The goal of this clinical trial is to learn if lung-protective ventilation can improve perioperative oxygenation and reduce postoperative pulmonary complications in patients undergoing elective laparoscopic gastrectomy. The main questions it aims to answer are: * Does lung-protective ventilation improve intraoperative and postoperative gas exchange compared to conventional ventilation? * What are the effects of this ventilation strategy on pulmonary mechanics, hemodynamic parameters, and the incidence of postoperative pulmonary complications? Researchers will compare lung-protective ventilation to conventional ventilation to see if the protective strategy safely mitigates atelectasis and improves oxygenation during surgery. Participants will: * Receive either conventional ventilation or lung-protective ventilation (using lower tidal volumes with appropriate PEEP and recruitment maneuvers) while under general anesthesia for their surgery. * Have their gas exchange, pulmonary mechanics, and hemodynamic parameters continuously monitored during and after the operation. * Be assessed for any postoperative pulmonary complications following the surgery.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
SINGLE
Enrollment
102
Patients in this group will receive conventional intraoperative mechanical ventilation during surgery. The ventilator settings include a tidal volume (VT) of 8 ml/kg based on predicted body weight (PBW) and a positive end-expiratory pressure (PEEP) of 5 cmH2O.
Patients assigned to the lung-protective ventilation arm will receive a standardized intraoperative strategy using Volume-Controlled Ventilation (VCV) with a tidal volume of 6 ml/kg based on predicted body weight, a respiratory rate of 12 breaths per minute, an I:E ratio of 1:2, and an inspiratory pause greater than 0.2 seconds to minimize resistance for compliance calculations. Following an initial alveolar recruitment maneuver, a decremental PEEP titration will be performed by starting at 14 cmH2O and decreasing by 2 cmH2O every 4 minutes down to a minimum of 6 cmH2O to identify and maintain the optimal PEEP level, which is defined as the point of highest dynamic lung compliance. Furthermore, automated alveolar recruitment maneuvers applying a sustained pressure of 40 cmH2O for 15 seconds will be systematically executed immediately after endotracheal intubation, repeated every 30 minutes throughout the surgical procedure, and performed a final time immediately before extubation.
University Medical Center HCMC
Ho Chi Minh City, Ho Chi Minh, Vietnam
Intraoperative and Postoperative Gas Exchange (PaO2/FiO2 Ratio)
The ratio of arterial oxygen partial pressure (PaO2) to fractional inspired oxygen (FiO2). This index is used to evaluate the efficiency of pulmonary gas exchange and oxygenation status. PaO2 values are obtained from arterial blood gas (ABG) analysis. A higher ratio indicates better oxygenation.
Time frame: Assessed at 4 specific time points: T1: Baseline (before induction of anesthesia). T2: 1 hour after the start of CO2 pneumoperitoneum. T3: 30 minutes after tracheal extubation. T4: Postoperative day 1 (approximately 24 hours after surgery).
Peak Inspiratory Pressure (Ppeak)
The study will evaluate pulmonary mechanics by measuring the peak inspiratory pressure (Ppeak).
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Driving Pressure (Pdriving)
The study will evaluate pulmonary mechanics by measuring the driving pressure (Pdriving).
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Plateau Pressure (Pplat)
The study will evaluate pulmonary mechanics by measuring the plateau pressure (Pplat).
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Dynamic Lung Compliance (Cdyn)
The study will evaluate pulmonary mechanics by measuring the dynamic lung compliance (Cdyn).
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Static Lung Compliance (Cstat)
The study will evaluate pulmonary mechanics by measuring the static lung compliance (Cstat).
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Intraoperative Mean Arterial Pressure
Hemodynamic stability will be evaluated by measuring the mean arterial pressure (MAP).
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Intraoperative Heart Rate
Hemodynamic stability will be evaluated by measuring the heart rate.
Time frame: Assessed intraoperatively (recorded at post-intubation, 30 minutes after CO2 insufflation, every hour during CO2 insufflation, 10 minutes after CO2 exsufflation, and before extubation).
Incidence of Intraoperative Hypotension and Vasopressor Use
The study will record the number of participants experiencing intraoperative hypotension, defined as mean arterial pressure \< 65 mmHg or systolic blood pressure \< 90 mmHg, and the number of participants requiring vasopressors (ephedrine or phenylephrine).
Time frame: During the anesthesia and surgical procedure.
Incidence of Postoperative Pulmonary Complications
The study will record the number of participants experiencing specific postoperative pulmonary complications, including atelectasis, pneumothorax, pneumonia, and acute respiratory distress syndrome (ARDS).
Time frame: Atelectasis and pneumothorax assessed on postoperative day 1; pneumonia and ARDS assessed within 7 days after surgery.
Incidence of Intensive Care Unit (ICU) Admission
The study will record the number of participants requiring transfer to the intensive care unit from the post-anesthesia care unit due to respiratory complications.
Time frame: Up to 7 days postoperatively
Length of Hospital Stay
The study will evaluate the length of hospital stay, calculated from the date of surgery to the date of hospital discharge.
Time frame: From the date of surgery until hospital discharge, assessed up to 30 days.
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