Critical care : the official journal of the Critical Care Forum
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The accuracy of the arterial pressure-based cardiac output FloTrac-Vigileo system remains unacceptably low during haemodynamic instability. Data show that the measurement of cardiac output (CO) is strongly influenced by changes in factors that affect arterial blood pressure (ABP) - for example, vascular tone and compliance and the arterial site - independently of true changes in CO. ⋯ These limitations make FloTrac-Vigileo accurate in stable haemodynamic conditions only, and until more robust algorithms and further validation studies become available, we should be aware that during haemodynamic instability or in extreme conditions of vasodilation or vasoconstriction, the measured CO may diverge from an independent bolus indicator dilution measurement, particularly if a peripheral artery is used. In these conditions, we advocate the use of transpulmonary indicator dilution via a femoral artery.
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Comment
Does anesthetic provide similar neuroprotection to therapeutic hypothermia after cardiac arrest?
In the previous issue of Critical Care, Meybohm and colleagues provide evidence to support hypothermia as a kind of therapeutic option for patients suffering cardiac arrest. Although anesthetics had been used to induce hypothermia, sevoflurane post-conditioning fails to confer additional anti-inflammatory effects after cardiac arrest. Further research in this area is warranted.
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Intra-abdominal hypertension is common in critically ill patients and is associated with increased morbidity and mortality. The optimal ventilation strategy remains unclear in these patients. We examined the effect of positive end-expiratory pressures (PEEP) on functional residual capacity (FRC) and oxygen delivery in a pig model of intra-abdominal hypertension. ⋯ In a pig model of intra-abdominal hypertension, PEEP up to 15 cmH2O did not prevent the FRC decline caused by intra-abdominal hypertension and was associated with reduced oxygen delivery as a consequence of reduced cardiac output. This implies that PEEP levels inferior to the corresponding intra-abdominal pressures cannot be recommended to prevent FRC decline in the setting of intra-abdominal hypertension.
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Fresh blood has many potential advantages over older blood, but there is no evidence that these properties translate into clinical benefit for intensive care patients. The observational multicenter study by Karam and colleagues provides some evidence suggesting that blood stored for less than 14 days is better than older blood in terms of new organ failure and reduction in length of stay in pediatric intensive care units. ⋯ As a consequence, it is ethical and certainly pertinent to conduct a randomized clinical trial in order to test the hypothesis that fresh blood might reduce mortality. The rationale is strong and the potential benefit of fresh blood is substantial.
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Over 500 million of the current world population will die from diseases caused by smoking cigarettes. The symptoms and signs of nicotine withdrawal are not well described in the critically ill. Since the various conditions of critical illness may lead to clinical manifestations mimicking nicotine withdrawal, describing its specific manifestations may not be easy. ⋯ However, retrospective studies have found that it may increase mortality. Despite the abundance of active smokers, there is a paucity of data describing nicotine withdrawal, and its prevention and treatment options in the critically ill. Future studies are warranted to address these issues.