4. Discussion
pleural effusion, atelectasis, PCV-VG, respiratory and cardiac illnesses, aeration loss with postoperative LUS, aeration loss, barotrauma
PLEURAL EFFUSION, ATELECTASIS, COMPLICATION
Using lung ultrasound, we found that aeration loss occurs during laparoscopic cholecystectomy in this randomized controlled trial. The ventilation modes, VCV and PCV-VG, did not influence the development and amount of atelectasis. LUS scores showed less aeration loss in the PCV-VG group only in the right region. The PCV-VG ventilation mode was associated with better lung mechanics in the patients.In our study, the results of the analysis of the mechanical ventilation parameters may be attributed to some advantages that the PCV-VG mode provides over the VCV. The PCV-VG mode delivers the preset tidal volume with a decelerating flow at the lowest possible pressure. When using the pressure-controlled ventilation mode, the required tidal volume is provided to the patient performing the compliance changes required to achieve a consistent tidal volume. The PCV-VG offers the benefits of PCV with better oxygenation and the security of consistent tidal volume. Due to all these reasons, the PCV-VG is useful for any surgical procedure including laparoscopy, where the patient’s compliance is expected to change perioperatively. As compared to volume-controlled ventilation, it provides better oxygenation at lower peak inspiratory pressures and higher mean airway pressures [Volume-controlled ventilation has been the traditional mode of controlled ventilation in anesthesia. In VCV, the ventilator delivers the preset tidal volume with a constant flow at the preset respiratory rate during a preset inspiratory time. It has been the preferred mode of mechanical ventilation in anesthesia applications due to its ability to control Minute Volume. However, the VCV uses a constant flow that may cause high peak pressures and thus expose the patient to the risk of barotrauma [Similarly in the study of Assad et al., the PCV-VG mode was determined to be superior to the VCV mode with a significantly lower peak inspiratory pressure and greater dynamic compliance than the VCV mode [Another study on laparoscopic gynecological surgeries drew a comparison between VCV and PCV and reported a significant increase in the peak airway pressure, compliance, plateau pressure, and airway resistance when VCV was used [One of the unique features of our study is that we evaluated aeration loss with postoperative LUS scores. When the LUS scores were evaluated, it was observed that all patients developed aeration loss following laparoscopic surgery with elevated LUS scores. The increase in the incidence of aeration loss in these patients was regardless of the perioperative mechanical ventilation parameters. However, it is worthy of note that the change in the postoperative LUS score inferoanterior zone of the right lung was significantly greater in the V group compared to the PV group. Another advantage besides effective ventilation was that atelectasis complication did not occur.In addition to intraoperative techniques to prevent atelectasis in abdominal surgeries, it would be pertinent to discuss several postoperative strategies. These include the use of noninvasive ventilator support or high-flow nasal cannula in high-risk patients such as those with a BMI > 30, respiratory and cardiac illnesses, prolonged surgery duration, and major surgery. Both these strategies can be employed as prophylactics, as well as therapeutics, in the postoperative period.Strategies to prevent atelectasis in the postoperative period include early mobilization, respiratory physiotherapy that expands the lungs, non-opioid analgesia that is effective, oxygen therapy, mucolytics, eliminating causes that may cause external compression of the thorax, reducing abdominal pressure, evacuating the stomach with a nasogastric tube, and draining any pleural effusion that may be present in the thorax [