Effect of Periodic Alveolar Recruitment Maneuvers on Intraoperative Atelectasis in Adult Patients Undergoing Prone Lumbar Spine Surgery

During general anesthesia, especially when patients are placed in the prone (face-down) position for spine surgery, parts of the lungs may partially collapse. This condition, called atelectasis, can reduce oxygen levels and affect breathing during and after surgery. Although anesthesiologists routinely use a breathing technique known as an alveolar recruitment maneuver to reopen collapsed lung areas, performing this maneuver only once at the beginning of surgery may not be sufficient to keep the lungs open throughout longer procedures. The purpose of this study is to determine whether performing alveolar recruitment maneuvers at regular intervals during surgery can better prevent lung collapse compared with performing a single maneuver at the start of surgery. The study will include adult patients undergoing elective lumbar spine surgery under general anesthesia in the prone position. All participants will receive standard anesthesia care and a baseline alveolar recruitment maneuver after being positioned for surgery. Participants will then be randomly assigned to one of two groups. One group will receive additional alveolar recruitment maneuvers approximately once every hour during surgery, while the other group will not receive further recruitment maneuvers beyond the initial one. Lung aeration will be assessed using lung ultrasound, a non-invasive imaging method that does not involve radiation. The main outcome of the study is the presence of significant lung collapse immediately before removal of the breathing tube at the end of surgery. Secondary outcomes include measurements of breathing mechanics, oxygen levels, and the occurrence of temporary drops in oxygen saturation. The results of this study may help determine the most effective way to maintain lung function during prone spine surgery and improve respiratory safety during anesthesia.

Detailed Description General anesthesia and mechanical ventilation are known to reduce functional residual capacity and promote the development of atelectasis, particularly during prolonged surgical procedures. The prone position, which is commonly required for lumbar spine surgery, may further exacerbate these effects by altering chest wall mechanics and increasing intraabdominal and intrathoracic pressures. Intraoperative atelectasis has been associated with impaired oxygenation and adverse respiratory outcomes in the perioperative period. Alveolar recruitment maneuvers are routinely used in anesthetic practice to reopen collapsed lung units and improve lung aeration. However, evidence from pediatric populations suggests that a single recruitment maneuver followed by standard positive end-expiratory pressure may be insufficient to maintain lung aeration during prolonged prone positioning. Whether a strategy of repeated, periodic recruitment maneuvers provides additional benefit in adult patients undergoing prone spine surgery remains unclear. This prospective, single-center, randomized controlled trial is designed to evaluate the effect of periodic intraoperative alveolar recruitment maneuvers on lung aeration and respiratory mechanics in adult patients undergoing elective lumbar spine surgery in the prone position. After induction of standardized general anesthesia and placement of the patient in the prone position, lung aeration will be assessed using lung ultrasound. Lung ultrasound is a bedside, radiation-free imaging modality that allows regional evaluation of lung aeration and detection of atelectasis through validated scoring systems. All participants will receive a baseline ultrasound-guided alveolar recruitment maneuver after the initial lung ultrasound assessment in the prone position. Following this baseline intervention, participants will be randomized to one of two parallel groups. In the periodic recruitment group, alveolar recruitment maneuvers will be repeated at regular intervals during surgery, approximately once per hour. In the control group, no additional recruitment maneuvers will be performed beyond the initial baseline maneuver. Ventilation settings and anesthetic management will otherwise be standardized and consistent between groups. Lung ultrasound examinations will be performed at predefined intraoperative time points by an investigator who is blinded to group allocation. Lung aeration will be quantified using a standardized lung ultrasound scoring approach, allowing comparison of the incidence and severity of atelectasis between groups. In addition to lung ultrasound findings, intraoperative respiratory mechanics, including peak inspiratory pressure and dynamic lung compliance, will be recorded at predefined time points. Oxygen saturation will be monitored continuously, and episodes of oxygen desaturation will be documented. The primary objective of the study is to compare the incidence of significant intraoperative atelectasis between patients receiving periodic alveolar recruitment maneuvers and those receiving a single baseline maneuver. Secondary objectives include evaluation of differences in respiratory mechanics, oxygenation parameters, and the occurrence of transient intraoperative or early postoperative respiratory events. Safety outcomes related to recruitment maneuvers, such as transient hypotension or oxygen desaturation, will also be monitored. By assessing lung aeration with lung ultrasound and focusing on a practical ventilation strategy that can be easily implemented during routine anesthesia care, this study aims to provide clinically relevant data on optimizing intraoperative respiratory management in adult patients undergoing prone lumbar spine surgery.