Gastric pH control in critically ill children receiving intravenous ranitidine

Abstract

Objective: To determine whether the dose of ranitidine recommended in commonly used pediatric drug dosage handbooks (2 to 4 mg/kg/day i.v.) results in successful gastric pH control (pH of >4) in critically ill children.

Design: Prospective sample.

Setting: Pediatric intensive care unit in a tertiary care children's hospital.

Patients: Fifty consecutive patients who received >24 hrs of scheduled intermittent intravenous ranitidine for stress ulcer prophylaxis were enrolled in the study. Patients with renal or hepatic dysfunction and those who received enteral nutrition through the nasogastric tube were excluded from enrollment.

Intervention: Gastric pH was determined at the end of the ranitidine dosing interval, 1 hr after the dose, and at the midpoint between doses. All pH measurements were made from a sample of nasogastric aspirate, using pH sensitive paper. Gastric pH control with ranitidine was considered unsuccessful (poorly controlled) if the pH was <4 for any of the three measurements.

Measurements and main results: Forty-five patients (median age 36 mos; range 2 wks to 264 mos) were included in the analysis. Eighty-two percent of the patients were mechanically ventilated, 16% were pharmacologically paralyzed, 18% required vasoactive infusions, 36% were nourished via transpyloric feeding tubes, and 7% received total parenteral nutrition. Gastric pH was poorly controlled in 36% of patients. Among these patients, the pH at the end of the dosing interval was significantly lower than the pH measured at 1 hr or at the midpoint between doses (p < .05). Seventy-one percent of patients who received <3 mg/kg/day of ranitidine had poor gastric pH control as compared with 19% who received a minimum of 3 mg/kg/day (p< .05). Poor control of gastric pH was not associated with feeding, intubation status, presence of pharmacologic paralysis, use of vasoactive infusions, or age (p > .05).

Conclusions: The minimum ranitidine dose recommended in commonly used pediatric drug references resulted in unsuccessful gastric pH control in a high percentage of pediatric intensive care unit patients. Critically ill children with normal renal and hepatic function should be treated with a minimum 3 mg/kg/day of intravenous ranitidine and the dose should be titrated to a gastric pH of > or =4.