Current opinion in critical care
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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.
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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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Volumetric capnography (VCap) measures the kinetics of carbon dioxide (CO2) elimination on a breath-by-breath basis. A volumetric capnogram contains extensive physiological information about metabolic production, circulatory transport and CO2 elimination within the lungs. VCap is also the best clinical tool to measure dead spaces allowing a detailed analysis of the functional components of each tidal volume, thereby providing clinically useful hints about the lung's efficiency of gas exchange. Difficulties in its bedside measurement, oversimplifications of its interpretation along with prevailing misconceptions regarding dead space analysis have, however, limited its adoption as a routine tool for monitoring mechanically ventilated patients. ⋯ Recent advances in VCap and our improved understanding of its clinical implications may help in overcoming the known limitations and reluctances to include expired CO2 kinetics and dead space analysis in routine bedside monitoring. It is about time to start using this powerful monitoring tool to support decision making in the intensive care environment.
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Many efforts have been made in the last decades to improve outcome in patients who are successfully resuscitated from sudden cardiac arrest. Despite some advances, postanoxic encephalopathy remains the most common cause of death among those patients and several investigations have focused on early neuroprotection in this setting. ⋯ Early cooling may contribute to enhance neuroprotection after cardiac arrest. Hemodynamic optimization is mandatory to avoid cerebral hypoperfusion in this setting. The combination of such interventions with other promising neuroprotective strategies should be evaluated in future large clinical studies.