Effects of Periodic Recruitment Maneuvers on Atelectasis and Respiratory Mechanics During Elective Spine Surgery Assessed by Lung Ultrasonography

Official title

Evaluation of the Effects of Periodic Recruitment Maneuvers on Atelectasis and Respiratory Mechanics in Elective Spine Surgery Using Lung Ultrasonography

Overview

During general anesthesia, particularly in patients undergoing spine surgery in the prone (face-down) position, increased intrathoracic and abdominal pressure may reduce lung compliance and promote the development of atelectasis (partial lung collapse). Atelectasis can impair intraoperative oxygenation and may increase the risk of postoperative pulmonary complications. Alveolar recruitment maneuvers (ARM) are routinely used in anesthesia practice to reopen collapsed lung regions; however, it remains unclear whether periodic application of ARM throughout surgery provides additional benefit compared with standard single-time application. This prospective, randomized controlled clinical study aims to evaluate whether periodic alveolar recruitment maneuvers applied during elective spine surgery in the prone position reduce intraoperative atelectasis and improve respiratory mechanics compared with the standard approach of performing ARM only after positioning and before extubation. Adult patients undergoing elective spine surgery under general anesthesia will be randomly assigned to either a periodic ARM group or a standard ARM group. Lung aeration will be assessed using lung ultrasound, a non-invasive and radiation-free bedside imaging method. The primary outcome is the incidence of intraoperative atelectasis assessed before extubation. Secondary outcomes include lung ultrasound aeration scores, respiratory mechanics parameters (such as airway pressures and compliance), oxygenation indices, and the occurrence of transient intraoperative respiratory or hemodynamic events. The findings of this study may help optimize intraoperative ventilation strategies in prone spine surgery and contribute to improved perioperative respiratory safety.

Detailed description

Atelectasis frequently develops during general anesthesia due to reduced functional residual capacity, diaphragmatic displacement, and alterations in ventilation-perfusion relationships. These effects may be more pronounced during spine surgery performed in the prone position, where increased intra-abdominal and intrathoracic pressures and altered chest wall mechanics can further impair lung compliance and promote regional lung collapse. Intraoperative atelectasis has been associated with impaired oxygenation and may contribute to postoperative pulmonary complications, making its prevention an important objective in anesthetic management.

Alveolar recruitment maneuvers (ARM) are commonly used in anesthesia practice to reopen collapsed alveoli and improve lung aeration. Standard practice often involves performing a recruitment maneuver after positioning and occasionally before extubation; however, maintenance of lung aeration throughout prolonged prone procedures may be challenging. Some previous studies, including studies in pediatric populations, suggest that repeated recruitment maneuvers during surgery may provide more sustained lung aeration compared with a single application. Nevertheless, data in adult patients undergoing prone spine surgery remain limited.

This investigator-initiated, single-center randomized controlled clinical trial has been designed to evaluate the impact of periodic intraoperative alveolar recruitment maneuvers applied at predefined intraoperative intervals according to the study protocol on lung aeration and respiratory mechanics in adult patients undergoing elective spine surgery in the prone position under general anesthesia. The study primarily aims to assess lung aeration using lung ultrasound, while secondary outcomes include respiratory mechanics and perioperative physiological parameters. The periodic recruitment strategy will be compared with a standard recruitment approach used in routine anesthesia care. All ventilation maneuvers will be performed within established safety limits commonly accepted in clinical practice and will be immediately discontinued if clinically indicated. No experimental drugs, devices, or additional invasive procedures are introduced as part of the study.

Lung aeration will be evaluated using transthoracic lung ultrasound, a bedside, radiation-free, non-invasive imaging modality increasingly adopted for perioperative pulmonary assessment. Lung ultrasound allows semi-quantitative evaluation of regional aeration loss and detection of atelectasis using validated scoring systems, providing dynamic information without exposing patients to ionizing radiation. Ultrasound assessments will be performed by a trained investigator blinded to group allocation in order to minimize assessment bias.

In addition to ultrasound-based aeration assessment, intraoperative respiratory parameters such as airway pressures, lung compliance, oxygenation indices, and relevant perioperative physiological variables will be recorded to characterize the respiratory effects of different recruitment strategies. Safety monitoring will include documentation of transient hemodynamic or respiratory changes potentially associated with recruitment maneuvers.

By evaluating a practical ventilation strategy that relies on routinely used anesthetic techniques and a non-invasive monitoring tool, this study aims to provide clinically applicable data on intraoperative respiratory management in prone spine surgery. The findings may contribute to improved understanding of whether periodic recruitment maneuvers support maintenance of lung aeration and respiratory physiology compared with standard approaches.

Interventions

• Procedure Alveolar Recruitment Maneuver
  Alveolar recruitment maneuvers will be performed under general anesthesia using standard mechanical ventilation techniques within routine clinical safety limits. After prone positioning, a baseline recruitment maneuver will be applied by stepwise increasing positive end-expiratory pressure (PEEP) from 8 cmH₂O to 10 cmH₂O and 15 cmH₂O while maintaining an upper airway pressure limit of ≤30 cmH₂O for approximately 10 seconds. Following the maneuver, mechanical ventilation will continue with a PEEP

Primary outcome measures

• Incidence of Significant Intraoperative Atelectasis Assessed by Lung Ultrasound [Time frame: Immediately prior to tracheal extubation under general anesthesia at the completion of surgery.]

Secondary outcome measures (8)

• Peak Inspiratory Pressure [Time frame: Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.]
• Dynamic Lung Compliance [Time frame: Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.]
• Peripheral Oxygen Saturation [Time frame: Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.]
• Incidence of Oxygen Desaturation [Time frame: From induction of anesthesia until 30 minutes after arrival in the post-anesthesia care unit (PACU).]
• Total Lung Ultrasound Aeration Score [Time frame: Assessed 15 minutes after prone positioning, immediately prior to tracheal extubation, and within 30 minutes after arrival in the post-anesthesia care unit (PACU).]
• Plateau Airway Pressure [Time frame: Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.]
• Alveolar-Arterial Oxygen Gradient [Time frame: Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, immediately prior to tracheal extubation, and within 30 minutes after arrival in the post-anesthesia care unit (PACU).]
• Driving Pressure [Time frame: Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.]

Eligibility criteria

Inclusion criteria

• Adults aged 18 to 65 years
• Scheduled for elective lumbar spine surgery under general anesthesia
• Surgery planned to be performed in the prone position
• Expected surgical duration of at least 2 hours
• American Society of Anesthesiologists (ASA) physical status I-II
• Ability to provide written informed consent

Exclusion criteria

• Body mass index (BMI) greater than 30 kg/m²
• History of thoracic surgery
• Known or suspected chronic pulmonary disease (e.g., chronic obstructive pulmonary disease, restrictive lung disease)
• Clinically significant cardiac disease
• Pregnancy or breastfeeding
• Known airway anomalies

Intraoperative surgical duration shorter than 2 hours

Refusal or inability to provide informed consent

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Prevention

Study locations

Turkey (Türkiye) · 1 center

• Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization — Istanbul

Publications

• York J, Nugent K. Using lung ultrasound to guide PEEP determination in mechanically ventilated patients. Southwest Respir Crit Care Chron. 2023;11(47):10-20.
• Lee JM, Lee SK, Kim KM, Kim YJ, Park EY. Comparison of volume-controlled ventilation mode and pressure-controlled ventilation with volume-guaranteed mode in the prone position during lumbar spine surgery. BMC Anesthesiol. 2019 Jul 27;19(1):133. doi: 10.1186/s12871-019-0806-7. PMID 31351445
• Gunenc FS, Seyidova I, Ozbilgin S, Ur K, Hanci V. Comparison of pressure controlled, volume controlled, and volume guaranteed pressure controlled modes in prone position in patients operated for lumbar disc herniation: A randomized trial. Medicine (Baltimore). 2024 Feb 9;103(6):e37227. doi: 10.1097/MD.0000000000037227. PMID 38335373
• Jang YE, Ji SH, Kim EH, Lee JH, Kim JT, Kim HS. Effect of regular alveolar recruitment on intraoperative atelectasis in paediatric patients ventilated in the prone position: a randomised controlled trial. Br J Anaesth. 2020 May;124(5):648-655. doi: 10.1016/j.bja.2020.01.022. Epub 2020 Mar 10. PMID 32169254
• Acosta CM, Maidana GA, Jacovitti D, Belaunzaran A, Cereceda S, Rae E, Molina A, Gonorazky S, Bohm SH, Tusman G. Accuracy of transthoracic lung ultrasound for diagnosing anesthesia-induced atelectasis in children. Anesthesiology. 2014 Jun;120(6):1370-9. doi: 10.1097/ALN.0000000000000231. PMID 24662376
• Guldner A, Kiss T, Serpa Neto A, Hemmes SN, Canet J, Spieth PM, Rocco PR, Schultz MJ, Pelosi P, Gama de Abreu M. Intraoperative protective mechanical ventilation for prevention of postoperative pulmonary complications: a comprehensive review of the role of tidal volume, positive end-expiratory pressure, and lung recruitment maneuvers. Anesthesiology. 2015 Sep;123(3):692-713. doi: 10.1097/ALN.00000 PMID 26120769
• Hartland BL, Newell TJ, Damico N. Alveolar recruitment maneuvers under general anesthesia: a systematic review of the literature. Respir Care. 2015 Apr;60(4):609-20. doi: 10.4187/respcare.03488. Epub 2014 Nov 25. PMID 25425708

Identifiers

NCT: NCT07325812 · CTERHO-SOZER-LUS-ARM-PRONE-001

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗