Surgery (Austin & Northern Health) - Research Publications
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ItemNo Preview AvailableIs reducing variability of blood glucose the real but hidden target of intensive insulin therapy?(BMC, 2009)Since the first report that intensive insulin therapy reduced mortality in selected surgical critically ill patients, lowering of blood glucose levels has been recommended as a means of improving patient outcomes. In this initial Leuven trial, blood glucose control by protocol using insulin was applied to 98.7% of patients in the intensive group but to only 39.2% (P < 0.0001) of patients in the control group. If appropriately applied, such protocols should decrease both the mean blood glucose concentration and its variability (variation of blood glucose concentration). Thus, it is logically possible that the benefit of intensive insulin therapy in the first Leuven trial was due to a decrease in mean glucose levels, a decrease in their variability, or both. Several recent studies have confirmed significant associations between variability of blood glucose levels and patient outcomes. Decreasing the variability of blood glucose levels might be an important dimension of glucose management, a possible mechanism by which an intensive insulin protocol exerts its putative beneficial effects, and an important goal of glucose management in the intensive care unit. Clinicians need to be aware of this controversy when considering the application of intensive insulin therapy and interpreting future trials.
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ItemNo Preview AvailableThe pursuit of a high central venous oxygen saturation in sepsis: growing concerns(BMC, 2008)In this issue of Critical Care, Dutch investigators report that, in a cohort of patients with sepsis/septic shock admitted to three different intensive care units (ICUs), low central venous oxygen saturation (ScvO2) was uncommon at the time of ICU admission, and hospital mortality was <30%. Their findings, taken together with those of recent reports from Australia and New Zealand (ANZ), raise serious concerns about the utility of early goal directed therapy (EGDT) outside the context of the original trial. Despite inclusion of EGDT into the Surviving Sepsis Guidelines, in response to growing uncertainty, ANZ and US investigators will soon begin randomization of patients into two large multicentre trials comparing EGDT to standard therapy. Until such studies are completed, basing international treatment guidelines on a single centre study performed in what may turn out to be a highly atypical environment would seem premature.
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ItemNo Preview AvailableBench-to-bedside review: The evaluation of complex interventions in critical care(BIOMED CENTRAL LTD, 2008)Complex interventions, such as the introduction of medical emergency teams or an early goal-directed therapy protocol, are developed from a number of components that may act both independently and inter-dependently. There is an emerging body of literature advocating the use of integrated complex interventions to optimise the treatment of critically ill patients. As with any other treatment, complex interventions should undergo careful evaluation prior to widespread introduction into clinical practice. During the development of an international collaboration of researchers investigating protocol-based approaches to the resuscitation of patients with severe sepsis, we examined the specific issues related to the evaluation of complex interventions. This review outlines some of these issues. The issues specific to trials of complex interventions that require particular attention include determining an appropriate study population and defining current treatments and outcomes in that population, defining the study intervention and the treatment to be used in the control group, and deploying the intervention in a standardised manner. The context in which the research takes place, including existing staffing levels and existing protocols and procedures, is crucial. We also discuss specific details of trial execution, in particular randomization, blinded outcome adjudication and analysis of the results, which are key to avoiding bias in the design and interpretation of such trials. These aspects of study design impact upon the evaluation of complex interventions in critical care. Clinicians should also consider these specific issues when implementing new complex interventions into their practice.
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ItemNo Preview AvailableBench-to-bedside review: Avoiding pitfalls in critical care meta-analysis-funnel plots, risk estimates, types of heterogeneity, baseline risk and the ecologic fallacy(BMC, 2008)Meta-analysis can be a powerful tool for demonstrating the applicability of a concept beyond the context of individual clinical trials and observational studies, including exploration of effects across different subgroups. Meta-analysis avoids Simpson's paradox, in which a consistent effect in constituent trials is reversed when results are simply pooled. Meta-analysis in critical care medicine is made more complicated, however, by the heterogeneous nature of critically ill patients and the contexts within which they are treated. Failure to properly adjust for this heterogeneity risks missing important subgroup effects in, for example, the interaction of treatment with varying levels of baseline risk. When subgroups are defined by characteristics that vary within constituent trials (such as age) rather than features constant within each trial (such as drug dose), there is the additional risk of incorrect conclusions due to the ecological fallacy. The present review explains these problems and the strategies by which they are overcome.
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ItemDexmedetomidine vs. haloperidol in delirious, agitated, intubated patients: a randomised open-label trial(BMC, 2009)INTRODUCTION: Agitated delirium is common in patients undergoing mechanical ventilation, and is often treated with haloperidol despite concerns about safety and efficacy. Use of conventional sedatives to control agitation can preclude extubation. Dexmedetomidine, a novel sedative and anxiolytic agent, may have particular utility in these patients. We sought to compare the efficacy of haloperidol and dexmedetomidine in facilitating extubation. METHODS: We conducted a randomised, open-label, parallel-groups pilot trial in the medical and surgical intensive care unit of a university hospital. Twenty patients undergoing mechanical ventilation in whom extubation was not possible solely because of agitated delirium were randomised to receive an infusion of either haloperidol 0.5 to 2 mg/hour or dexmedetomidine 0.2 to 0.7 microg/kg/hr, with or without loading doses of 2.5 mg haloperidol or 1 mug/kg dexmedetomidine, according to clinician preference. RESULTS: Dexmedetomidine significantly shortened median time to extubation from 42.5 (IQR 23.2 to 117.8) to 19.9 (IQR 7.3 to 24) hours (P = 0.016). Dexmedetomidine significantly decreased ICU length of stay, from 6.5 (IQR 4 to 9) to 1.5 (IQR 1 to 3) days (P = 0.004) after study drug commencement. Of patients who required ongoing propofol sedation, the proportion of time propofol was required was halved in those who received dexmedetomidine (79.5% (95% CI 61.8 to 97.2%) vs. 41.2% (95% CI 0 to 88.1%) of the time intubated; P = 0.05). No patients were reintubated; three receiving haloperidol could not be successfully extubated and underwent tracheostomy. One patient prematurely discontinued haloperidol due to QTc interval prolongation. CONCLUSIONS: In this preliminary pilot study, we found dexmedetomidine a promising agent for the treatment of ICU-associated delirious agitation, and we suggest this warrants further testing in a definitive double-blind multi-centre trial. TRIAL REGISTRATION: Clinicaltrials.gov NCT00505804.