestinal mucosa. Methods available to assess intestinal perfusion provide information on mesenteric blood flow, which may differ from mucosal flow. Intramucosal pH (pH(i)) is influenced by tissue oxygenation and perfusion. Gastric pH(i) can be measured using the technique of tonometry. A prospective observational clinical study was performed to examine relationships between measured gastric pH(i) and mucosal CO(2) (mCO(2)), and acid-base balance, gastrointestinal complications (necrotizing enterocolitis and perforation), and death in infants <1500 g birth weight. A nasogastric tonometry catheter (size 5F) was inserted into the stomach of infants, and pH(i) was calculated from mCO(2) levels measured using saline tonometry. Measurements were performed at 3, 12, 24, and 48 h, then daily until arterial access was unavailable. Two hundred eleven sets of measurements were performed on 38 infants [birth weight (mean +/-SD), 863 +/- 241 g; gestation, 26.5 +/- 1.8 wk; and median Clinical Risk Index for Babies score, 8.0 (interquartile range, 5.0-10.75)]. Mean pH(i) was 7.27 (95% confidence interval, 7.26-7.28) and mean mCO(2) was 47.0 mm Hg (95% confidence interval, 45.7-48.3 mm Hg). pH(i) and mCO(2) correlated significantly with arterial pH (pH(a)), arterial PCO(2) (PaCO(2)), and arterial base excess. There were no significant relationships between pH(a) and pH gap (pH(a)-pH(i)) or CO(2) gap (mCO(2)-PaCO(2)). Recurrent low pH(i) (<7.2 on more than one occasion) and an mCO(2)/PaCO(2) ratio of > or =1.29 were significantly associated with an increase in gastrointestinal complications. There were no statistically significant associations with death. In conclusion, changes in pH gap and CO(2) gap can occur without alteration in pH(a). Abnormalities in pH(i) might predict gastrointestinal complications in infants <1500 g.
