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[Oxygen transport in the blood of children with congenital heart defects]
Insights
In children with congenital heart defects, erythrocyte 2,3-DPG concentration significantly impacts oxygen transport. Higher 2,3-DPG levels improve oxygen release, especially in cyanotic heart defects, enhancing functional oxygen transport capacity.
Area of Science:
- Pediatrics
- Cardiology
- Physiology
Background:
- Congenital heart defects (CHDs) can impair oxygen transport.
- Understanding the factors affecting oxygen delivery is crucial for managing CHDs.
- Erythrocyte 2,3-diphosphoglycerate (2,3-DPG) influences hemoglobin's oxygen affinity.
Purpose of the Study:
- To investigate the relationship between erythrocyte 2,3-DPG concentration and various blood parameters in children with CHDs.
- To correlate 2,3-DPG levels with clinical parameters obtained during cardiac catheterization.
- To assess the impact of 2,3-DPG on functional oxygen transport capacity in different types of CHDs.
Main Methods:
- Blood samples were collected from 55 children (≥6 months) with CHDs.
- Measured parameters included hematocrit, hemoglobin, acid-base status, oxygen pressure, oxygen saturation, and erythrocyte 2,3-DPG content.
- Data were correlated with each other and with cardiac catheterization findings.
Main Results:
- Increased hematocrit was observed only with significant arteriovenous oxygen saturation differences (>30%) or low central venous saturation (<65%).
- A strong correlation was found between erythrocyte 2,3-DPG concentration and arteriovenous oxygen saturation difference (r=0.79) and central venous saturation (r=0.78).
- 2,3-DPG concentration correlated with the half-maximal oxygen saturation pressure (T50 value; r=0.73), and T50 values correlated with central venous oxygen saturation (r=0.61).
- Functional oxygen transport capacity increased by 15% in acyanotic CHDs and 40% in cyanotic CHDs due to rightward shifts in the O2-binding curve (higher T50 values).
- The effect of 2,3-DPG on the O2-binding curve was approximately twice that of the Bohr effect within the measured pH range.
Conclusions:
- Erythrocyte 2,3-DPG concentration markedly influences the oxygen-binding curve and peripheral oxygen release in children with CHDs.
- 2,3-DPG plays a significant role in compensating for impaired oxygen transport in CHDs, particularly in cyanotic cases.
- The findings highlight the importance of 2,3-DPG in optimizing oxygen delivery in pediatric cardiovascular conditions.
Abstract:
In 55 children with congenital heart defects (aged 6 months and older), hematocrit, hemoglobin concentration, acid-base status, oxygen pressure, oxygen saturation, and 2,3-DPG content of erythrocytes were determined in blood taken from the vena cava superior. The data were correlated with each other as well as with parameters obtained during cardiac catheterization. Whereas an increased hematocrit was seen only at a difference in arteriovenous oxygen saturation of more than 30%, or a central venous saturation below 65%, a close correlation between 2,3-DPG concentration in erythrocytes and these parameters was obtained already in the normal range (r = 0.79, and r = 0.78, respectively). A relatively close correlation was also found between 2,3-DPG concentration and half-maximal oxygen saturation pressure (T50 value; r equals 0.73), and the T50 values and the central venous oxygen saturation (r equals 0.61), respectively. Because of the shift to the right of the O2-binding curve the functional oxygen transport capacity was increased by an average 15% in children with acyanotic heart defects (mean T50 value of 31.6 mm Hg), and by 40% in children with cyanotic heart defects (mean T50 value of 34.6 mm Hg), as compared to healthy children (mean T50 value of 28.1 mm Hg). A marked influence on the position of the O2-binding curve and hence on oxygen release of the blood in the periphery is therefore exerted by the 2,3-DPG concentration, whose effect was about twice that of the Bohr effect in the pH range measured.