Evaluation of gastric pH and guaiac measurements in neonates receiving acid suppression therapy during extracorporeal membrane oxygenation.
OBJECTIVE
To assess gastric pH measurements, evaluate the frequency of guaiac-positive gastric aspirates, and characterize the appearance of gastric aspirates in neonates receiving acid suppression therapy during extracorporeal membrane oxygenation (ECMO).


METHODS
Retrospective, observational study.


METHODS
Intensive care unit in a 225-bed tertiary care pediatric referral hospital.


METHODS
Thirteen neonates receiving ECMO.


RESULTS
Gastric pH measurements, guaiac test results, appearance of gastric aspirates, and ranitidine and antacid dosing were recorded. On ECMO day 1, mean+/-SD gastric pH was 4.3+/-2.8 in the five neonates whose pH was documented. Intravenous ranitidine 2.9+/-0.4 mg/kg/day was started in all neonates by ECMO day 2. Gastric pH was less than 4.0 in seven neonates; these low pH values accounted for only 10% of gastric pH measurements. The frequency of positive guaiac results in neonates with pH measurements below 4.0 was 27% compared with 41% for neonates with a gastric pH of 4.0 or greater (p=0.125). Guaiac tests were positive in 69 (42%) aspirates in 11 neonates. Of the guaiac-positive aspirates that had a corresponding pH measurement, 94% had a pH of 4.0 or greater. Guaiac-positive aspirates had evidence of bile (49%), antacid (17%), and blood (7%) in gastric fluid. In six patients, ranitidine dosages were increased to 3.9+/-0.6 mg/kg/day due to low pH and/or positive guaiac results. In two of these neonates, gastric pH remained below 4.0 in nine of 35 pH measurements despite increased ranitidine dosing. Guaiac results remained positive in all subsequent aspirates in five out of six of these neonates. No neonates developed clinically significant upper gastrointestinal bleeding (UGIB).


CONCLUSIONS
Gastric pH is variable in neonates receiving histamine2-receptor antagonist and antacid therapy during ECMO, and gastric pH of 4.0 or greater does not decrease the frequency of guaiac-positive aspirates. Higher gastric pH measurements are confounded by duodenogastric reflux and the presence of blood and/or antacid in gastric fluid. Motility agents in combination with acid suppression therapy for prevention of UGIB may be necessary in this setting based on gastric pH measurements, appearance of gastric aspirates, and guaiac testing.
Departments of Pharmacy and Pharmacology, Center for Pediatric Pharmacokinetics and Therapeutics, University of Tennessee Health Science Center, Memphis, TN 38163, USA. ccrill@utmem.edu
Catherine M
CM
Crill
Mark C
MC
Bugnitz
Emily B
EB
Hak
D000863:Antacids / Q000494:pharmacology*; D000897:Anti-Ulcer Agents / Q000494:pharmacology*; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects*; D006138:Guaiac; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D009780:Occult Blood; D011899:Ranitidine / Q000494:pharmacology*; D012189:Retrospective Studies
D000863:Antacids; D000897:Anti-Ulcer Agents; D011899:Ranitidine; D006138:Guaiac