Effects of Proton Pump Inhibitors versus Histamine-2 Receptor Antagonists on Gastric pH and Stress Ulcer Incidence in Mechanically Ventilated Patients with ARDS in the ICU

Abstract

Background: Acute Respiratory Distress Syndrome (ARDS) is associated with an increased risk of stress-related mucosal disease (SRMD) due to hypoxemia, systemic inflammation, and prolonged mechanical ventilation. Stress ulcer prophylaxis is routinely administered in the intensive care unit (ICU), most commonly using proton pump inhibitors (PPIs) or histamine-2 receptor antagonists (H2RAs). Although PPIs provide more potent gastric acid suppression, their use has been associated with a higher risk of infection, and evidence regarding their superiority over H2RAs remains inconclusive. This study aimed to compare the efficacy of PPIs and H2RAs in maintaining gastric pH and preventing stress ulcers in mechanically ventilated patients with ARDS.
Methods: This single-blind randomized controlled trial included 40 adult patients diagnosed with ARDS who required mechanical ventilation. Participants were randomly assigned to receive either intravenous omeprazole 40 mg once daily (PPI group) or intravenous ranitidine 50 mg every 12 hours (H2RA group) for three days. Gastric pH was measured at baseline (day 1) and on day 4 using nasogastric aspirates.
Results: The PPI group demonstrated a statistically significant increase in gastric pH from day 1 to day 4 (p = 0.012), whereas no significant change was observed in the H2RA group (p = 0.528). The between-group comparison showed a significant difference in pH changes over time (p = 0.024), with the PPI group exhibiting a mean increase of 0.65 ± 0.99, while the H2RA group showed a mean decrease of 0.18 ± 1.21. However, there were no significant differences between groups in absolute gastric pH values on day 1 (p = 0.265) or day 4 (p = 0.117), nor in the incidence of stress ulcers (p = 1.000). ARDS severity did not differ significantly between groups on day 1 or day 4 (p = 0.058 and p = 0.655, respectively), and the proportion of patients with worsening ARDS severity was also comparable (30% vs. 15%, p = 0.451).
Conclusion: Both PPIs and H2RAs were effective for stress ulcer prophylaxis in mechanically ventilated ARDS patients, with similarly low rates of stress ulcer bleeding. Although PPIs resulted in a greater increase in gastric pH, this did not translate into superior clinical outcomes. Therefore, the choice between PPIs and H2RAs should consider not only their acid-suppressive effects but also potential adverse events, including infection risk.