Stress ulcer prophylaxis in critically ill patients. Resolving discordant meta-analyses

Multicenter clinical research in adult critical care

OBJECTIVE

To describe the development, organization, and operation of several collaborative groups conducting investigator-initiated multicenter clinical research in adult critical care.

DESIGN

To review the process by which investigator-initiated critical care clinical research groups were created using examples from Europe, Australia, the United States, and Canada. Various models of group structure and function are discussed, highlighting complementary approaches to protocol development, multicenter study management, and project funding.

DATA SOURCES

Published peer review research and unpublished terms of reference documents on the structure and function of these groups.

DATA SYNTHESIS

The overall goal of clinical critical care research groups engaged in multicenter studies is to improve patient outcomes through conducting large, rigorous investigations. Research programs we reviewed included the following: a) multicenter epidemiologic studies and surveys; b) technology evaluations of mechanical ventilation; c) investigations focused on three priority fields (acute lung injury, infection, and acute brain injury); d) a series of randomized trials of treatments for one syndrome (acute respiratory distress syndrome); and e) diverse methodologies addressing several clinical problems. The structure and function of these research groups differ according to their historical development, research culture, and enabling resources. Specific protocols emerge from clinical questions generated by investigators or from collectively prioritized research agendas. Project funding includes government support, peer-review grants, intensive care foundations, industry, local hospital funds, and hybrid models. Infrastructure for study management varies widely.

CONCLUSIONS

Several national and international groups have engaged in investigator-initiated multicenter critical care research. The development, organization, and operational methods of these groups illustrate several collaborative models for clinical investigations in the intensive care unit. Common characteristics of these groups are a cohesive spirit, a sense of mission to achieve shared research goals, and acknowledgment that such an organization is much more than the sum of its parts.

When small degrees of bias in randomized trials can mislead clinical decisions: an example of individualizing preventive treatment of upper gastrointestinal bleeding

OBJECTIVE

Although randomized trials yield less biased estimates of treatment effects than other study designs, unconcealed randomization and lack of blinding can lead to overestimates of the treatment benefit on the order of 15% to 40% on average. In applying the results of clinical trials to patient care, clinicians need to be concerned about bias of this order when it would change patient management. The aim of this study is to assess under which circumstances clinicians need to be concerned about bias in clinical trials.

DESIGN

Sensitivity analysis.

SETTING

Recently published meta-analysis of RCTs on the benefit of H2-blockers on the prevention of gastrointestinal bleeding in critically ill patients.

INTERVENTIONS

Assessment of the effect of different degrees of bias on clinical decision making in various clinical scenarios.

RESULTS

Bias of even a modest degree (15% to 40% overestimation of effect) changed clinical decisions more frequently when treatment benefits were small and when the patients' risk to suffer an adverse outcome was low. When the benefit was large and the patients were at high risk, clinical decisions remained unchanged, despite bias in the estimation of effect.

CONCLUSIONS

When treatments of moderate benefit are applied to patients of low to moderate risk, even small biases in the estimation of effects carry a high risk of erroneous decisions. When the treatment benefit is large and the patients are at high risk, clinicians need to be less concerned about bias in RCTs.

Pathophysiology of the upper gastrointestinal tract in the critically ill patient: rationale for the therapeutic benefits of acid suppression

Gastric mucosal damage occurs in critically ill patients in intensive care units and develops in the setting of severe physiologic stress. Within 24 hrs of admission to the intensive care unit, 75% to 100% of critically ill patients demonstrate evidence of stress-related mucosal disease. Stress ulcers present a risk of clinically important bleeding, which is associated with alterations in physiology, such as hypotension or tachycardia, or results in anemia or the need for transfusion. Clinically important bleeding occurs in approximately 1% to 4% of critically ill patients. The pathophysiology of stress-related mucosal disease is complex. Major factors responsible for stress ulcer are decreased blood flow, mucosal ischemia, and hypoperfusion and reperfusion injury. Acid-suppressive regimens that elevate the intragastric pH and maintain the pH over time have the potential to prevent stress-related mucosal disease. Intragastric pH studies have demonstrated that, whereas a pH of >4 may be adequate to prevent stress ulceration, a pH of >6 may be necessary to maintain clotting in patients at risk of rebleeding from peptic ulcer. Studies comparing the ability of intravenous administrations of histamine-2-receptor antagonists and proton pump inhibitors to raise and maintain intragastric pH suggest that, although both can raise the pH to >4, proton pump inhibitors are much more likely to maintain this pH. Unlike histamine-2-receptor antagonists, proton pump inhibitors can elevate and maintain the intragastric pH at >6. This is relevant for patients in the intensive care unit at risk for rebleeding from peptic ulcers after hemostasis.

Evidence-based medicine as it applies to acid suppression in the hospitalized patient

An evidence-based-medicine approach may be applied to studies in the medical literature to help physicians make sound judgments about efficacy and safety data and to improve clinical decision making. To assess the role of gastric acid suppression in the prevention of stress ulcer bleeding and in the management of upper gastrointestinal bleeding after successful hemostasis of bleeding peptic ulcer disease, the following questions should be addressed: Is it possible to identify risk factors for clinically important bleeding in critically ill patients? Can intravenous acid suppression prevent stress ulcer-related bleeding or prevent rebleeding in peptic ulcers after successful hemostasis? What is the most effective method of acid suppression for these disorders? An evidence-based-medicine review of published trials yields sufficient evidence to support the use of prophylactic acid suppression in critically ill patients with coagulopathy or in those who are receiving prolonged mechanical ventilation. Not enough data have accumulated to prove the superiority of intravenous proton pump inhibitors to intravenous histamine-2-receptor antagonists for prophylaxis of clinically important stress ulcer bleeding. With respect to acute gastrointestinal bleeding, however, two well-conducted trials indicate that an intravenous proton pump inhibitor is significantly more effective than an intravenous histamine-2-receptor antagonist or placebo in reducing the rate of rebleeding after hemostasis in patients with bleeding peptic ulcer. Analysis of the data from both trials shows that only five to six patients would need to receive an intravenous proton pump inhibitor to avoid one episode of rebleeding.

Stress-related mucosal disease in the critically ill patient: risk factors and strategies to prevent stress-related bleeding in the intensive care unit

Stress-related mucosal disease develops in patients in the intensive care unit and can result in clinically important bleeding, which is associated with increased mortality. Patients in the intensive care unit without either mechanical ventilation or coagulopathy, which are the primary risk factors for such bleeding, do not seem to need or to benefit from prophylactic acid suppression for stress-related mucosal disease. Although histamine-2-receptor antagonists significantly reduce clinically important bleeding in patients in the intensive care unit and are widely used for prophylaxis, their benefits are limited by the rapid development of tolerance. Previous data suggested that agents that elevate the intragastric pH may increase the susceptibility of patients in the intensive care unit to nosocomial pneumonia. However, the largest study to date showed that intravenous histamine-2-receptor antagonists may not significantly increase the risk of ventilator-associated pneumonia or mortality compared with sucralfate, an agent that does not affect intragastric pH. Intravenous proton pump inhibitors are more potent and longer-acting inhibitors of gastric acid production than intravenous histamine-2-receptor antagonists. The ability of proton pump inhibitors to prevent stress-related mucosal disease and clinically important bleeding seems to be clinically meaningful. Preliminary findings have shown that intermittent administration of intravenous pantoprazole, the first proton pump inhibitor available by this route in the United States, is as effective in raising intragastric pH on the first day as a continuous infusion of a histamine-2-receptor antagonist in clinical trials conducted within an intensive care unit setting. This suggests that for stress ulcer prophylaxis, intermittent dosing with an intravenous proton pump inhibitor may be an alternative to high-dose continuous infusions of a histamine-2-receptor antagonist. These agents must be compared in clinical trials conducted in an intensive care unit setting.

Ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) continues to complicate the course of 8 to 28% of patients receiving mechanical ventilation (MV). In contrast to infections of more frequently involved organs (e.g., urinary tract and skin), for which mortality is low, ranging from 1 to 4%, the mortality rate for VAP ranges from 24 to 50% and can reach 76% in some specific settings or when lung infection is caused by high-risk pathogens. The predominant organisms responsible for infection are Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacteriaceae, but etiologic agents widely differ according to the population of patients in an intensive care unit, duration of hospital stay, and prior antimicrobial therapy. Because appropriate antimicrobial treatment of patients with VAP significantly improves outcome, more rapid identification of infected patients and accurate selection of antimicrobial agents represent important clinical goals. Our personal bias is that using bronchoscopic techniques to obtain protected brush and bronchoalveolar lavage specimens from the affected area in the lung permits physicians to devise a therapeutic strategy that is superior to one based only on clinical evaluation. When fiberoptic bronchoscopy is not available to physicians treating patients clinically suspected of having VAP, we recommend using either a simplified nonbronchoscopic diagnostic procedure or following a strategy in which decisions regarding antibiotic therapy are based on a clinical score constructed from seven variables. Selection of the initial antimicrobial therapy should be based on predominant flora responsible for VAP at each institution, clinical setting, information provided by direct examination of pulmonary secretions, and intrinsic antibacterial activities of antimicrobial agents and their pharmacokinetic characteristics. Further trials will be needed to clarify the optimal duration of treatment and the circumstances in which monotherapy can be safely used.

Ventilator-associated pneumonia. Prevention, diagnosis, and therapy

Ventilator-associated pneumonia remains the nosocomial ICU infection of greatest concern. The authors have summarized the clinical trials that have assessed specific strategies to prevent VAP and the current controversies regarding the diagnosis and therapeutic approach to this condition. Improvements in care of patients who are at risk for or who have developed VAP will depend on the judicious application of this information for individual patients.

Use of enteral nutrition for stress ulcer prophylaxis

OBJECTIVE

To review the controversies involving the use of enteral nutrition support for stress ulcer prophylaxis and formulate recommendations.

DATA SOURCES

A MEDLINE search (1966-December 2000) was conducted using the MeSH of nutrition, ulcer, critical care, and acid to identify relevant articles. References of selected articles were reviewed, and relevant abstracts from critical care or gastrointestinal journals identified.

DATA EXTRACTION

Animal and human data from prospective studies, retrospective studies, and case series were evaluated for the effects of enteral nutrition on gastric pH, intramucosal pH, gastrointestinal blood flow, development of macroscopic mucosal erosions, and hemorrhage.

DATA SYNTHESIS

Intragastric administration of enteral nutrition has variable effects on gastric pH, enhances regional distribution of gastrointestinal blood flow, and may lower intramucosal pH. All substrates (carbohydrate, lipid, amino acid), when administered into the stomach, reduce the occurrence of mucosal erosions but do not entirely prevent their development. Few studies of stress ulcer prophylaxis regimens have reported use of enteral nutrition. Limited retrospective data suggest enteral nutrition support may be effective for preventing gastrointestinal hemorrhage, but the results of prospective studies are confounded by poor study design.

CONCLUSIONS

Definitive recommendations regarding the role of enteral nutrition for stress ulcer prophylaxis are not possible due to the lack of prospective, randomized studies. Therefore, the use of enteral nutrition as the only therapeutic agent for stress ulcer prophylaxis should be discouraged until definitive data are available. Initiation and discontinuation of pharmacologic stress ulcer prophylaxis should be independent of enteral nutrition.

Infection control in the ICU

Nosocomial infections (NIs) now concern 5 to 15% of hospitalized patients and can lead to complications in 25 to 33% of those patients admitted to ICUs. The most common causes are pneumonia related to mechanical ventilation, intra-abdominal infections following trauma or surgery, and bacteremia derived from intravascular devices. This overview is targeted at ICU physicians to convince them that the principles of infection control in the ICU are based on simple concepts and that the application of preventive strategies should not be viewed as an administrative or constraining control of their activity but, rather, as basic measures that are easy to implement at the bedside. A detailed knowledge of the epidemiology, based on adequate surveillance methodologies, is necessary to understand the pathophysiology and the rationale of preventive strategies that have been demonstrated to be effective. The principles of general preventive measures such as the implementation of standard and isolation precautions, and the control of antibiotic use are reviewed. Specific practical measures, targeted at the practical prevention and control of ventilator-associated pneumonia, sinusitis, and bloodstream, urinary tract, and surgical site infections are detailed. Recent data strongly confirm that these strategies may only be effective over prolonged periods if they can be integrated into the behavior of all staff members who are involved in patient care. Accordingly, infection control measures are to be viewed as a priority and have to be integrated fully into the continuous process of improvement of the quality of care.

The impact of clinically significant upper gastrointestinal bleeding acquired in a pediatric intensive care unit

OBJECTIVE

To determine the clinical and economic impact attributable to upper gastrointestinal bleeding (UGIB) acquired in a pediatric intensive care unit (PICU).

DESIGN

Prospective case-control-within-cohort study.

SETTING

PICU at a university hospital.

PATIENTS

All consecutive patients over a 1-yr period.

METHODS

All UGIB (hematemesis or blood in gastric tube) were reported. A UGIB was qualified as clinically significant (CS-UGIB) if a panel of reviewers assessed that a complication (decreased hemoglobin concentration, transfusion, multiple organ dysfunction syndrome, surgery, or death) was attributed to it. A UGIB was qualified as clinically nonsignificant (NS-UGIB) if none of these complications was attributed to it. The Ø-UGIB group comprised patients without UGIB. Pairing between the three groups was done according to these criteria: death or survival, Pediatric Risk of Mortality Score on admission, respiratory failure, coagulopathy, and age. Data considered for the impact analysis was prospectively monitored during the stay in PICU. Costs were estimated in Canadian dollars (1999) as follows: costs of stay + medical staff + ventilation + red blood cell transfusions.

RESULTS

The cohort included 1006 admissions. Sixteen cases of CS-UGIB were paired to 13 cases of NS-UGIB and 32 cases of Ø-UGIB. Compared with the Ø-UGIB group and the NS-UGIB group, the CS-UGIB group showed a significantly (p < 0.05) higher rate of red blood cell transfusions, duration of ventilation, length of stay in PICU, and a lower hemoglobin level. There was no difference between the NS-UGIB group and the Ø-UGIB group. The cost analysis demonstrated a significant difference (p < 0.05) between the CS-UGIB group (20,062.67 Can dollars/patient per stay) and the other groups (NS-UGIB, 6104.77 Can dollars/patient per stay; Ø-UGIB, 5457.25 Can dollars/patient per stay).

CONCLUSION

This study demonstrates a significant clinical and economic impact of CS-UGIB in PICU, although no impact was detected for NS-UGIB. Further studies on the benefit of UGIB prophylaxis for critically ill children with risk factors for CS-UGIB are needed.

Stress Ulceration Requiring Definitive Surgery after Severe Trauma

Despite antiulcer prophylaxis 19 severely injured patients at our institution developed stress ulceration (SU) between 1989 and 1999 requiring surgery for perforation (n = 4) or bleeding (n = 15). A herald bleed (HB) 10.7 ± 1.2 days after admission, 7.2 ± 1.2 days before definitive operative therapy, and requiring 7.1 ± 0.9 units of blood occurred in 93 per cent of patients operated on for bleeding. Bleeding preceded perforation in one patient. Central nervous system damage was part of the injury pattern in 68 per cent of the patients including spinal cord (42%), severe head injury (16%), or both (10%). Forty-two per cent had acalculous cholecystitis found at surgery. Eight patients had vagotomy and antrectomy (VA), and 11 patients had vagotomy and pyloroplasty (VP). VA required more time than VP (255 ± 41 vs 158 ± 13 minutes; P = 0.02). One patient (12.5%) rebled after VA versus two (18%) after VP; one patient in each group required reoperation. There was no difference in mortality, length of stay, or intensive care unit stay. A herald bleed preceded recurrent hemorrhage of SU by one week. Spinal cord or head injury increase the risk of SU. More than 40 per cent of patients with SU had acalculous cholecystitis found at operation. VA provides no benefit on rebleeding or reoperation over VP, so anatomical considerations and not rebleed rates should determine the surgical procedure.

Role of acid suppressants in intensive care medicine

Bleeding from stress-induced mucosal lesions continues to be a potential problem in critically ill patients, although its incidence has decreased dramatically over the past decade. Patients considered to be at risk are those with respiratory failure, coagulopathy, severe burns or tetraplegia. The most important cause of stress ulcer bleeding is tissue hypoxia. Provided that appropriate dosage regimens are administered, all agents approved for stress ulcer prophylaxis may reduce the incidence of overt as well as clinically important bleeding. However, the efficacy of stress ulcer prophylaxis does not correlate with the efficacy of gastric acid inhibition. Although numerous studies have demonstrated that an alkaline gastric juice is associated with gastric Gram-negative bacterial overgrowth, controversy remains over whether the pharmacological suppression of gastric acid in critically ill patients facilitates nosocomial pneumonia. The reasons for these divergent results are discussed, as is a possible association between gastric acid suppression and other systemic infections. Finally, several cost-effectiveness analyses performed over recent years have demonstrated that, in properly selected critically ill patients, stress ulcer prophylaxis is cost-effective.

Evidence-based medicine in intensive care

The life-threatening nature of critical illness, requiring simultaneous, multiple interventions, makes it difficult, if not impossible, to study the effects of any one treatment. It is often not possible to conduct trials in critically ill patients, as they can not give informed consent. Some high quality, prospective studies have influenced clinical practice in intensive care, but others with lower grades of evidence have led to some controversy. In intensive care, clinical practice is still influenced by a combination of theory, experience and evidence.

Upper Gastrointestinal Bleeding of Nonvariceal Origin in the ICU Setting

Upper gastrointestinal bleeding (UGI) is a common medical emergency in the intensive care unit (ICU). Although it can be caused by a number of gastrointestinal disorders, its management usually follows a few simple management rules. Prior to endoscopy, the key to management is to resuscitate the patient, to determine the need for airway protection, and to assess the need for transfusions according to the American Society of Gastrointestinal Endoscopy guidelines. During endoscopy, the key to management is to recognize the cause of the bleeding and to achieve hemostasis. Following endoscopy, the key to management is to determine the need for medical therapy and to determine a proper disposition for the patient given his potential risk for rebleeding. Stress-related erosions syndrome (SRES) is a disease that usually develops in the ICU setting and is known to be associated with a high degree of morbidity and mortality. Although it is approached in the same fashion as other causes of UGI bleeding, patients tend to do better if they are recognized early and treated prophylactically. Criteria for proper patient selection and the recommended prophylactic therapy are reviewed.

GI complications in patients receiving mechanical ventilation

Mechanical ventilation (MV) can be lifesaving by maintaining gas exchange until the underlying disorders are corrected, but it is associated with numerous organ-system complications, which can significantly affect the outcome of critically ill patients. Like other organ systems, GI complications may be directly attributable to MV, but most are a reflection of the severity of the underlying disease that required intensive care. The interactions of the underlying critical illness and MV with the GI tract are complex and can manifest in a variety of clinical pictures. Incorporated in this review are discussions of the most prevalent GI complications associated with MV, and current diagnosis and management of these problems.

Incidence, risk factors, and prognosis of gastrointestinal hemorrhage complicating acute renal failure

BACKGROUND

Few prospective data are currently available on acute gastrointestinal hemorrhage (AGIH) as a complication of acute renal failure (ARF). The aim of the present study was to define incidence, sources, risk factors, and outcome of AGIH in patients with ARF.

METHODS

We performed a prospective study on an inception cohort of 514 patients admitted for ARF to a nephrology intermediate care unit. Data on clinical risk factors for bleeding, frequency of occurrence of AGIH, length of hospital stay, and in-hospital mortality were collected. Independent predictors of AGIH were identified. The relative odds of death and the relative increase in length of hospital stay associated with AGIH were calculated after adjusting for baseline comorbidities.

RESULTS

Sixty-nine patients out of 514 [13.4% (95% CI, 10.6 to 16.7)] had AGIH as a complication of ARF; 59 were upper AGIH. Forty patients had clinically important bleeding. Erosions and/or ulcers accounted for 71% of cases of upper AGIH. Independent baseline predictors of AGIH were represented by severity of illness [odds ratio 1.45 (95% CI, 1.05 to 2.01) for every 10 point increase in APACHE II score], low platelet count [<50,000 mm3; 3.71 (1.70 to 8.11)], noncirrhotic chronic hepatic disease [2.22 (1.09 to 4.55)], liver cirrhosis [3.38 (1.50 to 7.60)], de novo ARF [2.77 (1.30 to 5.90)], and severe ARF [2.07 (1.10 to 3.88)]. In-hospital mortality was 63.8% in patients with AGIH and 34.2% in the other patients; after adjusting for baseline confounders, AGIH remained significantly associated with an increase in both mortality [2.57 (1.30 to 5.09), P = 0.006] and length of hospital stay [37% (1 to 87%), P = 0.047].

CONCLUSIONS

AGIH and clinically important bleeding are frequent complications of ARF. In this clinical condition, AGIH is more often due to upper gastrointestinal bleeding and is associated with a significantly increased risk of death and length of hospital stay. Both renal and extrarenal risk factors are related to the occurrence of AGIH.

Stress ulcer prevention--the controversy continues

A recently published meta-analysis has re-awakened the controversy regarding the risk and benefits of using acid-suppressant drugs to prevent stress ulceration in intensive care patients.

Hospital-acquired pneumonia: risk factors, microbiology, and treatment

Pneumonia complicates hospitalization in 0.5 to 2.0% of patients and is associated with considerable morbidity and mortality. Risk factors for hospital-acquired pneumonia (HAP) include mechanical ventilation for > 48 h, residence in an ICU, duration of ICU or hospital stay, severity of underlying illness, and presence of comorbidities. Pseudomonas aeruginosa, Staphylococcus aureus, and Enterobacter are the most common causes of HAP. Nearly half of HAP cases are polymicrobial. In patients receiving mechanical ventilation, P aeruginosa, Acinetobacter, methicillin-resistant S aureus, and other antibiotic-resistant bacteria assume increasing importance. Optimal therapy for HAP should take into account severity of illness, demographics, specific pathogens involved, and risk factors for antimicrobial resistance. When P aeruginosa is implicated, monotherapy, even with broad-spectrum antibiotics, is associated with rapid evolution of resistance and a high rate of clinical failures. For pseudomonal HAP, we advise combination therapy with an antipseudomonal beta-lactam plus an aminoglycoside or a fluoroquinolone (eg, ciprofloxacin).

A critical appraisal of review articles on the effectiveness of conservative treatment for neck pain

STUDY DESIGN

A criteria-based appraisal of review articles on neck pain.

OBJECTIVES

To assess the methodologic quality, conclusions, and extent of concordance among reviews on the conservative treatment of neck disorders.

SUMMARY OF BACKGROUND DATA

During the past decades there has been an increasing interest in summarizing and analyzing the available evidence on the effectiveness of conservative management of neck pain. Considering the growing number and quality of reviews, consumers may question which reviews to read and believe.

METHODS

Computerized bibliographic databases were searched without language restriction. The reviews assessed had been published before January 1998, included neck pain and evaluated conservative therapies, and reported at least one controlled clinical trial. Identification, selection, and quality assessment were performed independently by two investigators.

RESULTS

Of the 108 identified articles, 25 review articles were selected, of which 12 were systematic reviews. The reviews differed in their reporting of study population, interventions, and outcomes. Statistical pooling was performed in two high-quality systematic reviews, whereas in other reviews, the investigators explicitly decided not to pool data. The results of the current study show that the concordance among reviews varied. Regarding manipulation and traction, there is inconclusive evidence among reviews. Concordance regarding the effectiveness of other conservative interventions was absent. Many of the reviews displayed major methodologic flaws.

CONCLUSIONS

Consumers should consider reports of reviews both carefully and critically, given the wide variety of review methodology, descriptive information, and final conclusions. There is a paucity of evidence from primary studies on neck pain. Therefore, more research is needed to allow systematic reviews to formulate stronger conclusions.

Ethanol gastric lesion aggravated by lung injury in rat. Therapy effect of antiulcer agents

Hemorrhagic mucosal lesions in the stomach in the rat induced by an intragastrical application of 1 ml of 50 or 75% ethanol were aggravated by preceding lung damage provoked by an intratracheal instillation of pyrogen-free saline or HCl (pH 1.75) or 50-h exposure to 100% oxygen. Due to the particular preceding aggravating circumstances, these lesions were taken to be of a special kind, rather than ordinary. So far, it is not known whether and how antiulcer agents may influence these lesions. Rats received an intratracheal (i.t.) HCl instillation [1.5 ml/kg HCl (pH 1.75)] (lung-lesion), and an intragastric instillation of 96% ethanol (gastric lesion; 1 ml/rat, 24 h after i.t. HCl instillation), and were sacrificed 1 h after ethanol. Basically, in lung injured rats, the subsequent ethanol-gastric lesion was markedly aggravated. This aggravation, however, in turn, did not affect the severity of the lung lesions in the further period, at least for a 1-h observation. Taking intratracheal HCl-instillation as time 0, a gastric pentadecapeptide, GEPPPGKPADDAGLV, M.W.1419, coded BPC 157 (PL-10, PLD-116; 10 microg, 10 ng, 10 pg), ranitidine (10 mg), atropine (10 mg), omeprazole (10 mg), were given [/kg, intraperitoneally (i.p.)] (1) once, only prophylactically [as a pre-treatment (at -1 h), or as a co-treatment (at 0)], or only therapeutically (at +18 h or +24 h); (2) repeatedly, combining prophylactic/therapeutic regimens [(-1 h)+(+24 h) or (0)+(+24 h)], or therapeutic/therapeutic regimens [(+18 h)+(+24 h)]. In general, the antiulcer agents did protect against ethanol gastric lesions regardless of the presence of the severe lung injury, in all of the used regimens. Of note, combining their prophylactic and salutary regimens (at -1 h/+24 h, or at 0/+24 h) may increase the antiulcer potential, and the effect that had been not seen already with single application, became prominent after repeated treatment.

Acidification of formula reduces bacterial translocation and gut colonization in a neonatal rabbit model

BACKGROUND/PURPOSE

The authors hypothesized that gastric acidity is protective because it is bactericidal. They tested acidified formula for protection against gut colonization and bacterial translocation.

METHODS

In vitro: Formula was acidified to pH of 2, 3, 4, 5 and innoculated with Enterobacter. Growth over time was quantitatively assessed. In vivo: 442 premature rabbit pups were sorted randomly and fed formula of pH 2, 3, 4, or 7, with ranitidine. Two models were utilized: (1) with bacterial challenge using a known acid sensitive organism, (2) without bacterial challenge to simulate natural gut colonization and to test against organisms of unknown acid sensitivity. Normal acid animals received pH 7 formula, no ranitidine. On day 3, the mesenteric lymph nodes (MLN), spleen, liver, and cecum were harvested and cultured.

RESULTS

Bacterial growth was inhibited at pH 2 and 3, growth was logarithmic above pH 4 (P<.001). Total and organ-specific translocation was reduced at pH 3 and below in both models (P<.05). Translocation with formula pH 3 equaled normal acid animals. Quantitative cecal colonization was reduced in pups receiving pH 3 and below in both models (P<.05).

CONCLUSION

Acidification of formula below pH 4 is bactericidal to enteric organisms. Acidified formula decreases bacterial translocation and gut colonization.

Lung lesions and anti-ulcer agents beneficial effect: anti-ulcer agents pentadecapeptide BPC 157, ranitidine, omeprazole and atropine ameliorate lung lesion in rats

Anti-ulcer agents may likely attenuate lesions outside the gastrointestinal tract, since they had protected gastrectomized rats (a "direct cytoprotective effect"). Therefore, their therapeutic potential in lung/stomach lesions were shown. Rats received an intratracheal (i.t.) HCl instillation [1.5 ml/kg HCl (pH 1.75)] (lung lesion), and an intragastric (i.g.) instillation of 96% ethanol (gastric lesion; 1 ml/rat, 24 h after i.t. HCl instillation), then sacrificed 1 h after ethanol. Basically, in lung-injured rats, the subsequent ethanol-gastric lesion was markedly aggravated. This aggravation, however, in turn, did not affect the severity of the lung lesions in the further period, at least for 1 h of observation. Taking intratracheal HCl-instillation as time 0, a gastric pentadecapeptide, GEPPPGKPADDAGLV, M.W.1419, coded BPC 157 (10 microg, 10 ng, 10 pg), ranitidine (10 mg), atropine (10 mg), omeprazole (10 mg), were given [/kg, intraperitoneally (i.p.)] (i) once, only prophylactically [as a pre-treatment (at -1h)], or as a co-treatment [at 0)], or only therapeutically (at +18h or +24 h); (ii) repeatedly, combining prophylactic/therapeutic regimens [(-1 h)+(+24 h)] or [(0)+(+24 h)], or therapeutic/therapeutic regimens [(+18 h)+(+24 h)]. For all agents, combining their prophylactic and salutary regimens (at -1 h/+24 h, or at 0/+24 h) attenuated lung lesions; even if effect had been not seen already with a single application, it became prominent after repeated treatment. In single application studies, relative to controls, a co-treatment (except to omeprazole), a pre-treatment (at -1 h) (pentadecapeptide BPC 157 and atropine, but not ranitidine and omeprazole) regularly attenuated, while therapeutically, atropine (at +18 h), pentadecapeptide BPC 157 highest dose and omeprazole (at +24 h), reversed the otherwise more severe lung lesions.

Multicenter prospective study of ventilator-associated pneumonia during acute respiratory distress syndrome. Incidence, prognosis, and risk factors. ARDS Study Group

We investigated the incidence, risk factors for, and outcome of ventilator-associated pneumonia (VAP) in patients with acute respiratory distress syndrome (ARDS). We compared 134 patients with ARDS with 744 patients without ARDS on mechanical ventilation. Fiberoptic bronchoscopic examination and quantitative bacterial cultures (protected brush or catheter sampling [threshold: 10(3) cfu/ml], or bronchoalveolar lavage [threshold: 10(4) cfu/ml]) were used to diagnose pneumonia. VAP occurred in 49 patients (36.5%). The incidence of pneumonia was 23% (173 of 744 patients) among patients without ARDS (p < 0.002). Nonfermenting gram-negative rods caused significantly more pneumonia in ARDS patients. Mortality rates were identical in ARDS patients with (28 of 49 patients, 57%) and without (50 of 85 patients, 59%) pulmonary infection (p = 0.8). VAP resulted in a considerable increase in attributable time on mechanical ventilation of both the overall population of ARDS patients and of survivors. Both the use of sucralfate (adjusted odds ratio [OR]: 4. 42; 95% confidence interval [CI]: 2.01 to 9.7, p = 0.0002) and the duration of exposure to sucralfate (adjusted OR: 1.206; 95% CI: 1. 095 to 1.328, p = 0.0002) were associated with an increased risk of VAP during ARDS. VAP considerably prolongs the time on mechanical ventilation without affecting survival. Patients given sucralfate may be at greater risk of developing pulmonary infection during ARDS.

Which therapeutic interventions in critical care medicine have been shown to reduce mortality in prospective, randomized, clinical trials? A survey of candidates for the Belgian Board Examination in Intensive Care Medicine

OBJECTIVE

To highlight the lack of randomized controlled trial (RCT) evidence in support of accepted therapeutic interventions in the intensive care unit by assessing the ability of Intensive Care Board Examination candidates to cite relevant studies.

DESIGN

As part of the Board Examination for Intensive Care Medicine in Belgium, candidates were asked to name accepted therapeutic interventions that have been shown to reduce mortality in RCTs.

SETTING

Survey of doctors.

SUBJECTS

Candidates for the 1998 Board Examination for Intensive Care Medicine in Belgium.

INTERVENTIONS

None

MEASUREMENTS AND MAIN RESULTS

Of the 46 candidates, 25 (54%) gave no response and 3 (7%) stated that no such study exists; 16 responses from 13 doctors were considered acceptable answers.

CONCLUSIONS

Candidates for the Board Examination of Intensive Care in Belgium were unable to list many accepted interventions in critical care medicine that are supported by RCT evidence. The RCT may not be the most appropriate tool for assessing the value of an intervention in the intensive care environment.

Trauma intensive care

Management of the traumatically injured patient in the intensive care unit is a complex and challenging area of general surgery. The problems encountered in the intensive care unit are the source of exciting clinical and basic science research. The future of caring for the severely injured patient suffering from the complications of trauma will undoubtedly further bond the art of clinical medicine to the accomplishments of developing technology and molecular biology.

Nasogastric lansoprazole is effective in suppressing gastric acid secretion in critically ill patients

AIM

To evaluate the effect of nasogastric lansoprazole on acid suppression in critically ill patients.

METHODS

Patients were eligible for the study if they had a nasogastric tube in place and had not received acid-suppressive agents for 3 days prior to enrolment into the study. Patients with active gastrointestinal bleeding or a baseline gastric pH > 4.0 were excluded. Patients served as their own controls during a 24 h lead-in period. Lansoprazole 30 mg was administered once daily with water through a nasogastric tube for 2 days. Intragastric pH was measured by continuous 24 h pH-metry for 3 days.

RESULTS

Fifteen patients were enrolled into the study. The baseline median 24 h intragastric pH was 2.25 +/- 1.01, and increased to 6.70 +/- 0.82 (P= 0.001) after 2 days of lansoprazole. Mean percentage of time intragastric pH was > or = 4.0 was 25 +/- 13% at baseline, and increased to 84 +/- 14% (P=0. 001) after 2 days of lansoprazole.

CONCLUSIONS

Nasogastric lansoprazole 30 mg daily is effective in suppressing gastric acid secretion in critically ill patients.

The medical review article revisited: has the science improved?

BACKGROUND

The validity of a review depends on its methodologic quality.

OBJECTIVE

To determine the methodologic quality of recently published review articles.

DESIGN

Critical appraisal.

SETTING

All reviews of clinical topics published in six general medical journals in 1996.

MEASUREMENTS

Explicit criteria that have been published and validated were used.

RESULTS

Of 158 review articles, only 2 satisfied all 10 methodologic criteria (median number of criteria satisfied, 1). Less than a quarter of the articles described how evidence was identified, evaluated, or integrated; 34% addressed a focused clinical question; and 39% identified gaps in existing knowledge. Of the 111 reviews that made treatment recommendations, 48% provided an estimate of the magnitude of potential benefits (and 34%, the potential adverse effects) of the treatment options, 45% cited randomized clinical trials to support their recommendations, and only 6% made any reference to costs.

CONCLUSIONS

The methodologic quality of clinical review articles is highly variable, and many of these articles do not specify systematic methods.

The effect of acidified enteral feeds on gastric colonization in critically ill patients: results of a multicenter randomized trial. Canadian Critical Care Trials Group

OBJECTIVE

To evaluate the effect of acidified enteral feeds on gastric colonization in critically ill patients compared with a standard feeding formula.

DESIGN

Randomized, double-blind, multicenter trial.

SETTING

Eight mixed intensive care units at tertiary care hospitals.

PATIENTS

We recruited mechanically ventilated critically ill patients expected to remain ventilated for >48 hrs. We excluded patients with gastrointestinal bleeding, acidemia, and renal failure requiring dialysis. We enrolled 120 patients; 38% were female, age (mean +/- SD) was 57.6+/-19.3 yrs, and Acute Physiology and Chronic Health Evaluation II score (mean +/- SD) was 21.6+/-7.6.

INTERVENTIONS

Vital High Nitrogen (Abbott Laboratories, Ross Products Division, Columbus, OH) was used as the standard feeding formula for the control group (pH = 6.5). Hydrochloric acid was added to Vital High Nitrogen to achieve a pH of 3.5 in the experimental group.

MEASUREMENTS AND MAIN RESULTS

The main outcome measure was gastric colonization. Secondary outcomes included gastric pH, pneumonia, and mortality. The mean gastric pH in patients receiving acid feeds was lower (pH = 3.3) compared with controls (pH = 4.6; p<.05). One patient (2%) on acid feeds was colonized in the stomach with pathogenic bacteria, compared with 20 patients (43%) in the control group (p<.001). There was no difference in the incidence of pneumonia (6.1% in the acid feeds group vs. 15% in the control group; p = .19). Overall, there were 15 deaths in the acid feeds group and seven in the control group (p = .10); four patients in the acid feeds group and three in the control group died during the study period (p not significant).

CONCLUSIONS

Acidified enteral feeds preserve gastric acidity and substantially reduce gastric colonization in critically ill patients. Larger studies are needed to examine its effect on ventilator-associated pneumonia and mortality.

Meta-analysis: an adolescent in need of evidence and a watchful eye

Meta-analysis is a relatively new development in medicine. It is conceptually appealing, summarizing the medical literature in a rigorous manner and providing clinicians with a global picture regarding the merits of interventions. This process can help clinicians choose appropriate, evidence-based management options for their patients. The early enthusiasm for this approach has more recently been called into question. The reliability, and therefore the usefulness, of meta-analysis will improve as more evidence concerning the rigorous ways to conduct and report such studies is developed.

Systematic reviews and meta-analysis: a structured review of the methodological literature

OBJECTIVE

To systematically review methods for systematic review/meta-analysis in order to identify the different methodological and statistical methods that have been proposed. A summary of the main findings is presented here, with emphasis given to health services research topics.

METHODS

A thorough systematic search for methodological papers was carried out using a variety of methods, including the use of electronic databases. Approximately 1000 potentially relevant references were identified, a number of them from education, psychology and sociology.

RESULTS

After briefly reviewing the procedural methods required to carry out a review, and the basic statistical methods used to combine study estimates, less established methods are discussed. These include methods for dealing with publication bias, meta-regression, meta-analysis of individual patient data, the synthesis of non-randomized evidence alone and in combination with randomized studies. Bayesian modelling and economic evaluation through meta-analysis. Recommendations for meta-analytical practice are given; these are either distilled from previous guidelines, or constructed where there appears to be a broad consensus across the literature.

CONCLUSIONS

It is hoped that this review will provide a consistent and comprehensive, but concise, description of the methods available for synthesizing evidence, that it will promote better quality reviews of the results of health services research and identify specific areas which require methodological development.

Risk reduction in the intensive care unit

Many potentially preventable complications occur in patients who receive intensive care. We have reviewed the epidemiology of three important complications (venous thromboembolism, stress-related upper gastrointestinal bleeding, and vascular catheter-related infection) and evaluated common preventive treatments to provide evidence-based recommendations for prevention. We used English language articles located by MEDLINE or cross-citation, giving preference to articles published in the last 10 years, meta-analyses, and clinical trials that were randomized, double-blinded, and used intention-to-treat analysis. We recommend prophylaxis against venous thromboembolism in most patients, whereas those without respiratory failure or coagulopathy may not require prophylaxis against stress-related upper gastrointestinal hemorrhage. Chlorhexidine gluconate is the preferred antiseptic for disinfecting the skin prior to and during intravascular catheterization. Central venous catheters impregnated with antibacterial or antiseptic agents should be considered in patients at high risk for vascular catheter-related infection. Finally, central venous, pulmonary arterial, and systemic arterial catheters should be changed only when clinically indicated.

Stress ulcer prophylaxis in medical ICU patients: annual utilization in relation to the incidence of endoscopically proven stress ulceration

OBJECTIVE

To measure changes in the proportion of medical intensive care unit (MICU) patients prescribed pharmacologic stress ulcer prophylaxis therapy over a 4-year period in relation to the incidence of stress-related ulceration detected by endoscopy at our institution.

DESIGN

Retrospective 4-year review of pharmacy and endoscopy databases.

SETTING

A 35-bed MICU.

PATIENTS

Patients (n = 2941) admitted to the MICU for longer than 24 hours, between January 1, 1993, and December 31, 1996, without acute gastrointestinal hemorrhage on admission.

METHODS

Records were reviewed to identify patients prescribed pharmacologic stress ulcer prophylaxis (> 24 h of sucralfate or a histamine2-receptor antagonist [H2RA]), and patients with evidence of stress ulceration during endoscopy.

RESULTS

The number of patients per year receiving stress ulcer prophylaxis significantly (p < 0.001) decreased between 1993 and 1996: 1993, 492/693 (71%); 1994, 478/798 (60%); 1995, 295/670 (44%); 1996, 164/780 (21%). There was no difference between years in the median duration of stress ulcer prophylaxis therapy or the proportion of patients receiving sucralfate versus H2RA therapy. There was no difference (p = 0.91) between years in the annual incidence of definite or possible stress-related ulceration: 1993, 6/693 (0.87%); 1994, 5/798 (0.63%); 1995, 6/670 (0.90%); 1996, 5/780 (0.64%).

CONCLUSIONS

The incidence of endoscopically proven stress-related ulceration has remained unchanged over the past 4 years in our MICU despite significantly fewer patients receiving pharmacologic stress ulcer prophylaxis therapy.

[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.