Critical care : the official journal of the Critical Care Forum
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Airway mucus is a highly specialised secretory fluid which functions as a physical and immunological barrier to pathogens whilst lubricating the airways and humifying atmospheric air. Dysfunction is common during critical illness and is characterised by changes in production rate, chemical composition, physical properties, and inflammatory phenotype. Mucociliary clearance, which is determined in part by mucus characteristics and in part by ciliary function, is also dysfunctional in critical illness via disease related and iatrogenic mechanisms. ⋯ Mucolytic therapies are designed to decrease viscosity, improve expectoration/suctioning, and thereby promote mucus removal. Mucolytics, including hypertonic saline, dornase alfa/rhDNase, nebulised heparin, carbocisteine/N-Acetyl cysteine, are commonly used in critically ill patients. This review summarises the physiology and pathophysiology of mucus and the existing evidence for the use of mucolytics in critically ill patients and speculates on journey to individualised mucolytic therapy.
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Randomized Controlled Trial
Liberal versus restrictive transfusion strategies in subarachnoid hemorrhage: a secondary analysis of the TRAIN study.
The optimal hemoglobin (Hb) threshold to trigger red blood cell transfusions (RBCT) in subarachnoid hemorrhage (SAH) patients is unclear. This study evaluated the impact of liberal versus restrictive transfusion strategies on neurological outcome in patients with SAH. ⋯ A liberal transfusion strategy was not associated with a lower incidence of unfavorable outcome after SAH when compared to a restrictive strategy. However, in a multivariable analysis adjusted for confounders randomization to the liberal group was associated with lower risk of unfavorable outcome. The occurrence of cerebral ischemia was significantly lower in the liberal transfusion strategy group.
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Assessing and quantifying recruitability are important for characterizing ARDS severity and for reducing or preventing the atelectrauma caused by the cyclic opening and closing of pulmonary units. Over the years, several methods for recruitment assessment have been developed, grouped into three main approaches: 1) Quantitative CT Scanning: This method accurately measures the amount of atelectatic lung tissue that regains aeration; 2) Regional Gas Volume Measurement: Based on anatomical markers, this approach assesses gas volume within a specified lung region; 3) Compliance-Based Gas Volume Measurement: This technique compares actual gas volume at a given pressure to expected values, assuming respiratory system compliance is constant within the explored pressure range. ⋯ This paper details the distribution of opening and closing pressures throughout the lung parenchyma, which underpin the concept of recruitability. The distribution of recruitable regions corresponds to atelectasis distribution, with the pressure needed for recruitment varying according to whether the atelectasis is "loose" or "sticky." We also discuss the effects of different PEEP levels on preventing atelectrauma, the importance of keeping some lung areas closed throughout the respiratory cycle, and briefly cover the roles of sigh ventilation, prone positioning, and the closed lung approach.