In vitro, ex vivo and in vivo isotherms for renal cryotherapy.
OBJECTIVE
Preoperative planning for renal cryotherapy is based on isotherms established in gel. We replicated gel isotherms and correlated them with ex vivo and in vivo isotherms in a porcine model.


METHODS
PERC-17 CryoProbes (1.7 mm) and IceRods (1.47 mm) underwent trials in gel, ex vivo and in vivo porcine kidneys. Temperatures were recorded at 13 predetermined locations with multipoint thermal sensors.


RESULTS
At the cryoprobe temperatures were not significantly different along the probe in any medium for either system (p = 0.0947 to 0.9609). However, away from the probe ex vivo and in vivo trials showed warmer temperatures toward the cryoprobe tip for each system (p = 0.0003 to 0.2141). Mean +/- SE temperature 5 mm distal to the cryoprobe tip in vivo was 19.2C +/- 16.1C for CryoProbes and 27.3C +/- 11.2C for IceRods. Temperatures were consistently colder with CryoProbes than with IceRods in gel (p <0.00005), ex vivo (p <0.00005) and in vivo (p = 0.0014). At almost all sites temperatures were significantly colder in gel and in ex vivo kidney than in in vivo kidney for CryoProbes (p = 0.0107 and 0.0008, respectively) and for IceRods (each p <0.00005).


CONCLUSIONS
Gel and ex vivo isotherms do not predict the in vivo pattern of freezing. Thus, they should not be used for preoperative planning. The cryoprobe should be passed 5 mm beyond the tumor border to achieve suitably cold temperatures. Multipoint thermal sensor probes are recommended to record actual temperature during renal cryotherapy.
Young
Jennifer L
JL
University of California-Irvine, Orange, California, USA. jlyoung@uci.edu
Kolla
Surendra B
SB
Pick
Donald L
DL
Sountoulides
Petros
P
Kaufmann
Oskar G
OG
Ortiz-Vanderdys
Cervando G
CG
Huynh
Victor B
VB
Kaplan
Adam G
AG
Andrade
Lorena A
LA
Osann
Kathryn E
KE
Louie
Michael K
MK
McDougall
Elspeth M
EM
Clayman
Ralph V
RV
D000818:Animals; D003452:Cryosurgery / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D007668:Kidney / Q000601:surgery*; D013552:Swine