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Age-related changes in microvascular permeability: a significant factor in the susceptibility of children to shock?
1School of Sport and Exercise Sciences, Birmingham University, Birmingham, U.K. john.gamble@virgin.net
Insights
Vascular permeability, measured by filtration capacity (K(f)), is significantly higher in children than adults. This age-dependent difference may explain why children are more susceptible to hypovolemic shock in certain diseases.
Area of Science:
- Physiology
- Pathogenesis of Infectious Diseases
- Vascular Biology
Background:
- Dengue shock syndrome, a severe condition primarily affecting children, involves increased vascular permeability.
- Initial observations noted higher filtration capacity (K(f)) in healthy children compared to age-matched controls.
Purpose of the Study:
- To investigate the hypothesis that vascular permeability (K(f)) is age-dependent.
- To quantify K(f) across a wide age range in healthy individuals.
Main Methods:
- Calf K(f) was measured in 89 healthy Vietnamese subjects.
- Subjects ranged in age from 5 to 77 years.
Main Results:
- K(f) values were highest in the youngest children (median 7.53 K(f)U).
- K(f) values decreased significantly with age, being 3- to 4-fold lower by the end of the second decade (median 4.69 K(f)U).
Conclusions:
- Vascular permeability (K(f)) demonstrates a clear age-dependent decline from childhood to adulthood.
- Immature microvasculature in children, characterized by larger surface area and higher permeability, may predispose them to hypovolemic shock in conditions like dengue hemorrhagic fever.
Abstract:
During studies of the pathogenesis of dengue shock syndrome, a condition largely confined to childhood and characterized by a systemic increase in vascular permeability, we observed that healthy controls, age-matched to children with dengue shock syndrome, gave high values of filtration capacity (K(f)), a factor describing vascular permeability. We hypothesized that K(f) might be age dependent. Calf K(f) was studied in 89 healthy Vietnamese subjects aged 5 to 77 years. The K(f) was highest in the youngest children [7. 53 (1.96-15.46) K(f)U; median (range); where the units of K(f), K(f)U=ml.min(-1).100 ml(-1).mmHg(-1)]. Values were 3- to 4-fold lower towards the end of the second decade [4.69 (1.91-7.06) K(f)U]. Young mammals are known to have a larger microvascular surface area per unit volume of skeletal muscle than adults. During development the proportion of developing vessels is greater. Moreover, the novel microvessels are known to be more permeable to water and plasma proteins than when mature. These factors may explain why children more readily develop hypovolaemic shock than adults in dengue haemorrhagic fever and other conditions characterized by increased microvascular permeability.