ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Diagnostic imaging in patients with acute respiratory distress syndrome (ARDS) has an important role both for research and clinical purposes. In this review we discuss the role of chest radiograph and computed tomography (CT) as diagnostic imaging tools in ARDS. Chest radiograph remains the simplest, most efficient and routinely available method to assess the status of the lung parenchyma in the intensive care unit setting. However, although chest radiography gives an estimation of the general severity of the disease, CT scan provides more specific and detailed information. CT scan needs the transfer of the patients to scanning suites, which, if carefully organized, is not associated with increased morbidity. In our opinion, CT scan should be always performed in patients with ARDS in the early and late phase of the disease to define 1) the severity and distribution of the disease related to its specific etiology; 2) the morphologic changes of the lung parenchyma with time; 3) the regional distribution of recruitable and ovestretched lung regions with different ventilatory settings; and 4) the presence and evolution of iatrogenic and nosocomial complications. These informations may be extremely useful to select an appropriate ventilatory treatment, to improve diagnostic capabilities, and to monitor the clinical course of the patient. Further studies are needed to better define the role of CT scan in the daily clinical management of ARDS.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

In a nonhomogeneous lung with acute respiratory distress syndrome and at a transpulmonary pressure of 30 cm H2O, the forces acting on an atelectatic region surrounded by fully expanded lung could be subject to a pressure of 140 cm H2O. Stress caused by the repeated opening and closing of such alveolar units because of recruitment/derecruitment that may be exacerbated with ventilation at low positive end-expiratory pressure levels may also occur. Recent findings seem to confirm that only ventilatory strategies tailored to the estimation of mechanical stress in terms of respiratory mechanics (lower inflection and upper inflection points on the volume–pressure [V–P] curve, respectively) may prevent ventilator-induced lung injury. These data address the key role of the assessment of respiratory mechanics to identify, prevent, and treat ventilator-induced lung injury. The optimum method to clinically obtain the V–P curve has not been established as yet. Another caveat is the fact that the V–P curve takes into account both the lung and chest wall as opposed to measuring the V–P properties of the lung itself. In the case of a stiff chest wall (eg,in a patient with ascites), limiting the plateau pressure to less than 35 cm H2O would mean that the clinician is unnecessarily limiting tidal volumes. Clearly, extensive experience with the measurement of the inspiratory V–P curve should be obtained.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Gas exchange can be improved in patients with acute respiratory distress syndrome when they are turned from a supine to a prone body position. The mechanisms by which this improvement occurs is the result of shifting perfusion away from shunt areas at the time ventilation is more homogeneously distributed. Prone position is also associated with less atelectasis and less lung edema in experimental models of acute lung injury. The combination of nitric oxide with prone position seemed to have additive effects on oxygenation because prone position allows nitric oxide to reach previously shunted pulmonary vessels. Provided that oxygenation can be improved with prone position in nearly 70% of patients and the implementation of the technique into clinical practice is not associated with relevant complications, prone position might be a valuable adjunctive therapy to treat patients with acute respiratory distress syndrome.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Physiologic studies have assessed the mechanisms explaining the changes in gas exchange, in hemodynamics and in hormonal status observed under noninvasive ventilation (NIV). The change in alveolar ventilation was the main reason for improving oxygenation; the improvement in blood gases also probably accounted for most of the benefits observed in terms of salt and water retention.An important prospective randomized controlled trial assessed the efficacy of an early shift from invasive ventilation to NIV. The results were very promising with this approach and showed that the weaning success rate was higher in the group switched to NIV, which, in turn, was associated with a shorter time in the intensive care unit (ICU) and a reduced 2 months’ mortality rate. These results emphasize the fact that most of the demonstrated benefits of NIV result from the reduction of the complications associated with invasive mechanical ventilation.Another important prospective randomized controlled trial was reported assessing the efficacy of NIV in severely hypoxemic patients requiring ventilatory support. NIV reduced length of stay and infectious complications. The initial improvement in oxygenation was similar with the two modes of support. Patients surviving the ICU had a shorter duration of ventilation and length of stay in the ICU and suffered fewer complications. This is the first large study suggesting that major benefits can be obtained in this group of patients, and these results need to be confirmed.Lastly, interesting studies have assessed the performance of the ventilators proposed for NIV and also have compared different modes of ventilation.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Advances in microprocessor technology have resulted in increasing sophistication of mechanical ventilators. The other side of the sword of sophistication is complexity. The array of modes and features of mechanical ventilators challenges even the most dedicated clinician to keep current. This article reviews the new modes that have recently been introduced and are currently available. These include dual-control modes of ventilation (volume-assured pressure support, pressure augmentation, volume support, autoflow, adaptive pressure ventilation, pressure-regulated volume control, variable pressure control, and variable pressure support), AutoMode, adaptive support ventilation, and automatic tube compensation. The availability, terminology, operation, pitfalls, and literature regarding each technique are discussed.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

This article reviews innovations in mechanical ventilation in three distinct areas: high-frequency ventilation, tracheal gas insufflation, and nitric oxide. In all three of these areas, a number of important articles affecting actual or potential use of each of the techniques has been published. In high-frequency oscillation, adult trials are being conducted for the first time; with tracheal gas insufflation, refinement of administration techniques is ongoing; and, with nitric oxide, randomized controlled trials show no effect of nitric oxide on outcome in acute respiratory distress syndrome.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Monitoring is essential to patient care in the intensive care unit. Although arterial blood gas analysis is often considered the gold standard for evaluation of gas exchange, blood gases may be used excessively in many intensive care units. Pulse oximetry is commonly used to assess arterial oxygenation in critically ill patients. Capnometry is useful to detect esophageal intubation, but use of end-tidal PCO2as a noninvasive indicator of arterial PCO2is often unreliable. Transcutaneous monitoring of PO2and PCO2is commonly used in the neonatal intensive care unit but not with critically ill adults. A wealth of information is provided by ventilator waveforms such as the risk of alveolar overdistension and the presence of auto-positive end-expiratory pressure. There has been increasing enthusiasm recently for the use of pressure-volume curves to properly set the ventilator.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Helical computed tomography scanning reduces cost and mortality when compared to diagnostic alternatives, has replaced ventilation/perfusion scanning in many institutions, especially in the intensive care unit, and makes pulmonary angiography only rarely necessary. Although the role and limitations of helical computed tomography in critically ill patients remain to be more fully delineated, there is little question that it is a major advance in our ability to diagnose pulmonary embolism. For patients receiving thrombolysis, the only regimen which is known to confer a mortality benefit is streptokinase, 1.5 million units intravenously over 1 hour, but it is reasonable to presume that other thrombolytics would have a similar effect. For the anticoagulant treatment of thromboembolism, low molecular weight heparins and unfractionated heparin are interchangeable. Prophylaxis against thromboembolism is indicated in critically ill patients.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Severe community-acquired pneumonia (CAP) is one of the most common causes of admission to the intensive care unit, and ventilator-associated pneumonia (VAP) is one of the most serious complications of care in the intensive care unit. Important data regarding the time to reach clinical stability in patients with severe CAP potentially has an impact on clinical practice in important areas. Recent literature also has focused on the etiology, therapy, and possible prevention of CAP after aspiration. In VAP, the debate continues over the optimal diagnostic technique, diagnostic thresholds, and the impact of these on patient outcome. Further work on the etiology and prevention of VAP are reviewed. The importance of the initial choice of treatment for VAP and the difficulty in choosing appropriate initial empiric therapy are also highlighted.

ISSN:1070-5295    

出版商:OVID    

年代:1999

数据来源: OVID