What alternative clamping techniques, such as zero ischemia, off clamp, only arterial clamping, and selective and supra selective controls, can be used for a patient with impaired renal function undergoing partial nephrectomy?

Alternative Clamping Techniques for Partial Nephrectomy in Patients with Impaired Renal Function

For patients with impaired renal function undergoing partial nephrectomy, selective arterial clamping or off-clamp techniques should be strongly considered over standard hilar clamping to minimize ischemic injury and preserve renal function, particularly when longer ischemia times are anticipated. 1

Understanding the Clamping Options

Standard Hilar Clamping (En Bloc Control)

• Complete occlusion of the main renal artery using a Satinsky clamp provides a bloodless surgical field but subjects the entire kidney to warm ischemia 2
• Transperitoneal approaches typically use en bloc hilar control with Satinsky clamps, while retroperitoneal approaches traditionally used bulldog clamps for individual vessel control 2
• Mean warm ischemia time with total clamping averages 22.2 minutes in complex tumors 3
• This remains the most commonly used technique, with 75.1% of complex tumor cases using complete main renal artery clamping 3

Selective (Segmental) Arterial Clamping

• Involves clamping only the segmental artery feeding the tumor-bearing portion of the kidney, leaving the remainder of the kidney perfused 4, 5
• The American Urological Association data shows this technique is best suited for hilar and medially located renal tumors 1
• Preoperative renal angiography is essential to evaluate arterial anatomy—selective clamping is feasible in approximately 60% of right-sided and 40% of left-sided cases 4
• The feeding artery must be >10 mm in length for successful selective clamping 4
• Mean warm ischemia time with selective clamping is 21.2 minutes, comparable to total clamping 3
• Short-term increases in serum creatinine are significantly smaller with selective clamping compared to standard partial nephrectomy 4

Superselective (Progressive) Arterial Clamping

• Begins with segmental artery clamping and progressively extends to main renal artery clamping only if needed for hemostatic control 5
• This technique significantly decreases total renal ischemia time compared to total hilar clamping 5
• Mean warm ischemia time with early unclamping (a form of progressive technique) is 17.3 minutes 3
• Used in 10.8% of complex tumor cases 3

Off-Clamp (Zero Ischemia) Technique

• No arterial clamping is performed; hemostasis is achieved through meticulous surgical technique, early suturing of vessels, and use of hemostatic agents 1, 5
• Most commonly applied to small (<4 cm) and peripheral/exophytic renal tumors 1
• The tumor is retracted away from the developing partial nephrectomy bed with a suction cannula while excising with cold endoscopic shears to maintain a dry field 2
• Perirenal fat overlying the tumor can be used as a handle for retraction during tumor excision 2
• Used in only 5.4% of complex tumor cases 3

Arterial-Only vs. Arterial-Vein Clamping

• Arterial-only clamping (without venous occlusion) demonstrates superior long-term renal function preservation compared to combined arterial-vein clamping 6
• At last follow-up, arterial-only clamping shows a significantly lower percentage decrease in estimated glomerular filtration rate (eGFR) (p < 0.00001) 6
• No significant differences exist in warm ischemia time, operating time, transfusion rate, or estimated blood loss between the two approaches 6
• Early postoperative renal function is comparable, but long-term benefits favor arterial-only clamping 6

Clinical Application Algorithm

For Patients with Baseline eGFR <60 or Solitary Kidney:

1. First choice: Selective arterial clamping if tumor location is hilar/medial and preoperative angiography shows feeding artery >10 mm 4, 1
2. Second choice: Off-clamp technique if tumor is small (<4 cm), peripheral, and exophytic 1
3. Third choice: Progressive clamping starting with segmental control 5
4. If standard clamping required: Use arterial-only clamping (not arterial-vein) and keep warm ischemia time <25 minutes 6, 7

For Patients with Normal Contralateral Kidney:

• Standard hilar clamping remains acceptable with warm ischemia time <30 minutes 7, 8
• The role of elective minimally ischemic techniques in this population remains debatable 1

Important Technical Considerations and Caveats

Blood Loss Trade-offs

• Minimally ischemic and off-clamp techniques are associated with increased intraoperative blood loss and higher perioperative transfusion rates compared to on-clamp partial nephrectomy 1
• This increased bleeding risk must be weighed against potential functional benefits 1

Technical Demands

• These techniques are technically demanding and require considerable experience with partial nephrectomy surgery 1
• Surgeon experience significantly impacts outcomes, particularly for complex tumors 9, 8
• High-volume centers achieve better outcomes including lower complication rates and shorter hospital stays 7, 9

Underutilization in High-Risk Patients

• Even in patients with chronic kidney disease (eGFR <60), only 26.6% undergo minimal clamping techniques, with 73.4% still receiving total clamping 3
• In solitary kidneys, 83% still undergo total clamping, though mean warm ischemia time is kept low at 14.9 minutes 3
• This suggests significant opportunity for increased adoption of renal-protective techniques in appropriate candidates 3

Functional Outcome Assessment

• The impact of different clamping techniques on postoperative renal function requires assessment via renal scintigraphy for split renal function evaluation 1
• Intermediate-term follow-up (mean 411 days) shows no significant differences in renal function changes between clamping techniques, though long-term data favors arterial-only approaches 5, 6

When Arterial-Only Clamping is Preferred

• Always use arterial-only clamping (without venous occlusion) when hilar control is needed, as this provides superior long-term renal function preservation without compromising surgical outcomes 6