Critical care : the official journal of the Critical Care Forum
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The article by Van Herpe and colleagues in the previous issue of Critical Care describes the glycemic penalty index (GPI), which weights both hyperglycemic and hypoglycemic blood glucose measurements commensurate to their clinically significant difference from target. Although certain adverse consequences result from isolated severe hyperglycemic episodes, several specific outcomes depend upon overall hyperglycemia. In contrast, although mortality has been related epidemiologically to overall low blood glucose, specific negative outcomes may depend upon isolated episodes. Capturing both hypoglycemia and hyperglycemia in a single index will be shown to be useful if the GPI enables us to better define insulin strategies, outcomes, and targets.
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Kolar and colleagues contribute an additional and important incentive for rescuers to utilize end-tidal carbon dioxide tensions as a routine monitor to guide management and decision-making during cardiopulmonary resuscitation. They conclude that below-threshold levels of 14 mmHg (1.5 kPa) measured after 20 minutes of cardiopulmonary resuscitation reliably predict that spontaneous circulation cannot be restored.
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Simple methods to predict the effect of lung recruitment maneuvers (LRMs) in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are lacking. It has previously been found that a static pressure-volume (PV) loop could indicate the increase in lung volume induced by positive end-expiratory pressure (PEEP) in ARDS. The purpose of this study was to test the hypothesis that in ALI (1) the difference in lung volume (DeltaV) at a specific airway pressure (10 cmH2O was chosen in this test) obtained from the limbs of a PV loop agree with the increase in end-expiratory lung volume (DeltaEELV) by an LRM at a specific PEEP (10 cmH2O), and (2) the maximal relative vertical (volume) difference between the limbs (maximal hysteresis/total lung capacity (MH/TLC)) could predict the changes in respiratory compliance (Crs), EELV and partial pressures of arterial O2 and CO2 (PaO2 and PaCO2, respectively) by an LRM. ⋯ A PV-loop-derived parameter, MH/TLC of 0.3, predicted changes in lung mechanics better than changes in gas exchange in this lung injury model.
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Comparative Study
Circulating angiopoietin-1 and angiopoietin-2 in critically ill patients: development and clinical application of two new immunoassays.
In critically ill patients, the massive release of angiopoietin-2 (Ang-2) from endothelial Weibel-Palade bodies interferes with constitutive angiopoietin-1 (Ang-1)/Tie2 signaling in endothelial cells, thus leading to vascular barrier breakdown followed by leukocyte transmigration and capillary leakage. The use of circulating Ang-1 and Ang-2 as novel biomarkers of endothelial integrity has therefore gained much attention. The preclinical characteristics and clinical applicability of angiopoietin immunoassays, however, remain elusive. ⋯ Ang-1 and Ang-2 might serve as a novel class of biomarker in critically ill patients. According to preclinical and clinical validation, circulating Ang-1 and Ang-2 can be reliably assessed by novel immunoassays in the intensive care unit setting.
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In this issue of Critical Care, Dr Haenggi and co-workers present a study evaluating bispectral index (BIS), state entropy (SE) and response entropy in 44 patients sedated in the intensive care unit (ICU). As in recent studies attempting to correlate frontal electroencephalogram (EEG) measurements with clinical evaluations of sedative efficacy, there is considerable overlap in numerical EEG values and different clinical levels of sedation. This precludes the use of these monitors for monitoring or titrating sedation in the critically ill. ⋯ Meanwhile, clinical sedation protocols have emerged, improving important endpoints in critically ill patients needing sedation. A major underlying problem in applying EEG monitors in the ICU is that they have been developed for measuring anesthetic depth and the related risk of recall, rather than the acknowledged endpoints of sedation, namely reduction of anxiety and discomfort. Until an 'objective' monitor is developed to measure the degree of such symptoms, physicians should continue treating patients and not numbers.