Background and aims Colloid osmotic pressure (COP) of plasma and interstitial fluid play important roles in transvascular fluid exchange were small pressure alterations may result in fluid shifts into or out of the capillaries optimising homeostasis. This study was conducted to determine reference values of COP in healthy children, and to evaluate the methodology of harvesting interstitial fluid.
Methods COP in plasma and interstitial fluid isolated from nylon wicks implanted subcutaneously was measured in 99 healthy children from 2 to 10 years of age. Patients were sedated and intubated during wick implantation in arm and leg, and COP was analysed in a colloid osmometer.
Results Mean plasma COP in all children was 25.6 ± 3.3 mmHg. Arbitrary division of children in age groups, showed no significant difference in plasma or interstitial fluid COP values for patients less than 8 years, whereas patients of 8–10 years had significant higher COP both in plasma and interstitial fluid. There was no gender difference or correlation between COP in interstitial fluid sampled from arm and leg and no significant effect on interstitial COP of gravity. Prolonged implantation time did not affect interstitial COP.
Conclusions This study justifies the presumption that plasma and interstitial COP in healthy children are similar to adults. Children between 8 and 10 years had higher values than younger age groups. Knowledge of interaction between colloid osmotic forces in health and disease can be helpful in diseases associated with fluid imbalance and may be crucial in deciding different fluid treatment options.