Laparoscopic aortorenal bypass using a PTFE graft: survival study in the porcine model

Laparoscopic aortorenal bypass in an acute porcine model under warm ischemia: feasibility study and resident training module

BACKGROUND AND PURPOSE

Laparoscopic aortorenal bypass (LARB) in a human being has never been reported. Both the skills required and the concern over preserving renal parenchyma by minimizing ischemia time has limited laparoscopic renal revascularization. The limit of safe renal warm ischemia is 30 minutes, which, it may be argued, is too short to permit laparoscopic anastomosis by those who have never performed the procedure. We sought to demonstrate the feasibility of LARB by determining whether it can be performed under warm ischemia and entirely by a resident after sufficient training. We describe our training program and experience with LARB.

MATERIALS AND METHODS

An LARB was performed in four pigs. There were no practice pigs, as data were collected on the first pig, which was intentionally euthanized postoperatively, while the remaining three were allowed to survive for 24 hours. All procedures were performed by a resident with limited previous training after a regimented program in a "dry laboratory," beginning with basic skills and progressing to LARB modeling using cadaver pig kidneys.

RESULTS

The mean time needed for the graft-to-aorta anastomosis was 30.5 minutes (range 21-47 inutes). The renal arterial anastomosis was completed within 30 minutes in three of the four animals, including the first animal attempted (24, 32, 19, and 15 minutes, respectively). The mean total operative time was 3.1 hours.

CONCLUSIONS

With continuing refinements in technique, LARB under warm ischemia is feasible and not only for an elite few surgeons with advanced skills. We believe any surgeon can become capable of performing this procedure. In addition, LARB provides a porcine model for training that includes both advanced skill and time endpoints.

A pilot study of ice-slurry application for inducing laparoscopic renal hypothermia

OBJECTIVE

To assess, in a pilot study, the feasibility of delivering a microparticulate ice slurry (MPS) to provide regional hypothermia, as renal cooling during laparoscopic procedures is cumbersome and inefficient.

MATERIALS AND METHODS

An ex vivo preparation was used to simulate the boundary conditions of a kidney. Four pig kidneys were placed onto a thin membrane overlying a constant temperature bath (37 degrees C) with parenchymal thermocouples. Renal surfaces were coated with MPS and temperatures recorded. In an in vivo pig model we assessed laparoscopic delivery and cooling ability of the MPS under physiological conditions. Kidneys in two pigs were laparoscopically exposed; thermocouple probes were placed throughout the kidney and the hilum was clamped. MPS was delivered through a modified 5-mm laparoscopic suction/irrigation cannula. Cortical and core body temperatures were measured.

RESULTS

In the ex vivo study, the mean (sd) initial temperature was 37.1 (0.4) degrees C; the mean time to reach 15 degrees C was 10.3 (2.6) min and the mean nadir temperature was 13.0 (1.5) degrees C. In vivo, the MPS was delivered with no technical difficulty; the mean renal unit starting temperature and core body temperature were 37.2 degrees C and 37.0 degrees C, respectively. The mean (range) time to reach 15 degrees C was 16.5 (5.5-28.6) min. The mean nadir core body temperature was 34.0 degrees C.

CONCLUSION

This initial study showed efficient and rapid induction of renal hypothermia using MPS delivered through 5-mm laparoscopic ports, with no technical difficulty. These exploratory pilot findings support further, larger scale, histopathological and renal functional investigations of topical ice slurries as a means of providing renal hypothermia in laparoscopic procedures.