Considerations during clinical operation of two commercially available cryomachines

Background and Objectives: Advances in the technology of cryomachines in th e last 10 years have led to the development of both liquid nitrogen and arg on-based Joule-Thompson cryomachines; Theoretical and practical evaluation of the CMS Accuprobe(TM) and the ENDOcare CRYOcare(TM) was performed as res pective examples of these technologies. Methods: Thermal gradients were calculated about both probes for the best c ase scenario of probe surface temperature equaling that of the cryogen used . Also, experimental evaluation in gelatin phantoms was performed with five probe arrays. Results: Theoretically, a liquid nitrogen-cooled probe provides only a slig ht advantage over one cooled with liquid argon. However, the experimental p erformance evaluation demonstrated that the CRYOcare system creates an iceb all faster with steeper internal temperature gradients than the Accuprobe. Further, temperature outputs from the Accuprobe were shown to be in error, likely due to the position of the thermocouple within the probe. Conclusions: Cryomachine performance is determined more by technological in novations than by cryogen temperature. Thermocouple monitoring is urged for users of the Accuprobe. J. Surg. Oncol. 1999:71:106-111. (C) 1999 Wiley-Li ss, Inc.