Seminars in respiratory and critical care medicine
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The acute respiratory distress syndrome (ARDS) is a life-threatening syndrome that may occur in any patient without any predisposition and that is mostly triggered by underlying processes such as sepsis, pneumonia, trauma, multiple transfusions, and pancreatitis. ARDS is defined by (1) acute onset, (2) bilateral infiltrates in chest x-rays, (3) absence of left ventricular failure, and (4) severe arterial hypoxemia with a PaO2/FiO2 ratio less than 200 mmHg. Still, ARDS is feared (mortality 30-40%) and relatively frequent (incidence between 13.5 per 100,000 to 75 per 100,000). ⋯ Despite ongoing and intensive scientific research in this area, the mechanisms underlying ALI/ARDS are still not completely understood, and until recently, there were no studies demonstrating any beneficial effect of a single treatment modality in ARDS. The recent report that a specific approach to ventilatory support can significantly reduce mortality in ARDS underscores the need for better understanding of the pathophysiological events occurring in this syndrome. This review therefore summarizes the current pathophysiological concepts underlying the evolution of acute hypoxemic respiratory failure and focuses on: (1) possible reasons for the development of ALI/ARDS; (2) cellular and humoral mediator responses leading to a sustained and self-perpetuating inflammation of the lung; (3) consequences with regard to fluid balance, pulmonary perfusion, ventilation, and efficiency of gas exchange; and (4) mechanisms underlying the aggravating complications commonly seen in ARDS, especially ventilator-associated lung injury, ventilator-associated pneumonia, and lung fibrosis.
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Semin Respir Crit Care Med · Jun 2001
Ventilator-associated pneumonia complicating the acute respiratory distress syndrome.
Pulmonary infections span a wide spectrum, ranging from self-limited processes (e.g., tracheobronchitis) to life-threatening infections including both community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). Together, pneumonia and influenza rank as the sixth leading cause of death in the United States and lead all other infectious diseases in this respect. Pneumonia is the second-most-common hospital-acquired infection in the United States, accounting for 17.8% of all hospital-acquired infections and 40,000 to 70,000 deaths per year. ⋯ The greater hospital mortality associated with these "high-risk'' pathogens has been attributed to the virulence of these bacteria and the increased occurrence of inadequate initial antibiotic treatment of VAP due to the presence of antibiotic resistance. This review provides an overview of the clinical importance of VAP. We then describe how this nosocomial infection influences the management and outcomes of patients with the acute respiratory distress syndrome (ARDS).
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Semin Respir Crit Care Med · Jun 2001
Pulmonary and extrapulmonary forms of acute respiratory distress syndrome.
Acute respiratory distress syndrome (ARDS) is usually viewed as the functional and morphological expression of a similar underlying lung injury caused by a variety of insults. However, the distinction between ARDS due to a direct (ARDSp) versus an indirect (ARDSexp) lung injury is gaining more attention as a means of better comprehending the pathophysiology of ARDS and for modifying ventilatory management. ⋯ It is possible that the two insults may coexist (i.e., one lung with direct injury (as in pneumonia) and the other with indirect injury, through mediator release from the contralateral pneumonia); (2) the radiological pattern, by chest x-ray or computed tomography (CT), is different in ARDSp (characterized by prominent consolidation) and ARDSexp (characterized by prominent ground-glass opacification); (3) in ARDSp lung elastance is more markedly increased than in ARDSexp, where the main abnormality is the increase in chest wall elastance, due to abnormally high intra-abdominal pressure; (4) positive end-expiratory pressure (PEEP), inspiratory recruitment, and prone position are more effective to improve respiratory mechanics, alveolar recruitment, and gas-exchange in ARDSexp. Further studies are warranted to better define if the distinction between ARDS of different origins can improve clinical management and survival.
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Semin Respir Crit Care Med · Jan 2001
Multidisciplinary management of sedation and analgesia in critical care.
Management of sedation and analgesia in critical care medicine is a multidisciplinary process that involves physicians, nurses, pharmacists, and other healthcare providers. Optimal management of these common issues includes recognition of the importance of predisposing and causative conditions that contribute to the sensations of pain and discomfort, anxiety, and delirium. ⋯ Optimal use of sedative and analgesic medications involves matching unique properties of specific medications with individual patient characteristics. Guidelines that minimize unnecessary variability in practice, prevent excessive medication, and emphasize management based on individual patient characteristics improve the effective utilization of these medications.
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Semin Respir Crit Care Med · Jan 2001
Models of critical care delivery: physician staffing in the ICU.
Although a consensus has emerged over the value of intensive care units (ICUs) in improving both the outcome and efficiency of critical care, the optimal staffing configuration of physicians who provide this care remains controversial. The value of open ICUs, where many clinicians can admit and care for patients, versus closed ICUs, where an on-site intensivist or housestaff team (or both) provides primary care of the critically ill patient is one aspect of this controversy. The roles of the intensivist, the ICU housestaff team, and the ICU director have also been debated. This article reviews the available literature on physician staffing in critical care units and its relationship to outcome and cost-effectiveness of care.