Minerva anestesiologica
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Minerva anestesiologica · Jun 2005
ReviewThe use of positive end-expiratory pressure in the management of the acute respiratory distress syndrome.
Clinical and experimental research on the effects of positive end-expiratory pressure (PEEP) has produced a plethora of information during the last two decades. The application of PEEP is expected to increase PaO2; however, it is generally agreed that simply using increased PaO2 as the end point is inappropriate. Four mechanisms have been proposed to explain the improved pulmonary function and gas exchange with PEEP: 1) increased functional residual capacity; 2) alveolar recruitment; 3) redistribution of extravascular lung water; and 4) improved ventilation-perfusion matching. ⋯ The greater the alveolar collapse and pulmonary edema, the more the compliance curve of the respiratory system shifts downward and to the right. As PEEP is applied and alveoli recruited, the pressure-volume curve shifts upward and to the left. Despite its intuitive benefit, there were very few controlled studies of the effects of PEEP on ARDS outcome and no prospective randomised controlled trial of PEEP has been ever carried out in patients with acute lung injury and/ or ARDS to evaluate its efficacy until recently.
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Coagulopathy is a phenomenon which is a life threatening complication in the trauma patient who has sustained significant injuries and blood loss. With our increasing understanding of the mechanisms which drive the coagulopathy and the availability of new treatment options, most notably recombinant factor VIIa (rFVIIa), we are now able to treat those patients who have had a massive traumatic haemorrhage with greater efficacy. This paper reviews the current considerations in dealing with patients with trauma-induced coagulopathy and offers a strategy for their management.
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The transpulmonary thermodilution indicator (TPID) technique has been recently introduced and diffuse in clinical practice. This "less-invasive" device measures intermittent cardiac output and, based on pulse contour method, continuous cardiac output, that agree with cardiac output obtained with pulmonary artery catheter in different clinical setting. Moreover it allowed stroke volume variation and pulse pressure variation experimental and clinically validate fluid responsiveness index in controlled mechanically ventilated patients. ⋯ Cardiac output monitoring based on TPID technique is safe and accurate, as well as fluid responsiveness indicator (SVV and PPV). Intrathoracic blood volume seems to be a good preload index but the results reported in literature are not homogeneous in all its applications. Extra vascular lung water index is a very interesting parameter particularly in critically ill setting but its clinical application is not yet widely documented.
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One of the most challenging problems in critical care medicine is the acute respiratory distress syndrome (ARDS), the most severe form of acute lung injury (ALI). Evidence from experimental studies suggests that mechanical ventilation can cause or aggravate lung injury. ⋯ In 2000, the ARDS Network published reported a reduced mortality (from 40% to 31%) in a mixed population of patients with ALI and ARDS ventilated with half the tidal volume of the control group. However, almost forty years after the first description of ARDS, many investigators and experts in the field still apply essentially the same ventilatory strategy (tidal volume greater than 10 mL/kg body weight and PEEP levels less than 10 cmH2O) as in the original description of ARDS.
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In-hospital cardiac arrests, intensive care unit (ICU) admissions and unexpected deaths are commonly preceded by warning signs up to 24 hours prior to the event. As a result, some of these critical events are potentially preventable. Critical care physicians are increasingly familiar with patient care systems; trauma systems have become well established in most health services, and the chain of survival provides a system response to out of hospital cardiac arrests. ⋯ There is also potential to reduce morbidity. Morbidity caused by failure to adequately treat hypoxemia and hypovolemia on the wards, results in preventable cases of renal and respiratory failure, requiring prolonged, uncomfortable and expensive admissions to intensive care, along with the invasive therapy that ICU admission entails. The Medical Emergency Team (MET) system provides a potential solution.