NHLBI ARDS Network

Prospective, Randomized, Multi-Center Trial of Pulmonary Artery Catheter(PAC) vs. Central Venous Catheter (CVC) for Management of Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrom ARDS. and Prospective, Randomized, Multi-Center Trial of "Fluid Conservative" vs. "Fluid Liberal" Management of Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS).

This study examined two different strategies for managing intravenous fluids and fluid balance in patients with acute lung injury. During ARDS, the lung is vulnerable to the accumulation of fluid in the airspaces. There is considerable variation in current recommendations about how to best use and adjust intravenous fluids and there were no large randomized clinical trials available to guide clinicians. This trial tested a fluid liberal strategy (that would be expected to improve the overall state of the circulation) versus a fluid conservative strategy (that would potentially avoid excess lung fluid accumulation). A second goal of this trial was to determine if a Pulmonary Artery Catheter (PAC) is superior to a smaller, and less invasive central venous catheter in the management of patients with ARDS. This important question arose from a retrospective examination of practice at six hospitals that suggested the pulmonary artery catheter, which has been widely used to guide management of patients with ARDS for may years, may actually be harmful (Connors AF, Jr., Speroff T, Dawson NV, et al. The effectiveness of right heart catheterization in the initial care of critically ill patients. JAMA 1996;276:889-897). A subsequent consensus conference reviewed this and numerous other studies of PAC effectiveness and concluded that randomized controlled trials in patients with ARDS and sepsis were urgently needed (Bernard GR, Sopko G, Cerra F, Demling R, Edmunds H, Kaplan S, Kessler L, Masur H, Parsons P, Shure D, Webb C, Weidemann H, Weinmann G, Williams D. Pulmonary artery catheterization and clinical outcomes: National Heart, Lung, and Blood Institute and Food and Drug Administration Workshop Report. Consensus Statement. JAMA. 2000 May 17;283(19):2568-72).

This trial attempted to answer two important questions in a single trialusing a 2x2 factorial design. The goals of the studies were to 1) assess the safety and the efficacy of PAC vs. CVC guided management in reducing mortality, need for mechanical ventilation, and morbidity in patients with ALI and ARDS; and 2) assess the safety and efficacy of "fluid conservative" vs. "fluid liberal" management strategies on lung function, non-pulmonary organ function, as well as mortality and the need for mechanical ventilation. enrolled. Patients were treated with the specific fluid management strategy (to which they were randomized) for 7 days or until unassisted ventilation, whichever occurs first. The study enrolled 1000 patients and showed no benefit with PAC guided fluid therapy over the less invasive CVC guided therapy. The study also showed that the liberal approach, which resulted in fluid balance that mirrored traditional ICU practices, was inferior to the new conservative approach. The conservative approach increased the number of days free from mechanical ventilation and the intensive care unit without harming other organ function, including kidney function or the need for dialysis. The survival was similar with both approaches but survivors managed with the conservative approach were liberated from the mechanical ventilator 3.2 days faster. To realize the benefits from this approach, most clinicians will need to substantially change their fluid management practices. These two studies were published in the New England Journal of Medicine in 2006 (The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med 2006;354:2564-2575. and The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network. Pulmonary-artery versus central venous catheter to guide treatment of acute lung injury. N Engl J Med 2006;354:2213-2224)