An interventional study of Low Fresh Gas Flow (0.5 L/min) and High Fresh Gas Flow (4 L/min) in Postoperative Atelectasis and Pulmonary Atelectasis, sponsored by Adiyaman University. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-08-07.
Sponsored by Adiyaman University · Not applicable, Interventional, and Treatment
This prospective randomized clinical trial aims to evaluate the effects of different fresh gas flow rates on postoperative pulmonary aeration using lung ultrasonography in patients undergoing elective laparoscopic cholecystectomy. Patients will be randomly assigned to receive either low-flow anesthesia (0.5 L/min) or high-flow anesthesia (4 L/min) during maintenance of general anesthesia. The primary objective is to compare postoperative lung ultrasound scores and the incidence of atelectasis between the two groups.
Pulmonary atelectasis is one of the most common postoperative pulmonary complications following general anesthesia. Fresh gas flow is an important component of inhalational anesthesia and may influence airway humidity, gas exchange, respiratory mechanics, and pulmonary physiology. Although low-flow anesthesia has recognized economic, environmental, and physiological advantages, the effect of different fresh gas flow rates on postoperative lung aeration has not been adequately investigated.
This prospective, randomized, parallel-group clinical trial will be conducted at Adıyaman University Training and Research Hospital. Adult patients scheduled for elective laparoscopic cholecystectomy under general anesthesia will be randomly allocated to either a low-flow group (0.5 L/min) or a high-flow group (4 L/min) after an initial fresh gas flow of 4 L/min for 8 minutes following endotracheal intubation. Standardized anesthesia management will be applied to all participants.
Postoperative lung ultrasonography will be performed 30 minutes after extubation in the post-anesthesia care unit. Lung Ultrasound Score (LUS) and the incidence of postoperative atelectasis will be compared between the study groups. The findings are expected to provide evidence regarding the effects of different fresh gas flow strategies on postoperative pulmonary outcomes and may contribute to optimizing intraoperative anesthesia management.
377 studies on the registry are indexed under Pulmonary Atelectasis; 93 are open to participants now.
This study's planned enrollment of 120 is above the median of 60 across 268 interventional studies indexed under Pulmonary Atelectasis.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive general anesthesia with a fresh gas flow rate of 0.5 L/min during the maintenance phase following an initial fresh gas flow of 4 L/min for 8 minutes after endotracheal intubation. Postoperative lung ultrasonography will be performed 30 minutes after extubation.
Procedure: Low Fresh Gas Flow (0.5 L/min)
Participants will receive general anesthesia with a fresh gas flow rate of 4 L/min during the maintenance phase following an initial fresh gas flow of 4 L/min for 8 minutes after endotracheal intubation. Postoperative lung ultrasonography will be performed 30 minutes after extubation.
Procedure: High Fresh Gas Flow (4 L/min)
General anesthesia will be maintained using a fresh gas flow rate of 0.5 L/min after an initial fresh gas flow of 4 L/min for 8 minutes following endotracheal intubation.
General anesthesia will be maintained using a fresh gas flow rate of 4 L/min after an initial fresh gas flow of 4 L/min for 8 minutes following endotracheal intubation.
Postoperative Lung Ultrasound Score
Lung ultrasonography will be performed 30 minutes after extubation. Both lungs will be divided into 12 regions, with 6 regions assessed in each lung. Each region will be scored from 0 to 3: 0 indicates normal aeration with A-lines or fewer than three B-lines; 1 indicates at least three well-spaced B-lines; 2 indicates coalescent B-lines; and 3 indicates lung consolidation. The scores from all regions will be summed, resulting in a total score ranging from 0 to 36. Higher scores indicate greater loss of lung aeration.
Time frame: 30 minutes after extubation
Incidence of postoperative atelectasis
Atelectasis will be defined as a consolidation score ≥2 in any lung region assessed by lung ultrasonography
Time frame: 30 minutes after extubation
Peripheral oxygen saturation (SpO₂)
Time frame: During surgery
Mean arterial pressure
Time frame: During surgery
Heart rate
Time frame: During surgery
Peak airway pressure
Peak airway pressure will be recorded during general anesthesia and compared between the low and high fresh gas flow groups.
Time frame: Throughout the intraoperative period
Plan to share: No
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Adiyaman University