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 (pHi) is influenced by tissue oxygenation and perfusion. Gastric pHi can be measured using the technique of tonometry. A prospective observational clinical study was performed to examine relationships between measured gastric pHi and mucosal CO2 (mCO2), 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 pHi was calculated from mCO2 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 pHi was 7.27 (95% confidence interval, 7.26–7.28) and mean mCO2 was 47.0 mm Hg (95% confidence interval, 45.7–48.3 mm Hg). pHi and mCO2 correlated significantly with arterial pH (pHa), arterial Pco2 (Paco2), and arterial base excess. There were no significant relationships between pHa and pH gap (pHa−pHi) or CO2 gap (mCO2−Paco2). Recurrent low pHi (<7.2 on more than one occasion) and an mCO2/Paco2 ratio of ≥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 CO2 gap can occur without alteration in pHa. Abnormalities in pHi might predict gastrointestinal complications in infants <1500 g.
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Abbreviations
- pHi:
-
intramucosal pH
- pHa:
-
arterial pH
- mCO2:
-
mucosal CO2
- GI:
-
gastrointestinal
- NEC:
-
necrotizing enterocolitis
- VLBW:
-
very low birth weight
- CI:
-
confidence interval
- CV:
-
coefficient of variability
- SMA:
-
superior mesenteric artery
- CRIB:
-
clinical risk index for babies
- Paco2:
-
arterial Pco2
References
Nowicki PT, Nankeveris CA 1994 The role of the circulation in the pathogenesis of necrotizing enterocolitis. Clin Perinatol 219: 219–234
Coombs RC, Morgan ME, Durbin GM, Booth IW, McNeish AS 1992 Abnormal gut blood flow velocities in neonates at risk of necrotizing enterocolitis. J Pediatr Gastroenterol Nutr 15: 13–19
Uauy RD, Fanaroff AA, Korones SB, Phillips EA, Phillips JB, Wright LL 1991 Necrotizing enterocolitis in very low birthweight infants: biodemographic and clinical correlates. J Pediatr 119: 630–638
Schanler RJ, Shulman RJ, Lau C, Smith EO, Heitkemper MM 1999 Feeding strategies for premature infants: randomized trial of gastrointestinal priming and tube-feeding method. Pediatrics 103: 434–439
LaGamma EF, Browne LE 1994 Feeding practices for infants weighing <1500 g at birth and the pathogenesis of necrotizing enterocolitis. Clin Perinatol 21: 271–306
Antonsson JB, Boyle CC III, Kruithoff KL, Wang H, Sacristan E, Rothschild HR, Fink MP 1990 Validation of tonometric measurement of gut intramural pH during endotoxemia and mesenteric occlusion in pigs. Am J Physiol 259: G519–G523
Boros M, Kaszaki J, Ordogh B, Nagy S 1994 Intramucosal pH changes following complete segmental small intestinal ischaemia, as compared with the effects of superior mesenteric artery occlusion. Eur Surg Res 26: 76–86
Hartmann M, Montgomery A, Jonsson K, Haglund U 1991 Tissue oxygenation in hemorrhagic shock measured as transcutaneous oxygen tension, subcutaneous oxygen tension, and gastrointestinal intramucosal pH in pigs. Crit Care Med 19: 205–210
Montgomery A, Hartmann M, Jonsson K, Haglund U 1989 Intramucosal pH measurement with tonometers for detecting gastrointestinal ischemia in porcine hemorrhagic shock. Circ Shock 29: 319–327
Campbell ME, VanAerde JE, Cheung PY, Mayes D 1999 Tonometry to estimate intestinal perfusion in the newborn piglet. Arch Dis Child 81: 105–109
Maynard N, Bihari D, Beale R, Smithies M, Baldock G, Mason R, McColl I 1993 Assessment of splanchnic oxygenation by gastric tonometry in patients with acute circulatory failure. JAMA 270: 1203–1210
Boyle NH, Pearce A, Hunter D, Owen WJ, Mason RC 1998 Scanning laser Doppler flowmetry and intraluminal recirculating gas tonometry in the assessment of gastric and jejunal perfusion during oesophageal resection. Br J Surg 85: 1407–1411
Elizalde JI, Hernandez C, Llach J, Monton C, Bordas JM, Pique JM, Torres A 1998 Gastric intramucosal acidosis in mechanically ventilated patients: role of mucosal blood flow. Crit Care Med 26: 827–832
Hatherhill M, Tibby SM, Evans R, Murdoch IA 1998 Gastric tonometry in septic shock. Arch Dis Child 78: 155–158
Casado-Flores J, Mora E, Perez-Corral F, Martinez-Azagra A, Garcia-Teresa MA, Ruiz-Lopez MJ 1998 Prognostic value of gastric intramucosal pH in critically ill children. Crit Care Med 26: 1123–1127
Duke T, Butt W, South M, Shann F 1997 The DCO2 measured by gastric tonometry predicts survival in children receiving extracorporeal life support: comparison with other hemodynamic and biochemical information. Chest 111: 174–179
The International Neonatal Network 1993 The CRIB (clinical risk index for babies) score: a tool for assessing initial neonatal risk and for comparing performance of neonatal intensive care units. Lancet 342: 193–198
Takala J, Parviainen I, Siloaho M, Ruokonen E, Hamalainen E 1994 Saline pCO2 is an important source of error in the assessment of gastric intramucosal pH. Crit Care Med 22: 1877–1879
Knichwitz G, Kuhmann M, Brodner G, Mertes N, Goeters C, Brussel T 1996 Gastric tonometry: precision and reliability are improved by a phosphate buffered solution. Crit Care Med 24: 512–516
Kolkman JJ, Groenveld AB, Meuwissen SG 1994 Effect of ranitidine on basal and bicarbonate enhanced intragastric pCO2: a tonometric study. Gut 35: 737–741
Heard SO, Helsmoortel CM, Kent JC, Shahnarian A, Fink MP 1991 Gastric tonometry in healthy volunteers: effects of ranitidine on calculated intramural pH. Crit Care Med 19: 271–274
Parviainen I, Vaisanen O, Ruokonen E, Takala J 1996 Effect of nasogastric suction and ranitidine on the calculated gastric intramucosal pH. Intensive Care Med 22: 319–323
Calvet X, Baigorri F, Duarte M, Saura P, Royo C, Joseph D, Mas A, Artigas A 1998 Effect of ranitidine on gastric intramucosal pH in critically ill patients. Intensive Care Med 24: 12–17
Guzman JA, Kruse JA 1996 Development and validation of a technique for continuous monitoring of gastric intramucosal pH. Am J Respir Crit Care Med 153: 694–700
Heinonen PO, Jousela IT, Blomqvist KA, Olkkola KT, Takkunen OS 1997 Validation of air tonometric measurement of gastric regional concentration of CO2 in critically ill septic patients. Intensive Care Med 23: 524–529
Reinoso-Barbero F, Calvo C, Lopez-Herce J, Bueno M, Garcia S 1998 Reference values of gastric intramucosal pH in children. Paed Anaesthesia 8: 135–138
Krafte-Jacobs B, Carver J, Wilkinson JD 1995 Comparison of gastric intramucosal pH and standard perfusional measurements in pediatric septic shock. Chest 108: 220–225
Duke TD, Butt W, South M 1997 Predictors of mortality and multiple organ failure in children with sepsis. Intensive Care Med 23: 684–692
Friedman G, Berlot G, Kahn RJ, Vincent JL 1995 Combined measurements of blood lactate concentrations and gastric intramucosal pH in patients with severe sepsis. Crit Care Med 23: 1184–1193
Reverte M, Garcia-Barrada MJ, Moratinos J 1991 Change in plasma glucose and lactate evoked by alpha and beta-2-adrenoreceptor stimulation in conscious fasted rabbits. Fund Clin Pharmacol 5: 663–676
James JH, Luchette FA, McCarter FD, Fischer JE 1999 Lactate is an unreliable indicator of tissue hypoxia in injury or sepsis. Lancet 354: 505–508
Hatherhill M, Tibby SM, Denver L, Marsh MJ, Murdoch I 1998 Early detection of necrotizing enterocolitis by gastrointestinal tonometry. Acta Paediatr 87: 344–345
Cullen J, Eger EI 1974 Cardiovascular effects of carbon dioxide in man. Anaesthesiology 41: 345–349
Guzman JA, Kruse JA 1999 Splanchnic hemodynamics and gut mucosal-arterial Pco2 gradient during systemic hypocapnia. J Appl Physiol 87: 1102–1106
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Funded by a grant from the Joint Research Board of St. Bartholomew's Hospital (M.E.C.).
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Campbell, M., Costeloe, K. Measuring Intramucosal pH in Very Low Birth Weight Infants. Pediatr Res 50, 398–404 (2001). https://doi.org/10.1203/00006450-200109000-00016
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DOI: https://doi.org/10.1203/00006450-200109000-00016
