Transcript ACUTE CHEST SYNDROME

ACUTE CHEST
SYNDROME
Dr.Padma Gadde
Dr. Dora Alvarez
ACUTE CHEST
SYNDROME
 “Acute
chest syndrome" (ACS) broadly
describes a disease
 leading cause of death
 second most common cause of
hospitalization in patients with sickle cell
disease
ACUTE CHEST SYNDROME
 Its
rapid clinical course, with or
without fever, is characterized by
chest pain, cough, progressive
anemia, hypoxemia, and the
presence of new pulmonary
infiltrates on chest radiographs
Learning Objectives
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To identify the causes of acute chest
syndrome (ACS) in patients with sickle
cell disease

To understand the pathophysiology of
ACS

To recognize elements that are important
in appropriate management of ACS
ACUTE CHEST SYNDROME
(5)
The approach to diagnosis, monitoring, and
treatment requires
recognition of the complication,
correction, if possible, of inciting factors,
maintenance of euvolemia,
pain control, and
use of transfusions and
(6)
administration of oxygen, if needed.
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(1)
(2)
(3)
(4)
ACUTE CHEST SYNDROME
Risk factors
Younger age
 Homozygous sickle cell or sickle cell-beta°
thalassemia genotype
 Winter months
 Fever

ACUTE CHEST SYNDROME
Risk factors
Surgery
 Avascular necrosis of bone
 Previous pulmonary events
 High hemoglobin levels
 High steady-state leukocyte counts
 Low fetal hemoglobin concentration

Pathophysiology
The pathogenesis of parenchymal lung
infiltrates in ACS is incompletely understood.
 Pulmonary infiltrates may result from either
one process or a combination of several
interacting processes, which may include
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atelectasis,
infection,
fat embolism,
thromboembolism and,
most commonly, in situ microvascular occlusion
within the pulmonary vasculature by sickled
erythrocytes
Pathophysiology

The importance of nonembolic microvascular
occlusion in causing ACS is demonstrated by
findings on thin-cut computed tomographic
scans: Arterioles and venules are either
absent or diminished in number, and groundglass opacities appear in a mosaic, patchy, or
multifocal distribution
pathophysiology
 Fat
embolism from bone marrow
necrosis seems to be an important and
often unrecognized cause of ACS
pathophysiology
Patients with pulmonary fat embolism are
more likely than others to have severe bone
and chest pain, changes in mental status, and
a prolonged hospital course.
 A complete blood cell count in these patients
shows more severe anemia and
thrombocytopenia than in patients without
pulmonary fat embolism, and chest
radiographs reveal more multilobar infiltrates
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pathophysiology
sPLA2 liberates free fatty acids from
phospholipids.
 Measurement of secretory phospholipase A2
(sPLA2) levels may be helpful, because they
have recently been found to be elevated in
patients with sickle cell disease and ACS from
pulmonary fat embolism
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pathophysiology
An early rise in these levels precedes the
development of ACS and thus may be a
useful marker in predicting its occurrence.
 Furthermore, sPLA2 levels correlate with
disease severity.
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Mechanisms of hypoxemia
 Hypoventilation
due to
 Direct chest-wall splinting from either rib
and sternal infarctions or abdominal
crisis
 Excessive sedation from narcotic
analgesics, leading to decreased
oxygen exchange
Mechanisms of hypoxemia
Ventilation-perfusion mismatch possibly
caused by diseases that underlie or result
from acute chest syndrome
 Pneumonia
 Mucous plugging
 Aspiration
 Bronchospasm
 Pulmonary hypertension
 Cor pulmonale
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Mechanisms of hypoxemia
 Impaired
oxygen diffusion from
repetitive episodes of acute chest
syndrome that ultimately result in
restrictive lung disease (2,3)
Evaluation
 ACS
is more severe in adolescents and
adults than in children.
 Patients most commonly present with
shortness of breath, chills, and pleuritic
chest pain, but no fever
Evaluation
 In
some cases, physical signs of
disease are delayed and are first noted
during hospitalization.
Evaluation
These include
 chest-wall tenderness secondary to rib
infarction.
 dullness to percussion caused by
pleural effusion.
 and auscultatory rales from pulmonary
consolidation.
Evaluation
Results of laboratory studies may show
 anemia with thrombocytopenia
 or thrombocytosis,
 leukocytosis,
 and evidence of hemolysis,
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including elevated LDH
bilirubin levels
Evaluation
 Findings
on chest radiographs,
although not pathognomonic,
include
patchy lower-lobe involvement in a
segmental, lobar, or multilobar
distribution, with or without pleural
effusion.
 Correlation between the extent of
consolidation found on chest
radiographs and the severity of
hypoxemia is poor
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Evaluation
 The
presence of bilateral pulmonary
infiltrates, however, identifies a subset of
patients who are more likely to have
serious illness.
 Their clinical course is characterized by
tachycardia, protracted hypoxemia,
longer duration of fever, and a greater
fall in hemoglobin levels
Diagnostic tests for acute chest syndrome
 Sputum
analysis for Gram's stain
 Blood cultures
 Chest radiographs
 Thin-cut computed tomographic scan of
chest
 Serial measurement of arterial blood gases
 Ultrasound or impedance plethysmography
 Bone scan
 Flexible bronchoscopy with
bronchoalveolar lavage
Management of acute chest syndrome in
patients with sickle cell disease
 Identify
and treat all underlying
precipitating factors
 Maintain adequate oxygenation,
improve oxygen-carrying capacity,
and improve tissue oxygen delivery
Administer supplemental oxygen to
maintain PaO2 in 70-100 mm Hg range
Management of acute chest syndrome in
patients with sickle cell disease
Give simple or exchange transfusion to
enhance oxygen capacity or reduce
hemoglobin S concentration to reverse
episodes
 For severe respiratory failure, use mechanical
ventilation with positive end-expiratory
pressure (PEEP) or continuous positive
airway pressure (CPAP
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Management of acute chest
syndrome in patients with SSD
 Prevent
further alveolar collapse by
using incentive spirometry, CPAP,
and PEEP
 Maintain adequate fluid volume
Give hypotonic saline (D5W or 5%
dextrose in 0.25% normal saline) to
maintain normovolemic state
Management of acute chest
syndrome in patients with SSD
 Control
pain
Give adequate amounts of narcotic
analgesics to alleviate pain, avoiding
hypoventilation from excessive sedation
 Nonsteroidal anti-inflammatory
medications (if not contraindicated by
underlying peptic ulcer or renal disease)
 Morphine sulfate, 0.1-0.15 mg/kg every
3-4 hours intravenously, through fixed
scheduling or patient-controlled
analgesia
Management of acute chest
syndrome in patients with SSD
Treat underlying infection
Provide empirical coverage for communityacquired pneumonia, pending results from
other studies; use second- or third-generation
cephalosporin or selected beta-lactam/betalactamase inhibitor in combination with
macrolide
 Prescribe bronchodilator
Use albuterol (Airet, Proventil, Ventolin)
through metered-dose inhaler or nebulizer
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Management of acute chest
syndrome in patients with SSD
 Fluid
administration
If the patient is unable to consume fluids
orally, 5% dextrose in water or 5%
dextrose in 0.25% normal saline solution
should be administered intravenously to
maintain euvolemia once any existing
volume deficits have been corrected.
Management of acute chest
syndrome in patients with SSD
Dehydration must be remedied, because it
can result in increased plasma osmolarity and
intracellular dehydration of red blood cells.
 Under those conditions, erythrocytes are
more likely to sickle. Hypotonic saline
solutions are used because free water enters
the relatively hypertonic red blood cells.
 This process causes osmotic swelling,
decreased mean corpuscular hemoglobin
concentration and, consequently, a reduced
tendency for sickling.
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Management of acute chest
syndrome in patients with SSD
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Decisions regarding transfusion are best guided by
the patient's clinical condition.
Simple transfusion is indicated for patients with mild
to moderate ACS; the goal is a hemoglobin value of
10 g/dL
Exchange transfusions should be reserved for severe
crises, when it is important to decrease the
hemoglobin S concentration rapidly.
Unlike simple transfusions, exchange transfusions
avoid the problems related to increased blood volume
and viscosity. It is suggested that a PaO2 of less than
60 mm Hg, clinical deterioration, or a worsening
condition seen on chest radiographs should prompt
exchange transfusion.
Management of acute chest
syndrome in patients with SSD
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The goal is to reduce the hemoglobin S
concentration to 20% to 30% and the
hematocrit to 30% (5). Patients with recurrent
episodes of ACS may also benefit from
regular exchange transfusions to maintain the
hemoglobin S concentration below 30%.