Evaluating the Novel Veress Plus Needle

In total two Thiel embalmed bodies were used over three days. The first body was a 72 year old male with no previous laparotomy or abdominal scars, who had died of myocardial infarction (Length: 170 cm; bodyweight: 70 kg). The 2nd body was a male of 65 years without abdominal scars. The cause of death had been a hospital acquired pneumonia and pulmonary embolism secondary to metastatic pancreatic cancer (length186 cm; bodyweight: 80kg).

An Aesculap laparoscopy tower set up (Aesculap, 3773 Corporate Parkway, Center Valley, 18034 PA, USA) was used with a 10 mm 30 degrees scope, which was inserted through a balloon trocar (Medtronic Netherlands, Larixplein 4, 5616VB Eindhoven, The Netherlands) in the abdomen just below the umbilicus. Intra-abdominal pressure was stabilized using CO2 (Carbon Dioxide) to 4 mm Hg(Mercury). This pressure-level was as low as possible to allow for unambiguous visualization of the insertions but almost equalling normal abdominal pressure. Two different needle types were used, a thin bore needle with a diameter of 2 millimeter (mm) and a length of 145 mm and a wide bore with 2.8 mm diameter and 145 mm length. The study was registered under number FRECMDS-2021-134 of the Ethical Committee of Faculty of Medicine and Surgery of the University of Malta.

Questionnaire The investigators used a questionnaire which consisted of questions about gender, age and previous experience. A 1 to 5 Likert scale was used to score the "life-likeness" of the Thiel embalmed bodies, realism of the procedure, safety the VN+ procedure, and difficulty of using the new needle design.

Protocol After completing the first part of the questionnaire, the participants were instructed and explained how the mechanism works. During the instruction phase, they were allowed to try the needle on a dedicated area, away from the intended research area, until they were able to manage their grip and found their best insertion strategies. To minimize the risk of hitting organs upon entering the abdominal cavity, certain areas are dedicated for VN (Veress Needle) placement such as Palmer's point in the left upper quadrant of the abdomen. In order to use the bodies as efficiently as possible whilst offering a similar experience in terms of abdominal composition to all participants, the whole upper part of the abdomen was used for the insertions, which were done in an alternating fashion (with and without the safety mechanism) for 12 punctures (2x6) from cranial to caudal so a "fresh" part (with no defect or lesion) of abdominal wall was used for each attempt. The participants were with their backs to the video monitor so they were blinded to what was happening inside the abdomen. Insertion of the VN+ was successful when the mechanism fully unlocked. If not, the attempt was noted as an unsuccessful trial, the cause was determined and the insertion data was removed. After the hands- on part, the participants were asked to fill out the last part of the questionnaire with questions about the quality of the bodies and procedures based on their personal experiences and the difficulty of using the VN+ device. It is important to note that the VN+ dislodge action is not influenced by the amount of insertion force but only by the position of the inner stylet.

Data comparison and Statistical analysis Video footage was used by three observers to determine the insertion depth, indicated by the number of markings engraved on the part of the needle surface inside the abdomen. The true insertion depth was calculated in Excel based on the known distance between each marking. After the participants completed the tests, any differences in maximum insertion depth between the VNc and VN+ groups were determined with a Student's t-test (SPSS v16, SPSS, Inc., Chicago, IL). A p-value < 0.05 was considered a significant difference. The same was done comparing the wide bore with the small bore needles and other variables including the different genders. The potential learning curve was established based on a regression analysis executed on the averaged outcomes per trial including all trial data. The potential influence of wear was established based on a regression analysis conducted on 12 separately executed trials with the wide bore needles. Wear is defined as diminishing sharpness of the bevel of the Veress needle after each attempt. For the regression analysis a p-value <0.05 was considered significantly different.