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

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

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.

Study Overview

• Status: Recruiting
• Conditions: General Anesthesia; Mechanical Ventilation; Prone Position; Atelectasis
• Intervention / Treatment: Procedure: Alveolar Recruitment Maneuver

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.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Serap KARACALAR, MD (Doctor of Medicine); Phone Number: +90 532 395 93 03; Email: skaracalar@yahoo.com
• Study Contact Backup: Name: Serencan OZER, MD (Doctor of Medicine); Phone Number: +90 506 423 96 68; Email: serencanozalp@gmail.com

Study Locations

• Turkey (Türkiye)
  • Istanbul, Turkey (Türkiye)
    • Recruiting
    • Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization
    • Contact: Serap KARACALAR, MD (Doctor of Medicine); Phone Number: +90 532 395 93 03; Email: skaracalar@yahoo.com
    • Contact: Serencan OZER, MD (Doctor of Medicine); Phone Number: +90 506 423 96 68; Email: serencanozalp@gmail.com
    • Principal Investigator: Serap KARACALAR, MD (Doctor of Medicine)
    • Sub-Investigator: Serencan OZER, MD (Doctor of Medicine)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Periodic Alveolar Recruitment Maneuver Group; Participants assigned to this arm will receive standardized general anesthesia and mechanical ventilation according to routine clinical practice. After prone positioning, all participants will undergo a baseline alveolar recruitment maneuver performed within established clinical safety limits. In this experimental arm, additional alveolar recruitment maneuvers will be applied approximately once per hour throughout the intraoperative period to help maintain lung aeration. A final recruitment maneuver will also be performed before extubation as part of standard anesthetic care. Apart from the timing of recruitment maneuvers, intraoperative anesthetic and ventilatory management will be conducted according to routine clinical practice and individualized based on patient requirements.	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 level of approximately 8 cmH₂O according to routine clinical practice. In the periodic recruitment group, additional recruitment maneuvers will be repeated approximately once per hour during the intraoperative period. In the standard recruitment group, no additional intraoperative maneuvers will be applied apart from a final recruitment maneuver performed before extubation as part of routine anesthetic care.; Other Names: Lung Recruitment Maneuver
Active Comparator: Standard Alveolar Recruitment Maneuver Group; Participants assigned to this arm will receive standardized general anesthesia and mechanical ventilation according to routine clinical practice. After prone positioning, a baseline alveolar recruitment maneuver will be performed within established clinical safety limits. No additional recruitment maneuvers will be applied during the intraoperative period apart from a final recruitment maneuver performed before extubation as part of standard anesthetic care. Intraoperative anesthetic and ventilatory management will otherwise follow routine clinical practice and will be guided by patient safety considerations.	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 level of approximately 8 cmH₂O according to routine clinical practice. In the periodic recruitment group, additional recruitment maneuvers will be repeated approximately once per hour during the intraoperative period. In the standard recruitment group, no additional intraoperative maneuvers will be applied apart from a final recruitment maneuver performed before extubation as part of routine anesthetic care.; Other Names: Lung Recruitment Maneuver

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Significant Intraoperative Atelectasis Assessed by Lung Ultrasound	Significant intraoperative atelectasis will be defined as the presence of significant loss of lung aeration identified by transthoracic lung ultrasound, corresponding to a regional score of 2 or higher in at least one predefined lung region using a standardized 12-region semi-quantitative lung ultrasound aeration scoring system. In this system, each region is scored from 0 to 3, with higher scores indicating greater loss of lung aeration. Lung ultrasound examinations will be performed according to a predefined scanning protocol, and image interpretation will be conducted by an assessor blinded to group allocation.	Immediately prior to tracheal extubation under general anesthesia at the completion of surgery.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak Inspiratory Pressure	Peak inspiratory pressure will be recorded from the anesthesia ventilator during mechanical ventilation and documented prospectively to characterize intraoperative respiratory mechanics.	Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.
Dynamic Lung Compliance	Dynamic lung compliance will be calculated from ventilator-derived tidal volume and airway pressure measurements during mechanical ventilation and documented prospectively to characterize respiratory system mechanics under general anesthesia.	Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.
Peripheral Oxygen Saturation	Peripheral oxygen saturation (SpO2) will be recorded using standard pulse oximetry at predefined intraoperative study time points for analysis. Peripheral oxygen saturation (SpO₂) will be continuously monitored using standard pulse oximetry during general anesthesia and early postoperative recovery. Recorded values will be documented at predefined time points for analysis.	Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.
Incidence of Oxygen Desaturation	Oxygen desaturation will be defined as any documented episode of peripheral oxygen saturation (SpO2) below 95 percent measured by pulse oximetry during intraoperative monitoring or within 30 minutes after arrival in the post-anesthesia care unit (PACU).	From induction of anesthesia until 30 minutes after arrival in the post-anesthesia care unit (PACU).
Total Lung Ultrasound Aeration Score	Total lung aeration will be assessed using transthoracic lung ultrasound with a standardized 12-region semi-quantitative lung ultrasound aeration scoring system. Each region will be scored from 0 to 3 (0 = normal aeration, 1 = moderate loss of aeration, 2 = severe loss of aeration, 3 = lung consolidation), resulting in a total score ranging from 0 to 36, where higher scores indicate greater loss of lung aeration. The total lung ultrasound score represents a semi-quantitative measure of global loss of lung aeration. Examinations will be performed by an investigator blinded to group allocation.	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	Plateau airway pressure will be recorded from the anesthesia ventilator during mechanical ventilation and documented prospectively to characterize intraoperative respiratory mechanics.	Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.
Alveolar-Arterial Oxygen Gradient	The alveolar-arterial oxygen gradient will be calculated using arterial blood gas measurements together with the corresponding inspired oxygen fraction (FiO2) values obtained at predefined study time points to evaluate gas exchange. Measurements will be recorded in parallel with lung ultrasound assessments and at approximately hourly intraoperative intervals.	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	Driving pressure will be calculated from ventilator-derived airway pressure measurements as the difference between plateau pressure and positive end-expiratory pressure during mechanical ventilation and documented prospectively to characterize respiratory mechanics.	Assessed 15 minutes after prone positioning, at approximately hourly intraoperative intervals, and immediately prior to tracheal extubation.

Collaborators and Investigators

• Sponsor: Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization
• Investigators: Principal Investigator: Serap KARACALAR, MD (Doctor of Medicine), Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

Publications and helpful links

General Publications

• 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.
• 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.
• 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.0000000000000754.
• 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.
• 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.
• 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.

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026

Study Registration Dates

• First Submitted: December 25, 2025
• First Submitted That Met QC Criteria: December 25, 2025
• First Posted (Actual): January 8, 2026

Study Record Updates

• Last Update Posted (Actual): April 8, 2026
• Last Update Submitted That Met QC Criteria: April 2, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Prone Position; Atelectasis; Respiratory Mechanics; Lung Ultrasound; Alveolar Recruitment Maneuver
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Lung Diseases; Pulmonary Atelectasis
• Other Study ID Numbers: CTERHO-SOZER-LUS-ARM-PRONE-001

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No