Percutaneous carbon dioxide excretion in the newborn infant

Percutaneous carbon dioxide excretion was studied in 42 newborn infants between 25 and 39 weeks gestation, using a closed skin cell attached to the abdomen. The rate of excretion during the first few days of life was inversely related to gestation, increasing from a mean of 31 ml/m2/h at term to 198 ml/m2/h below 30 weeks gestation. Postnatally there was a rapid fall in the rate of excretion in very preterm infants to values about twice those found at term. The rate of excretion was linearly related to the CO2 diffusion gradient, and zero diffusion would be expected when there was no diffusion gradient. It is estimated that up to 15% of resting CO2 excretion occurs through the skin of very preterm infants, and more if the tissue PCO2 is elevated.