The Performance of 17-gauge Cryoprobes In Vitro

Abstract

In cryosurgery it is crucial that the performance of cryoprobes is predictable and constant. In this study we tested the intra- and interneedle variation between 17-gauge cryoprobes in two homogeneous mediums. Also, a multiprobe setup was tested. Cryoprobe performance was defined as the time it takes one cryoprobe to lower the temperature from 0 to -20 degrees C as measured by four thermosensors each at 3 mm distance from the cryoprobe. In agar eight cryoprobes were tested during six freeze cycles, and in gel four cryoprobes during four freeze cycles; each freeze cycle in a different cup of agar or gel. Using more accurate 'bare' thermosensors three cryoprobes were tested in gel during two freeze cycles. A multiprobe configuration with four cryoprobes was tested during two freeze cycles in both agar and gel. Statistical analyses were done using ANOVA for repeated measures. There was no significant intraneedle variation, whereas both in agar and gel there was a significant interneedle variation (p<0.05). Mean performance in gel was better than in agar (p<0.001). Also, there was a significant variation between the four thermosensors (p<0.001). Using bare thermosensors mean performance was 2.7 times faster compared to measurements by regular thermosensors (p<0.001). In a multiprobe configuration, overall performance seems less variable and more reproducible compared to a single cryoprobe. In conclusion, the performance of cryoprobes differs depending on the medium and measuring device used. Cryoprobes deliver reproducible freeze cycles, although there is variation between different cryoprobes. In a multiprobe configuration performance seems less variable.

Laparoscopic renal cryoablation using ultrathin 17‐gauge cryoprobes: mid‐term oncological and functional results

“…These ultrathin cryoprobes are easily introduced into the kidney, minimize bleeding from the puncture tract and reduce the risk of renal fracture [3]. Although different ice ball sizes are available, the ablation zone achieved is smaller and therefore multiple cryoprobes [4], acting synergistically, need to be inserted [5]. The clinical safety of ultrathin cryoprobes is proven [6] but concerns about their efficacy might still exist.…”

Are Multiple Cryoprobes Additive or Synergistic in Renal Cryotherapy?

“…Beemster et al 19 found the performance of 17-gauge cryoprobes was less variable in a multiple probe configuration than a single cryoprobe when the temperature was measured 3 mm from the cryoprobe in agar and gel. In that study, the average temperature variation was 3.8°C greater in the multiple probe group.…”

Multipoint Thermal Sensors Associated with Improved Oncologic Outcomes Following Cryoablation

“…The flow of 37°C blood within or adjacent to the cryoablated region may lead to heat dissipation by the ''heat sink effect'' and complicate attainment of requisite freeze temperatures for the appropriate duration. 20,21 Multipoint thermal sensor (MTS) needles allow accurate and reproducible temperature determination across multiple points along the needle, 22 providing the surgeon a direct means to ascertain CA temperatures within the area of the RCN. Utilizing MTS needles can help overcome differences in renal tumor microanatomy and vascular distribution, and inform cryoprobe placement and freeze times, hypothetically decreasing the risk of incomplete ablation.…”