GASTRIC PH CONTROL IN CRITICALLY ILL CHILDREN RECEIVING INTRAVENOUS RANITIDINE

Objective: To determine whether the dose of ranitidine recommended in commonly used pediatric drug dosage handbooks (2 to 4 mg/kg/day iv) re sults in successful gastric pH control (pH of greater than or equal to 4) in critically ill children, Design: Prospective sample. Setting: P ediatric intensive care unit in a tertiary care children's hospital,Pa tients: Fifty consecutive patients who received greater than or equal to 24 hrs of scheduled intermittent intravenous ranitidine for stress ulcer prophylaxis were enrolled in the study. Patients with renal or h epatic dysfunction and those who received enteral nutrition through th e nasogastric tube were excluded from enrollment. Intervention: Gastri c pH was determined at the end of the ranitidine dosing interval, 1 hr after the dose, and at the midpoint between doses. Alt pH measurement s 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 mo s; range 2 wks to 264 mos) were included in the analysis, Eighty-two p ercent of the patients were mechanically ventilated, 16% were pharmaco logically paralyzed, 18% required vasoactive infusions, 36% were nouri shed 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 significa ntly lower than the pH measured at 1 hr or at the midpoint between dos es (p < .05). Seventy-one percent of patients who received <3 mg/kg/da y of ranitidine had poor gastric pH control as compared with 19% who r eceived a minimum of 3 mg/kg/day (p < .05). Poor control of gastric pH was not associated with feeding, intubation status, presence of pharm acologic paralysis, use of vasoactive infusions, or age (p > .05). Con clusions: The minimum ranitidine dose recommended in commonly used ped iatric drug references resulted in unsuccessful gastric pH control in a high percentage of pediatric intensive care unit patients. Criticall y ill children with normal renal and hepatic function should be treate d with a minimum 3 mg/kg/day of intravenous ranitidine and the dose sh ould be titrated to a gastric pH of greater than or equal to 4.