Carbon dioxide (CO2) pneumoperitoneum and clasp-knife positioning are commonly used to improve surgical access during robot-assisted laparoscopic urological surgery. However, these methods are sometimes associated with several unwanted cardiopulmonary effects such as increased mean arterial pressure, decreased pulmonary compliance and functional residual capacity, increased peak inspiratory pressure, and respiratory acidosis in association with hypercarbia. Volume-controlled ventilation (VCV) is the most commonly used method of ventilation during general anesthesia. It provides fixed minute ventilation and pulmonary resistance, which affect airway pressure. In pressure-controlled ventilation (PCV), constant inspiratory airway pressure can be achieved by decelerating the flow. However, minute ventilation is not fixed . CO2 pneumoperitoneum in the clasp-knife positioning can influence hemodynamic variables, including blood pressure, heart rate, and cardiac output. This is because changes in airway pressure affect intrathoracic pressure and the function of the heart itself. In this randomized study, we investigated the effects of VCV and PCV on peak inspiratory pressure during robot-assisted laparoscopic urological surgery involving CO2 pneumoperitoneum in the clasp-knife position.

After careful screening, 60 patients were enrolled in the trial. The investigators monitored patients' breathing, circulation and carbon metabolism by measuring arterial gas, cardiac output monitoring, respiratory parameters and circulation parameters at different times in both groups of patients.

Inclusion Criteria:

• Patients undergoing urological surgery in clasp-knife position
• between the age of 18 and 65
• America Society of Anesthesiologist Grades I-II.

Exclusion Criteria:

• Morbid obesity
• systolic blood pressure < 90 mmHg)
• heart rate < 60 beats per minute or > 100 beats per minute
• peripheral blood oxygen saturation < 90%
• Complicated with severe liver and kidney injury.