Current opinion in critical care
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Curr Opin Crit Care · Feb 2010
ReviewClinical trials in ventilator treatment: current perspectives and future challenges.
Mortality/morbidity-based end points have been useful in evaluating treatments that modulate 'mediator variables' with a large effect size. Ventilation is usually a supportive measure, and hence is best seen as a 'moderator variable'. It can, therefore, have only a modest impact on disease-specific mortality. In this context, over reliance on final outcome-based end points (mortality, length of stay, etc.) risks the abandonment of several potentially useful developments. These concepts are important in considering how future developments should be evaluated. ⋯ It is crucial that a more dynamic approach, not based on final outcome alone, is considered in designing new clinical trials involving new ventilation strategies.
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In the last 2 years, several reports have dealt with recruitment/positive end-expiratory pressure (PEEP) selection. Most of them confirm previous results and few add new information. ⋯ Indiscriminate application of recruitment maneuver in unselected acute respiratory distress syndrome population does not provide benefits. However, in the most severe patients, recruitment maneuver has to be considered and higher PEEP applied. To individualize PEEP, the expiratory phase has to be considered, and the esophageal pressure measurement to compute the transpulmonary pressure should be progressively introduced in clinical practice.
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The ventilation of patients with acute brain injuries can present significant challenges. Frequently, guidelines recommending management strategies for patients with traumatic brain injuries come into conflict with what is now considered best ventilatory practice. In this review, we will explore many of these areas of conflict. ⋯ There are unlikely to be randomized controlled trials advising how best to ventilate patients with acute brain injuries because of the heterogeneous nature of such injuries. Hypoxia should be avoided. The more widespread use of multimodal brain monitoring, including brain tissue oxygen and cerebral blood flow monitoring, may allow clinicians to tolerate a higher arterial partial pressure of carbon dioxide than has been traditional, allowing a less injurious ventilatory strategy. Modest positive end-expiratory pressure can be used. In severe respiratory failure, most 'rescue' strategies have been attempted in patients with acute brain injuries. Choice of rescue therapy at present is best decided on a case-by-case basis in conjunction with local expertise.
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Allocation of grafts for lung transplantation has been directed in many countries to patients in life-threatening conditions. Advances in technology for extracorporeal devices led to new concepts and increased use for bridging to lung transplantation. Taking these two developments into account, it seems that bridging technologies are used more frequently around the world. ⋯ Bridge to lung transplantation is of increasing importance with new allocation systems and the increasing demand. New extracorporeal technologies address this demand with reliable function for some weeks. But these developments also raise ethical questions of how to use these new tools wisely individually and also collectively for the field of lung transplantation.