Therapeutic goals and treatment options for prevention of stress ulcer syndrome

Gastroprotective effects of Pikad Tri-phol-sa-mut-than herbal remedy on multiple gastric ulcer models in rats

In Thai traditional medicine, Pikad Tri-phol-sa-mut-than has long been used to alleviate gastrointestinal symptoms, renal disease, inflammation-related disorders, and severe malady. This recipe is composed of dried fruits of Morinda citrifolia L., Coriandrum sativum L., and Aegle marmelos (L.) Corrêa. The aim of this study was to assess the anti-gastric ulcer property of the water extract of Pikad Tri-phol-sa-mut-than (TS), using various animal models with different inducers, including restraint water immersion stress, indomethacin, and ethanol/hydrochloric acid (EtOH/HCl). Its mechanisms of anti-gastric ulcer actions were also elucidated using both in vitro and in vivo experiments. When compared with the control groups, the oral pretreatment of TS at the doses of 150, 300 and 600 mg/kg significantly reduced the gastric ulcer formation in all models. It was also found that TS at the dose of 600 mg/kg could increase gastric wall mucus in rats but could not produce the significant reduction of the gastric volume or total acidity of gastric content. Results from hematoxylin and eosin (H&E) and Periodic acid-Schiff (PAS) staining examinations of gastric tissues confirmed that TS visibly reduced gastric mucosal damage, while immunohistochemistry revealed that TS remarkably suppressed the protein expression of Bcl-2-associated X (BAX), a regulator of apoptosis, compared to those of the control group. The DPPH, ABTS, and FRAP assays showed antioxidant effects of TS. All of these findings demonstrated that TS has gastroprotective effects, which may be related to the increase in the gastric wall mucus secretion, not anti-secretory activity, as well as its antioxidant and antiapoptotic activities.

Nervous mechanisms of restraint water-immersion stress-induced gastric mucosal lesion

Stress-induced gastric mucosal lesion (SGML) is one of the most common visceral complications after trauma. Exploring the nervous mechanisms of SGML has become a research hotspot. Restraint water-immersion stress (RWIS) can induce GML and has been widely used to elucidate the nervous mechanisms of SGML. It is believed that RWIS-induced GML is mainly caused by the enhanced activity of vagal parasympathetic nerves. Many central nuclei, such as the dorsal motor nucleus of the vagus, nucleus of the solitary tract, supraoptic nucleus and paraventricular nucleus of the hypothalamus, mediodorsal nucleus of the thalamus, central nucleus of the amygdala and medial prefrontal cortex, are involved in the formation of SGML in varying degrees. Neurotransmitters/neuromodulators, such as nitric oxide, hydrogen sulfide, vasoactive intestinal peptide, calcitonin gene-related peptide, substance P, enkephalin, 5-hydroxytryptamine, acetylcholine, catecholamine, glutamate, γ-aminobutyric acid, oxytocin and arginine vasopressin, can participate in the regulation of stress. However, inconsistent and even contradictory results have been obtained regarding the actual roles of each nucleus in the nervous mechanism of RWIS-induced GML, such as the involvement of different nuclei with the time of RWIS, the different levels of involvement of the sub-regions of the same nucleus, and the diverse signalling molecules, remain to be further elucidated.

Pharmacologic Prophylaxis of Stress Ulcer in Non-ICU Patients: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

PURPOSE

Acid-suppressive medications are widely used in non-intensive care unit (non-ICU) patients for stress ulcer (SU) prophylaxis. However, SU prophylaxis in this population is still controversial. The purpose of this study was to systematically evaluate the efficacy and tolerability of these agents for SU prophylaxis in non-ICU patients.

METHODS

Electronic databases including Cochrane, ClinicalTrials.gov, Ovid-Medline, Embase, Chinese CNKI, and Wanfang Data were systematically searched on July 10, 2019, for randomized controlled trials (RCTs) that evaluated acid-suppressive medications in non-ICU patients. Network meta-analysis and pairwise meta-analysis were performed to calculate odds ratios (ORs) and 95% CIs. A random-effects model was used for generating pooled estimates. The primary outcome was occurrence of SU bleeding, and the adverse drug events (ADEs) were described as the secondary outcome.

FINDINGS

A total of 17 RCTs involving 1985 patients were eligible. Meta-analysis results indicated that the occurrence of SU bleeding was significantly decreased with all acid-suppressive medications compared with placebos (gastric mucosa protectants, OR = 0.29 [95% CI, 0.14-0.61]; H2-receptor antagonists, OR = 0.3 [95% CI, 0.18-0.50]; proton pump inhibitors [PPIs]: OR = 0.08 [95% CI, 0.04-0.16]). The occurrence of SU bleeding was significantly decreased with PPIs compared with gastric mucosa protectants (OR = 0.29; 95% CI, 0.12-0.72) and H2-receptor antagonists (OR = 0.28; 95% CI, 0.16-0.48). There was no significant difference between any 2 classes of PPIs on SU bleeding or any 2 acid-suppressive medications on ADEs.

IMPLICATIONS

PPIs could significantly decrease SU bleeding risk without increasing ADEs than other acid-suppressive medications for SU prophylaxis in non-ICU patients. However, RCTs of high quality were required to confirm the findings of this investigation.

Comparison of three acute stress models for simulating the pathophysiology of stress-related mucosal disease

Stress-related mucosal disease (SRMD) is highly prevalent in intensive care patients leading to increasing treatment cost and mortality. SRMD is a disease elusive of ideal treatment. Evaluation of drugs is very pertinent for the efficient and safe treatment of SRMD. It relies mainly on in vivo screening models. There are various stress models, and till date, none of them is validated for simulating the SRMD pathophysiology. The present study aims to choose the best model, which reproduce pathophysiology of SRMD, among previously established stress models. This study evaluates ulcer index, hexosamine content, microvascular permeability, and gastric content in three acute stress models (cold-restraint, restraint, and water immersion restraint). Macroscopic pictures of the ulcerogenic stomach explain that in contrast to other models, cold-restraint stress (CRS) exposure produced marked ulcers on the fundic area of the stomach. Results of the present study depicted that each stress model significantly increased ulcer index, microvascular permeability and decreased hexosamine level, however, the maximum in the case of CRS-exposed rats. Total acidity and pH of the gastric content remains unchanged in all the stress models. On the contrary, the gastric volume significantly decreased only in case of CRS, while unchanged in other stress models. The overall results revealed that the CRS resembles the pathophysiology of SRMD closely. It is the best and feasible model among all the models to evaluate drugs for the treatment of SRMD.

The Antisecretory Effects of Ranitidine Administered by Continuous Infusion

Prevention of stress-induced upper gastrointestinal ul ceration and bleeding is an important issue for clinicians caring for critically ill patients. Although H2 blockers have been demonstrated as effective in treating patients with stress ulcers and bleeding, the ideal regimen of administration has not yet been devised. One method, continuous intravenous infusion, minimizes variation in drug effects by controlling for pharmacokinetic vari ables. Even with the use of continuous infusion, consis tent control of gastric pH may not be attained. Because of the pharmacokinetic, pharmacodynamic, and patient variables, there is often a discrepancy between H2 blocker dose and effects. Studies in healthy persons and patients with duodenal ulcers demonstrate a circadian variation in gastric acid production and in the effects of H2 blockers on gastric pH. In particular, H2 blockers may be less effective in the evening. To address this concern in intensive care patients, continuous intrave nous infusions of H2 blockers can be used, but variable rates of intravenous infusions may be more effective, allowing for the circadian variations in gastric acidity. Further study is needed to define patient groups that most require intravenous H2 blockers, to devise regi mens that are more effective in continuously controlling gastric pH in critically ill patients, and to clarify dose- response relationships for H2 blockers.

Pneumonia prevention in intubated patients given sucralfate versus proton-pump inhibitors and/or histamine II receptor blockers

BACKGROUND

Ventilator-associated pneumonia (VAP) is a common cause of infectious morbidity and mortality in the intensive care unit (ICU). The type of stress-ulcer prophylaxis (SUP) given to ventilated patients may, in part, be responsible. We observed an increase in VAP as ventilator bundle compliance increased and a decrease in VAP when bundle compliance decreased. We reasoned that SUP which raises gastric pH such as proton-pump inhibitors (PPIs) and histamine II (H2) receptor antagonists as opposed to SUP which does not raise pH such as sucralfate (S) may be responsible and also may alter the causative bacteria.

MATERIALS AND METHODS

This is a single-center retrospective cohort analysis of all intubated, adult surgical patients admitted to the surgical ICU between January and June during the 3-y period 2012-2014. Demographics, APACHE II, Injury Severity Score, VAP occurrence, culprit bacteria, ventilator days, and ICU days were recorded based on the type of SUP given.

RESULTS

There were 45 instances of VAP in the 504 study patients, 33 in the PPI/H2 group, and 12 in the S group (P < 0.01). VAP per 1000 ventilator days were 10.2 for PPI/H2 and 3.7 for S (P < 0.01). Culprit bacteria were mostly Pseudomonas, gram-negative bacilli, and methicillin-resistant Staphylococcus aureus in PPI/H2 patients (n = 29) compared with oropharyngeal flora in S patients (n = 6; P < 0.001).

CONCLUSIONS

There was a substantial difference in VAP occurrence and in the culprit bacteria between S and PPI/H2 treated patients due perhaps to gastric alkalization.

[Guidelines of treatment for peptic ulcer disease in special conditions]

The pathogenesis, incidence, complication rates, response to acid suppression and Helicobacter pylori (H. pylori) eradication therapy in peptic ulcer associated with chronic disease such as liver cirrhosis, chronic renal failure, diabetes mellitus, and critically ill conditions are different from those with general population, so that the management strategies also should be differentiated. The eradication of H. pylori are not so effective for preventing recurrence of peptic ulcer in liver cirrhosis patients as shown in general population, and conservative managements such as preventing deterioration of hepatic function and decrease in portal pressure are mandatory to reduce the risk of ulcer recurrence. The standard triple therapy for H. pylori eradication are as effective in chronic renal failure patients as in normal population, but the frequency of side effects of amoxicillin is higher in the patients not receiving dialysis therapy. Delay in eradication therapy until beginning of dialysis therapy or modification of eradication regimen should be considered in such cases. High prevalence of asymptomatic peptic ulcers and increased mortality in complicated peptic ulcer disease warrant regular endoscopic surveillance in diabetic patients, especially with angiopathy. The prolongation of duration of eradication therapy also should be considered in diabetic patients with angiopathic complication because of lower eradication rate with standard triple regimens as compared to normal population. Prophylactic acid suppressive therapy is highly recommended in critically ill patients with multiple risk factors. Herein, we propose evidence-based treatment guidelines for the management of peptic ulcer disease in special conditions based on literature review and experts opinion.

Stress ulceration in the intensive care unit: use of H2-receptor antagonists

H2-receptor antagonist drug therapy is the mainstay of peptic ulcer treatment in the USA. About 75% of patients in intensive care units receive parenteral H2-antagonists. The rationale for their use is that parenteral H2-antagonists offer about a four-fold protective effect compared with placebo against significant upper gastrointestinal haemorrhage. Parenteral administration of H2-receptor antagonists appears to be preferred to oral antacid or sucralfate regimens because of ease of administration and, perhaps, lower treatment costs. Recommended dosage schedules for intravenously administered H2-receptor antagonists are at fixed intervals, 6- to 8-h intervals for cimetidine and ranitidine and 12-h intervals for famotidine. These dosage schedules assume a fixed dose-response relationship (i.e. a given dose of H2-antagonist results in equivalent acid suppression throughout the circadian, or 24-h, period). However, human basal gastric acid secretion exhibits circadian variation, with peak rates occurring during the evening hours. Recent evidence from 24-h continuous intragastric pH studies in fasting patients with healed duodenal ulcer suggests that larger doses of intravenous H2-antagonists are required in the evening than in the morning to achieve equivalent acid suppression. These findings are consistent with a changing H2-antagonist dose/acid-inhibiting response over the circadian period. Continuous infusion has the advantage of providing consistent and sustained suppression of gastric acid secretion in patients at risk for stress ulceration. Results of a double-blind, randomized, crossover study indicated that equally effective suppression of acidity and time-to-onset of pharmacological effect can be achieved with and without priming bolus doses of ranitidine, and presumably other H2-receptor antagonists as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Stress ulcer bleeding

Although upper gastrointestinal (GI) bleeding from stress-related mucosal disease (SRMD) in critically ill patients is common, significant bleeding with hemodynamic instability is not. Risk factor assessment can assist in identifying patients with a greater likelihood of developing significant SRMD. Prophylaxis against stress ulcer bleeding with luminal agents (eg, antacids and sucralfate) or drugs that inhibit acid secretion (eg, histamine 2-receptor antagonists and proton-pump inhibitors) can reduce major bleeding but has little or no effect on mortality. Currently, the mainstays of prophylactic therapy for SRMD are intravenously administered H2RAs and PPIs. Wider usage of PPIs reflects their enhanced efficacy in suppressing acid secretion as well as lack of tolerance for H2RAs. Guidelines for the prophylactic use of H2RAs or PPIs in treatment of SRMD will require large, randomized studies that also examine cost effectiveness of individual strategies.

Stress-related mucosal disease: risk factors and prophylactic therapy

BACKGROUND

The term stress-related mucosal disease (SRMD) represents a continuum of conditions ranging from stress-related injury (superficial mucosal damage) to stress ulcers (focal deep mucosal damage). Caused by mucosal ischemia, SRMD is most commonly seen in critically ill patients in the intensive care unit (ICU). Prophylaxis of stress ulcers may reduce major bleeding but has not yet been shown to improve survival.

OBJECTIVES

This article reviews currently available agents for the prophylaxis of SRMD and discusses their uses and potential adverse effects.

METHODS

Relevant articles in the English-language literature were identified through a MEDLINE search (1968-2003) using the key words stress-related mucosal disease, stress-related injury, ulcer, prophylaxis, intensive care unit, and upper gastrointestinal bleeding.

RESULTS

The most widely used drugs for stress-related injury are the intravenous histamine(2)-receptor antagonists. These drugs raise gastric pH but are associated with the development of tolerance and possible drug interactions and neurologic manifestations. Sucralfate, which can be administered by the nasogastric route, can protect the gastric mucosa without raising pH, but may decrease the absorption of concomitantly administered oral medications. The prostaglandin misoprostol has not been shown to be of benefit in the prophylaxis of SRMD. Antacids lower the risk of gastrointestinal bleeding, but large volumes of antacids are required and treatment is labor intensive. Proton pump inhibitors (PPIs) are the most potent acid-suppressive pharmacologic agents available. Esomeprazole, lansoprazole, omeprazole, pantoprazole, and rabeprazole substantially raise gastric pH for up to 24 hours after a single dose. The availability of an intravenous formulation of pantoprazole may help improve the treatment of SRMD in ICU patients, particularly those receiving mechanical ventilation. Tolerance does not develop, and few adverse effects have been reported.

CONCLUSIONS

Recent studies of PPIs have shown promising results in high-risk patients, making this class of drugs an option for the prophylaxis of SRMD.

Stress-related Mucosal Disease

Stress-related mucosal disease (SRMD) includes stress-related injury (superficial mucosal damage) and stress ulcers (focal deep mucosal damage). Both types are caused by mucosal ischemia, and both show a propensity for the acid-producing corpus and fundus. Prophylaxis of stress ulcers may reduce major bleeding but, so far, has not been shown to improve survival. The most widely used drugs for stress-related injury are the intravenous histamine H(2)-receptor antagonists. Proton pump inhibitors (PPIs) are the most potent acid-suppressive pharmacologic agents. The available PPIs significantly increase gastric pH for up to 24 hours after one dose. Tolerance does not develop, and adverse effects are few. Preliminary studies have demonstrated a significant reduction in SRMD bleeding for patients receiving PPI prophylaxis. PPIs may become an effective tool for reducing the incidence of SRMD in critically ill patients.

The use of intravenous H2-receptor antagonists in a tertiary care hospital

OBJECTIVE

The rationale for the widespread use of intravenous H2 receptor antagonists(IVH2 RA) in hospitalized patients is not clear. We therefore examined prescribing patterns and, using strict criteria, determined whether use was appropriate. Cost of administration and potential savings were also determined.

METHODS

Data were obtained prospectively on 100 consecutive patients prescribed intravenous ranitidine and retrospectively on patients admitted with gastrointestinal (GI) bleeding.

RESULTS

For the prospective study, various indications for prescribing intravenous ranitidine were given, including postoperative patients and patients treated with steroids. Using criteria from published literature 80% of the use was considered inappropriate. Nearly 40% of the doses were given while the patient was tolerating oral intake. Creatinine clearance was impaired in 26% of patients, though only one had dosage reduction. Estimated annual cost of intravenous ranitidine was $317,000. The retrospective study of 86 consecutive patients admitted with GI bleeding revealed that all patients received intravenous ranitidine on admission, none of which was considered appropriate. The final diagnoses were peptic ulcer (49), colonic process (11), esophagitis (seven), gastric erosions (five), esophageal varices (five), Mallory-Weiss tears (four), duodenitis (two), no diagnosis (three), and jejunal ulcer (one).

CONCLUSIONS

Inappropriate use of intravenous ranitidine is common. This includes inappropriate indication, dosage, and duration of use. Large financial benefits could have been obtained if close attention was given to prescribing patterns.

[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.

Nutrition support is not beneficial and can be harmful in critically ill patients

The introductory remark by Lucretius serves as a reminder that nutrient intake can have very different consequences in different subjects. In the patient with an acute or serious illness, metabolic derangements can transform a substance that is normally a source of energy into a source of metabolic toxins. The potential for organic nutrients to become organic toxins in the diseased host is a phenomenon that deserves more attention in the debate about the value of nutrition support in critically ill patients.

Hemorrhagic shock

A great deal has been learned about the pathophysiologic condition of hemorrhagic shock. The response of the hormonal and inflammatory mediator systems in patients in hemorrhagic shock appears to represent a distinct set of responses different from those of other forms of shock. The classic neuroendocrine response to hemorrhage attempts to maintain perfusion to the heart and brain, often at the expense of other organ systems. This intense vasoconstriction occurs via central mechanisms. The response of the peripheral microcirculation is driven by local tissue hypoperfusion that results in vasodilation in the ischemic tissue bed. Activation of the systemic inflammatory response by hemorrhage and tissue injury is an important component of the pathophysiologic condition of hemorrhagic shock. Activators of this systemic inflammatory response include ischemia/reperfusion injury and neutrophil activation. Capillary "no-flow" with prolonged ischemia and "no-reflow" with reperfusion may initiate neutrophil activation in patients in hemorrhagic shock. The mechanisms that lead to decompensated and irreversible hemorrhagic shock include (1) "arteriolar hyposensitivity" as manifested by progressive arteriolar vasodilation and decreased responsiveness of the microcirculation to alpha-agonists, and (2) cellular injury and activation of both proinflammatory and counterinflammatory mechanisms. These changes represent a failure of the microcirculation. Redistribution of cardiac output and persistent gut ischemia after adequate resuscitation may also contribute to the development of irreversible hemorrhagic shock. Treatment of hemorrhagic shock includes rapid operative resuscitation to limit activation of the mediator systems and abort the microcirculatory changes that result from hemorrhagic shock. Volume resuscitation and control of hemorrhage, should occur simultaneously. The end point in volume resuscitation of hemorrhagic shock must be maintenance of organ system and cellular function. Whether we use adequate urine output, correction of lactic acidemia, optimization of oxygen delivery, or oxygen consumption as our specific goal, the general objective is to provide adequate crystalloid solution and packed red blood cells to achieve and maintain normal organ and cellular perfusion and function.

Changing perspectives of stress gastritis prophylaxis

OBJECTIVE

To present recent advances in stress gastritis prophylaxis in the critically ill and review considerations in selection of a prophylactic agent.

DATA SOURCES

Information was obtained from MEDLINE search, reference lists from articles identified in search, and from review articles.

STUDY SELECTION

Emphasis was placed on controlled trials conducted within the last 5 years.

DATA EXTRACTION

All literature was assessed for methodology, results, and conclusions. Results of prospective, randomized trials, and meta-analyses are summarized.

DATA SYNTHESIS

Histamine2-receptor antagonists, antacids, and sucralfate appear equally effective in preventing stress gastritis in the critically ill. A definitive cause-effect relationship between histamine2-receptor antagonists and increased incidence of nosocomial pneumonia has not yet been established. The indications for using a prophylactic agent and consideration in selecting an agent should include an evaluation of the following: risk factors for gastritis including the type of intensive care patient, comparative efficacy, adverse effects, drug interactions, cost, and ease of administration. The least expensive, safest agent requiring minimal monitoring is sucralfate. Prevention of stress gastritis has never been shown to reduce morbidity or mortality significantly.

CONCLUSIONS

Controversies still exist regarding the need to provide prophylaxis, the choice of an agent, and the relative importance of previously identified risk factors. Further well-designed studies are needed before consensus can be reached.

Optimal therapy for stress gastritis

OBJECTIVE

The authors compared the results of sucralfate versus H2 blocker +/- antacid as prophylaxis for stress ulceration in an intensive care unit patient population.

SUMMARY BACKGROUND DATA

Stress ulceration carries high morbidity and mortality for the patient who is critically ill. Gastric acid neutralization is an effective prophylaxis. The impact of increased gastric colonization with bacterial pathogens on nosocomial pneumonia after acid neutralization is unclear. The efficacy of sucralfate prophylaxis for stress ulceration and its the effect on the nosocomial pneumonia rate is controversial. The financial implications of sucralfate prophylaxis versus H2 blocker-based acid neutralization therapy has not been studied.

METHODS

Ninety-eight injured patients who were critically ill and who required intubation and intensive care unit (ICU) support for at least 72 hours without gastric feeding were randomized and received either maximal H2 blocker infusion therapy (continuous infusion of ranitidine at 0.25 mg/kg/hr after a loading dose of 0.5 mg/kg) plus antacids (for persistent pH < 4) or sucralfate (1 g every 6 hours via nasogastric tube) for stress ulcer prophylaxis. Efficacy in preventing stress ulcer complications was determined. The impact of each therapeutic approach on development of nosocomial pneumonia was evaluated. The charges/cost for each approach was analyzed.

RESULTS

Heme-positive gastric aspirates occurred in 99% of the patients, whereas 12 (7 in the H2 blocker group and 5 in the sucralfate group) were grossly positive for blood. However, only one from each group required transfusion, and one in the H2 blocker group required operation. Gastric colonization preceded tracheobronchial colonization in five patients in the H2 blocker group and one patient in the sucralfate group; simultaneous gastric/oropharyngeal colonization preceded positive tracheobronchial growth in six patients who received H2 blocker and one patient who received sucralfate. The overall pneumonia rate was 27.5% in the H2 blocker group and 20.8% in the sucralfate group (p = 0.48). Days on ventilator were 13.5 versus 9.1, (p = 0.06), ICU lengths of stay were 14.7 versus 10.2 (p = 0.06), and hospital lengths of stay were 27.8 versus 20.0 (p = 0.029) for the H2 blocker group and sucralfate group, respectively. Based on current charges and protocols for optimal H2 blocker and sucralfate prophylaxis, use of sucralfate rather than H2 blockers would decrease the annual cost by more than $30,000 per bed.

CONCLUSIONS

Sucralfate is as efficacious as maximal H2 blocker therapy for stress ulceration prophylaxis, and may have a beneficial effect on the incidence of nosocomial pneumonia. Sucralfate has a major reduction on nursing requirements for stress ulcer prophylaxis and would save approximately $30,000 per ICU bed per year in patient charges.

Antacids. Indications and limitations

Antacids have served us well for over a century. In terms of peptic ulcer disease, the attitude in the late 1950s to 1970s that antacids should be taken only on demand was unjustified and erroneous. 13 recent endoscopic controlled studies have confirmed the efficacy of antacids in the healing of duodenal ulcer, achieving about 75% healing in 4 weeks. The efficacy of antacids in promoting gastric ulcer healing has been less well studied and the results are controversial. The most appropriate and economical antacid regimens for the treatment of duodenal ulcer disease should include tablets or liquid that have acid neutralising capacity of 400 mmol/day given at least an hour after meals. As a long term therapy, antacids appear to work, but need be taken in multiple daily doses, a regimen which is unlikely to meet with long term patient compliance. Patients with gastro-oesophageal reflux disorders or pregnancy-related reflux have also benefited from the usage of antacids ad libitum. Early previous studies have clearly demonstrated the efficacy of antacids in reducing gastro-oesophageal reflux and healing of reflux oesophagitis. The acidity of the gastric contents is the major determining factor in the outcome of the aspiration pneumonitis occurring during delivery. The prophylactic use of antacids during delivery has helped to reduce the severity of this complication. Similarly, the prophylactic administration of antacid aiming to maintain gastric pH between 3.5 to 7.0 has resulted in significant reduction of bleeding due to stress associated ulcers and/or erosive haemorrhagic gastritis in critically ill patients. Antacid therapy, however, is controversial in the management of nonulcer dyspepsia or nonsteroidal anti-inflammatory drug related upper gastrointestinal mucosal damage. Undoubtedly, antacids have major roles to play in the treatment of gastric acid related disorders. They have clear advantages and disadvantages when compared with the antisecretory agents. New proton pump inhibitors in particular have certainly superseded antacids and even the H2-receptor antagonists in many respects. However, the long term safety record of antacids remains unsurpassed by any of the new antisecretory agents.

Twenty-four-hour intragastric pH patterns in ICU patients on ranitidine

Thirty critically ill patients with mixed diagnoses underwent continuous intragastric pH monitoring for 72 hr while confined to a shock/trauma intensive care unit. The first 24 hr were monitored under no specific acid-suppressing therapy (placebo control). During the second and third consecutive 24-hr periods, patients received continuous infusion of intravenous ranitidine in the dose of 6.25 mg/hr and 12.5 mg/hr, respectively. Results of the placebo-control 24-hr study revealed that one third (N = 10) of the patients were gastric acid hyposecretors (24-hr median intragastric pH values above pH 4.0). In the normosecreting group (N = 20), both ranitidine schedules significantly elevated 24-hr median pH values, when compared to placebo (placebo 24-hr median intragastric pH 1.75; ranitidine 6.25 mg/hr 24-hr median intragastric pH 4.625, P < 0.0001; ranitidine 12.5 mg/hr 24-hr median intragastric pH 6.29, P = 0.0099). Five patients (18%) failed to adequately respond to the ranitidine 12.5 mg/hr dose (24-hr median intragastric pH < 4.0). These findings suggest that a significant percentage of intensive care unit patients are not in need of acid-suppressing therapy as prophylaxis against stress-induced ulceration. Conversely, other patients may require more intensive acid-suppressing regimens because of failure to respond to high dose H2-antagonist therapy.

Pharmacokinetics of ranitidine in a homogeneous population of intensive care unit patients during intermittent and continuous administration

The pharmacokinetics of ranitidine during two different modes of intravenous administration was studied in a homogeneous group of postoperative intensive care unit patients (n = 18). Patients at risk of developing stress-related lesions were randomized to receive repeated injections, 50 mg every 6 h (group A), or a continuous infusion, 50-mg bolus followed by 0.125 mg/kg/h (group B). Before treatment all patients received a single 50-mg ranitidine dose. Serum ranitidine concentrations were measured for 12 h after the single dose and during the treatment period, to calculate individual pharmacokinetic variables. From the single-dose study the calculated half-life, volume of distribution, and clearance were 3.14 +/- 0.61 h, 1.45 +/- 0.42 l/kg, and 0.40 +/- 0.14 l/kg/h for group A and 3.33 +/- 1.08 h, 1.16 +/- 0.20 l/kg, and 0.35 +/- 0.21 l/kg/h, for group B, respectively. Ranitidine pharmacokinetics after the single dose was comparable in the two groups. No statistically significant differences could be detected between the ranitidine pharmacokinetics after the first single dose and the multiple dose or continuous infusion.

Management of Stress Gastritis

Management of stress gastritis is primarily directed toward prevention of gastrointestinal bleeding. Antacids and H2 blockers have been the standard agents used for prophylactic therapy in critically ill patients. However, growing evidence that gastric alkalization leads to an increased incidence of nosocomial pneumonias has led to the development of other prophylactic agents that do not decrease gastric acidity. These cytoprotective agents presumably enhance gastric mucosal defenses and stimulate mucosal repair. Approximately 3% of patients bleed despite prophylactic therapy. Bleeding is usually controlled with intensive medical management, and the need for surgical intervention is rare.

Stress gastritis revisited

In current ICU populations, overt bleeding from stress gastritis occurs in 10% to 20% of patients. Bleeding rates may be reduced to about 3% in patients receiving prophylactic therapy. Although patients with bleeding have higher mortality rates than other critically ill patients, it is not clear that the mortality rate is improved with prophylactic therapy, as most patients die from their underlying disease. As new complications of prophylactic therapy are identified, better definitions of the population at risk to develop complications of stress gastritis will be necessary to select those patients who will benefit most from prophylactic therapy.

Surgical treatment of peptic ulcer disease

Elective surgery for peptic ulcer disease has diminished significantly over the past 15 years. However, emergency surgery has not shown a decline. Some series have even reported an increase in hospitalizations and operations for hemorrhage. The appropriate surgical procedure for peptic ulcer disease must be tailored to the specific needs of the individual patient. During emergency operations for hemorrhage from duodenal ulcer, we recommend suture ligature of the bleeding vessel and vagotomy-pyloroplasty for high-risk patients, or vagotomy-antrectomy for the lower-risk patient. Bleeding gastric ulcers should be resected, if possible. For massive hemorrhage from stress ulceration requiring surgery, near-total or total gastrectomy should be performed. Perforated duodenal ulcers are best managed by closure and a definitive ulcer operation, such as vagotomy-pyloroplasty. Perforated gastric ulcers are best excised but may be simply closed if conditions do not favor resection. In these situations, biopsy should be performed. We recommend truncal vagotomy-antrectomy for patients presenting with obstruction. Vagotomy (truncal or proximal gastric) with drainage is an acceptable alternative in this situation. For patients with intractable ulcer disease or for those who are noncompliant, proximal gastric vagotomy is the preferred operation. However, other operations may need to be considered, depending on the specific situation. Recurrent ulceration needs appropriate work-up to determine the possible cause. Although patients with ulcer recurrence initially may be placed on medical treatment, about 50% will require reoperation. The most effective procedure for peptic ulcer disease is truncal vagotomy-antrectomy, which has a recurrence rate of less than 1%. The procedure with the least morbidity and the fewest undesirable side effects is proximal gastric vagotomy. Ulcer recurrence after proximal gastric vagotomy or truncal vagotomy-pyloroplasty is in the range of 10% to 15%.

Stress erosive gastritis

Bleeding from stress erosive gastritis continues to be a potential problem in critically ill and injured patients, but fortunately its incidence has decreased dramatically over the last decade. The explanation for this circumstance is probably multifactorial, but clearly relates to our increased knowledge of its pathophysiology. This understanding has led to the routine use of measures to reduce intragastric acidity (luminal acid being a prerequisite for stress ulcer to occur), coupled with improved techniques for the treatment of shock and the accompanying gastric mucosal hypoperfusion (another prerequisite for the formation of stress ulcers). A number of measures have been used to lower intragastric acidity with H2 receptor blockers emerging as the agents of choice to accomplish this goal. In the unlikely event that bleeding occurs despite these prophylactic measures, aggressive medical management will result in cessation of hemorrhage in over 80% of patients. In those few individuals requiring surgery to control bleeding, no operation has emerged as the recognized procedure of choice. Thus, we believe that a conservative operative approach is indicated in this setting and recommend vagotomy and pyloroplasty with oversewing of the bleeding erosions as appropriate therapy for most patients requiring surgical intervention.

The effect of duodenojejunal alimentation on gastric pH and hormones in intensive care unit patients

We evaluated effects of duodenojejunal (DJ) feeding on gastric pH and selected gastrointestinal hormones in 13 randomly selected patients in an intensive care unit (ICU). To obtain baseline values for gastric pH, a nasogastric (NG) tube was placed in each patient and gastric pH was measured every 30 minutes for 2 hours. To obtain control values, a Dobbhoff tube was placed fluoroscopically and 0.45 percent saline solution (NaCl), 75 ml, was infused for 1 hour and gastric pH was measured again; the previously placed NG tube was left in position. Then, by randomization, either 0.45 percent NaCl (pH = 5) was continued (n = 6) or a high-nitrogen, isotonic, enteral feeding solution (Osmolite HN, pH = 6.4) (n = 7) was infused, both at 75 ml/h. Gastric pH was noted hourly for 96 hours; antacid (Maalox TC, 15-ml aliquots) was given by NG tube when the pH was 4 or less. After 96 hours, the infusion was stopped and gastric pH was noted for 4 additional hours. Before and during initial saline solution infusion; after 24, 48, 72, and 96 hours of continuous infusion; and 4 hours after stopping the infusion, peripheral venous blood was obtained for measurement of plasma gastric inhibitory polypeptide (GIP) and serum gastrin. Data were analyzed by ANOVA (RMD), Fishers' exact test, and the unpaired t-test. Groups did not differ demographically. Throughout the infusion, gastric pH tended to be higher with the enteral feeding solution than with saline solution, but this was significant only at 24 hours. Less antacid was required with the enteral feeding solution at 24 and 48 hours than with saline solution. Plasma GIP levels were significantly higher with the enteral feeding solution than with saline solution during most of the infusion. Serum gastrin levels did not differ between the groups. In this cohort, infusion of the enteral feeding solution tended to maintain a gastric pH of more than 4 and was associated with increased plasma GIP levels, which may inhibit gastric acid secretion. Early enteral feeding may benefit certain ICU patients.

A graded combination regimen for maintenance of gastric pH above 3.5 in critically ill patients

Prophylaxis of acute upper gastrointestinal bleeding by control of gastric pH has been widely advocated for intensive care patients. H2-blockers and antacids have been used and demonstrated to be incompletely effective at maintaining gastric pH above 4. A study of 100 patients measured the efficacy of two-hourly gastric pH measurement and titrated therapy consisting of five levels: 1. no therapy 2. ranitidine 50 mg 8 hourly intravenously 3. ranitidine plus Mylanta 30 ml 2 hourly by nasogastric tube 4. ranitidine plus Mylanta 60 ml 2 hourly and 5. ranitidine 100 mg 8 hourly intravenously plus Mylanta II 60 ml 2 hourly. The level of treatment required by proportions of the total study group were (1) 15%, (2) 71%, (3) 96%, (4) 100%. Head-injured and intubated patients generally fell in the more resistant group while patients having had major elective surgery required lower levels of therapy. If control of gastric pH is to be uniformly achieved, a technique of titrated therapy based on gastric pH measurements is supported as cheaper and more effective than other standardised treatment regimens.

Prevention of stress ulcer bleeding: a review

The pathophysiology of stress ulcers is complex. There is either too much acid and pepsin or inadequate mucosal defenses. The incidence of upper GI bleeding due to stress ulcers in the ICU is 5-25% depending upon the minimum criterion of bleeding. For the individual patient the risk of bleeding is determined by his underlying condition and the number of risk factors. SAPS and APACHE II may assist in identifying those patients. Attainment of an increase in intragastric pH is effective and frequently necessary to prevent stress ulcer bleeding and reduces the incidence of overt bleeding. Based on presently available information the most suitable regime for prevention of stress ulcer bleeding is a continuous infusion or fixed bolus dosing of cimetidine or ranitidine. With respect to the side effects, ranitidine appears to be the more favorable of these two H2 blockers. The position of sucralfate in the prophylaxis has not yet been established.

Role of histamine (H2)-receptor antagonists in total parenteral nutrition patients

Hospitalized patients, especially those who are critically ill, are often at risk for malnutrition and may require nutritional support. Although the enteral approach is generally preferred when providing nutritional support, parenteral nutrition is frequently required. These patients are also likely to receive therapeutic or prophylactic parenteral histamine (H2)-receptor antagonists. Patients receiving both total parenteral nutrition and parenteral H2-receptor antagonists may benefit from receiving the drug in combination with the total parenteral nutrition admixture. Parenteral cimetidine and ranitidine are stable in various total parenteral nutrition fluids. Clinically, cimetidine has been studied more extensively than ranitidine. Clinical benefits and cost savings may be realized from this method of drug delivery.