Current concepts in achieving renal hypothermia during laparoscopic partial nephrectomy

Open partial nephrectomy: current review

Partial nephrectomy (PN) is increasingly considered the gold standard treatment for localized renal cell carcinomas (RCCs) where technically feasible. The advantage of nephron-sparing surgery lies in preservation of parenchyma and hence renal function. However, this advantage is counterbalanced with increased surgical risk. In recent years with the popularization of minimally invasive partial nephrectomy (laparoscopic and robotic), the contemporary role of open PN (OPN) has changed. OPN has several advantages, particularly in complex patients such as those with a solitary kidney, multi-focal tumors, and significant surgical history, as well as providing improved application of renoprotective measures. As such, it is a technique that remains relevant in current urology practice. In this article we discuss the evidence, indications, operative considerations and surgical technique, along with the role of OPN in contemporary nephron-sparing surgery.

Kidney temperature during living donor kidney transplantation is associated with short-term measured glomerular filtration rate - a prospective study

The duration of warm ischaemia time is associated with short- and long-term kidney transplant function. A quick rise in graft temperature is reported during the vascular anastomosis. This study was initiated to gain insight into the effect of graft temperature on short-term transplant function. From 2013 to 2015, data of living donor kidney transplant recipients were prospectively collected. At set intraoperative time points, the graft temperature was measured using a noncontact infrared thermometer. Primary endpoint was measured glomerular filtration rate (mGFR) at 3- and 6-month post-transplantation. Univariable and multivariable associations were identified using linear regression analyses. Multivariable analysis included models with donor, recipient and procedure characteristics. We evaluated 152 patients, 83 (55%) were male, mean ±SD age was 50.3 ± 13.4 years, and 79 (52%) were pre-emptively transplanted. In univariable analysis graft temperature, after 10 min of warm ischaemia was significantly associated with 3- and 6-month mGFR, β -0.22 (95% CI -0.39 to -0.04, P = 0.01) and β-0.22 (95% CI: -0.44 to -0.01, P = 0.04). The association remained significant in multivariable models. An independent association between kidney graft temperature and 3- and 6-month mGFR was identified. This association opens up the opportunity to further investigate the clinical impact of kidney rewarming during transplantation.

Infrared Thermometer: an accurate tool for temperature measurement during renal surgery

PURPOSE

To evaluate infrared thermometer (IRT) accuracy compared to standard digital thermometer in measuring kidney temperature during arterial clamping with and without renal cooling.

MATERIALS AND METHODS

20 pigs weighting 20Kg underwent selective right renal arterial clamping, 10 with (Group 1 - Cold Ischemia with ice slush) and 10 without renal cooling (Group 2 - Warm Ischemia). Arterial clamping was performed without venous clamping. Renal temperature was serially measured following clamping of the main renal artery with the IRT and a digital contact thermometer (DT): immediate after clamping (T0), after 2 (T2), 5 (T5) and 10 minutes (T10). Temperature values were expressed in mean, standard deviation and range for each thermometer. We used the T student test to compare means and considered p < 0.05 to be statistically significant.

RESULTS

In Group 1, mean DT surface temperature decrease was 12.6 ± 4.1°C (5-19°C) while deep DT temperature decrease was 15.8 ± 1.5 °C (15-18 °C). For the IRT, mean temperature decrease was 9.1 ± 3.8 °C (3-14°C). There was no statistically significant difference between thermometers. In Group 2, surface temperature decrease for DT was 2.7 ± 1.8°C (0-4°C) and mean deep temperature decrease was 0.5 ± 1.0 °C (0-3 °C). For IRT, mean temperature decrease was 3.1 ± 1.9°C (0-6°C). No statistically significant difference between thermometers was found at any time point.

CONCLUSIONS

IRT proved to be an accurate non-invasive precise device for renal temperature monitoring during kidney surgery. External ice slush cooling confirmed to be fast and effective at cooling the pig model.

Basis for the use of localized hypothermia during radical pelvic surgery

Controlled tissue cooling, or hypothermia, has been used therapeutically for decades to mitigate the negative effects of traumatic, ischemic, and surgical insults. When applied systemically, moderate hypothermia can attenuate or prevent the extent of neurologic sequelae. Localized hypothermia, on the other hand, has the capacity to reduce tissue edema, suppress inflammation, and minimize the severity of peripheral nerve injury. Therapeutic hypothermia has been used in critical care, neurosurgery, ophthalmology, otolaryngology, cardiothoracic surgery and most recently in urology. Nerve injury during radical pelvic surgery can result in urinary incontinence or retention, impotence and bowel dysfunction. Localized hypothermia during radical prostatectomy has demonstrated improved recovery of urinary continence and erectile function, and similar benefits might be observed in other types of radical pelvic surgery.

Laparoscopic renal cooling device

A new medical device has been designed for inducing hypothermia in kidneys, via laparoscopic deployment, without leaving residual fluid in the abdomen. It was tested in laboratory and animal trials to ascertain its suitability for achieving a target renal temperature of 15 degrees C for tissue preservation within a 30-min period. A simple theoretical model was developed to calculate cooling rates under ideal circumstances. In the laboratory, a potato was used as the model for the kidney and an average minimum temperature of 15.8 degrees C was reached in 30 min. The theoretical model calculated this as 9.9 degrees C. In the animal trials, an average minimum temperature of 11.4 degrees C was reached in 30 min, compared to the calculated temperature of 9.8 degrees C from the theoretical model. In conclusion, the new device can cool as affectively as other techniques trialled, with the added advantage that it does not release cold fluid or ice into the abdomen.

Comparison of prolonged warm and cold ischemia on the solitary kidney during partial nephrectomy in a rabbit model

The aim of this study was to investigate the patterns of renal function recovery during partial nephrectomy (PN) on an experimental solitary kidney rabbit model and establish the upper tolerable time limits of applied ischemia. Forty-eight New Zealand rabbits underwent an open right nephrectomy and after 30 days, the animals were clustered into five groups (A, B, C, D, E). The first four groups received an open left PN, under different types of ischemia. Groups A (n = 8) and B (n = 10) were subjected to 90 and 60 min of warm ischemia (WI), respectively, while groups C (n = 10) and D (n = 10) received 90 and 120 min of cold ischemia (CI) with ice-slush cooling. Group E (n = 10) served as sham group. Serum determinations of creatinine (SCr) and BUN were recorded preoperatively and on postoperative days (POD) 1, 3, 6 and 15. The animals were euthanized and the remaining kidneys were harvested and evaluated microscopically. The type and duration of ischemia were statistically significant parameters (P < 0.001). Groups B, C and D exhibited a similar pattern of recovery from trial initiation to the 15th POD (P = 0.788 and P = 0.068, respectively). Group A was extremely differentiated, with 100% mortality caused by uremia. The microscopic findings were consistent to the serum biochemistry. In our solitary kidney rabbit model, the upper limits of tolerable WI seem to be set on 60 min. CI can safely preserve the model's renal function--even up to 120 min.

Recovery of Renal Function After Complete Renal Hilar Versus Artery Alone Clamping During Open and Laparoscopic Surgery

PURPOSE

It is generally accepted that simultaneous occlusion of the renal artery and vein during warm ischemia is more damaging than occlusion of the artery alone. Pneumoperitoneum during laparoscopy may impair venous backflow, negating the benefits of clamping the artery alone. We evaluated the effect of laparoscopic vs open surgery on the recovery of renal function after clamping of the renal artery and vein, and the artery alone in a solitary kidney porcine model.

MATERIALS AND METHODS

Right laparoscopic nephrectomy was performed in 36 pigs. After a 12-day recovery period the animals were randomized into 3 groups, including 1) 120-minute warm ischemia with renal artery and vein occlusion, 2) 120-minute warm ischemia with artery alone occlusion and 3) control sham surgery. The groups were further subdivided into an open and a laparoscopic arm. Serum creatinine was assessed preoperatively, and on postoperative days 1, 3, 8 and 15.

RESULTS

Artery alone clamping resulted in a significantly lower serum creatinine increase on postoperative days 1 and 3 in the open arm compared to the laparoscopic arm. Compared to open renal artery and vein clamping the increase in serum creatinine for open artery alone clamping was also significantly lower on postoperative days 1 and 3. No significant difference in postoperative serum creatinine was found between the laparoscopic artery alone, and the renal artery and vein arms at any time point. No significant serum creatinine changes were observed in the control sham surgery group compared to preoperative values at all followup time points.

CONCLUSIONS

In this porcine model clamping of the artery alone during open surgery better protected the kidney from warm ischemia compared to renal artery and vein occlusion. This benefit was not observed during laparoscopic surgery. We speculated that the presence of pneumoperitoneum causes at least partial occlusion of the renal vein, thus, negating the benefit of renal artery clamping only.