Dr Atul Jindal AIIMS Raipur

1. Acute Chest Syndrome
Atul Jindal (MD, DM)
Assistant Professor
AIIMS, Raipur

2. Overview
Definition
Pathophysiology
Clinical features
Challenges in the diagnosis of ACS
Course & Outcome
Monitoring & Investigations
Treatment of ACS
Chronic complications & Prevention

3. Definition
Acute Chest Syndrome (ACS) is defined as
an acute illness characterised by fever
and/or respiratory symptoms,
accompanied by a new pulmonary
infiltrate on chest X-ray.

4. Pathophysiology

5. Etiology
Pulmonary infection - identified in 38% who underwent
extensive sampling
Seasonal variation - 3 times more common in winter
More common in children
<10 years - Viral infection (commonest RSV)
Mycoplasma pneumonia (14%), Staph, pneumococcus,
H.influenzae

6. Etiology
Fat embolism
Microvascular pulmonary infarction
Hypoventilation/atelectasis - rib pain,
opiate narcosis, post-operative period
Asthma

7. Clinical Features
Second most common reason for
hospitalisation
Nearly half of patients present initially
with a painful VOC
ACS will often develop 24-72 hr after the
onset of severe pain

8. Symptoms & Signs
Data from Vichinsky et al, 1997, 2000
Clinical signs often precede the CXR findings.
Sometimes Chest examination can be normal and hence
it is important that the diagnosis is not excluded at this stage.

9. Challenges in the Diagnosis
of ACS
Pulmonary embolism - CT angio
Fluid overload - Fluid balance chart
Opiate narcosis - Monitoring of RR,
sedation, and pain scores
Alveolar hypoventilation due to pain

10. Monitoring and
Investigations
High Clinical suspicion + Clinical features = Straight
forward diagnosis
Diagnosis can be difficult
clinical features may be few
hypoxia is difficult to determine on clinical examination
unless severe
Radiological signs often lag behind the physical signs

11. Monitoring and
Investigations
Standard monitoring includes
At-least 4 hrly SpO2 (on Air), HR, RR, BP
Daily Clinical examination
CBC, CXR, Cr, LFT, Blood C/S, Bld group and
cross match, ABG, Sputum C/S and PCR if
facilities available

12. Investigations - CXR

13. Investigations - CBC
Acute fall in Hb conc. or Platelet count are often
seen
Decreasing platelet count to <2lac is an
independent risk factor for neurological
complications and the need for mechanical
ventilation
Reticulocyte count - normal count excludes red
cell aplasia by parvo B 19.

14. Investigations -
Biochemical tests
RFT & LFT - MODS as a consequence of Systemic fat
embolism
CRP - monitor progress
ABG - on room air (if SpO2<94%)
Patients in clear resp. distress or in whom SpO2 falls
rapidly to <85% when O2 is removed need escalation of
therapy.
PaO2 < 82 mm hg (70% of cases)

15. Investigations - other
Investigations
CT - high sensitivity and specificity (84%
and 97%)
High radiation dose - not recommended
Use in Pulm. Embolism
Secretory Phospholipase A2 (sPLA2) -
levels elevated in ACS

16. ACS - Treatment
Oxygen - titrate to SpO2>95% or within 3% of patient baseline
value
IVF - Euvolemic (maintain I/O Chart)
Pain relief - Adequate analgesia with frequent review and
assessment of pain and sedation scores and cardiorespiratory
monitoring
Incentive Spirometry & Chest Physiotherapy
Antimicrobials - treat for organisms for community acquired
pneumonia + atypical organisms

17. ACS - Treatment
Blood Transfusion -

18. ACS - Treatment
Respiratory Support
Bronchodilators -
Demonstrable reversible airway disease
History s/o asthma
Acute bronchospasm

19. ACS - Treatment
iNO - case reports , No RCT - insufficient evidence
Corticosteroids - Significant variability in their
efficacy
Current evidence - mild to moderate ACS - not
recommended due to its adverse effects
If associated with Acute Asthma - Yes

20. ACS - Chronic
complications
Scarring
Pulmonary fibrosis
Chronic Sickle Lung Disease
Poor Lung Function

21. ACS - Prevention
Hydroxyurea - Significantly decrease the incidence of ACS in
patients with recurrent severe pain and also in unselected
children with HbSS.
Long term transfusion - has been shown to decrease the
incidence of ACS in patients who are being transfused for
stroke prevention.
Transfusion in preoperative period significantly reduces the
incidence of post-operative ACS.
Consider HSCT if both fails in preventing ACS episodes.

22. SCD - Wheeze or Asthma?
Asthma in SCD - 17%-48%
Challenge - Asthma or SCD?
Wheezing: common in SCD and independently
associated with morbidity
Cooperative Study - out of 1722 ACS episodes -
11% were wheezing at admission and 26%
ultimately had during the course.

24. SCD - Wheeze or Asthma?
Episode of wheezing producing shortness of
breath is associated increased risk of future
episode of ACS (IRR 1.7, p=0.04)

25. SCD - Wheeze or Asthma?
NHLBI guidelines
1) Assess for signs and symptoms of respiratory
problems by history and physical examination;
2) In patients with signs or symptoms of respiratory
problems, further assessment (including pulmonary
function testing) is recommended.

26. SCD - Wheeze or Asthma?
Knight-Madden and Greenough have termed “Recurrent
Wheezing in Sickle Cell Disease (RWIS)”.
Once we have a better understanding of the mechanisms
underlying airway abnormalities in SCD we can begin to
explore the impact of therapeutic interventions on recurrent
wheezing, airway obstruction, and/or asthma on short and
long term SCD outcomes.
This is an important, understudied area that warrants further
investigation in an attempt to reduce morbidity and mortality
in these patients.