The preparation and execution of this study were discontinued due to a range of practical constraints. Including logistical and operational challenges that would have compromised the study's feasibility and effective and questioning reliable results.

The optimization of ventilation is especially important during general anaesthesia, when active, physiologic respiration suspends and is replaced by non-physiologic mechanical positive pressure ventilation. Aiming at preserving compliance of lung tissue to guarantee an effective gas exchange is to avoid an excessive pressure application, especially in extreme positioning of the patient (Trendelenburg positioning) and/or pneumoperitoneum resulting in additional non-physiologic intrathoracic pressure. Perioperative lung protection strategies have steadily improved in recent years to reduce complications from mechanical ventilation, but postoperative pulmonary complications remain a risk factor for increased morbidity and mortality.

Mechanical ventilation is crucial during general anesthesia, with ongoing efforts to refine strategies for optimal respiratory support. Important articles on perioperative ventilation explored key aspects, including PEEP application, tidal volume effects, PPC after major surgeries, and perioperative oxygen titration to mitigate oxidative stress. PEEP plays a pivotal role in enhancing oxygenation and preventing atelectasis during mechanical ventilation. Landmark studies by the ARDS Network highlight the importance of customizing PEEP application. This tailored approach not only improves respiratory mechanics but also reduces the risk of barotrauma, underscoring the crucial impact of personalized PEEP strategies. Concurrently, adopting a lung-protective strategy with low tidal volumes, has proven effective in mitigating ventilator-induced lung injury. These strategies aim to strike a balance between optimal oxygenation and minimizing potential complications associated with mechanical ventilation. Despite advancements in perioperative care, PPC remain a concern, particularly following major surgical procedures. Recent investigations emphasize the multifactorial nature of these complications. Early identification of risk factors and meticulous monitoring are crucial to reducing the incidence of complications such as atelectasis, pneumonia, and respiratory insufficiency. Understanding the interplay between mechanical ventilation strategies and postoperative outcomes is essential for improving patient recovery. The pursuit of optimal oxygenation must be balanced against the potential for oxygen toxicity and oxidative stress. Available studies shed light on the delicate equilibrium required in maintaining adequate oxygen delivery while avoiding the detrimental effects of hyperoxia. Clinicians must consider individual patient factors and tailor oxygen therapy to prevent oxidative stress, which can contribute to tissue damage and compromise overall patient well-being. FCV is a new ventilation strategy designed to minimize the mechanical effects of perioperative ventilation on lung tissue. Compared to traditionally employed ventilation strategies, gas flow is controlled during both inspiration and expiration in FCV. In particular, the almost linear pressure drop during the expiratory phase of FCV has been shown in various ex vivo/experimental and clinical studies to improve gas exchange and the proportion of ventilated lung tissue.

Ongoing advancements in mechanical ventilation shape anesthesia practices with a focus on evidence-based approaches for patient safety. Building on prior findings, this study explores the benefits of the novel ventilation approach, FCV, aiming to reduce dissipative energy and alveolar stress. The investigators hypothesize positive impacts on perioperative ventilation, vital parameters, and a decreased incidence of PPC, contributing to overall postoperative morbidity and mortality reduction.

Inclusion Criteria:

• Patient undergoing elective robot-assisted laparoscopic surgery (either abdominal, urologic or gynecologic surgery) with a duration of expected ventilation of ≥ 90 minutes
• Male or female aged ≥ 18 years
• ASA Physical Status Classification System score I - III
• Must be willing and able to give written informed consent to participate in the study and agree to comply with the study protocol prior to initiation of any study-mandated procedure and study intervention

Exclusion Criteria:

• Patient with weight < 40 kg ideal body weight
• ASA Physical Status Classification System score IV - VI
• Previous enrolment into the current study
• Enrolment of study investigator, his/her family members, employees and other dependent persons
• If female and of childbearing potential: known pregnancy or a positive urine pregnancy test (confirmed by a positive serum pregnancy test), or lactating

single blinded to the participant