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Blood Flow Measurements in Renal Transplant Surgery |
Intraopearative Blood Flow Measurements |
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Courtesy of Anders Lundell, MD, PhD, Nils H. Persson, MD, PhD, Transplantation Unit, Dept. of Surgery, Malmö General
Hospital, Malmö, Sweden |
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Why Measure Flow ? |
Renal transplantation offers surgeons an opportunity to augment their clinical assessment of a donor kidney with objective intraoperative flow measurement data. Transit-time ultrasound flowmetry quantifies the success of the transplant.
- Measurements Present Immediate Information about Renal Graft Circulation in the Transplanted Kidney
"The ultrasonic transit time flowprobe accurately measures postreperfusion renal blood flow and offers a practical and noninvasive method for assessing renal reperfusion injury after transplantation. This can help optimize immunosuppressive strategies to maximize renal recovery.”1 Low or decreasing flow could indicate a technical error which, if left uncorrected, could endanger the transplant.2
- Low Blood Flow Indicates a Delayed Onset of Graft Function “Measurements correlate significantly with the occurrence of delayed onset of graft function and the need for post-transplant dialysis.…Immediate information on blood flow data would, therefore, be valuable in critical cases when initiation of antibody prophylaxis is considered on the day of operation, especially in patients with uncertain graft urine production.”2
- Measurable Data for the Operative Record
Flow measurement during renal transplant provides quantitative data to include in the operative record.
- Donor to Recipient Vessel Match
Whereas in living donor liver transplant (LDLT), graft size mismatch is a major concern because hyperperfusion to the newly grafted liver may lead to graft dysfunction and poor survival, renal transplant pioneers at the Mayo Clinic in Rochester, MN and at Hermann Hospital in Houston, TX are presently examining a similar correlation between renal blood flow in donor and in recipient.
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| Surgical Approach |
A. Cadaver Donor Kidney Transplantation
In primary transplantations, we use the hypogastric artery for the arterial anastomosis. In re-transplantations or in cases where the
internal iliac is atherosclerotic the external iliac artery is used. In selected cases, we use a flow measurement to decide which artery to use. For the venous
anastomosis, the external iliac is used. No venous flow measurements are made.
After completion of the arterial and venous anastomoses, and immediately after restoration of blood flow to the kidney, but before
completion of the ureteroneocystostomy, the flow in the renal artery is measured. We use a 4 or 6 mm probe which is placed, preferably, distal to the anastomosis. The
space between the probe and the vessel is filled with sterile physiological saline. Care is taken to avoid kinking the artery and to place the probe parallel to the
longitudinal axis of the vessel. Before the flow is recorded, we allow the flow signal to stabilize for 15-20 seconds. At the end of the operation, after the
ureteroneocystostomy is completed and before the wound is closed, we make a second measurement.
B. Living Donor Kidney Transplantation
The first measurement is made on the renal artery before the kidney is removed from the donor. The second and third measurements are made
as described in A.
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Hepatic Hemodynamics: Transplanted Kidney |
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Cadaver Kidney ml/min
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Living Donor Kidney ml/min
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Donor Blood Flow |
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381 ± 150SD |
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After Flow Restoration |
283 ± 148SD |
338 ± 155SD |
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At End of Operation |
422 ± 204SD |
505 ± 177SD |
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Recommended Probe Sizes |
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Conduit |
Recommended probe size (mm)
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External iliac a. |
6-8 |
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Hypogastric a. |
4-6 |
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Renal a. |
4 |
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References
- Bretan, P.N. Jr. Lobo, E., Dumitrescu, O., Miller, B., Yen, T.S., “Experimental and Clinical Assessment of Preservation-Induced Reperfusion Injury Comparing Renal Transplant Blood Flow and Renal Endothelin Concentrations,”Transplantation Proceedings 1997;29(8):3520-3521. (54V)
- Lundell, A., Persson, N.H., Kallen, R., Ekberg, H.,“Impaired Renal Artery Blood Flow at Transplantation Is Correlated to Delayed Onset of Graft Function” Transplant International1996;9(1)57-61. (685AH)
- Bretan, P.N. Jr. Lobo, E.,Chang, J.A., Dumitrescu, O., Miller, B., Yen, T.S., Assessment of Preservation Induced Reperfusion Injury Via Intraoperative RenalTransplant Blood Flow and Endothelin Concentration Studies, J Urology 1997;158(3):714-18. (1093AH) (53V)
This is a validation study as well as a research and clinical study. Validation of the clinicalflowprobe was conducted with actual renal blood flow with a graduated cylinder and stopwatchobserved and plotted against measured flow. Bretan et al conclude that “a one-hour compared tothe immediate (5 minutes) post-reperfusion renal blood flow ratio can be a prognostic indicator ofsubsequent renal function
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