The trial was performed in live animals and in human cadaver models. Experiments were conducted under institutional review board approval. The live animal model was intended to evaluate quality of the tissue obtained with CB as well as bleeding times and compare those of FNA results. The human cadaver model was intended to assess handling of the device with EUS equipment in the human anatomy. The comparator for all experiments was FNA. The cryosurgical equipment used for this study consisted of a cryogen (carbon dioxide) console with an 18-gauge cryoprobe (Erbe, Tübingen, Germany) (Fig. 1). The cooling system is based on the Joule-Thompson effect, whereby the cooling agent

Afatinib datasheet is applied under high pressure (57 bar at room temperature) through the central canal of the probe. The gas is delivered through an inner tube located in the other sheath of the probe. The nozzle of the inner gas delivery tube has a diameter of 60 μm and is located in the tip of the probe, which concomitantly serves as a gas expansion chamber. Because of the sudden difference in pressure, the gas expands, resulting in a cooling effect at the tip of the probe. The gas emitted cools the tip of the probe to −35°C. The cryoprobe used in our experiments is a novel prototype with an 18-gauge diameter that

resembles an injection needle with a ridge. The ridge incises the tissue before advancing the probe forward into the target tissue. For biopsy extraction, the probe is inserted into the working channel of the endoscope and is advanced into the target tissue under EUS guidance.

Once the probe is correctly placed, freezing of the probe is activated. Bcl-xL apoptosis The tip of the cryoprobe is cooled to -35°C after activation. Because of the cryoadhesive effect, the frozen tissue remains adherent at the probe’s tip and can be extracted by manual retraction of the probe. There is a positive correlation between biopsy size and freezing time. The biopsy size for the given organ has been determined experimentally before this study was started and was chosen not to be larger than the inner diameter of the oversheath to allow retrieval of the biopsy specimen through the oversheath. The freezing time was standardized in very every group and set to 2 seconds. The probe together with the biopsy specimen is then pulled back into an oversheath and withdrawn through the working channel of the endoscope. The stiffness of the probe is not altered when carbon dioxide is delivered. Pancreatic biopsy specimens were obtained in 4 anaesthetized pigs under laparotomy control to assess bleeding time associated with each technique. CB was tested as direct puncture with the probe (CB-1) and in conjunction with different specimen retrieval sheaths (1.6-mm sheath, group CB-2; 1.75-mm sheath, group CB-3; 2.53-mm sheath, group CB-4; and via transduodenal puncture (group CB-5), resulting in 5 CB biopsy groups. FNA and TC biopsies also were obtained from each animal.