Use of Cavitation Ultrasonic Surgical Aspirators for partial nephrectomies

Partial nephrectomies are technically challenging surgeries but preserve healthy renal tissue and therefore function. To minimise bleeding the major blood vessels are usually clamped and tumour extraction completed under ischemic conditions – the renal tissue is deprived of oxygen and nutrients due to restricted blood flow. Although ischemic conditions for less than 25 minutes have minimal reported impact on renal function (Volpe et al., 2015), more complex tumours result in prolonged ischemia making the preservation of healthy tissue more difficult. In recent years several zero-ischemic techniques, including minimally invasive and robotic approaches (Gill et al., 2011, Simone et al., 2013), have been developed that do not require renal artery clamping.

A recent report from Weibl et al. (2015) prospectively assessed 13 partial nephrectomy patients whose tumour removal was achieved using a Cavitation Ultrasonic Surgical Aspirator (CUSA). The patients showed a range of tumour characteristics of varied severities. Weibl et al. assessed operative time, time required for tumour removal, estimated blood loss and the requirement for transfusion. Additionally measures of renal function – estimated glomerular filtration rate and relevant serum protein levels – were collected preoperatively and postoperatively for comparison. CUSA technology has previously been used for partial nephrectomies, although predominantly in animals (Addonizio et al., 1984), and is regularly used in hepatic and neurological surgeries.

CUSA instruments use ultrasonic vibrations to induce cavitation in cells with high water content, such as neoplastic tissue. The formation and subsequent destruction of small bubbles, induced by changes in pressure, results in shockwaves capable of separating cells from tissue. The vibrations can only penetrate up to 2mm through tissue and will cut smoothly through organ tissue without damaging vascular, duct or nerve tissue. The inclusion of an aspirator and electrocautery element enables simultaneous dissection, tissue fragment removal and control of blood loss from smaller vessels. However, larger vessels still require clamping or suturing during dissection to minimise blood loss and maintain visibility.

All of the 13 patients reported in Weibl et al. underwent partial nephrectomies without the need for renal artery clamping. The median blood loss was only 250mL and only one patient required blood transfusion during surgery. Any bleeding was controlled with sutures, and the cut surface was covered with a fibrin sealant adhesive and sutured as required. The medial surgical time was 175 minutes with 12 minutes for tumour removal. Although four of the patients had post-operative complications these were easily managed and are similar to the complications seen after other partial nephrectomy techniques.

A variety of histologies were identified in the tumours including clear cell, papillary and hybrid renal cell carcinomas (RCC), suggesting this method could be effective in the majority of RCC patients. Clear resection boundaries of 1-4mm of healthy tissue around the tumour were confirmed in 12/13 cases with the remaining tumour having a 2-3mm focal positive boundary. There was no decline in renal function in any of the patients post-surgery or in the subsequent three months.

The ability to remove tumours without further reducing kidney function is of particular importance in patients with inherited forms of renal cancer as they are more likely to develop subsequent tumours in either kidney. There are other surgical techniques being developed which also aim to preserve renal function; large randomised trials are required to determine if a particular method, or methods, is best suited to different patients and tumour types. However, this pilot trial from Weibl et al. suggests that the use of CUSAs is feasible and safe for a range of tumour types and severities, and should be further assessed in additional cases.

  • Addonizio JC, Choudhury MS, Sayegh N, Chopp RT (1984). Cavitron ultrasonic surgical aspirator. Applications in urologic surgery. Urology. May;23(5):417-20. PMID: 6719660.
  • Gill IS, Eisenberg MS, Aron M, Berger A, Ukimura O, Patil MB, Campese V, Thangathurai D, Desai MM (2011). “Zero ischemia” partial nephrectomy: novel laparoscopic and robotic technique. Eur Urol. Jan;59(1):128-34. PMID: 20971550.
  • Simone G, Ferriero M, Papalia R, Costantini M, Guaglianone S, Gallucci M (2013). Zero-ischemia minimally invasive partial nephrectomy. Curr Urol Rep. Oct;14(5):465-70. PMID: 23893291.
  • Volpe A, Blute ML, Ficarra V, Gill IS, Kutikov A, Porpiglia F, Rogers C, Touijer KA, Van Poppel H, Thompson RH (2015). Renal Ischemia and Function After Partial Nephrectomy: A Collaborative Review of the Literature. Eur Urol. Jul;68(1):61-74. PMID: 25703575.
  • Weibl P, Shariat SF, & Klatte T (2015). Partial nephrectomy driven by cavitron ultrasonic surgical aspirator under zero ischemia: a pilot study. World journal of urology PMID: 25935329.

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