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Long-term vascular volume expansion maintains elevated thoracic duct lymph flow
1Division of Perinatal Biology, Loma Linda University, CA.
American Journal of Obstetrics and Gynecology
|November 1, 1992
Summary
Lymphatic vessels can effectively manage fluid overload during prolonged blood volume expansion, a crucial mechanism for preventing edema. This study demonstrates their capacity to increase lymph flow and maintain fluid balance.
Area of Science:
- Physiology
- Cardiovascular System
- Lymphatic System
Background:
- Pregnancy is often associated with edema, suggesting potential alterations in fluid regulation.
- The lymphatic system's role in managing fluid balance, especially during conditions of increased capillary filtration, requires further investigation.
Purpose of the Study:
- To investigate the capacity of lymphatic vessels to pump high fluid volumes over extended periods.
- To understand the mechanisms underlying edema formation during pregnancy by examining lymphatic function.
Main Methods:
- Utilized chronically catheterized nonpregnant ewes for the study.
- Administered a balanced isotonic solution at 1 L/hr for 20 hours to induce volume loading.
- Administered conjugated estrogens during the final 3 hours to assess effects on lymphatic contractility.
Main Results:
- Prolonged volume loading significantly increased lymph flow rate, blood volume, and arterial pressure.
- Vascular compliance decreased, and interstitial fluid volume remained unchanged, indicating effective fluid management.
- Transcapillary oncotic pressure and venous pressure increased, favoring fluid movement into the interstitium, yet lymph flow compensated.
Conclusions:
- Lymphatic vessel function is capable of compensating for increased capillary filtration during sustained blood volume expansion.
- The lymphatic system plays a vital role in preventing edema by adapting its pumping capacity to fluid load.