Pulmonary capillary pressures during the acute respiratory distress syndrome
TL;DR: Pulmonary capillary pressure cannot be predicted from PAOP during early and established ARDS, and the high variability in Pcap−PAOP increases the risk for underestimation of filtration pressures and consequently the risk of lung edema.
Abstract: (1)To describe the evolution of pulmonary capillary pressure (Pcap) and of the pressure drop across the pulmonary venous bed from early to established acute respiratory distress syndrome (ARDS), (2) to assess Pcap under different levels of positive end-expiratory pressure (PEEP) and (3) to compare the visual method and a mathematical model to determine Pcap. Prospective, intervention study. Intensive care unit in a teaching institution. Nine ARDS patients, according to the ARDS Consensus Conference criteria. Pulmonary arterial pressures were measured during routine respiratory mechanics measurements throughout ARDS. Four PEEP levels (6, 9, 12 and 15 cmH2O) were studied. Pulmonary artery occlusions were made in triplicate at each PEEP level. Pcap was determined for every occlusion trace by three observers (visual method) and a mathematical model. Diastolic pulmonary artery pressure (PAPd) and pulmonary artery occlusion pressure (PAOP) were measured. The visually determined Pcap showed a bias of 2.5±2.1 mmHg as compared to the mathematical estimation. PAPd, Pcap and PAOP tended to decrease from early to late ARDS (p=0.128, 0.265, 0.121). Pcap−PAOP (6.3±2.7 mmHg) did not change throughout ARDS. Higher PEEP levels were associated with increased PAPd, Pcap and PAOP, as well as with larger Pcap−PAOP throughout ARDS. Pulmonary capillary pressure cannot be predicted from PAOP during early and established ARDS. The high variability in Pcap−PAOP increases the risk for underestimation of filtration pressures and consequently the risk for lung edema. Pcap can be estimated at the bedside by either the visual or mathematical methods.
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01 Jan 2008
TL;DR: After years of debate about its adverse effects, recent largescale studies clearly demonstrate that the use of the PAC does not alter the outcome of critically ill patients.
Abstract: After its initial description by Swan and Ganz more than 30 years ago (1), the pulmonary artery catheter (PAC) technique rapidly became more and more popular in the following years. To date, the PAC remains the monitoring tool that enables more extensive hemodynamic assessment of the critically ill. Furthermore, its use has stimulated the comprehension of physiologic concepts of hemodynamics and tissue oxygenation in various situations of acute circulatory failure. After years of debate about its adverse effects, recent largescale studies clearly demonstrate that the use of the PAC does not alter the outcome of critically ill patients.
Cites background from "Pulmonary capillary pressures durin..."
...The difference between the PAOP (refl ecting the pressure into a large pulmonary vein) and the distal wedge pressure is high in the case of high pulmonary venous resistance (veno-occlusive disease [26], ARDS [ 22 , 23], and α-agonist catecholamine therapy [27])....
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References
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TL;DR: An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
43,884 citations
TL;DR: In this article, an alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability, which is often used in clinical comparison of a new measurement technique with an established one.
9,160 citations
TL;DR: The acute respiratory distress syndrome (ARDS), a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies, carries a high morbidity, mortality, and financial cost.
Abstract: The acute respiratory distress syndrome (ARDS), a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies, carries a high morbidity, mortality (10 to 90%), and financial cost. The reported annual incidence in the United States is 150,000 cases, but this figure has been challenged, and it may be different in Europe. Part of the reason for these uncertainties are the heterogeneity of diseases underlying ARDS and the lack of uniform definitions for ARDS. Thus, those who wish to know the true incidence and outcome of this clinical syndrome are stymied. The American-European Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important in order to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.
6,233 citations
TL;DR: As compared with conventional ventilation, the protective strategy was associated with improved survival at 28 days, a higher rate of weaning from mechanical ventilation, and a lower rate of barotrauma in patients with the acute respiratory distress syndrome.
Abstract: Background In patients with the acute respiratory distress syndrome, massive alveolar collapse and cyclic lung reopening and overdistention during mechanical ventilation may perpetuate alveolar injury. We determined whether a ventilatory strategy designed to minimize such lung injuries could reduce not only pulmonary complications but also mortality at 28 days in patients with the acute respiratory distress syndrome. Methods We randomly assigned 53 patients with early acute respiratory distress syndrome (including 28 described previously), all of whom were receiving identical hemodynamic and general support, to conventional or protective mechanical ventilation. Conventional ventilation was based on the strategy of maintaining the lowest positive end-expiratory pressure (PEEP) for acceptable oxygenation, with a tidal volume of 12 ml per kilogram of body weight and normal arterial carbon dioxide levels (35 to 38 mm Hg). Protective ventilation involved end-expiratory pressures above the lower inflection poin...
3,323 citations
"Pulmonary capillary pressures durin..." refers background in this paper
...The protective approach to ventilation in ARDS advocates high positive end-expiratory pressure (PEEP) levels and low tidal volumes [8]....
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TL;DR: An expanded definition of ARDS is proposed that takes into account new knowledge about adult respiratory distress syndrome and its clinical features, physiologic disturbances, prognosis, and pathologic findings.
Abstract: More than twenty years ago, Ashbaugh and coworkers, (1), in a now classic article, described. 12 patients whose striking but uniform clinical, physiologic, roentgenographic,and pathologic abnormalities distinguished them from among 272adult patients who had received respiratory support in the intensive care units of Colorado General Hospital and Denver General Hospital. The 12patients all had severedyspnea, tachypnea, cyanosis that was refractory to oxygen therapy, decreased respiratory system compliance, and diffuse alveolar infiltrations on their chest radiographs. Pathologic examination in seven patients who died revealed atelectasis, vascular congestion and hemorrhage, severe pulmonary edema and hyaline membranes. Shortly afterward, Petty and coworkers (2), called this constellation of findings the adult respiratory distress syndrome (ARDS). Since then, ARDS has been recognized as an entity throughout the world and has been the subject of numerous conferences, hundreds of articles, and several books. As a result of this activity, much descriptive information has been obtained about ARDS, and we have learned a lot about its clinical features, physiologic disturbances, prognosis, and pathologic findings. And yet formidable problems remain: there is disagreement about exactly what ARDS is and on what causes it; more importantly, available empiric treatment is inadequate, and mortality remains unacceptably high (600/0 or more) (3). This appears to be one of the few points of agreement among investigators, but even that statement is arguable (4). We believe that much of the controversy concerning ARDS is explained by the lack of a satisfactory definition of this elusivesyndrome. How can you collect, much less compare, epidemiologicdata and mortality figures when there is no uniformly accepted (and used) definition? How can you study basic pathophysiologic mechanisms, understand natural history, and above all, evaluate new therapeutic approaches in what appears now to be an amalgam of many different disorders? The purpose of this article, therefore, is to propose an expanded definition of ARDS that takes into account new knowledge about
2,372 citations
"Pulmonary capillary pressures durin..." refers background in this paper
.../sex) (year) diagnosis (cmH2O) compliance [11] (ml/cmH2O)...
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...Demographic and clinical data [11] are presented in Table 1....
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