This study investigates how different breathing machine (ventilator) settings affect the energy delivered to the lungs during surgery. Mechanical power is a measure of this energy, and high levels can sometimes lead to lung irritation. In clinical practice, a mode called Pressure-Regulated Volume Control (PRVC) is often used because it lowers the "peak" pressure in the airways, which is generally thought to be safer. However, doctors have noticed that even though the peak pressure goes down in PRVC mode, the total mechanical power displayed on the monitor might actually increase compared to the standard Volume-Controlled Ventilation (VCV) mode. In this study, patients undergoing gallbladder surgery will be monitored using both ventilation modes in a random order. The researchers will compare the machine-calculated mechanical power for both modes to see if the perceived benefit of lower peak pressure in PRVC actually results in lower overall energy transfer to the lungs.
Patients undergoing elective laparoscopic cholecystectomy surgery.
Patients between 18 and 75 years of age.
American Society of Anesthesiologists (ASA) physical status I, II or III.
Body Mass Index (BMI) between 18.5 and 35 kg/m².
History of significant chronic obstructive pulmonary disease (COPD) or asthma.
Previous lung resection or major thoracic surgery.
Heavy smokers (more than 20 cigarettes per day).
Presence of spontaneous breathing effort during mechanical ventilation.
Crossover
Volume-Controlled Ventilation (VCV)
DeviceParticipants will be ventilated with the traditional Volume-Controlled Ventilation (VCV) mode. Tidal volume, respiratory rate, PEEP, and I:E ratio will be set according to the study protocol and kept constant during the measurement period.
Pressure-Regulated Volume Control (PRVC)
DeviceParticipants will be ventilated with the Pressure-Regulated Volume Control (PRVC) mode. This is a hybrid mode that uses a decelerating flow to deliver the target tidal volume at the lowest possible pressure. Settings will be identical to the VCV mode for each patient.
Device-Displayed Mechanical Power
The mechanical power value (expressed in Joules per minute - J/min) is automatically calculated and displayed on the monitor of the Mindray A9 anesthesia machine. This value represents the total energy delivered by the ventilator to the patient's respiratory system per minute. The study aims to compare how this machine-calculated value differs between the Volume-Controlled Ventilation (VCV) and Pressure-Regulated Volume Control (PRVC) modes under identical clinical conditions.
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