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. Author manuscript; available in PMC: 2016 Dec 18.
Published in final edited form as: Lancet. 2016 Jun 18;387(10037):2545–2553. doi: 10.1016/S0140-6736(16)00145-8

Figure 2. Proposed pathophysiology in children with sickle-cell anaemia with early-onset ACS.

Figure 2

Postulated mechanism for why early-onset ACS in children with sickle-cell anaemia younger than 4 years is associated with both short-term and long-term acute lung morbidity (ACS, asthma, or both). The initial ACS event results in airway inflammation and hyper-responsiveness, which predispose the airways to narrowing from a second hit, either a repeat viral infection (young children have about six viral infections a year), exposure to an environmental irritant (eg, cigarette smoke), or a history of atopy with exposure to an aeroallergen to which there is sensitivity. A second event then leads to a sequence of events that result in a repeat severe vaso-occlusive episode. ACS=acute chest syndrome. HbS=haemoglobin S.