The Lancet Infectious Disease
Apr 2009   Volume 9  Number 4   Pages 203 – 264
http://www.thelancet.com/journals/laninf/issue/current

Review
The prevalence of hypoxaemia among ill children in developing countries: a systematic review
Rami Subhi, Matthew Adamson, Harry Campbell, Martin Weber, Katherine Smith, Trevor Duke, for the Hypoxaemia in Developing Countries Study Group
Hypoxaemia is a common complication of childhood infections, particularly acute lower respiratory tract infections. In pneumonia-a disease that disproportionately impacts developing countries, and accounts for more than two million deaths of children worldwide-hypoxaemia is a recognised risk factor for death, and correlates with disease severity. Hypoxaemia also occurs in severe sepsis, meningitis, common neonatal problems, and other conditions that impair ventilation and gas exchange or increase oxygen demands.