Stress ulcer accompanying subarachnoid hemorrhage--a new rat model

Stress-Related Gastrointestinal Bleeding in Patients with Aneurysmal Subarachnoid Hemorrhage: A Multicenter Retrospective Observational Study

BACKGROUND/OBJECTIVE

Stress-related mucosal bleeding (SRMB) occurs in approximately 2-4% of critically ill patients. Patients with aneurysmal subarachnoid hemorrhage (aSAH) have a (diffuse) space-occupying lesion, are critically ill, often require mechanical ventilation, and frequently receive anticoagulation or antiplatelet therapy after aneurysm embolization, all of which may be risk factors for SRMB. However, no studies have evaluated SRMB in patients with aSAH. Aims of the study were to determine the incidence of SRMB in aSAH patients, evaluate the effect of acid suppression on SRMB, and identify specific risk factors for SRMB.

METHODS

This was a multicenter, retrospective, observational study conducted across 17 centers. Each center reviewed up to 50 of the most recent cases of aSAH. Patients with length of stay (LOS) < 48 h or active GI bleeding on admission were excluded. Variables related to demographics, aSAH severity, gastrointestinal (GI) bleeding, provision of SRMB prophylaxis, adverse events, intensive care unit (ICU), and hospital LOS were collected for the first 21 days of admission or until hospital discharge, whichever came first. Descriptive statistics were used to analyze the data. A multivariate logistic regression modeling was utilized to examine the relationship between specific risk factors and the incidence of clinically important GI bleeding in patients with aSAH.

RESULTS

A total of 627 patients were included. The overall incidence of clinically important GI bleeding was 4.9%. Of the patients with clinically important GI bleeding, 19 (61%) received pharmacologic prophylaxis prior to evidence of GI bleeding, while 12 (39%) were not on pharmacologic prophylaxis at the onset of GI bleeding. Patients who received an acid suppressant agent were less likely to experience GI bleeding than patients who did not receive pharmacologic prophylaxis prior to evidence of bleeding (OR 0.39, 95% CI 0.18-0.83). The multivariate regression analysis identified any instance of elevated intracranial pressure, creatinine clearance < 60 ml/min and the incidence of cerebral vasospasm as specific risk factors associated with GI bleeding. Cerebral vasospasm has not previously been described as a risk for GI bleeding (OR 2.5 95% CI 1.09-5.79).

CONCLUSIONS

Clinically important GI bleeding occurred in 4.9% of patients with aSAH, similar to the general critical care population. Risk factors associated with GI bleeding were prolonged mechanical ventilation (> 48 h), creatinine clearance < 60 ml/min, presence of coagulopathy, elevation of intracranial pressure, and cerebral vasospasm. Further prospective research is needed to confirm this observation within this patient population.

Gastrointestinal prophylaxis in neurocritical care

The aim of this study is to review and summarize the relevant literature regarding pharmacologic and non-pharmacologic methods of prophylaxis against gastrointestinal (GI) stress ulceration, and upper gastrointestinal bleeding in critically ill patients. Stress ulcers are a known complication of a variety of critical illnesses. The literature regarding epidemiology and management of stress ulcers and complications thereof, is vast and mostly encompasses patients in medical and surgical intensive care units. This article aims to extrapolate meaningful data for use with a population of critically ill neurologic and neurosurgical patients in the neurological intensive care unit setting. Studies were identified from the Cochrane Central Register of controlled trials and NLM PubMed for English articles dealing with an adult population. We also scanned bibliographies of relevant studies. The results show that H(2)A, sucralfate, and PPI all reduce the incidence of UGIB in neurocritically ill patients, but H(2)A blockers may cause encephalopathy and interact with anticonvulsant drugs, and have been associated with higher rates of nosocomial pneumonias, but causation remains unproven and controversial. For these reasons, we advocate against routine use of H(2)A for GI prophylaxis in neurocritical patients. There is a paucity of high-level evidence studies that apply to the neurocritical care population. From this study, it is concluded that stress ulcer prophylaxis among critically ill neurologic and neurosurgical patients is important in preventing ulcer-related GI hemorrhage that contributes to both morbidity and mortality. Further, prospective trials are needed to elucidate which methods of prophylaxis are most appropriate and efficacious for specific illnesses in this population.

Acute gastric changes after intracerebral hemorrhage in rats

Severe intracerebral hemorrhage (ICH) produces gastric pathology in about 30% of the patient population, even after the standard treatment of H2 receptor blockers or proton pump inhibitors. This study was undertaken to establish a rat model of ICH-induced gastric ulcer. Adult male Sprague-Dawley rats (300-350 g) were divided into two hemorrhage groups and a sham control group. ICH was produced either by injection of 100 microl of autologous arterial blood or by injection of 4 microl saline containing 0.6 unit of bacterial collagenase VII into the right basal ganglia. Rats were sacrificed at 24, 48, 72 h, and 7 days after ICH to harvest brains and stomachs. Greater degrees of hemorrhage and brain edema were observed in collagenase-induced ICH. Motor behavior decreased significantly after 24 h in both models. The incidence of acute ulceration with destruction of the forestomach epithelium was extremely low at 8.7% in the collagenase injection model and 4.8% in the blood injection rats. Small, pinpoint hemorrhages (petechiae) were noticed in 38% of rats after blood injection and 22% after collagenase injection, in the glandular portion of the gastric mucosa with penetration of red blood cells and inflammatory cells into the gastric mucosa. Enhanced tumor necrosis factor alpha (TNFalpha) and cyclooxygenase 2 (COX-2) expressions were observed in gastric tissues after ICH with more intense staining occurring at 24 and 48 h. Due to the low incidence of ulceration, ICH-induced gastric ulceration in rodents may not appropriate for evaluating the potential human risk of gastric ulceration after ICH.

Neurogenic stress ulceration caused by laparotomy under anesthesia plus restraint. The device of a new rat model

We report herein, a new method devised of producing neurogenic stress ulceration in rats. An experimental subarachnoid hemorrhage (SAH) was produced in rats by injecting 0.2 ml of arterial blood from other rats into the cisterna magna. Three days later, the rats were laparotomized for 1 hour under ether anesthesia, followed by restraint for 3 hours in wakefulness. The SAH rats were found to develop stress ulcers (UL-I) in the glandular stomach, which were significantly (p less than 0.001) more marked than those in non-SAH rats. Measurements were performed on gastric acid secretion, an important aggressive factor. It was found that the SAH rats undergoing the laparotomy-restraint stress showed a more marked increase in gastric acid secretion and a more marked reduction in MBF, than the non-SAH rats. The effects of bilateral vagotomy, upper abdominal sympathectomy and bilateral adrenalectomy were examined, and it was revealed that the SAH rats were under the condition of hyperreactivity both in the sympathetic and parasympathetic systems and, on this basis, the laparotomy-restraint stress caused the stress gastric ulceration. In this rat model, the laparotomy stress was applied under anesthesia and any exposure to low temperatures which may have interfered with blood circulation was avoided.