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Alterations in renal microcirculation during cardiopulmonary bypass
V L Pathi1, J Morrison, A MacPhaden
1Department of Cardiac Surgery, Royal Infirmary, Glasgow, Scotland.
The Annals of Thoracic Surgery
|May 16, 1998
Summary
Hypothermic cardiopulmonary bypass reduced renal vascular resistance and glomerular size by narrowing capillaries. Rewarming led to superficial cortical underperfusion, potentially damaging nephrons during increased metabolic demand.
Area of Science:
- Cardiovascular Surgery
- Nephrology
- Medical Physiology
Background:
- Investigating renal microvascular changes during cardiopulmonary bypass (CPB).
- Understanding the impact of CPB on kidney hemodynamics and morphology.
Purpose of the Study:
- To assess alterations in renal microvasculature during hypothermic CPB.
- To evaluate the effects of CPB duration and rewarming on renal perfusion and structure.
Main Methods:
- Utilized a porcine model with four groups undergoing different CPB durations and temperatures.
- Employed radiolabeled microspheres for renal cortical blood flow measurement.
- Applied corrosion casting and scanning electron microscopy for microvascular morphology analysis.
Main Results:
- CPB decreased renal vascular resistance, with equal perfusion to superficial and deep cortex during hypothermia.
- Glomerular size was significantly reduced due to capillary narrowing, indicating blood diversion.
- Normothermic reperfusion resulted in superficial cortical underperfusion and reduced cortical thickness.
Conclusions:
- Hypothermic CPB alters renal hemodynamics and microvasculature, reducing glomerular size.
- Restoration of normothermia post-CPB can lead to detrimental underperfusion of the superficial renal cortex.
- Potential for nephron damage exists during rewarming due to altered perfusion patterns.