Current opinion in critical care
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Curr Opin Crit Care · Jun 2014
ReviewThe impact of oxygen and carbon dioxide management on outcome after cardiac arrest.
To describe the impact of oxygen and carbon dioxide management on patient outcomes following cardiac arrest. ⋯ Current data for oxygen and carbon dioxide management following resuscitation suggest that hyperoxia and hypocapnia may be injurious and should be avoided, and that mild hypercapnia may increase the likelihood of discharge home amongst survivors. Such data should be viewed as hypothesis generating. Randomized controlled trials have commenced to clarify the safety, feasibility and efficacy of targeting different oxygen and carbon dioxide tensions following cardiac arrest.
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The ultimate purpose of fluid administration in states of hypovolemia is to correct cardiac output to improve microcirculatory perfusion and tissue oxygenation. Observation of the microcirculation using handheld microscopes gives insight into the nature of convective and diffusive defect in hypovolemia. The purpose of this article is to introduce a new platform for hemodynamic-targeted fluid therapy based on the correction of tissue and microcirculatory perfusion assumed to be at risk during hypovolemia. ⋯ We hypothesized that the optimal amount of fluid needed for correction of hypovolemia is defined by a physiologically based functional microcirculatory hemodynamic platform where convection and diffusion need to be optimized. Future clinical trials using handheld microscopes able to automatically evaluate the microcirculation at the bedside will show whether such a platform will indeed optimize fluid therapy.
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To discuss the role of extracorporeal membrane oxygenation (ECMO) in patients with cardiac arrest. ⋯ This review highlights that ECPR is feasible for both IHCA and OHCA. In the recent series, the outcome of ECPR in IHCA is satisfactory, with survival rates good with neurologic outcome reaching the 40-50% range. All series converge in highlighting that time from cardiac arrest to ECMO flow is a critical determinant of outcome, with survival rates of 50% when initiated within 30 min of IHCA, 30% between 30 and 60 min, and 18% after 60 min. Results of ECPR in OHCA are more challenging. Recent series suggest that good outcome can be obtained in 15-20% of the patients, provided that time from arrest to ECMO is shorter than 60 min. Duration of cardiac arrest seems to be more important than location of cardiac arrest. ECPR thus seems to be a valuable option in selected cases.
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Spontaneous breathing has been shown to induce both positive and negative effects on the function and on injury of lungs and diaphragm during critical illness; thus, monitoring of the breathing effort generated by the patient might be valuable for a better understanding of the mechanisms of disease and to set properly ventilation. The purpose of this review is to summarize the recent findings on the different techniques available to measure the patient's breathing effort, mainly during spontaneous assisted ventilation. ⋯ The development of measurement techniques and their introduction in clinical practice will allow us to understand the role of spontaneous breathing effort in the pathophysiology of lung injury and weaning failure, and how to adjust the breathing workload in an individual patient.
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Studies in patients with acute respiratory distress syndrome (ARDS) have been unable to demonstrate a survival advantage with higher levels of positive end-expiratory pressure (PEEP) to open atelectatic lung regions or prevent their cyclic collapse. This review will discuss the challenges of accurately measuring pleural pressure with balloon-tipped catheters in the oesophagus, and the utility of such pressure monitoring to set PEEP and assess lung mechanics, focusing on patients with ARDS. ⋯ Changes in oesophageal pressure likely accurately reflect global changes in pleural pressure in supine patients with ARDS. However, absolute oesophageal pressure values in such patients may be subject to local artefacts and may substantially overestimate pleural pressure in other lung regions. Setting PEEP high enough to achieve a targeted end-expiratory transpulmonary pressure in the region of the oesophageal balloon catheter could overdistend other lung regions. Measurement of oesophageal pressure is feasible, but its clinical utility to titrate PEEP, compared with routine assessment, awaits experimental confirmation.