Background: Intra-abdominal pressure during laparoscopic insufflation with pressurized carbon dioxide (CO₂) gas is strongly influenced by mechanical ventilation. Resulting pressure fluctuations can destabilize the surgical workspace and potentially cause harm associated with high insufflation pressures. To address this, a novel CO₂ insufflator was developed using a radial fan and a gas reservoir to generate and maintain continuously stable insufflation pressures (radial fan-based insufflator, RFBI). This first-in-human study evaluated its safety and feasibility during laparoscopic surgery. Methods: Adults undergoing elective intraperitoneal laparoscopic procedures were included. All procedures were performed using the RFBI and an 11 mm study trocar. Primary outcomes were safety, defined as the absence of serious or harmful adverse device effects (SADEs or ADEs), and feasibility, defined as completing the procedure without switching to a conventional insufflator. Secondary outcomes included pressure stability at the device outlet and documentation of observed events affecting pressure stability (e.g., trocar insertion/repositioning, leaks, suction, etc.). Results: Twelve patients were enrolled, having a total RFBI insufflation time of 35.9 h in seven different laparoscopic procedures. No SADEs occurred. One ADE occurred while inserting a 5 mm instrument into the 11 mm study trocar that resulted in high air leakage, causing temporary loss of surgical workspace but no harm. All procedures were completed without the need to switch to a conventional insufflator. Pressure remained stable at both target pressures of 10 mmHg (median 10.0 mmHg, interquartile range (IQR) 0.12) and 14 mmHg (median 14.0 mmHg, IQR 0.15). The RFBI rapidly re-established the target pressure after observed events affecting stability, without manual intervention or procedural delay. Conclusion: This first-in-human study demonstrates that RFBI technology is safe, feasible, and capable of maintaining stable insufflation pressures across varied adult laparoscopic procedures. Radial fan-based insufflation effectively compensated for pressure fluctuations from ventilation and surgical events, warranting further evaluation of clinical benefits.

How do neuromuscular blockade (NMB) and pre-stretching affect abdominal insufflation dynamics, and how can surgical safety and efficiency during minimally access surgery (MAS) improve by novel insufflation techniques and trocar design?
This dissertation presents a series of studies in a porcine model which investigated the effects of NMB and pre-stretching on abdominal insufflation dynamics. For data acquisition and to maintain stable physiological conditions throughout the experiments, specialized tools were developed. A new method, endoscopic oscillometry, was introduced to monitor abdominal compliance in real time. To this respect, a novel fan-based insufflator was developed and tested to determine its ability to perform endoscopic oscillometry and in maintaining stable abdominal pressures compared to conventional systems.
The study found that NMB had minimal impact on abdominal compliance, but pre-stretching using repeated insufflation significantly influenced intra-abdominal compliance and volume. The fan-based insufflator, more specifically a centrifugal fan, demonstrated superior pressure stability, eliminating the pressure peaks observed with conventional insufflators. Additionally, various trocar designs were evaluated, particularly focusing on their performance in preventing air leaks and surgical smoke during MAS. It was found that trocar design played a critical role in air leak performance, with implications for patient safety, particularly concerning surgical smoke evacuation during the COVID-19 pandemic. The research concluded that improved insufflation control, particularly using a fan-based system, could enhance surgical outcomes by providing more stable operating conditions and reducing risks associated with air leaks and surgical smoke. Moreover, the pressure stability enhances respiratory conditions, as the abdomen exerts less upward pressure on the diaphragm. These findings have potential implications in paediatric, bariatric, robotic, and thoracic surgeries, where precise control over abdominal pressure is crucial. Further research, particularly in clinical settings, is needed to validate these findings and adapt the technology for broader use in surgery.

Background: Establishing a pneumoperitoneum for laparoscopy is common surgical practice, with the goal to create an optimal surgical workspace within the abdominal cavity while minimizing insufflation pressure. Individualized strategies, based on neuromuscular blockade (NMB), pre-stretching routines, and personalized intra-abdominal pressure (IAP) to enhance surgical conditions are strategies to improve surgical workspace. However, the specific impact of each factor remains uncertain. This study explores the effects and side-effects of modifying intra-abdominal volume (IAV) through moderate and complete NMB in a porcine laparoscopy model. Methods: Thirty female Landrace pigs were randomly assigned to groups with complete NMB, regular NMB and a control group. Varying IAP levels were applied, and IAV was measured using CT scans. The study evaluated the maximum attainable IAV (V_max), the pressure at which the cavity opens (p₀), and the ease of expansion (λ_exp). Cardiorespiratory parameters, including peak inspiratory pressure (PIP), mean arterial pressure (MAP), heart rate (HR), and cardiac output (CO), were continuously recorded to evaluate side-effects. Results: There were no significant weight differences between NMB groups (median 21.1 kg). Observed volumes ranged from 0 to 4.7 L, with a mean V_max of 3.82 L, mean p₀ of 1.23 mmHg, and mean λ_exp of 0.13 hPa⁻¹. NMB depth did not significantly affect these parameters. HR was significantly increased in the complete NMB group, while PIP, MAP, and CO remained unaffected. Repeated insufflation positively impacted V_max; ease of opening; and expanding the cavity. Conclusion: In this porcine model, the depth of NMB does not alter abdominal mechanics or increase the surgical workspace. Cardiorespiratory changes are more related to insufflation pressure and frequency rather than NMB depth. Future studies should compensate for the positive effect of repeated insufflation on abdominal mechanics and surgical conditions.

In laparoscopic surgery the abdominal cavity is insufflated with pressurized carbon dioxide gas to create workspace. This pressure is exerted through the diaphragm onto the lungs, competing with ventilation and hampering it. In clinical practice the difficulty of optimizing this balance can lead to the application of harmfully high pressures. This study set out to create a research platform for the investigation of the complex interaction between insufflation and ventilation in an animal model. The research platform was constructed to incorporate insufflation, ventilation and relevant hemodynamic monitoring devices, controlling insufflation and ventilation from a central computer. The core of the applied methodology is the fixation of physiological parameters by applying closed-loop control of specific ventilation parameters. For accurate volumetric measurements the research platform can be used in a CT scanner. An algorithm was designed to keep blood carbon dioxide and oxygen values stable, minimizing the effect of fluctuations on vascular tone and hemodynamics. This design allowed stepwise adjustment of insufflation pressure to measure the effects on ventilation and circulation. A pilot experiment in a porcine model demonstrated adequate platform performance. The developed research platform and protocol automation have the potential to increase translatability and repeatability of animal experiments on the biomechanical interactions between insufflation and ventilation.

Objective: To develop a realistic simulation model for laparotomy-assisted fetoscopic spina bifida aperta (SBa) surgery, to be used for training purposes and preoperative planning. Methods: The predefined general requirement was a realistic model of an exteriorized uterus, allowing all neurosurgical steps of the intervention. The uterus was modelled using ultrasound and MRI images of a 25 weeks’ gravid uterus, consisting of flexible polyurethane foam coated with pigmented silicone. The fetal model, contained an opening on the dorsal side for a customizable spinal insert with all the aspects of a SBa, including a cele, placode, and myofascial and skin layer. The model was assessed in a series of validation experiments. Results: Production costs are low, uterus and fetus are reusable. Placental localization and the level and size of the spinal defect are adjustable, enabling case-specific adaptations. All aspects of the simulator were scored close to realistic or higher for both appearance and functional capacities. Conclusions: This innovative model provides an excellent training opportunity for centers that are starting a fetoscopic SBa repair program. It is the first simulation model with adjustable spinal defect and placental localisation. Further objective validation is required, but the potential for using this model in preoperative planning is promising.

Background: During minimal access surgery, surgical smoke is produced which can potentially be inhaled by the surgical team, leading to several health risks. This smoke can escape from the abdominal cavity into the operating room due to trocar leakage. The trocars and insufflator that are used during surgery influence gas leakage. Therefore, this study compares particle escape from a valveless (Conmed AirSeal iFS), and a conventional (Karl Storz Endoflator) system. Materials and methods: Using an in vitro model, a conventional and a valveless trocar system were compared. A protocol that simulated various surgical phases was defined to assess the surgical conditions and particle leakage. Insufflation pressures and instrument diameters were varied as these are known to affect gas leakage. Results: The conventional trocar leaked during two distinct phases. Removal of the obturator caused a sudden release of particles. During instrument insertion, an average of 211 (IQR 111) particles per second escaped when using the 5 mm diameter instrument. With the 10 mm instrument, 50 (IQR 13) particles per second were measured. With the conventional trocar, a higher abdominal pressure increased particle leakage. The valveless trocar demonstrated a continuously high particle release during all phases. After the obturator was removed, particle escape increased sharply. Particle escape decreased to 1276 (IQR 580) particles per second for the 5 mm instrument insertion, and 1084 (IQR 630) particles per second for 10 mm instrument insertion. With the valveless trocar system, a higher insufflation pressure lowered particle escape. Conclusions: This study shows that a valveless trocar system releases more particles into the operating room environment than a conventional trocar. During instrument insertion, the leakage through the valveless system is 6 to 20 times higher than the conventional system. With a valveless trocar, leakage decreases with increasing pressure. With both trocar types leakage depends on instrument diameter.

Background: Abdominal compliance describes the ease of expansion of the abdominal cavity. Several studies highlighted the importance of monitoring abdominal compliance (C_ab) during the creation of laparoscopic workspace to individualize the insufflation pressure. The lack of validated clinical monitoring tools for abdominal compliance prevents accurate tailoring of insufflation pressure. Oscillometry, also known as the forced oscillation technique (FOT), is currently used to measure respiratory mechanics and has the potential to be adapted for monitoring abdominal compliance. This study aimed to define, develop and evaluate a novel approach which can monitor abdominal compliance during laparoscopy using endoscopic oscillometry. Materials and methods: Endoscopic oscillometry was evaluated in a porcine model for laparoscopy. A custom-built insufflator was developed for applying an oscillatory pressure signal superimposed onto a mean intra-abdominal pressure. This insufflator was used to measure the abdominal compliance at insufflation pressures ranging from 5 to 20 hPa (3.75 to 15 mmHg). The measurements were compared to the static abdominal compliance, which was measured simultaneously with computed tomography imaging. Results: Endoscopic oscillometry recordings and CT images were obtained in 10 subjects, resulting in 76 measurement pairs for analysis. The measured dynamic C_ab ranged between 0.0216 and 0.261 L/hPa while the static C_ab based on the CT imaging ranged between 0.0318 and 0.364 L/hPa. The correlation showed a polynomial relation and the adjusted R-squared was 97.1%. Conclusions: Endoscopic oscillometry can be used to monitor changes in abdominal compliance during laparoscopic surgery, which was demonstrated in this study with a comparison with CT imaging in a porcine laparoscopy model. Use of this technology to personalize the insufflation pressure could reduce the risk of applying excessive pressure and limit the drawbacks of insufflation.

Background
During laparoscopy, the abdominal cavity is insufflated with carbon dioxide (CO2) that could become contaminated with viruses and surgical smoke. Medical staff is potentially exposed when this gas leaks into the operating room through the instruments and past trocar valves. No detailed studies currently exist that have quantified these leakage pathways. Therefore, the goal of this study was to quantify the gas leakages through trocars and instruments, during minimally invasive procedures.

Methods
A model of the surgical environment was created, consisting of a rigid container with an interface for airtight clamping of laparoscopic equipment such as trocars and surgical instruments. The model was insufflated to 15 mm Hg using a pressure generator and a pneumotachograph measured the equipment gas leak. A protocol of several use cases was designed to simulate the motions and forces the surgeon exerts on the trocar during surgery.

Results
Twenty-three individual trocars and twenty-six laparoscopic instruments were measured for leakage under the different conditions of the protocol. Trocar leakages varied between 0 L/min and more than 30 L/min, the instruments revealed a range of leakages between 0 L/min and 5.5 L/min. The results showed that leakage performance varied widely between trocars and instruments and that the performance and location of the valves influenced trocar leakage.

Conclusions
We propose trocar redesigns to overcome specific causes of gas leaks. Moreover, an international testing standard for CO2 leakage for all new trocars and instruments is needed so surgical teams can avoid this potential health hazard when selecting new equipment.