title: Effect of ranitidine on gastric intramucosal pH in critically ill patients.
abstract: OBJECTIVE
  To determine whether ranitidine a) increases the values of gastric intramucosal pH (pHi) in critically ill patients, as determined by tonometry; b) reduces the variability of these measurements.
  
  
  METHODS
  Prospective, double blind, randomized, placebo-controlled study.
  
  
  METHODS
  General Intensive Care Unit of a teaching hospital.
  
  
  METHODS
  Twenty-five critically ill, mechanically ventilated patients requiring arterial catheter and nasogastric tube.
  
  
  METHODS
  Tonometer placement; blind, random administration of intravenous ranitidine (50 mg) or placebo.
  
  
  RESULTS
  Tonometer saline PCO2 (PCO2i), arterial blood gases, gastric juice pH and pHi were determined immediately before, and 2, 4, 6 and 8 h after, ranitidine (12 patients) or placebo (13 patients). Ranitidine significantly increased gastric juice pH, but did not affect PCO2i or pHi; pHi was 7.34 +/- 0.14 before ranitidine, and 7.30 +/- 0.12, 7.31 +/- 0.11, 7.31 +/- 0.14 and 7.31 +/- 0.12-2, 4, 6 and 8 h, respectively, after ranitidine administration (p = 0.55). Ranitidine did not modify the coefficients of variation of PCO2i or pHi, either. No significant changes in gastric juice pH, PCO2i or pHi were observed in the placebo group.
  
  
  CONCLUSIONS
  In critically ill patients, ranitidine has no effect on pHi values, and does not increase the reproducibility of pHi measurements.
authors.affiliation: Department of Internal Medicine, Hospital de Sabadell, Barcelona, Spain. xcalvet@siberia.chpt.es
authors.forename: X
authors.initials: X
authors.lastname: Calvet
authors.forename: F
authors.initials: F
authors.lastname: Baigorri
authors.forename: M
authors.initials: M
authors.lastname: Duarte
authors.forename: P
authors.initials: P
authors.lastname: Saura
authors.forename: C
authors.initials: C
authors.lastname: Royo
authors.forename: D
authors.initials: D
authors.lastname: Joseph
authors.forename: A
authors.initials: A
authors.lastname: Mas
authors.forename: A
authors.initials: A
authors.lastname: Artigas
mesh_terms: D018806:APACHE; D000368:Aged; D016638:Critical Illness; D004311:Double-Blind Method; D005260:Female; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism; D006635:Histamine H2 Antagonists / Q000627:therapeutic use*; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011899:Ranitidine / Q000627:therapeutic use*; D012121:Respiration, Artificial
chemical_list: D006635:Histamine H2 Antagonists; D011899:Ranitidine