Effect of Different Inspired Oxygen Concentrations on Intraoperative Recruitment Outcomes in Patients Undergoing Abdominal Surgery
Phase: NA
Conditions: Pulmonary Atelectasis, Postoperative
Sponsor: Northern Jiangsu People's Hospital

Research Protocol
Effect of Different Inspired Oxygen Concentrations on Intraoperative Lung Recruitment
Efficacy in Patients Undergoing Abdominal Surgery
Sponsoring Institution: Northern Jiangsu People's Hospital
Leading Institution: NA
Responsible Department: Department of Anesthesiology
Principal Investigator: Gao Ju
Study Period: December 2024 to February 2026
Version Number: V1.0
Version Date: October 16, 2024
Table of Contents
1. Protocol Summary 3
2. Research Background 4
3. Research Objectives 6
4. Study Design, Principles, and Procedures 6
4.1 Study Design 6
4.2 Study Procedures 6
4.3 Indications 6
4.4 Study Endpoints 7
5. Study Subjects 7
5.1 Study Population 7
5.2 Inclusion Criteria 7
5.3 Exclusion Criteria 7
5.4 Exclusion Criteria 7
5.5 Recruitment Process 8
5.6 Criteria for Terminating the Study 8
6. Research Methods and Technical Route 8
6.1 Study Grouping 8
6.2 Intervention Measures 8
6.3 Study Intervention Protocol 8
6.4 Concomitant Medications 9

6.5 Study Flowchart 9
6.6 Study-Related Laboratory Tests 9
6.7 Study-Related Imaging Examinations 10
7. Efficacy Evaluation Criteria 10
8. Observation Items and Detection Time Points 10
9. Observation of Adverse Events 10
9.1 Definition and Assessment of Adverse Events 10
9.2 Recording and Handling of Adverse Events 10
9.2.1 Recording of Adverse Events 10
9.2.2 Handling of Adverse Events 11
9.2.3 Reporting of Adverse Events 11
10.
Quality Control and Quality Assurance 11
11.
Data Safety Monitoring 11
12.
Statistical Analysis 12
12.1 Statistical Methods (Including Description of Statistical Methods, Statistical Software
and Version) 12
12.2 Sample Size Calculation Process 12
13.
Ethics of Clinical Research 12
14.
Collection and Storage of Samples/Specimens 13
15.
Study Progress 13
16.
References 14
1. Protocol Summary
Item
Details
Project
Name
Effect of Different Inspired Oxygen Concentrations on Intraoperative Lung
Recruitment Efficacy in Patients Undergoing Abdominal Surgery
Research
Objective
To investigate the effect of different inspired oxygen concentrations on
intraoperative lung recruitment efficacy in patients undergoing abdominal
surgery
Study
Design
A single-center, prospective, randomized controlled studyStudy population:
Patients undergoing elective abdominal surgeryTrial protocol: Primary
outcome measure: Time to recovery of lung compliance; Secondary

outcome measures: Comparison of oxygenation index before anesthesia
induction and after extubation, degree of atelectasis at the end of surgery,
incidence of hypoxemia during PACU stay, and incidence of pulmonary
complications within 3 days after surgery.
Sample Size
88 casesSample size calculation process Based on preliminary experimental
results, sample size was calculated using PASS, with a 20% dropout rate,
resulting in a total sample size of 88 cases (22 cases in each group).
Input：
Power and Alpha
Power 0.95
Alpha 0.05
Group 4
Group Allocation Equal
Effect size
Means 30 34 50 53
K 1
σ 7 6 15 19
Case
Selection
Target population: Patients undergoing abdominal surgery
Inclusion CriteriaPatients with ASA physical statusⅠ-Ⅱ;Patients who
voluntarily participate in the study and sign the informed consent
form;Patients undergoing elective abdominal surgery under general
anesthesia;Gender 不限，aged 18-64 years, BMI 18-25 kg/m²;Expected
operation time ≥1.5 hours, and intraoperative blood loss ≤500 ml.

Exclusion CriteriaPrevious thoracic surgery; chest X-ray or CT indicating
pneumothorax or pulmonary bullae;Pulmonary diseases: chronic bronchitis,
asthma, moderate to severe obstructive ventilatory dysfunction; preoperative
pulse oxygen saturation (SpO2) <90% in room air or <95% with oxygen
inhalation; contraindications to lung recruitment: high intracranial pressure,
hypovolemic shock, right heart failure;Severe heart disease (New York Heart
Association, NYHA class III or IV; acute coronary syndrome or persistent
ventricular tachyarrhythmia);Participation in other interventional studies or
refusal to enroll.
Treatment
Protocol
None
Efficacy
Evaluation
Efficacy evaluation indicators (primary and secondary efficacy
indicators)Primary outcome indicator: Time for dynamic lung compliance
(Cdyn) to return to baseline after lung recruitment;Secondary outcome
indicators: Degree of atelectasis immediately after extubation, evaluated by
lung ultrasound; oxygenation index at T0-T5; incidence of hypoxemia and
duration of oxygen therapy during PACU stay; pulmonary complications
within 3 days after surgery, evaluated by postoperative chest X-ray or CT,
with atelectasis assessed by lung ultrasound.
Safety evaluation indicators: None
Statistical
Methods
Descriptive statistics, Mann-Whitney U test, t-test, Chi-square test, etc.
2. Research Background
During perioperative mechanical ventilation, high fractional inspired oxygen (FiO2) is usually
administered to prevent hypoxemia. Although numerous studies have shown that the use of
high FiO2 during surgery can improve oxygen supply to vital organs such as the heart, brain,
and kidneys, inhalation of high-concentration oxygen is also a risk factor for postoperative
pulmonary complications. Therefore, there is no consensus on the optimal intraoperative
FiO2 setting[1].
Lung recruitment typically includes manual lung recruitment and ventilator-driven lung
recruitment, with the latter including vital capacity maneuver, pressure-controlled method,
and volume-controlled method. Various lung recruitment methods can effectively open
alveoli and improve oxygenation[3].
Evaluation of lung recruitment efficacy includes pressure-volume (P-V) curve, electrical
impedance tomography (EIT), and lung ultrasound (LUS).
The P-V curve describes the relationship between airway pressure and tidal volume,
reflecting the mechanical properties of the lungs and chest wall, and can assist in judging the

ventilation status of the lungs. A normal P-V curve is "S"-shaped, with the zero point
representing functional residual capacity (FRC), and the volume change range being tidal
volume. The P-V curve is an effective bedside tool for evaluating respiratory mechanics and
lung recruitment efficacy.
The basic principle of EIT is to apply weak voltage and current to the human body through
local electrodes, sense changes in internal bioelectrical impedance, and reconstruct internal
structure images using algorithms. High extracellular fluid content, high electrolyte
concentration, large cell volume, and multiple intercellular connections reduce impedance,
while adipose tissue, bone, and air increase impedance. This method is non-invasive, simple,
and provides rich information, and can be used for bedside detection and monitoring. Gas
has high impedance, and blood flow has low impedance; thoracic impedance changes with
ventilation and blood flow. Moreover, lung tissue is close to the body surface, so changes in
lung volume and conductivity can be easily detected. In animal models, indicators such as
ventilation center shift, compliance of dependent and non-dependent lung regions, and tidal
distribution index on EIT can assist in judging changes in local ventilation distribution during
lung recruitment[4]. Spadaro et al. dynamically monitored the ventilation status of the gravity-
dependent static lung zone (DSS) using EIT and evaluated lung recruitment efficacy using
the P-V curve. During lung recruitment, with the increase of PEEP, DSS decreased while
lung recruitment volume increased. The opposite change occurred when PEEP decreased.
DSS was correlated with changes in lung recruitment volume (r=0.734, P<0.001). EIT can
calculate the compliance of local lung regions to judge the impact of PEEP on local alveolar
ventilation and can also be used for titrating individualized PEEP.
Although computed tomography (CT) is considered the "gold standard" for evaluating lung
recruitment efficacy, its high requirements for equipment and site, as well as large radiation
dose, limit its use. LUS can also be used to check the ventilation status of the lungs,
because diseases change the ratio of gas to fluid in the lungs, and LUS shows
corresponding signs such as tissue-like changes and "fragment sign". Quantitative
evaluation can also be performed using LUS scores. Song et al.[5] used ultrasound-guided
lung recruitment in children under 1 year old, which significantly reduced the incidence of
atelectasis. Wu et al.[6] compared the effects of ultrasound-guided lung recruitment, manual
lung recruitment, and mechanical ventilation without lung recruitment in laparoscopic
gynecological surgery, and the results showed that lung recruitment improved intraoperative
oxygenation and reduced LUS scores, with the ultrasound-guided group having the best
effect. Even 30 minutes after tracheal extubation, the difference in LUS scores between
groups remained significant. However, no differences were observed in PPC, postoperative
pain, or postoperative hospital stay, which may be related to normal preoperative lung
function and short operation time in all patients.
Most current studies tend to inhale low-concentration oxygen while ensuring adequate
oxygenation. Studies have shown that inhalation of high-concentration oxygen during
surgery and before extubation can lead to postoperative atelectasis and even impair
postoperative oxygenation function. However, blindly reducing FiO2 before extubation may
bring troubles to crisis management after extubation, and it is not beneficial to blindly reduce
FiO2 without ensuring adequate airway patency[7]. Studies have shown that applying 10
cmH2O continuous positive airway pressure before and during induction, and 10 cmH2O

PEEP during surgery can improve oxygenation function in patients undergoing laparoscopic
surgery. This seems to suggest that if high-concentration oxygen is inhaled during surgery,
alveolar patency can be maintained by applying continuous positive airway pressure, and
then FiO2 can be gradually reduced to reduce the risk of postoperative atelectasis and
hypoxemia.
Dynamic lung compliance can monitor alveolar changes in real-time, which is of great
significance for evaluating intraoperative lung function. The value of compliance represents
the number of gas-containing alveoli; the more alveoli collapse, the less gas-containing
tissue, and the lower the compliance, which can objectively reflect lung function. With the
continuous development of medical technology, laparoscopic surgery has become
increasingly popular. Studies have found that intraoperative pneumoperitoneum can
increase intra-abdominal pressure, cause diaphragmatic elevation, significantly reduce end-
expiratory lung volume, and abnormal distribution of ventilation/perfusion ratio. In
gynecological laparoscopic surgery, patients usually adopt the Trendelenburg position.
Under the influence of gravity, the Trendelenburg position further exacerbates the
compression of the diaphragm, leading to alveolar collapse, further reduction of functional
residual capacity and dynamic lung compliance, and increased risk of postoperative
atelectasis[2].
As part of the lung-protective ventilation strategy, lung recruitment has been widely used.
However, there is no unified consensus on lung recruitment strategies in current
international guidelines. The time for lung compliance to return to baseline after lung
recruitment is unclear, and the optimal inspired oxygen concentration that can benefit
patients from lung recruitment is uncertain. Based on this, this study intends to evaluate the
effect of different inspired oxygen concentrations on lung recruitment efficacy in patients
undergoing abdominal surgery.
3. Research Objectives
3.1 Primary objective: To investigate the effect of different inspired oxygen concentrations on
the time for lung compliance to return to baseline after lung recruitment in patients
undergoing abdominal surgery;
3.2 Secondary objectives: To explore the comparison of oxygenation index before
anesthesia induction and after extubation, incidence of hypoxemia during PACU stay,
incidence of atelectasis after extubation, and incidence of pulmonary complications within 3
days after surgery in patients undergoing abdominal surgery with different inspired oxygen
concentrations after lung recruitment;
4. Study Design, Principles, and Procedures
4.1 Study Design
Study design type: A single-center, prospective, randomized controlled study
Grouping method: Patients were randomly divided into 4 groups using a random number
table method: Group A, Group B, Group C, and Group D, with 22 cases in each group.

Randomization was generated by computer using R software (version 3.5.1, R Foundation
for Statistics Computing, Vienna, Austria). An assistant not involved in the study concealed
the allocation in opaque envelopes and handed them to the attending anesthesiologist
before general anesthesia induction. The ultrasound examiner (BRK or HB) was completely
blinded to group allocation.
Blinding level: Blinding was applied to subjects and data collectors
Study center: Northern Jiangsu People's Hospital
Rationality of indications: Lung recruitment is a mechanical ventilation scheme proposed for
alveolar collapse, which fully opens alveoli by means of continuous high airway pressure or
intermittent increase of alveolar peak pressure, and applies appropriate positive end-
expiratory pressure to maintain alveolar patency to improve oxygenation in patients.
4.2 Study Procedures
Study population: Patients undergoing elective abdominal surgery
Grouping: Group A: FiO2=30% (if SpO2<94%, increase FiO2; if FiO2≥40%, the patient was
excluded); Group B: FiO2=40%; Group C: FiO2=60%; Group D: FiO2=80%. Inspired oxygen
concentrations were adjusted to the respective group levels after the start of surgery.
Trial protocol: Patients entered the operating room, preoxygenated for 3 minutes, followed
by anesthesia induction. After the drugs took full effect, tracheal intubation was performed.
Inspired oxygen concentrations were adjusted to the respective group levels after the start of
surgery. The first lung recruitment was performed 10 minutes later. The second lung
recruitment was performed after lung compliance returned to baseline. All patients
underwent lung recruitment immediately at the end of surgery. Respiratory mechanics
parameters, hemodynamic parameters, etc., were recorded. The incidence of hypoxemia
during PACU stay and postoperative atelectasis evaluated by ultrasound were recorded.
4.3 Indications
Atelectasis after general anesthesia
4.4 Study Endpoints
Incidence of pulmonary complications within 3 days after surgery.
5. Study Subjects
5.1 Study Population
Patients undergoing elective abdominal surgery;
5.2 Inclusion Criteria
Patients with ASA physical statusⅠ-Ⅱ;

Patients who voluntarily participate in the study and sign the informed consent form;
Patients undergoing elective abdominal surgery under general anesthesia;
Gender unlimited, aged 18-64 years, BMI 18-25 kg/m²;
Expected operation time ≥1.5 hours, and intraoperative blood loss ≤500 ml.
5.3 Exclusion Criteria
Previous thoracic surgery; chest X-ray or CT indicating pneumothorax or pulmonary bullae;
Pulmonary diseases: chronic bronchitis, asthma, moderate to severe obstructive ventilatory
dysfunction; preoperative pulse oxygen saturation (SpO2) <90% in room air or <95% with
oxygen inhalation; contraindications to lung recruitment: high intracranial pressure,
hypovolemic shock, right heart failure;
Severe heart disease (New York Heart Association, NYHA class III or IV; acute coronary
syndrome or persistent ventricular tachyarrhythmia); participation in other interventional
studies or refusal to enroll.
5.4 Exclusion Criteria
In Group A (FiO2=30%), if SpO2<94%, FiO2 was increased; if FiO2≥40%, the patient was
excluded.
5.5 Recruitment Process
Subjects were visited one day before surgery to understand whether their medical history
met the inclusion and exclusion criteria. After confirmation, the experimental process and
anesthesia method were communicated with the family members. If the subjects and their
families agreed, the anesthesia consent form and clinical trial informed consent form were
signed. Eligible subjects were enrolled and randomly grouped.
5.6 Criteria for Terminating the Study
Considerations for the safety of subjects. For example, situations where it is inappropriate to
continue the study, including: worsening of the condition, serious adverse events, poor
compliance, etc. Postoperative occurrence of surgery-related complications such as
postoperative bleeding requiring reoperation should result in termination of the study.
6. Research Methods and Technical Route
6.1 Study Grouping
Grouping: Group A: FiO2=30% (if SpO2<94%, increase FiO2; if FiO2≥40%, the patient was
excluded); Group B: FiO2=40%; Group C: FiO2=60%; Group D: FiO2=80%. Inspired oxygen
concentrations were adjusted to the respective group levels after the start of surgery.

6.2 Intervention Measures
Lung recruitment
6.3 Study Intervention Protocol
Patients entered the operating room, preoxygenated for 3 minutes, followed by anesthesia
induction. After the drugs took full effect, tracheal intubation was performed. Inspired oxygen
concentrations were adjusted to the respective group levels after the start of surgery. The
first lung recruitment was performed 10 minutes later. The second lung recruitment was
performed after lung compliance returned to baseline. Respiratory mechanics parameters,
hemodynamic parameters, etc., were recorded. The incidence of hypoxemia during PACU
stay and postoperative atelectasis evaluated by ultrasound were recorded.
6.4 Concomitant Medications
There were no concomitant medications in this study.
6.5 Study Flowchart
![img](Patients enter the operating room
Preoxygenation followed by tracheal intubation
Adjust to group-specific FiO2 after surgery starts
Group A: FiO2 30%
Group B: FiO2 40%
Group C: FiO2 60%
Group D: FiO2 80%
First lung recruitment after 10 minutes
Record the duration of improved lung compliance
Next lung recruitment after compliance returns to baseline, and so on
All patients undergo lung recruitment immediately at the end of surgery,
Transfer to PACU, record incidence of hypoxemia and duration of oxygen therapy)
6.6 Study-Related Laboratory Tests
Liver and kidney function, blood routine, coagulation function, blood gas analysis
6.7 Study-Related Imaging Examinations
Electrocardiogram
7. Efficacy Evaluation Criteria

Observation of primary outcome indicators: Time for dynamic lung compliance (Cdyn) to
return to baseline after lung recruitment. Respiratory mechanics parameters and
hemodynamic parameters at T1-T5 were recorded, including Cdyn, PIP, Ppeak, Pplat, Vt,
PEEP, MP, Pdrive, BP, HR;
Observation of secondary outcome indicators: Degree of atelectasis immediately after
extubation, evaluated by lung ultrasound; oxygenation index at T0-T5; incidence of
hypoxemia and duration of oxygen therapy during PACU stay; pulmonary complications
within 3 days after surgery, evaluated by postoperative chest X-ray or CT, with atelectasis
assessed by lung ultrasound.
8. Observation Items and Detection Time Points
Before the first lung recruitment (RM1) after surgery starts (T1), immediately after RM1 (T2),
before RM2 (T3), immediately after RM2 (T4), and immediately at the end of surgery (T5).
Primary and secondary outcome indicators were observed. Degree of atelectasis
immediately after extubation, evaluated by lung ultrasound; oxygenation index at T0-T5;
incidence of hypoxemia and duration of oxygen therapy during PACU stay; pulmonary
complications within 3 days after surgery, evaluated by postoperative chest X-ray or CT, with
atelectasis assessed by lung ultrasound.
9. Observation of Adverse Events
9.1 Definition and Assessment of Adverse Events
Adverse Event (AE) refers to any untoward medical event that occurs after a subject
receives the investigational product, which may present as symptoms, signs, diseases, or
abnormal laboratory tests, but is not necessarily causally related to the investigational
product.
Serious Adverse Event (SAE) refers to an adverse medical event that occurs after a subject
receives the investigational product, including death, life-threatening conditions, permanent
or severe disability or functional loss, need for hospitalization or prolongation of
hospitalization, and congenital anomalies or birth defects.
Adverse Drug Reaction (ADR) refers to any harmful or unintended reaction that may be
related to the investigational product in clinical trials. There is at least a reasonable
possibility of a causal relationship between the investigational product and the adverse event,
i.e., the correlation cannot be excluded.
Suspected Unexpected Serious Adverse Reaction (SUSAR) refers to a suspected and
unexpected serious adverse reaction whose nature and severity exceed the information in
the investigator's brochure, labeling, or product characteristic summary of the investigational
drug.
Investigators will closely observe adverse events in subjects. All adverse events reported by
subjects or observed by investigators from randomization to the end of the study or early
withdrawal must be recorded in medical records or CRFs, including laboratory and auxiliary
examinations, and at least include the name of the AE, time of occurrence, end time,

severity, whether corrective treatment was given, outcome, and causal relationship with the
study.
During the study, changes in vital signs, physical examinations, clinical manifestations, and
laboratory tests of subjects should be evaluated. When signing the informed consent form,
the name and phone number of the researcher whom the subject can contact in case of
emergency, or when reporting any medical symptoms or subject-related AEs, must be
provided. Pre-existing toxic reactions or AEs in subjects before participating in the clinical
study are only recorded as AEs if the grade increases by one or more levels compared with
the baseline assessment results during the study.
CTCAE Grade
Equivalent
Definition
Grade 1
Mild
Mild physical discomfort,
not affecting daily life and
function
Grade 2
Moderate
Physical discomfort,
affecting daily life and
function, no indication for
treatment
Grade 3
Severe
Symptomatic, affecting
daily life and function,
with indication for
treatment
Grade 4
Life-
threatening/disability/functional
loss
Life-threatening, with
indication for emergency
treatment, physical
disability or intellectual
impairment
Grade 5
Death
Adverse event resulting
in death
AE and Study Correlation Analysis Table
Definite
Probable
Possible
Suspected
Impossible
Reasonable time
sequence with
+
+
+
+
-

medication/intervention
Known drug/reaction
type
+
+
+
+
-
Symptom relief or
disappearance after
stopping intervention
+
+
±
±
-
Recurrence of reaction
after re-intervention
+
?
?
?
-
Cannot be explained
by disease or
concomitant
medication
+
+
-
±
-
9.2 Recording and Handling of Adverse Events
9.2.1 Recording of Adverse Events
While observing efficacy, investigators should pay attention to adverse events or reactions.
Investigators should explain to subjects and require them to truthfully report changes in their
condition after medication, avoiding leading questions.
All adverse events, whether related to the trial drug or not, should be recorded in detail.
Investigators should closely monitor clinical and laboratory evidence of adverse events in
each patient, including the date of occurrence, symptoms, laboratory test results, severity,
outcome, duration, and results of the event, and fill in the "Adverse Event Form".
Investigators should promptly judge the causal relationship between the adverse event and
the study drug and analyze the correlation between the adverse event and the trial drug.
Concomitant medications should be recorded in detail, along with signatures and dates.
9.2.2 Handling of Adverse Events
9.2.3 Reporting of Adverse Events
Adverse events include intraoperative hypotension, bradycardia, hypoxemia, etc.
10. Quality Control and Quality Assurance
Investigators visited subjects one day before surgery to understand their medical history.
Eligible subjects were enrolled only after obtaining their informed consent in strict
accordance with the inclusion and exclusion criteria. If serious adverse events occurred
during surgery, the trial should be stopped immediately.

11. Data Safety Monitoring
A data safety monitoring plan corresponding to the risk level will be formulated for the clinical
study. All adverse events are recorded in detail, properly handled, and followed up until they
are properly resolved or the condition is stable. Serious adverse events and unexpected
events are reported to the ethics committee, competent authorities, sponsors, and drug
regulatory authorities in a timely manner in accordance with regulations; the principal
investigator regularly reviews all adverse events cumulatively, and if necessary, holds an
investigator meeting to evaluate the risks and benefits of the study; emergency unblinding
can be performed in double-blind trials to ensure the safety and rights of subjects; studies
with greater than minimal risk will arrange independent data monitors to monitor study data,
and high-risk studies will establish an independent data safety monitoring committee to
monitor accumulated safety and efficacy data to make recommendations on whether to
continue the study.
12. Statistical Analysis
12.1 Statistical Methods
All data were statistically analyzed using SPSS 26.0 software, with P<0.05 indicating a
statistically significant difference. Count data were expressed as cases or percentages and
analyzed using the Chi-square test or Fisher's exact test. Normality of measurement data
was evaluated using the Kolmogorov-Smirnov test or Shapiro-Wilk test. Measurement data
conforming to a normal distribution were expressed as mean ± standard deviation (x±s) and
analyzed using the t-test; count data with repeated measurements were analyzed using one-
way ANOVA; skewed or unknown-distribution measurement data were expressed as median
(interquartile range) [median (IQR)] and analyzed using the Mann-Whitney U test.
12.2 Sample Size Calculation Process
88 casesSample size calculation process Based on preliminary experimental
results, sample size was calculated using PASS, with a 20% dropout rate,
resulting in a total sample size of 88 cases (22 cases in each group).
Input：
Power and Alpha
Power 0.95
Alpha 0.05
Group 4
Group Allocation Equal
Effect size
Means 30 34 50 53

K 1
σ 7 6 15 19
13. Ethics of Clinical Research
The clinical study will follow the World Medical Association Declaration of Helsinki and other
relevant regulations. Before the start of the study, the trial protocol will be implemented only
after approval by the ethics committee. Before each subject is enrolled in the study, the
investigator is responsible for fully and comprehensively introducing the purpose, procedures,
and possible risks of the study to the subject or their agent, and a written informed consent
form will be signed. Subjects should be informed that they have the right to withdraw from
the study at any time. The informed consent form should be retained as a clinical study
document for reference. The privacy and data confidentiality of subjects will be protected
during the study.
14. Collection and Storage of Samples/Specimens
None.
15. Study Progress
Not available.
16. References
[1] Young CC, Harris EM, Vacchiano C, Bodnar S, Bukowy B, Elliott RRD, Migliarese J,
Ragains C, Trethewey B, Woodward A, Gama de Abreu M, Girard M, Futier E, Mulier JP,
Pelosi P, Sprung J. Lung-protective ventilation for the surgical patient: international expert
panel-based consensus recommendations. Br J Anaesth. 2019 Dec;123(6):898-913. doi:
10.1016/j.bja.2019.08.017. Epub 2019 Oct 3. PMID: 31587835.
[2] Neira VM, Kovesi T, Guerra L, Campos M, Barrowman N, Splinter WM. The impact of
pneumoperitoneum and Trendelenburg positioning on respiratory system mechanics during

laparoscopic pelvic surgery in children: a prospective observational study. Can J Anaesth.
2015 Jul;62(7):798-806. doi: 10.1007/s12630-015-0369-0. Epub 2015 Apr 23. PMID:
25902890.
[3] Young CC, Harris EM, Vacchiano C, Bodnar S, Bukowy B, Elliott RRD, Migliarese J,
Ragains C, Trethewey B, Woodward A, Gama de Abreu M, Girard M, Futier E, Mulier JP,
Pelosi P, Sprung J. Lung-protective ventilation for the surgical patient: international expert
panel-based consensus recommendations. Br J Anaesth. 2019 Dec;123(6):898-913. doi:
10.1016/j.bja.2019.08.017IF: 9.1 Q1 . Epub 2019 Oct 3. PMID: 31587835.
[4] Andrade F, Ambrosio AM, Rodrigues RR, et al. The optimal PEEP after alveolar
recruitment maneuver assessed by electrical impedance tomography in healthy horses [ J].
Front Vet Sci,2022,9:1024088.DOI: 10.3389/fvets.2022.1024088.
[5] Wu XZ, Xia HM, Zhang P, Li L, Hu QH, Guo SP, Li TY. Effects of ultrasound-guided
alveolar recruitment manoeuvres compared with sustained inflation or no recruitment
manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by
ultrasonography: a randomized clinical trial. BMC Anesthesiol. 2022 Aug 16;22(1):261. doi:
10.1186/s12871-022-01798-z. PMID: 35974310; PMCID: PMC9380300.
[6] Lee JH, Choi S, Ji SH, Jang YE, Kim EH, Kim HS, Kim JT. Effect of an ultrasound-guided
lung recruitment manoeuvre on postoperative atelectasis in children: A randomised
controlled trial. Eur J Anaesthesiol. 2020 Aug;37(8):719-727. doi:
10.1097/EJA.0000000000001175. PMID: 32068572.
[7] Edmark L, Östberg E, Scheer H, Wallquist W, Hedenstierna G, Zetterström H. Preserved
oxygenation in obese patients receiving protective ventilation during laparoscopic surgery: a
randomized controlled study. Acta Anaesthesiol Scand. 2016 Jan;60(1):26-35. doi:
10.1111/aas.12588. Epub 2015 Aug 3. PMID: 26235391.
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