Effects of age and cardiac shunts on the measured uptake of nitrous oxide in children.
The uptake of nitrous oxide (N2O) was calculated by using a new application of pharmacokinetics involving cumulative fractional expired N2O concentration at 90 percent steady state. The effect of age on N2O uptake was investigated in 33 normal children undergoing non-cardiac surgery. Uptake was also investigated in 17 children with right-to-left cardiac stunts and 18 children with left-to-right shunts undergoing corrective or palliative cardiac surgery. There was a significant correlation of N2O elimination half-life (T1/2) with age for normal children (p less than 0.001), and for children with right-to-left (p less than 0.001) or left-to-right (p = 0.05) shunts. Elimination T1/2 in children with left-to-right shunts correlated significantly with the calculated shunt fraction (p less than 0.05). By providing a useful means for comparison, this method of measuring N2O uptake permits determination of the effects of age, weight and cardiac shunts on the uptake kinetics of N2O.
O'Callaghan
A C
AC
Department of Anaesthesia, Hospital for Sick Children, Toronto, Ontario.
Koren
G
G
Sloan
I A
IA
D000367:Age Factors; D006348:Cardiac Surgical Procedures; D002648:Child; D002675:Child, Preschool; D005652:Functional Residual Capacity; D006207:Half-Life; D006330:Heart Defects, Congenital / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D009609:Nitrous Oxide / Q000493:pharmacokinetics*
D009609:Nitrous Oxide