Acute Chest Syndrome In SCD
Abdullah M. Al-Olayan.
MBBS, SBP, ABP.
Assistant Professor of Pediatrics.
Pediatric Pulmonologist.
Objectives :
1-Introduction.
2-Epidemiology.
3-Pathogenesis.
4-Etiology.
5-Diagnosis.
6-Management.
Introduction :
Acute and chronic pulmonary complications
occur frequently in patients with SCD.
ACS is one of the acute pulmonary
complications.
ACS is a major cause of morbidity and
mortality.
Epidemiology :
ACS is a common complication in children with SCD.
In a report from the Cooperative Study of Sickle Cell Disease
(CSSCD) :
The peak incidence for ACS was in children between 2 and 4 years of
age with a higher prevalence during the winter months.
For patients with SCD, ACS is the second most common cause of
hospitalization with a reported rate of 12.8 hospitalizations per 100
patient years.
(Castro O, Brambilla DJ, Thorington B, et al.
The Cooperative Study of Sickle Cell Disease. Blood 1994; 84:643).
Epidemiology :
It is the most common cause of death.
In a report from the CSSCD, the death rate
in patients with ACS is 1.8 % in children
and 4.3 % in adults.
Epidemiology :
The incidence of ACS is :
Inversely proportional to the concentration of
fetal hemoglobin and the degree of anemia.
Directly proportional to the steady state WBC
count.
ACS is more likely to occur in children with a
history of asthma or exposure to
environmental tobacco smoke in the home.
Pathogenesis :
The pathogenesis of acute pulmonary
disease in SCD is complex, and the
establishment of a specific cause in any
single case is difficult.
Within the pulmonary vasculature, a variety
of triggers leading to Hgb S
polymerization and sickling of the red
blood cell that results in vasoocclusion,
ischemia, and endothelial injury.
Pathogenesis :
Multiple factors may be present and
contribute to ACS including:
Inflammation secondary to infection or fat
embolus from necrotic bone marrow
leading to alveolar hypoxia and
obstruction of smaller airways, collapse of
distal air spaces, air trapping, and altered
ventilation-perfusion relationships.
Pathogenesis :
In a study of 102 children with SCD who
underwent pulmonary function testing,
patients with obstructive lung disease had
twice the rate of hospitalizations for pain
or ACS as compared with those with
restrictive disease (2.5 versus 1.2
hospitalizations).
Pathogenesis :
Endothelial dysfunction of the pulmonary
microvasculature with increased
expression of vascular adhesion
molecules, increased platelet and plasma
coagulation activation, and disordered
nitric oxide metabolism leading to
thromboembolism and/or hemolysis.
Etiology :
In about 40 % of cases, a specific cause of
ACS can be determined.
This was illustrated by a prospective report
from the National Acute Chest Syndrome
Study Group (NACSSG) that evaluated 671
episodes of ACS in 538 patients.
Etiology :
Definite etiology was established in 38 % of
episodes.
Unknown cause 46 %
Pulmonary infarction 16 %
Fat embolism 9 %
Chlamydophila pneumoniae 7 %
Mycoplasma pneumoniae 7 %
Viral infection 6 %
Mixed infections 4 %
Other pathogens 1 %
Etiology :
Children ≤9 years of age :
Infectious causes of ACS included :
Virus (11%)
Mycoplasma (9 %)
Chlamydia (9 %)
Bacteria (4 %)
Etiology :
Children 10 to 19 years of age :
Infectious causes of ACS included :
Chlamydia (8 %),
Mycoplasma (4 %),
Virus (3 %)
Bacteria (3 %)
Etiology :
Adults >20 years of age :
Infectious causes of ACS included :
Chlamydia (9 %)
Bacteria (7 %)
Mycoplasma (5 %)
Virus (1 %)
Etiology :
Vasoocclusive crisis :
Data from the NACSSG demonstrated that almost
half of all patients who develop ACS were initially
admitted for other reasons, frequently (VOC).
VOC of the spine, ribs, and abdomen leads to
hypoventilation with alveolar hypoxia,
development of atelectasis, and (V/Q) mismatch.
The subsequent regional drop in (PaO2) results in
further sickling of red blood cells.
Etiology :
Postoperative complication :
ACS may present as a postoperative
complication in children with SCD,
especially following abdominal surgeries
Careful perioperative management,
including appropriate presurgical
transfusion support and postoperative
pulmonary care can minimize the risk for
this complication.
Etiology :
Asthma :
Asthma is particularly common and more
often severe in the African-American
population and is associated with higher
rates of morbidity and mortality.
Etiology :
Chronic hypoxemia :
Chronic hypoxemia has been suggested as a
risk factor for complications of SCD,
including cerebrovascular disease,
recurrent vasoocclusive crisis, ACS, and
possibly pulmonary hypertension.
Diagnosis :
The diagnosis of ACS in a patient with SCD
is made clinically and requires both of the
following criteria :
1) A new pulmonary infiltrate involving at
least one complete lung segment.
Diagnosis :
2) One or more of the following signs or
symptoms :
1-Chest pain.
2-Temperature >38.5ºC.
3-Tachypnea, wheezing, cough.
4-Hypoxemia.
Management :
ACUTE MANAGEMENT :
Fluid :
If Dehydration is present, it should be
corrected.
Hypovolemia should be corrected with the
administration of isotonic solution.
Euvolemia should be maintained using
hypotonic fluids.
Management :
ACUTE MANAGEMENT :
Fluid :
Overhydration should be avoided because
they may result in pulmonary edema or
heart failure.
Weights should be monitored daily along
with intake/output.
Management :
ACUTE MANAGEMENT :
Pain control :
Adequate analgesia of spine, thoracic, and
abdominal pain is important to prevent
hypoventilation and atelectasis.
Ketorolac is an excellent NSAID in the acute
setting (0.5 mg/kg IV, followed by 0.5 mg/kg
IV every 6 hours, maximum dose 15 mg, for
up to three or five days).
Management :
ACUTE MANAGEMENT :
Pain control :
For patients requiring morphine or other
opioids, careful attention to dosing is
required, as high doses of morphine are
associated with increased risk of
developing ACS.
Management :
ACUTE MANAGEMENT :
Respiratory support :
1-Respiratory rate.
2-Auscultation.
3-Use of accessory muscles of respiration.
4-Mental status.
5-Color and perfusion.
6-SpO2.
Management :
ACUTE MANAGEMENT :
Respiratory support :
1-Oxygen supplementation to maintain oxygen
saturation ≥92%.
2-Incentive spirometry, at least every two hours to
prevent atelectasis from hypoventilation.
3-CPAP or BiPAP for patients with poor respiratory
effort or rising oxygen requirements.
4-Inhaled bronchodilators for patients with reactive
airway disease.
Management :
ACUTE MANAGEMENT :
Infection :
Broad spectrum antibiotics with :
Third generation cephalosporin (eg, ceftriaxone).
Macrolide (eg, azithromycin).
should be initiated immediately on admission.
For the severely ill patient, with large or
progressive pulmonary infiltrates, consider adding
vancomycin.
Management :
ACUTE MANAGEMENT :
Transfusion :
Simple transfusion :
Simple transfusions are used to treat ACS for the following
indications:
1-To improve oxygenation.
2-Severe anemia, defined as a Hct that is 10 to 20%.
3-Clinical or radiological progression of disease.
4-If exchange transfusion will be delayed.
The goal of simple transfusion is to increase the Hct to 30% or
Hgb to 11 g/dL.
Management :
ACUTE MANAGEMENT :
Transfusion :
Exchange transfusion :
Partial exchange transfusion should be performed for the
following indications:
1-Progression of ACS despite simple transfusion.
2-Severe hypoxemia.
3-Multi-lobar disease.
4-Previous history of severe ACS or cardiopulmonary disease.
The goal of therapy should be to decrease the level of Hgb S to
<30% of the total hemoglobin concentration.
Management :
ACUTE MANAGEMENT :
Corticosteroids :
Intravenous steroids may be beneficial in
cases of mild to moderate ACS.
There is a potential for relapse VOC when
corticosteroids are rapidly discontinued.
Management :
LONG-TERM MANAGEMENT :
The goal of chronic management of the
child with a history of ACS is to :
1-Prevent recurrence.
2-Monitor for long-term consequences.
Management :
LONG-TERM MANAGEMENT :
Infection prevention :
1-Prophylactic antibiotics for first five years
of life.
2-Complete immunization for
Streptococcus pneumoniae, Haemophilus
influenzae type B, hepatitis B virus, and
influenza.
Management :
LONG-TERM MANAGEMENT:
Pulmonary :
The pulmonary status of all patients with
SCD should be monitored with periodic
assessment of resting oxygen
concentration by pulse oximetry and PFT
to assess for reactive airway disease.
Management :
LONG-TERM MANAGEMENT :
Pulmonary :
PFT should begin at 6 years of age, and should
be repeated every five years for patients
without asthma or ACS, or every two to three
years for patients with a history of asthma or
ACS.
All episodes of reactive airway disease should
be recognized early and treated promptly with
bronchodilator therapy.
Management :
LONG-TERM MANAGEMENT :
Hematologic :
Hydroxyurea :
Hydroxyurea has been shown to
decrease the frequency of ACS.
In children with SCD, there was
a threefold reduction of ACS in
patients treated with hydroxyure.
Management :
LONG-TERM MANAGEMENT :
Hematologic :
Transfusion :
Transfusion therapy is an effective intervention for
the prevention of recurrent ACS.
Therapy can be
1-Short-term (less than six months).
2-Long-term (greater than six months).
Short-term transfusion is used during high risk
periods for ACS (eg, winter months with
increased frequency of respiratory illnesses) or
during the transition to hydroxyurea therapy.
Management :
LONG-TERM MANAGEMENT :
Hematologic :
Hematopoietic cell transplantation :
For patients who have experienced multiple
ACS events and who have an HLA-matched
sibling donor, hematopoietic cell
transplantation is an accepted alternative,
with a better than 80% success rate.
Complications :
1-Neurologic events :
A reversible posterior leukoencephalopathy
syndrome, silent cerebral infarcts, and acute
necrotizing encephalitis.
2-Respiratory failure : requiring mechanical
ventilation occurs in about 10% of ACS
cases.
3-Pulmonary thromboembolism (PE) or
infarction.
Summery :
ACS is the second most common cause of
hospitalization.
It is the most common cause of death, with
one-fourth of SCD-related deaths due to
ACS.
The specific cause of ACS is often not
identifiable or may be multifactorial.
Summery :
Infection and vasoocclusive crisis are the most
common identifiable causes.
Infectious agents include viruses, mycoplasma,
chlamydia, and bacterial organisms.
The diagnosis of acute chest syndrome is defined as
a new pulmonary infiltrate and one or more of
the following: chest pain; temperature >38.5ºC;
hypoxemia; and signs of tachypnea, wheezing,
cough, or the appearance of increased work of
breathing.
Summery :
Acute management involves treating the
underlying factors that contribute to
sickling of the red blood cells and
reversing the sickling process.
Long-term management is directed towards
preventing recurrence of ACS.
Thank You