CHAPTER 63: Allograft Function

EARLY ALLOGRAFT FUNCTION

• Most transplant allografts with short cold ischemic time begin to produce urine in the operating room or soon thereafter.

• We monitor graft function in the first 24 hours by:

  • Hourly urine output

    • Since polyuria is common during this period, we maintain volume status with a combination of maintenance crystalloid at 1 mL/kg/hour and a replacement crystalloid measured 1:1 for hourly urine output.

    • In cases of very high urine output, a fluid warmer is useful to maintain body temperature.

    • Close and continuous monitoring prevents complications within the first 24 hours.

    • Vital signs: The newly implanted kidney is susceptible to hypotension. We aim for systolic blood pressure >120 mm Hg during this period (we prefer to follow systolic rather than mean pressures).

    • If urine output declines abruptly:

      • Suspect a vascular compromise until proven otherwise, and act rapidly.

        • A duplex Doppler ultrasound should be obtained immediately.

      • A quick initial approach is to irrigate the urinary catheter and verify that it is placed and working correctly.

        • Hematuria is common after surgery, and if significant, blood clots are possible.

        • It is also important to confirm the correct placement of the urinary catheter, since twists, kinks, and obstruction by a partially inflated balloon or residue from the bladder may account for obstruction.

        • In instances of possible urinary catheter dysfunction, we prefer to remove the dysfunctional one and place a new one (disruption of a fresh ureter–bladder anastomosis is unusual with such replacement).

      • Urgent renal ultrasound (US) with arterial and venous Doppler duplex studies to evaluate for surgical complications, including:

        • Vascular thrombosis

        • Inflow/outflow vascular compromise

        • Outflow urinary obstruction

        • Mechanical or functional obstruction

        • Extravasation of blood and/or urine

          • Renal US can detect perinephric fluid collections. Differential diagnoses include:

            • – Hematoma

            • – Lymphocele

            • – Urinoma

        • Fluid draining from the wound or aspirated from a collection can be evaluated for creatinine concentration to differentiate between urinary leaks, urinomas, or lymphoceles.

          • In urine leaks and urinomas, the creatinine concentration is similar to that in urine (which is much higher than that in the serum).

          • In non-urinoma collections, the fluid creatinine resembles that in serum.

          • In order to be able to compare, it is useful to obtain simultaneously the creatinine concentrations in the serum. In instances of delayed graft function, especially when the recipient is undergoing dialysis, the serum creatinine will be elevated.

      • Urgent electrolyte and complete blood count. Hyponatremia and/or hyperkalemia may be early signs of obstruction. Hyponatremia, hyperkalemia, high chloride, and low bicarbonate levels in blood are suggestive of a urinary leak, with urine being reabsorbed in the retro-peritoneum or intra-peritoneally.

• Graft function postoperative day 1 (POD #1)

  • Hourly urine output and daily weights.

    • Once the patient is ambulatory, we discontinue the urinary catheter.

      • The day of removal of the urinary catheter is based on how confident the surgeon feels with the ureter–bladder anastomosis.

        • Good surgical technique with full-thickness anastomoses can tolerate removal of urinary catheters within 24 hours of transplantation.

        • Otherwise, urinary catheters are removed 72 hours (3 ...