REVIEW ARTICLE
S149
0021-7557/03/79-Supl.2/S149
Jornal de Pediatria
Copyright
©
2003 by Sociedade Brasileira de Pediatria
1. Assistant Professor, Clinical Pediatrics and Emergency Medicine, State
University of New York at Buffallo. The Children’s Hospital of Buffalo.
2. MD, Intensive Care Unit, Children’s Hospital, Buffalo, NY.
3. Fellow in Pediatric Intensive Care, The Children’s Hospital of Buffalo,
Buffalo, NY, USA.
Abstract
Objective: To review the current support and treatment strategies of the acute respiratory distress
syndrome.
Sources of data: Original data from our research laboratory and from representative scientific articles
on acute respiratory distress syndrome and acute lung Injury searched through Medline.
Summary of the findings: Despite advances in the understanding of the pathogenesis of acute
respiratory distress syndrome, this syndrome still results in significant morbidity and mortality. Mechanical
ventilation, the main therapeutic modality for acute respiratory distress syndrome, is no longer considered
simply a support modality, but a therapy capable of influencing the course of the disease. New ventilation
strategies, such as high-frequency oscillatory ventilation appear to be promising. This text reviews the
current knowledge of acute respiratory distress syndrome management, including conventional and non-
conventional ventilation, the use of surfactant, nitric oxide, modulators of inflammation, extracorporeal
membrane oxygenation and prone position.
Conclusions: The last decade was marked by significant advances, such as the concept of protective
ventilation for acute respiratory distress syndrome. The benefit of alternative strategies, such as high-
frequency oscillatory ventilation, the use of surfactant and immunomodulators continue to be the target of
study.
J Pediatr (Rio J) 2003;79(Suppl 2):S149-S60: Acute respiratory distress syndrome, mechanical
ventilation, high-frequency ventilation, surfactant, nitric oxide.
Management of the acute respiratory distress syndrome
Alexandre T. Rotta,
1
Cláudia L. Kunrath,
2
Budi Wiryawan
3
Introduction
Acute respiratory distress syndrome (ARDS) is an entity
marked by a significant inflammatory response to a local
(pulmonary) or remote (systemic) insult which invariably
results in hypoxemia and marked alterations to pulmonary
mechanics. By definition four clinical criteria must be met
to establish a diagnosis of ARDS
1
: 1) Acute disease onset,
2) bilateral pulmonary infiltrates on chest x-ray, 3) pulmonary
capillary wedge pressure < 18 mmHg or absence of clinical
evidence of left atrial hypertension, and 4) ratio between
arterial oxygen partial pressure (PaO
2
) and the fraction of
inspired oxygen (FiO
2
) < 200. Patients that meet criteria 1
to 3, but exhibit a PaO
2
/ FiO
2
ratio >200 and < 300 are
defined as having Acute Lung Injury (ALI), a process
physiopathologically similar to ARDS but of lesser clinical
severity. Based on the above criteria, it is estimated that
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Jornal de Pediatria - Vol.79, Supl.2, 2003
ARDS has an incidence of 13.5 cases per 100,000 people
and that ALI affects 17.9 of every 100,000 people.
2
Despite
significant advances in general intensive care therapies, the
dramatic alterations that are characteristic of ARDS are
associated with an elevated mortality, varying between
35% and 71%.
3-5
Despite having first been described several decades
ago
6
and being a significant causer of morbidity and mortality
in pediatric intensive care units all over the world, ARDS
has no specific pharmacological treatment. However,
advances in the understanding of the pathogenesis and
pathophysiology of ARDS over the years have resulted in
the development of a series of support therapies capable of
having an impact on the outcome of patients affected by this
pathology (Table 1).
resources and a large capacity for integration among
participating centers. The availability of clinical data specific
to the pediatric ARDS population is even more limited due
to the almost non-existence of controlled studies in this
population. This being the case, many of the strategies
employed for the management of pediatric ARDS and their
indications have been adapted or inferred from studies of
adult patients.
ARDS treatment strategies
Control of the causative factor
While ARDS has no specific treatment, many of the
factors causing and perpetuating the disease process can be
treated or controlled. For example, patients with
hypovolemic shock should be quickly identified and treated
with rapid volumetric replacement, in order to minimize the
impact on the evolution and maintenance of ARDS.
Similarly, patients with infectious acute abdomen should be
treated with antibiotics and early surgical intervention when
indicated. Patients with septic shock or pneumonia that
evolve to ARDS should be promptly treated with
intravascular expansion and antibiotics, since the treatment
of the infectious factor and hemodynamic control are
fundamental to the success of managing the subsequent
pulmonary pathology.
Controlled oxygen exposure
By definition, patients with ARDS exhibit significant
hypoxemia (PaO
2
/FiO
2
< 200).
1
For this reason, oxygen is
indicated for the management of the initial phase of the
acute respiratory insufficiency. Severe hypoxemia in patients
with ARDS is due to the intrapulmonary shunt, in which
unventilated lung zones that result from edema, atelectasis
or consolidation continue to receive blood supply, despite
being incapable of participating in its oxygenation. Oxygen
therapy, via mask, tent or non-invasive ventilation apparatus
is capable of producing symptomatic improvement during
the initial phase of acute respiratory failure. However, the
rapid natural progression of ARDS with diminishing
pulmonary compliance, increased exertion of respiratory
muscles and subsequent exhaustion means that oxygen
therapy only has value as a temporary symptom relief
measure until mechanical ventilation is introduced. The
great majority of patients that meet diagnostic criteria for
ARDS cannot be managed exclusively with oxygen therapy,
and will require mechanical ventilation. The health care
professional who understands the pathophysiologic process
of ARDS should recognize that a patient that meets diagnostic
criteria and requires an accelerated escalation in oxygen
therapy will need mechanical ventilation. Oxygen therapy
should not delay the institution of ventilatory support, since
intubation and initiation of mechanical ventilation for ARDS
should be an elective decision made before the patient
develops full-blown respiratory failure.
Table 1 -
Therapeutic Strategies in ARDS
Control of the causative factor (sepsis, shock, etc.)
Mechanical Ventilation
–
Controlled oxygen exposure
–
Avoidance of volutrauma (using reduced tidal volumes)
–
Avoidance of atelectrauma (using adequate PEEP)
Careful fluid administration
Optimization of hemodynamics and tissue oxygen delivery
Non-conventional ventilation
–
High-frequency ventilation
–
Ventilação não invasive
–
Liquid ventilation
Drug-based therapies
–
Surfactant
–
Nitric oxide
–
Corticosteroids and other anti-inflammatory agents
Extracorporeal membrane oxygenation (ECMO)
Position therapy (proning)
Prevention and early diagnosis of intercurrent infections
Analgesia and sedation
Nutritional support
Psychological support (patient and family)
Acute respiratory distress syndrome – Rotta AT
et alii
Despite having been successful in an experimental
laboratory environment, many of the methods available for
the management of ARDS have not been shown effective or
have not yet been properly tested in clinical practice. This
is primarily due to the fact that patients with ARDS form an
extremely heterogeneous population, who needs to be
evaluated in studies of large samples, requiring significant