Frequency of upper gastrointestinal bleeding in a pediatric intensive care unit

Omeprazole pharmacodynamics and gastric acid suppression in critically ill pediatric transplant patients

OBJECTIVE: To characterize the pharmacodynamics and pharmacokinetics of omeprazole suspension in critically ill pediatric liver/intestinal transplant patients. DESIGN: Open-label pharmacodynamic and pharmacokinetic study. SETTING: Pediatric intensive care unit of an academic medical center. PATIENTS: Eleven pediatric liver and/or intestinal transplant patients. INTERVENTIONS: Extemporaneously prepared 0.5 mg/kg omeprazole suspension every 12 hrs via nasogastric tube before sequential measurements of omeprazole serum concentration and gastric pH monitoring. Gastric pH was monitored continuously for 48 hrs and plasma omeprazole concentrations were determined upon first and multiple dosing. MEASUREMENTS AND MAIN RESULTS: Mean onset of action of omeprazole in a sodium bicarbonate vehicle was 62 +/- 82 mins (range, 2-226 mins). Subjects <4 yrs of age exhibited a more variable onset of omeprazole action (range, 3-226 mins) when compared with older subjects (onset of action, 2-40 min). Omeprazole maximum concentration and area under the concentration-time curve for the dosage interval were significantly greater upon multiple dosing when compared with the first dose. Mean baseline gastric pH in this study population was 1.0 +/- 0.8. Gastric pH remained >4.0 for 78.8% +/- 18.9% of the first dosage interval and 97.8% +/- 5.4% of multiple dosage intervals regardless of age when administered twice daily as a suspension. CONCLUSION: These results support the use of omeprazole administered twice daily as a suspension to maintain gastric pH of >4.0 and to achieve maximal pharmacodynamic effect in pediatric liver and/or intestinal transplant patients.

Pharmacokinetics and pharmacodynamics of ranitidine in critically ill children

OBJECTIVE

To determine the pharmacokinetics and pharmacodynamics of ranitidine in critically ill children and to design a dosage regimen that achieves a gastric pH > or =4.

DESIGN

Prospective, open-label, pharmacokinetic-pharmacodynamic study.

SETTING

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

PATIENTS

Mechanically ventilated, critically ill children > or =10 kg who required intravenous ranitidine for stress ulcer prophylaxis.

INTERVENTIONS

Ranitidine pharmacokinetics were determined after a single intravenous dose. Gastric pH was monitored hourly via nasogastric pH probe. After the last blood sample, patients received an intravenous bolus of ranitidine (0.5 mg/kg) followed by a continuous infusion (0.1 mg x kg(-1) x hr(-1)). The infusion was increased incrementally (0.05 mg x kg(-1) x hr(-1)) until reaching gastric pH > or =4 for > or =75% of a 24-hr period, after which steady-state plasma concentrations were measured. Plasma concentrations were analyzed by high-pressure liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

Twenty-three children (ranging in age from 1.4 to 17.1 yrs) were studied. Pharmacokinetic variables included a clearance of 511.7 +/- 219.7 mL x kg(-1) x hr(-1), volume of distribution of 1.53 +/- 0.99 L/kg, and half-life of 3.01 +/- 1.35 hrs. After the single intravenous dose (1.52 +/- 0.47 mg/kg), gastric pH increased from 1.6 +/- 1.0 to 5.1 +/- 1.1 (p <.001), which was associated with a plasma concentration of 373 +/- 257 ng/mL. Based on the pharmacokinetic variables, the dose of intravenous ranitidine required to target 373 ng/mL as the average steady-state concentration is 1.5 mg/kg administered every 8 hrs. During the continuous infusion, the mean steady-state ranitidine concentration associated with gastric pH > or =4 was 287 +/- 133 ng/mL. This concentration may be achieved with an intravenous loading dose of 0.45 mg/kg followed by a continuous infusion of 0.15 mg x kg(-1) x hr(-1).

CONCLUSIONS

The pharmacokinetics of ranitidine in critically ill children are variable. The description of ranitidine's pharmacokinetics and pharmacodynamics in this study may used to design an initial ranitidine dosage regimen that targets a gastric pH > or =4. Thereafter, gastric pH should be monitored and the dose of ranitidine adjusted accordingly.

The attributable mortality and length of intensive care unit stay of clinically important gastrointestinal bleeding in critically ill patients

OBJECTIVE

To estimate the mortality and length of stay in the intensive care unit (ICU) attributable to clinically important gastrointestinal bleeding in mechanically ventilated critically ill patients.

DESIGN

Three strategies were used to estimate the mortality attributable to bleeding in two multicentre databases. The first method matched patients who bled with those who did not (matched cohort), using duration of ICU stay prior to the bleed, each of six domains of the Multiple Organ Dysfunction Score (MODS) measured 3 days prior to the bleed, APACHE II score, age, admitting diagnosis, and duration of mechanical ventilation. The second approach employed Cox proportional hazards regression to match bleeding and non-bleeding patients (model-based matched cohort). The third method, instead of matching, derived estimates based on regression modelling using the entire population (regression method). Three parallel analyses were conducted for the length of ICU stay attributable to clinically important bleeding.

SETTING

Sixteen Canadian university-affiliated ICUs.

PATIENTS

A total of 1666 critically ill patients receiving mechanical ventilation for at least 48 hours.

MEASUREMENTS

We prospectively collected data on patient demographics, APACHE II score, admitting diagnosis, daily MODS, clinically important bleeding, length of ICU stay, and mortality. Independent adjudicators determined the occurrence of clinically important gastrointestinal bleeding, defined as overt bleeding in association with haemodynamic compromise or blood transfusion.

RESULTS

Of 1666 patients, 59 developed clinically important gastrointestinal bleeding. The mean APACHE II score was 22.9 +/- 8.6 among bleeding patients and 23.3 +/- 7.7 among non-bleeding patients. The risk of death was increased in patients with bleeding using all three analytic approaches (matched cohort method: relative risk [RR]= 2.9, 95% confidence interval (CI)= 1.6-5.5; model-based matched cohort method: RR = 1.8, 95% CI = 1.1-2.9; and the regression method: RR = 4.1, 95% CI = 2.6-6.5). However, this was not significant for the adjusted regression method (RR = 1.0, 95% CI = 0.6-1.7). The median length of ICU stay attributable to clinically important bleeding for these three methods, respectively, was 3.8 days (95% CI = -0.01 to 7.6 days), 6.7 days (95% CI = 2.7-10.7 days), and 7.9 days (95% CI = 1.4-14.4 days).

CONCLUSIONS

Clinically important upper gastrointestinal bleeding has an important attributable morbidity and mortality, associated with a RR of death of 1-4 and an excess length of ICU stay of approximately 4-8 days.

Gastrointestinal bleeding in infancy and childhood

Gastrointestinal (GI) bleeding is an alarming problem in children. Although many causes of GI bleeding are common to children and adults, the frequency of specific causes differs greatly, and some lesions, such as necrotizing enterocolitis or allergic colitis, are unique to children. This article reviews the spectrum of GI bleeding in infants and children. The causes, diagnostic evaluation, and management are discussed, and differences with adult medicine are highlighted.

Risk factors for clinically important upper gastrointestinal bleeding in patients requiring mechanical ventilation. Canadian Critical Care Trials Group

OBJECTIVE

To evaluate the incidence and risk factors for clinically important upper gastrointestinal bleeding in critically ill patients requiring mechanical ventilation.

DESIGN

In duplicate, blinded adjudicators determined the presence of clinically important gastrointestinal bleeding using a priori criteria, evaluating relevant clinical, laboratory, and diagnostic data. Cox proportional hazards regression analyses were used to examine baseline and time-dependent risk factors for bleeding.

SETTING

Sixteen university-affiliated intensive care units (ICUs) in Canada.

PATIENTS

A total of 1,077 critically ill ICU patients ventilated for at least 48 hrs.

INTERVENTIONS

Patients were randomized to stress ulcer prophylaxis with intravenous ranitidine or nasogastric sucralfate; otherwise, management was at the discretion of the ICU team.

MEASUREMENTS AND MAIN RESULTS

Demographic data included patient characteristics, Acute Physiology and Chronic Health Evaluation II score, and multiple organ dysfunction (MOD) score. Each day in the ICU, physiologic measurements including MOD score, feeding, and other treatment variables were recorded. The significant risk factors for upper gastrointestinal bleeding in the univariable analyses were low platelet count, maximum serum creatinine, maximum MOD score, maximum pulmonary component of the MOD score, maximum hepatic component of the MOD score, maximum renal component of the MOD score, enteral nutrition, and stress ulcer prophylaxis with ranitidine. The only independent predictors of bleeding in the multivariable analysis were maximum serum creatinine (relative risk = 1.16 [95% confidence interval = 1.02-1.32]), enteral nutrition (relative risk = 0.30 [95% confidence interval = 0.13-0.67]), and ranitidine administration (relative risk = 0.39 [95% confidence interval = 0.17-0.83]).

CONCLUSIONS

In critically ill ventilated patients, renal failure was independently associated with an increased risk of clinically important gastrointestinal bleeding, whereas enteral nutrition and stress ulcer prophylaxis with ranitidine conferred significantly lower bleeding rates.

Disorders of the stomach and duodenum in children

Over the past year, there have been continued efforts to increase our understanding of the epidemiology, natural history, and pathogenic mechanisms of Helicobacter pylori infection in children. In an attempt to delineate the spectrum of disease associated with this organism, several teams of investigators have also examined the association of H. pylori infection with other disorders, from food allergy to inflammatory bowel disease. Developmental aspects of gastric and duodenal motility, risk factors for gastrointestinal bleeding in pediatric intensive care unit patients, and the use of uncooked cornstarch in the treatment of dumping syndrome are among other topics covered in this review.

Upper gastrointestinal tract bleeding in critically ill pediatric patients

Similar to adults, children under physiologic stress can develop an imbalance in defensive (mucosal layer, motility) and aggressive (gastric acid, bile salts, enzymes) factors responsible for maintaining a healthy gastrointestinal tract. Hypoxia in the gastrointestinal tract likely disrupts the defensive factors, thereby permitting damage by aggressive factors to upper gastrointestinal epithelium that may progress to stress ulceration and acute upper gastrointestinal tract bleeding (UGIB). The basic pathophysiology may be similar in children and adults; however, differences in the time to developing ulceration, ulcer location, and number of ulcers have been reported. Functional development of the gastrointestinal tract is influenced by disease, gestational and postnatal age, and exposure to and type of enteral feedings, thereby confounding the development and prophylaxis of UGIB in neonates and infants. In addition, pharmacotherapy decisions are often complicated by drug administration issues and adverse effects.

Clinically significant upper gastrointestinal bleeding acquired in a pediatric intensive care unit: a prospective study

OBJECTIVES

To determine the incidence, risk factors, and complications associated with or attributable to clinically significant upper gastrointestinal (GI) bleeding acquired in a pediatric intensive care unit (ICU).

METHODS

Prospective, descriptive epidemiologic study in a multidisciplinary pediatric ICU of a tertiary-care university hospital. Upper GI bleeding was considered to be present if hematemesis occurred or blood was present in the gastric tube. An upper GI bleed was qualified as clinically significant if two or three reviewers independently assessed that at least one of the six complications considered for analysis was attributable to the upper GI bleed.

RESULTS

A cohort of 1114 consecutive admissions was enrolled; 108 (9.7%) were excluded mostly (37.0%) because they already had an upper GI bleed at entry to the pediatric ICU. The final sample included 1006 admissions (881 patients); 103 upper GI bleeds (10.2%) were diagnosed, including 16 clinically significant upper GI bleeds (1. 6%). Complications attributed to an upper GI bleed included: decreased hemoglobin concentration (10 cases), transfusion (10), hypotension (3), and surgery (1). Three independent risk factors for clinically significant upper GI bleeding were retained by multivariate analysis: respiratory failure, coagulopathy, and pediatric risk of mortality score >/=10. Nine of the 16 cases (56. 3%) with clinically significant upper GI bleeding had three risk factors, 14 (87.5%) had two, and 1 (6.3%) had none.

CONCLUSIONS

Clinically significant upper GI bleeds are rare in critically ill children. Prophylaxis to prevent them may be limited to patients who present with at least two risk factors.

[Concept of stress ulcer prevention. Is re-thinking necessary?]

BACKGROUND

The efficiency of stress ulcer prophylaxis in the prevention of gastrointestinal bleeding in critically ill patients has led to its widespread use. The lower incidence of stress ulcer bleeding, the side-effects and the cost of the prophylaxis have made it necessary targeting this preventive therapy to those patients most likely to benefit. Metaanalysis of studies on patients who received no stress ulcer prophylaxis showed few critically ill patients with important gastrointestinal bleeding.

INDICATIONS

Patients who benefit most from receiving stress ulcer prophylaxis are critically ill patients with coagulopathy, or those requiring mechanical ventilation for more than two days. In patients with headinjuries, widespread burns or severe hypotension, the effects of stress ulcer prophylaxis have not been fully researched, but we would recommend administering stress ulcer prophylaxis in these cases.

TREATMENT

Following a recent metaanalysis, stress ulcer prophylaxis is performed either with H2-blockers (ranitidine, famotidine) or sucralfate.

A comparison of sucralfate and ranitidine for the prevention of upper gastrointestinal bleeding in patients requiring mechanical ventilation. Canadian Critical Care Trials Group

BACKGROUND

Critically ill patients who require mechanical ventilation are at increased risk for gastrointestinal bleeding from stress ulcers. There are conflicting data on the effect of histamine H2-receptor antagonists and the cytoprotective agent sucralfate on rates of gastrointestinal bleeding, ventilator-associated pneumonia, and mortality.

METHODS

In a multicenter, randomized, blinded, placebo-controlled trial, we compared sucralfate with the H2-receptor antagonist ranitidine for the prevention of upper gastrointestinal bleeding in 1200 patients who required mechanical ventilation. Patients received either nasogastric sucralfate suspension (1 g every six hours) and an intravenous placebo or intravenous ranitidine (50 mg every eight hours) and a nasogastric placebo.

RESULTS

The patients in the two groups had similar base-line characteristics. Clinically important gastrointestinal bleeding developed in 10 of 596 (1.7 percent) of the patients receiving ranitidine, as compared with 23 of 604 (3.8 percent) of those receiving sucralfate (relative risk, 0.44; 95 percent confidence interval, 0.21 to 0.92; P=0.02). In the ranitidine group, 114 of 596 patients (19.1 percent) had ventilator-associated pneumonia, as compared with 98 of 604 (16.2 percent) in the sucralfate group (relative risk, 1.18; 95 percent confidence interval, 0.92 to 1.51; P=0.19). There was no significant difference between the groups in mortality in the intensive care unit (ICU) (23.5 percent in the ranitidine group and 22.9 percent in the sucralfate group) or the duration of the stay in the ICU (median, nine days in both groups).

CONCLUSIONS

Among critically ill patients requiring mechanical ventilation, those receiving ranitidine had a significantly lower rate of clinically important gastrointestinal bleeding than those treated with sucralfate. There were no significant differences in the rates of ventilator-associated pneumonia, the duration of the stay in the ICU, or mortality.

A randomized, controlled study of prophylactic ranitidine in preventing stress-induced gastric mucosal lesions in neonatal intensive care unit patients

OBJECTIVE

To assess endoscopically the effect of prophylactic short-term ranitidine treatment in the prevention of stress-induced gastric lesions in neonatal intensive care unit (ICU) patients.

DESIGN

Prospective, randomized study.

SETTING

Department of Neonatal Intensive Care, University Hospital of Tampere.

PATIENTS

Fifty-three infants were enrolled in a randomized, controlled study. Forty-eight (90%) of these patients underwent endoscopic examination and were evaluated.

INTERVENTIONS

A histamine-2-receptor blocker, ranitidine, was given prophylactically after birth for 4 days to infants mechanically ventilated and treated in the neonatal ICU. The gastric mucosa was both visually and histologically evaluated after 3 to 6 days, and the outcome of the infants was registered.

MEASUREMENTS AND MAIN RESULTS

In the 23 infants prophylactically treated with ranitidine, the gastric mucosa was visually classified as normal in 14 (61%) infants as compared with five (20%) of 25 controls (p < .004). Histologic lesions showed parallel results (57% vs. 16%, p < .004). Eight gastric ulcers were diagnosed endoscopically in the control group vs. none in the treatment group. The ulcers were all clinically "silent" at the time of endoscopy. According to logistic regression modeling, the decreased risk for gastric mucosal lesions in infants receiving prophylactic ranitidine was 0.03 (95% confidence interval 0.003 to 0.178). Surfactant treatment for infant respiratory distress syndrome also decreased the risk for stress-induced gastric mucosal lesions (odds ratio 0.083; 95% confidence interval 0.009 to 0.788), whereas other variables (birth weight, gestational age, Apgar scores, cord blood pH, and duration of intubation) had no significant effect. No side effects could be attributed to the ranitidine treatment.

CONCLUSION

We conclude that short-term prophylactic ranitidine treatment prevents gastric mucosal lesions in newborn infants under stress.

Prophylaxis for stress-related gastrointestinal hemorrhage: a cost effectiveness analysis

OBJECTIVE

To assess the cost-effectiveness of prophylaxis for stress-related gastrointestinal hemorrhage in patients admitted to the intensive care unit.

DESIGN

Decision model of the cost and efficacy of sucralfate and cimetidine, two commonly used drugs for prophylaxis of stress-related hemorrhage. Outcome estimates were based on data from published studies. Cost data were based on cost of medications and costs of treatment protocols at our institutions.

MEASUREMENTS AND MAIN RESULTS

The marginal cost-effectiveness of prophylaxis, as compare with no prophylaxis, was calculated separately for sucralfate and cimetidine and expressed as cost per bleeding episode averted. An incremental cost-effectiveness analysis was subsequently employed to compare the two agents. Sensitivity analyses of the effects of the major clinical outcomes on the cost per bleeding episode averted were performed. At the base-case assumptions of 6% risk of developing stress-related hemorrhage and 50% risk-reduction due to prophylaxis, the cost of sucralfate was $1,144 per bleeding episode averted. The cost per bleeding episode averted was highly dependent on the risk of hemorrhage and, to a lesser degree, on the efficacy of sucralfate prophylaxis, ranging from a cost per bleeding episode averted of $103,725 for low-risk patients to cost savings for very high-risk patients. The cost per bleeding episode averted increased significantly if the risk of nosocomial pneumonia was included in the analysis. The effect of pneumonia was greater for populations at low risk of hemorrhage. Assuming equal efficacy, the cost per bleeding episode averted of cimetidine was 6.5-fold greater than the cost per bleeding episode averted of sucralfate.

CONCLUSIONS

The cost of prophylaxis in patients at low risk of stress-related hemorrhage is substantial, and may be prohibitive. Further research is needed to identify patient populations that are at high risk of developing stress-related hemorrhage, and to determine whether prophylaxis increases the risk of nosocomial pneumonia.

Risk factors for gastrointestinal bleeding in critically ill patients. Canadian Critical Care Trials Group

BACKGROUND

The efficacy of prophylaxis against stress ulcers in preventing gastrointestinal bleeding in critically ill patients has led to its widespread use. The side effects and cost of prophylaxis, however, necessitate targeting preventive therapy to those patients most likely to benefit.

METHODS

We conducted a prospective multicenter cohort study in which we evaluated potential risk factors for stress ulceration in patients admitted to intensive care units and documented the occurrence of clinically important gastrointestinal bleeding (defined as overt bleeding in association with hemodynamic compromise or the need for blood transfusion).

RESULTS

Of 2252 patients, 33 (1.5 percent; 95 percent confidence interval, 1.0 to 2.1 percent) had clinically important bleeding. Two strong independent risk factors for bleeding were identified: respiratory failure (odds ratio, 15.6) and coagulopathy (odds ratio, 4.3). Of 847 patients who had one or both of these risk factors, 31 (3.7 percent; 95 percent confidence interval, 2.5 to 5.2 percent) had clinically important bleeding. Of 1405 patients without these risk factors, 2 (0.1 percent; 95 percent confidence interval, 0.02 to 0.5 percent) had clinically important bleeding. The mortality rate was 48.5 percent in the group with bleeding and 9.1 percent in the group without bleeding (P < 0.001).

CONCLUSIONS

Few critically ill patients have clinically important gastrointestinal bleeding, and therefore prophylaxis against stress ulcers can be safely withheld from critically ill patients unless they have coagulopathy or require mechanical ventilation.