Selective digestive tract decontamination in intensive care medicine. Fundamentals and current evaluation

Selective digestive tract decontamination (SDD) is a method where topical non-absorbable antibiotics are applied to the oropharynx and stomach which primarily is aimed at the prevention of ventilator-associated pneumonia. The rationale for SDD is that ventilator associated pneumonia usually originates from the patients'own oropharyngeal microflora. SDD is also used for the prevention of gut-derived infections in acute necrotizing pancreatitis and in liver transplantation. Despite numerous clinical trials and several meta-analyses, SDD is still a controversial topic. It is now commonly accepted that the incidence of pneumonia is reduced,however, the concept of using topical antibiotics has its inherent limitations and the best results have been obtained by combination with a short course of intravenous antibiotics. Several issues surrounding the notorious difficulties in establishing the diagnosis of ventilator-associated pneumonia especially in the presence of antibiotics are an on-going matter of debate.Furthermore, pneumonia is the leading cause of death from nosocomial infections and its prevention was not adequately followed by reduced mortality in most individual trials, however, a benefit was suggested by recalculation of data in meta-analyses.Patients are not well defined by their need for ICU admission and mechanical ventilation and the attributable mortality of infections depends more on the type and severity of the underlying diseases.Recently published trials substantially improved our understanding as to which patients may derive most benefit from SDD.Currently, it seems that an improved survival can be achieved in surgical and trauma patients with severe but salvageable diseases, which might be classified e.g.by calculation of APACHE-II scores on admission.However, the most important drawback of SDD is the development of resistance and an increased selection pressure towards Gram-positive pathogens, especially in institutions with endemic multi-resistant microorganisms.Thus, it appears that "selective" must not only be interpreted as selective suppression of pathogenic bacteria but rather as selection of appropriate groups of patients with respect to underlying diseases and severity of illness. Furthermore, it means selection of ICUs where the endemic resistance patterns might allow the use of SDD at a relatively low risk for selection of resistant microorganisms, which is still the major concern associated with SDD.     

Best evidence in critical care medicine

Question  

In patients with septic shock and relative adrenal insufficiency, does adrenal replacement therapy improve survival compared to placebo?     

Best evidence in critical care medicine

Background  

Thrombolysis is considered to be standard therapy for patients with pulmonary embolism presenting with shock, despite a paucity of large clinical trials. The benefit of thrombolysis in submassive pulmonary embolism (right ventricular dysfunction without shock) is debated.     

Best evidence in critical care medicine

Question  

Does daily interruption of sedative infusions in critically ill patients receiving mechanical ventilation decrease the duration of mechanical ventilation and length of stay in the intensive care unit (ICU) and hospital?     

Best evidence in critical care medicine

Question  

Does therapeutic hypothermia improve neurologic outcome in patients who have survived a cardiac arrest with ventricular fibrillation or tachycardia?     

Best evidence in critical care medicine

Background  

Critically ill patients require supplementaryiv fluids to support vital functions. Crystalloids and colloids (naturally-occurring and synthetic) are frequently used for fluid support. The choice of the type of fluid used on mortality among the critically ill remains controversial, as the effect of this choice remains unknown.     

Best evidence in critical care medicine

Question  

Does daily intermittent hemodialysis improve survival as compared with conventional (alternate day) intermittent dialysis in patient with acute renal failure?     

Best evidence in critical care medicine Central venous catheterization: the impact of insertion site

Background  

Central venous catheterization is a common procedure in critical care medicine and anesthesia. Infection impacts patient outcome and, depending on definition, complicates 5–19% of central venous catheter (CVC) insertions. One of the factors hypothesized to affect infection rates is the site of venous cannulation.     

Selective decontamination of the digestive tract: a stratified, randomized, prospective study in a mixed intensive care unit.

To evaluate the use of selective decontamination of the digestive tract (SDD) (polymyxin, amphotericin, tobramycin, and intravenous cefotaxime) in a mixed intensive care unit, we performed a stratified, randomized, prospective study. The 331 patients were recruited over an 18-month period, with 256 patients remaining more than 48 hours. Stratification by acute physiology and chronic health evaluation (APACHE II) preceded randomization to control (standard antibiotic therapy) or treatment (SDD) groups. Nosocomial infection was significantly reduced in the SDD group (16.7%; 21 of 126 patients) compared with the control group (30.8%; 40 of 130 patients; p = 0.008). No difference was found in overall mortality rate or length of stay between the two groups. Those patients with admission APACHE II scores 10 to 19 demonstrated the most significant reduction in nosocomial infection (23 of 70 control vs 13 of 76 SDD; p = 0.03) and mortality (15 of 70 control vs 8 of 76 SDD; p = 0.07). Emergence of multiresistant microorganisms was not a clinical problem, but a definite change occurred in the ecology of environmental and colonizing bacteria. With the exception of cefotaxime, a reduction was noted in systemic antibiotic usage in the SDD group. We conclude that SDD is useful in selected patients in a mixed intensive care unit.     

Use of selective decontamination of the digestive tract in United Kingdom intensive care units*

The use of selective decontamination of the digestive tract (SDD) remains controversial despite several large randomised‐controlled trials and meta‐analyses. A postal survey of intensive care units in the United Kingdom was conducted to document current use of SDD, and to identify factors influencing this practice. The response rate was 71%. The vast majority (182 units, 95%) do not use SDD mainly because practising clinicians do not believe it works or that there is not enough evidence (51%), and because of concerns about antibiotic resistance (47%). Of the 10 units using SDD, three apply it to all intubated patients and five do not use intravenous antibiotics in their protocol.     

Selective decontamination of the digestive tract in surgical patients: a systematic review of the evidence

OBJECTIVE: To determine the comparative efficacy of selective decontamination of the digestive tract in critically ill surgical and medical patients, and in selected subgroups of surgical patients with pancreatitis, major burn injury, and those undergoing major elective surgery and transplantation. DATA SOURCES: The MEDLINE database was searched from January 1966 to December 1996 using the terms "decontamination or prophylaxis," "intensive care units," and "antibiotics." The search was limited to English-language studies evaluating the efficacy of selective decontamination of the digestive tract in human subjects. STUDY SELECTION: The primary review was restricted to prospective randomized trials. DATA EXTRACTION: End points of interest included rates of nosocomial pneumonia, bacteremia, urinary tract infection, wound infection, mortality, and length of intensive care unit stay. Methodologic quality of individual studies was assessed using a previously described model. DATA SYNTHESIS: Odds ratios (ORs) together with their (95% confidence interval [Cls]) were reported and determined using the Mantel-Haenszel method. Mortality was significantly reduced with the use of selective decontamination of the digestive tract in critically ill surgical patients (OR, 0.7, 95% CI, 0.52-0.93), while no such effect was demonstrated in critically ill medical patients (OR, 0.91; 95% CI, 0.71-1.18). The greatest effect was demonstrated in studies where both the topical and systemic components of the regimen were used. Rates of pneumonia were reduced in both subsets of patients, while those of bacteremia were significantly reduced only in surgical patients. CONCLUSIONS: Selective decontamination of the digestive tract notably reduces mortality in critically ill surgical patients, while critically ill medical patients derive no such benefit. These data suggest that the use of selective decontamination of the digestive tract should be limited to those populations in whom rates of nosocomial infection are high and in whom infection contributes notably to adverse outcome.