For Patients with Severe Lung Injury, Less Is More
Study Answers Long-Debated Questions on Fluid Management in
Critical Care
Results from the largest controlled clinical trial of fluid management
methods in patients with severe lung injury provide important new
information on the risks and benefits of patient care strategies
currently used in the intensive care unit. The trial showed that
for patients with acute lung injury or its more severe form, acute
respiratory distress syndrome, less fluid is better than more, and
a shorter, less invasive catheter is as helpful as and safer than
a longer catheter for monitoring patients. The study was conducted
by scientists from the Acute Respiratory Distress Syndrome Clinical
Research Network of the National Heart, Lung, and Blood Institute
(NHLBI), part of the National Institutes of Health.
Investigators from the Fluid and Catheter Treatment Trial (FACTT)
presented the findings May 21 at the American Thoracic Society (ATS)
International Conference in San Diego. The results were also published
early online by the New England Journal of Medicine (NEJM). The
two studies that comprise the trial – one comparing the use
of the longer pulmonary artery catheter to the shorter central venous
catheter for managing patients and the other evaluating the effects
of conservative versus liberal fluid management -- will appear in
the May 25 and June 15 print issues of NEJM, respectively.
Acute lung injury (ALI) and Acute Respiratory Distress Syndrome
(ARDS) are life-threatening lung conditions that affect more than
190,000 people in the United States each year, based on an estimate
published in the October 20, 2005, NEJM. Thirty to 60 percent of
cases result in death. ALI/ARDS develops in patients who are critically
ill with other diseases such as pneumonia or sepsis (severe and
widespread bacterial infection), or who have sustained major injuries.
Fluid builds up in the lungs, and as a result, breathing is difficult,
and other organs such as kidneys, liver, heart or brain fail if
they do not get enough oxygen from the blood. There is no specific
drug treatment for ALI/ARDS. Patients are placed in the intensive
care unit (ICU) and supported with mechanical ventilators (breathing
machines) and intravenous fluids such as saline (salt water), blood,
or drugs such as dobutamine to improve heart function or diuretics
to increase fluid output.
"A key focus of caring for these critically ill patients is
management of fluids," said NHLBI Director Elizabeth G. Nabel,
MD. "Fluid management in patients with ALI/ARDS has been the
subject of intense debate for decades. 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."
FACTT was designed to clarify: Is it better to give ALI/ARDS patients
more fluids (liberal fluid management) or smaller amounts of fluids
(conservative fluid management)? Is a pulmonary artery catheter
(PAC) superior to a central venous catheter (CVC) for monitoring
these patients? The two studies were conducted simultaneously at
20 clinical centers, with 1,000 participants randomized to receive
either of the two fluid management strategies with either of the
two catheters.
For the fluid management component of the study, approximately
one-half (503) of the participants were assigned to receive a conservative
fluid strategy and the other half (497) received liberal fluid management
for 7 days. Patients were monitored continuously, and treatment
was adjusted according to the study protocol based on the status
of key factors measured at least every four hours. Composition of
the fluids and treatments for patients in shock were left to the
judgment of the physician.
At 60 days, FACTT researchers did not detect a difference in the
numbers of deaths between patients receiving conservative fluid
management compared to those on a liberal fluid management strategy.
However, compared to the liberal fluid management approach, the
conservative fluid strategy improved lung function and shortened
the time that patients needed mechanical ventilation and intensive
care, without increasing the risk of organ failure, the researchers
report.
"Based on these results, we recommend that a conservative
fluid management approach be used in patients with ALI or ARDS,"
said Herbert P. Wiedemann, M.D., chairman of the Department of Pulmonary,
Allergy and Critical Care Medicine at the Cleveland Clinic, and
lead author of the fluid management paper. “Less time on the
ventilator and fewer days in the ICU could translate into cost savings
and lower risk for patients.”
The amount of fluid in the body must be carefully monitored and
adjusted to maximize lung and heart function. A conservative fluid
approach limits the amount of fluids patients are given in an attempt
to decrease the amount of fluid in the lungs. However, limiting
fluids can strain the heart and further limit oxygen delivery to
kidneys and other organs. Conversely, a more liberal use of fluids
might help keep blood and oxygen flowing to other organs, but could
further damage lungs by adding to the amount of fluid build-up.
"Fluid management is a complex issue, and, until now, it was
not clear whether providing more or less fluids was more beneficial,"
noted Gordon Bernard, MD, director of the Division of Allergy, Pulmonary
and Critical Care Medicine at Vanderbilt University in Nashville,
and chair of the NHLBI ARDS Clinical Research Network Steering Committee.
"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."
In a separate, but interrelated component of FACTT, investigators
evaluated the safety and efficacy of a PAC compared to a CVC to
guide management of patients with ALI and ARDS. Both types of catheters
are used to deliver fluids to the patient and to assess heart and
lung function by measuring pressures in specific blood vessels.
With a CVC, a short tube is placed in a large vein. A PAC provides
additional information on heart and lung function, such as the pressures
in the lung and cardiac output, because the catheter passes through
the heart and into a large artery in the lung. Because the PAC is
more invasive, concerns had been raised about whether increased
risks for other complications outweigh the benefits of the device.
In general, patient outcomes in the two catheter groups in FACTT
were similar. After 28 days in the study, the numbers
of ventilator-free days and ICU-free days also were similar between
the two groups. However, participants in the PAC group had twice
as many complications related to catheters compared to those in
the CVC group.
"The PAC did not provide any additional benefit over CVC to
patients with acute lung injury," noted Arthur P. Wheeler,
MD, Associate Professor of Medicine, Vanderbilt University Medical
Center, and lead author of the FACTT catheter study. "Patients
managed with pulmonary-artery catheters are more likely to have
complications such as disturbances in their heart rhythms, so we
do not recommend routine use of PACs to manage patients with acute
lung injury."
FACTT investigators also reported that they found no interaction
between the type of catheter used and the fluid management strategy.
"The fluid management and catheter treatment study represents
another key finding concerning the importance of supportive care
for patients with ALI/ARDS," said Andrea Harabin, PhD, NHLBI
project officer for the NHLBI ARDS Clinical Research Network. "FACTT
was a large randomized clinical trial with a highly defined protocol
followed under rigorous monitoring. These results are relevant to
ALI patients and clinicians nationwide."
FACTT is one of six clinical trials conducted by the NHLBI ARDS
Clinical Research Network, which was formed in 1994 to hasten the
development of effective therapies for ALI and ARDS by evaluating
new treatments and management practices. The network's first clinical
trial, a ventilator management study, was stopped early in 1999
when data showed that death rates were lowered by approximately
25 percent among patients receiving small breaths of air from the
mechanical ventilator compared to patients receiving large breaths
of air, which were the standard of care at that time. The results
have been heralded as signaling a new era of research and management
of the critically ill. Recently published results from another ARDS
Network study showed that corticosteroids do not improve survival
and may increase complications in patients with late-stage ARDS.
For more information:
Acute
Respiratory Distress Syndrome (for patients and the public)
(http://www.nhlbi.nih.gov/health/dci/Diseases/Ards/Ards_WhatIs.html)
ARDS Clinical Research
Network
(http://www.ardsnet.org/index.php)
To interview Dr. Harabin about this study, please contact the NHLBI
Communications Office, (301) 496-4236 or nhlbi_news@nhlbi.nih.gov.
To reach Dr. Wiedemann, please contact Kate Nagel at Cleveland Clinic’s
Department of Media Relations at 216-445-6472 or nagelk@ccf.org.
To reach Dr. Bernard or Dr. Wheeler, please contact John Howser
at the Vanderbilt University Medical School Public Affairs Office
at (615) 322-4747.
Part of the National Institutes of Health, the National Heart,
Lung, and Blood Institute (NHLBI) plans, conducts, and supports
research related to the causes, prevention, diagnosis, and treatment
of heart, blood vessel, lung, and blood diseases; and sleep disorders.
The Institute also administers national health education campaigns
on women and heart disease, healthy weight for children, and other
topics. NHLBI press releases and other materials are available online
at: www.nhlbi.nih.gov.
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and is a component of the U. S. Department of Health and Human Services.
It is the primary federal agency for conducting and supporting basic,
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the causes, treatments, and cures for both common and rare diseases.
For more information about NIH and its programs, visit http://www.nih.gov.
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