Carbon Dioxide Production in Acutely Ill Malnourished Children

Summary of published paper¹

A recent study set out to test the hypothesis that the rate of carbon dioxide production is less in marasmic children with acute infection when compared to well-nourished children, but greater when compared to uninfected marasmic children. The study took place at Queen Elizabeth Central hospital, in Blantyre, Malawi. Using a stable isotope tracer dilution method, rates of carbon dioxide production were measured in children aged 12-60 months while receiving feeding. Results from 56 children were compared, 28 with marasmus and acute infection, 16 with marasmus, and 12 well nourished with acute infection. Those with acute infection had malaria, pneumonia or sepsis.

Well nourished children with acute infection produced more carbon dioxide than marasmic children. However, the rate of carbon dioxide production in marasmic children with acute infection was not greater than in uninfected children. The observed rate of carbon dioxide production was greater than that which could be produced from the dietary intake alone.

The study concluded that marasmic children do not increase energy expenditure in response to acute infection, as well nourished children do. The data suggest that children with proteinenergy malnutrition and acute infection expend less energy, largely due to a lower body temperature and the absence of fever. Although not raising body temperature in response to acute infection conserves scarce nutrients, it also determines that the immunological benefits of fever are not realised. Fever activates cellular immunity, stimulates the acute phase response, enhances iron sequestration and is associated with better survival. The clearance of the malaria parasite is also accelerated by fever.

Dietary energy intake in the 44 marasmic children studied was 350 kj/kg/day (84 kcal/kg/d), the level recommended for malnourished children from experience in treating malnourished children in Jamaica. The data from the rate of carbon dioxide production suggests that to match energy expenditure, intake should have been increased by 25% to about 440 kj/kg/day (105 kcal/kg.d), when the thermic effect of food is considered. Current standard recommendations are that during the initial phase of treatment, severely malnourished children should receive 336-420 kj/kg/day (80-100 kcal/kg/d). Further research is needed to determine whether increased dietary energy improves the response to acute infection, and whether these children might be better served by increasing their dietary intake.

¹Manary, M et al (2004). Carbon dioxide production during acute infection in malnourished Malawian children. European Journal of Clinical Nutrition, vol 58, pp 116-120