Key Point

Researchers recommend a more conservative approach to managing patients with ALI and ARDS than that employed in usual care.

NEW YORK CITY—Less invasive catheters and smaller amounts of fluids are recommended for patients with acute lung injury (ALI) or ARDS, according to results of the National Heart, Lung, and Blood Institute (NHLBI) ARDS Clinical Research Network (ARDSNet) Fluid and Catheter Treatment Trial (FACTT). These findings were presented by Arthur P. Wheeler, MD, and Herbert P. Wiedemann, MD, during a press briefing at the 2006 American Thoracic Society International Conference.¹

"We now have answers to two important questions to help guide critical care specialists on the best ways to support patients with severe lung injury," commented NHLBI Director Elizabeth G. Nabel, MD. Those questions are: Is it better to give patients with ALI or ARDS more fluids (liberal fluid management) or smaller amounts of fluids (conservative fluid management)? and Is a pulmonary artery catheter (PAC) superior to a central venous catheter (CVC) for monitoring these patients?

Patients were eligible for participation in FACTT if they had been intubated and were receiving mechanical ventilation, had a Pao2/Fio2 ratio of less than 300, and had bilateral infiltrates on chest radiography consistent with the presence of pulmonary edema without evidence of left atrial hypertension. A total of 1,001 patients from 20 clinical centers who had ALI or ARDS were randomized to either conservative or liberal fluid management, as well as either a PAC or a CVC. One patient withdrew consent. Patients were similar in terms of demographics, ICU location, cause of lung injury, coexisting illness, and illness severity at baseline. The primary end point was mortality at 60 days, and secondary end points included the number of ventilator-free days and organ failure–free days and measures of lung physiology.

LESS OR MORE FLUID?

Dr. Wiedemann noted that determining which fluid management strategy is appropriate for critically ill patients has been a controversial topic in recent medical literature. "If you’re looking at prioritizing lung function alone, you’d say, ‘We should keep these patients as dry as possible to hopefully reduce the degree of pulmonary edema.... On the other hand, if you were to prioritize other organ functions ..., you might want to keep the patient wet, so to speak," he explained.

What he and his colleagues found in FACTT was that although no significant difference in 60-day mortality was observed between the two groups of patients, those who received conservative fluid management had improved lung function and shortened duration of mechanical ventilation and stay in the ICU, with no increase in nonpulmonary organ failure.² Mortality at 60 days was 25% in the conservative group and 28% in the liberal group. Compared with patients in the liberal group, those in the conservative group showed improvements in oxygenation index and lung injury scores and had more ventilator-free days (14.6 vs 12.1) and days out of the ICU (13.4 vs 11.2) during the first 28 days. Ten percent of patients in the conservative group and 14% of patients in the liberal group experienced renal failure.

CATHETERS—PAC Versus CVC

According to Dr. Wheeler, until recently, the prevailing thought has been that the PAC provides unique physiological information that is useful for managing critically ill patients, compared with the simpler CVC. However, in the catheter portion of FACTT, he and his colleagues found that PAC-guided therapy did not improve survival or organ function and was actually associated with more complications than CVC-guided therapy.³

The research team reported that mortality rates in the PAC and CVC groups were approximately 27% and 26%, respectively. Numbers of both ventilator-free days and days not spent in the ICU were also similar between the two groups, although patients in the CVC group had more ICU-free days during the first week of the study.

Complication rates per catheter insertion were 0.08 in the PAC group and 0.06 in the CVC group. Although this difference was not significant, the PAC group had approximately 50% more catheter insertions and thus had a higher total number of complications than the CVC group (100 vs 41).

Arrhythmias were the most common complication in the PAC group, occurring in 42 patients. Twenty patients in the PAC group had catheter-related infection; bleeding and clotting complications occurred in 12 of these patients—and 10% more patients in the PAC group had a transfusion in the first week of the study. In comparison, common complications in the CVC group included infection (15 cases), bleeding and clotting (11 cases), arrhythmia (seven cases), and pneumothorax (six cases).

RECOMMENDATIONS

The researchers recommended a conservative fluid management approach for patients with ALI or ARDS. "Current trends in usual care appear to more closely resemble the liberal fluid management arm of this study—the study arm with worse outcomes. This suggests that changing usual practice and adapting more conservative fluid management would better serve ALI and ARDS patients," said Gordon Bernard, MD, Chair of the NHLBI ARDSNet Steering Committee and Director of the Division of Allergy, Pulmonary, and Critical Care Medicine at Vanderbilt University in Nashville.

However, editorialist Emanuel P. Rivers, MD, commented, "[T]he timing of the titration of fluid administration ... after disease presentation has important effects on the pathogenesis of inflammation, therapy, and mortality."⁴ According to Dr. Rivers, "Conservative fluid management during the established phase of ALI is just as important as titrated liberal administration during the acute phase of the inciting insult." He noted that "in contrast to what is true in politics, in fluid management of ALI, it is OK to be both liberal and conservative."

Drs. Wheeler and Wiedemann also recommended that routine use of PACs to manage patients with ALI or ARDS be avoided. "The results of our study do not mean that all critically ill patients should receive a conservative fluid management strategy or that the PAC is not useful in any group of patients who are critically ill.... There are still times when it might be beneficial," cautioned Dr. Wheeler.

Commenting on this recommendation, editorialist Deborah Shure, MD, conceded. "The bottom line with respect to PAC use is that it should no longer be part of the routine management of a number of conditions for which it has been widely used," she said, adding that "it still has a role in diagnosis and in certain types of treatment, particularly the treatment of patients with suspected pulmonary arterial hypertension and right ventricular dysfunction. PACs may also have a role in populations of patients not included in the study … such as those with severe COPD or with conditions requiring complex fluid management."⁵

Dr. Wheeler noted that the findings on participants’ long-term outcomes, in addition to the economic impact of using these catheters and fluid management strategies, should be available in the upcoming months.

—Karen L. Spittler

Reference
1. Wiedemann HP, Wheeler AP. Results of the ARDS Network Fluid and Catheter Treatment Trial—Press Briefing. Presented at: American Thoracic Society International Conference; May 21, 2006; San Diego, Calif.
2. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network; Wiedemann HP, Wheeler AP, Bernard GR, et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006;354:2564-2575.
3. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network; Wheeler AP, Bernard GR, Thompson BT, et al. Pulmonary-artery versus central venous catheter to guide treatment of acute lung injury. N Engl J Med. 2006;354:2213-2224.
4. Rivers EP. Fluid-management strategies in acute lung injury—liberal, conservative, or both? N Engl J Med. 2006;354:2598-2600.
5. Shure D. Pulmonary-artery catheters—peace at last? N Engl J Med. 2006;354:2273-2274.

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