Effects of Replacing Routine Chest Radiography With Lung Ultrasound for Patients Undergoing Thoracic Surgery: A Randomised Controlled Trial
Phase: NA
Conditions: Thoracic Surgery, Ultrasonography
Sponsor: Uppsala University Hospital

 
 
 
 
 
 
 
 
 
 
 
Effects of replacing routine chest radiography with 
lung ultrasound for patients undergoing thoracic 
surgery: A randomised controlled trial 
 
 
 
 
 
 
 
 
Version: 
2.5 
 
Date:  
02-04-2024 
 
Trial Registration Number: 
NCT ID not yet assigned   
 

Table of Contents 
 
Table of Contents 
Administrative Information 
Abstract 
Trial Flow Chart 
List of Abbreviations 
Protocol Summary 
1 
Introduction and Background 
     1.1       Patients and Peri-operative Settings 
     1.2       Current Treatment 
     1.3       Trial Interventions 
     1.4       Adverse Effects of LUS 
     1.5       Risk and Benefits 
     1.6       Ethical Justification and Trial Rationale 
      
    1.6.1       Ethical Conduct of the Trial 
      
    1.6.2       Disclosure of Investigator Relationship 
      
    1.6.3       Outcome Considerations 
     1.7       Trial Conduct 
2 
Trial Objectives 
     2.1       Primary Objectives 
     2.2       Secondary Objectives 
3 
Trial Design 
     3.1       Trial Design 
     3.2       Randomization 
     3.3       Blinding 
     3.4       Participant Timeline 
4 
Selection of Participants 
     4.1       Inclusion Criteria 
     4.2       Exclusion Criteria 
     4.3       Participant Discontinuation and Withdrawal 
      
     4.3.1       Discontinuation and Withdrawal at the choice of the participant 
      
     4.3.2       Discontinuation and Withdrawal at the choice of the investigator 
      
     4.3.3       Discontinuation and Withdrawal at the choice of the treating physician 
 

5 
Trial Interventions 
     5.1       Experimental Intervention 
 
5.1.1 
Lobectomy Intervention Arm 
5.1.2 
Wedge Resection Intervention Arm 
     5.2       Control Intervention 
 
5.2.1 
Lobectomy Control Arm 
5.2.2 
Wedge Resection Control Arm 
6 
Outcomes 
     6.1       Primary Outcome 
     6.2       Secondary Outcomes 
 
6.2.1 
PPC-driven Interventions 
 
6.2.2 
Adverse Events 
 
6.2.3 
Psychometric Outcome 
 
6.2.4 
Inter-rater Variability Outcome 
7 
Safety  
     7.1     Definitions 
 
    7.1.1       Assessment of Adverse Events 
 
 
7.1.1.2      Assessment of Intensity 
 
 
7.1.1.3      Assessment of Causality 
 
    7.1.2       Serious Adverse Events 
     7.2     Reporting 
    7.2.1       Reporting of Serious Adverse Reactions and Events    
     7.3     Risks and Issues in the Current Trial 
8       Procedures, Assessments and Data Collection 
     8.1     Inclusion Procedure 
      
     8.1.1       Screening 
      
     8.1.2       Procedures for Informed Consent 
     8.2     Data Collection 
      
     8.2.1       Method 
 
 
8.2.1.1      Lung Ultrasound Case Report Form 
 
 
8.2.1.2      Ventilatory Endpoints 
 
 
8.2.1.3      Patient Satisfaction Endpoint 
 
 
8.2.1.4.     Chest Radiograph 
 
 
8.2.1.5      Inter-observer Agreement 
      
     8.2.2       Timing 
9 
Data Handling and Record Keeping  
     9.1     Data Management 
     9.2     Confidentiality and Access to Data 

 
10 
Statistical Analysis  
     10.1     Sample Size Estimation and Power Calculations 
      
10.1.1     Sample Size Estimation for the Primary Outcome 
     10.2     Statistical Methods 
      
10.2.1     Pre-planned Subgroup Analyses 
 
10.2.2    Significance 
 
10.2.3    Interim Analysis 
 
10.2.4    Early Stopping Criteria 
 
10.2.5    Accountability Procedure for Missing Data/Population for Analysis 
11 
Quality Control and Quality Assurance 
     11.1     Monitoring of the Intervention Group 
     11.2     Subject Log 
12 
Legal and Organizational Aspects 
     12.1     Finance 
      
12.1.1     Trial Funding 
      
12.1.2     Compensation 
     12.2     Insurance 
     12.3    Plan for Publication, Authorship and Dissemination 
      
12.3.1     Publication and Authorship 
     12.4    Intellectual Property Rights 
     12.5    Organizational Framework 
     12.6    Trial Timeline 
13 
References 
14 
Appendices 
 
 
 
 
 
 

Administrative Information 
 
Sponsors 
 
Laila Hellgren Johansson, MD PhD 
Associate professor, Senior consultant thoracic surgery 
Department of Surgical Sciences, Thoracic Surgery, Uppsala University 
Uppsala University Hospital Akademiska sjukhuset, entrance 50, 4 floors 
751 85 Uppsala 
Email: laila.hellgren.johansson@akademiska.se 
Phone: +46 709 969 379  
 
 
Karl-Henrik Grinnemo, MD PhD 
Professor, Senior consultant thoracic surgery 
Department of Surgical Sciences, Thoracic Surgery, Uppsala University 
Uppsala University Hospital Akademiska sjukhuset, entrance 50, 4 floors 
751 85 Uppsala 
Email: karl-henrik.grinnemo@uu.se 
Phone: +46 708 868 968 
 
 
Principal investigators 
 
Sebastian Ullmark 
RN ICU, PhD candidate 
Department of Surgical Sciences, Thoracic Surgery 
Uppsala University Hospital Akademiska sjukhuset, entrance 50, 4 floors 
751 85 Uppsala 
Email: sebastian.ullmark@uu.se 
Phone: +46 733 890 505 
 
 
 

Julia Jakobsson, MD PhD 
Consultant cardiothoracic anaesthesia and intensive care 
Uppsala University Hospital Akademiska sjukhuset, entrance 50, 4 floors 
751 85 Uppsala 
Email: julia.o.jakobsson@akademiska.se 
Phone: +46 736 754 138 
 
 
Other investigators 
 
Emma Thorén, MD PhD 
Consultant cardiothoracic surgery 
Uppsala University Hospital  
Akademiska sjukhuset, entrance 50, 4 floors 
751 85 Uppsala 
Email: emma.thoren@akademiska.se 
Phone: +46 703 047 036 
 
Joakim Engström, PhD 
RN ICU 
Institution of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala 
University 
University Hospital of Uppsala, Akademiska sjukhuset 
Akademiska sjukhuset, entrance 70, 1 floors 
751 85 Uppsala 
Email: joakim.engstrom@uu.se 
Telephone: +46 703 047 741 
 
 

Abstract 
 
Background: Patients undergoing thoracic surgery are subject to a series of chest 
radiographs (CXR) throughout their hospital stay.  Lung ultrasound (LUS) has shown 
good agreement with routine chest radiograph (CXR) in several settings and 
feasibility in the postoperative period in observational studies. 
 
Objectives: To assess if LUS can replace CXR in adult patients undergoing thoracic 
surgery in the early postoperative period. 
 
Design: Single-centre, randomised, controlled, non-blinded trial  
 
Inclusion and Exclusion Criteria: Inclusion criteria: Patients aged 18 years or older 
undergoing lung surgery (segment resections or lobectomies) providing informed 
consent. Exclusion criteria: pneumonectomy, surgical procedures involving pleural 
resections or reoperations due to complications, admittance to ICU care, pregnancy, 
non-available research team or if the operating surgeon or other responsible 
consultant deems study participation not suitable.  
 
Intervention: LUS will be performed in the intervention group before and after chest 
removal. In the control group, chest radiographs will be performed routinely for 
lobectomies and if deemed necessary by the operating surgeon for segment 
resections. CXR can be performed at any time in the intervention group at the 
discretion of the operating surgeon or other consultant involved in patient care. 
Before discharge from the hospital all patients will have a CXR. 
 
Outcomes: The primary end-point is the reduction in performed chest radiographs in 
the intervention group. Secondary end-points include time to chest drain removal, 
any adverse event leading to interventions such as reoperation or need for re-
insertion of chest drain, patient satisfaction and interobserver variability of LUS.  
 
Trial Size: Assuming a reduction of CXR in the intervention group of at least 20%, 
55 patients in each group are required (two-sided alpha= 0.05 and 80% power). 

Time Schedule: Autumn 2023: Ethical and formal approval applications, education 
of care providers and other preparations.  
Winter 2023/2024: First patient enrolled. 
Spring/summer 2024: Last patient enrolled. 
Summer 2024 – Autumn 2024: Data analysis and submission for publication.  
 
 
   
 
 
 
 

 
Trial Flow Chart 
 
 
 

 
List of Abbreviations 
 
 
Abbreviation 
 
 
Explanation 
 
CFR  
 
 
 
Case Report Form 
CT 
 
 
 
 
Computer Tomography 
CXR  
 
 
 
Chest Radiograph 
DICOM 
 
 
 
Digital Imaging and Communications in Medicine 
EPJ 
 
 
 
 
Electronic Patient Journal 
GCP  
 
 
 
Good Clinical Practice 
ICU 
 
 
 
 
Intensive Care Unit 
LUS  
 
 
 
Lung Ultrasound 
OLV  
 
 
 
One-Lung Ventilation 
PPC  
 
 
 
Pulmonary Post-operative Complications 
sO2 
 
 
 
 
Oxygen Saturation 
SaO2  
 
 
 
Arterial Oxygen Saturation 
POD  
 
 
 
Post-operative Day 
RATS  
 
 
 
Robot-Assisted Thoracic Surgery 
VATS  
 
 
 
Video-Assisted Thoracic Surgery 
 
 
 
 

Protocol Summary 
 
 
 
   PROTOCOL IDENTITY AND OBJECTIVES 
Protocol Title: Effects of replacing routine chest radiography with lung 
ultrasound for patients undergoing thoracic surgery: A randomised 
controlled trial 
 
 
 
   METHODOLOGY 
Trial Design: Randomiced controlled single-centre trial 
Settings: Tertiary referral hospital/university hospital 
Primary endpoint: Reduction of Chest Radiographs 
 
 
 
   POPULATION OF TRIAL SUBJECTS 
Description of Trial Subjects: Patients aged >18 years undergoing lung 
surgery 
Number of Subjects: 110 patients  
 
 
 
   TRIAL TIMETABLE 
First Subject In: 2024 Q1 
Last Subject In: 2024 Q3 
Last Subject Out: 2024  
 
 
 
 
 

1 
Introduction and Background 
 
1.1 
Patients and Peri-operative Settings 
A variety of thoracic surgical procedures involve the lung and pleura such as pulmectomies, 
lobectomies, lobe and wedge resections and pleurodeses. These are usually performed by 
open thoracotomy or thoracoscopically video (VATS) or robot-assisted (RATS). In order to 
gain surgical access, one-lung ventilation (OLV) is often used during which the operated lung 
is closed off and collapsed while the non-operated lung is ventilated [1]. The operated lung is 
then opened and re-expanded under surgical vision and chest drain inserted before the chest 
is closed. After extubation the patient is transferred to the recovery unit (PACU) for 
observation.  If air leakage and pleural effusion is negligible, the chest drain is removed. 
Radiographic evaluation of the lungs is performed to dismiss PPC and, patients are 
discharged 
 
1.2 
Current Treatment 
Chest radiographic imaging (CXR) remains the standard method for detecting postoperative 
pulmonary complications and ensure adequate lung expansion after thoracic surgery [2]. 
After lung surgery, a series of CXRs can be performed depending on patient status and 
physician’s preference. Also, the extent and method of surgery influence the number of 
performed CXR. A summary of CXR guidelines at our department is listed in table 1. 
Patients undergoing lobectomies, including segment resections, receive two or more CXR, 
while wedge resections receive one CXR as follow-up after chest tube removal.  
The typical projection of the CXR is antero-posterior with the patient either semi-recumbent 
or standing up [3]. Lateral projections are performed if requested.  
 
 
PACU 
Clamped chest tube 
Post-removal of chest tube 
Lobectomy 
 
 
 
    Segmental lobectomy 
 
 
 
    Bilobectomy 
 
 
 
Wedge resection 
 
 
 
Table 1: Suggestion of CXR distribution in routine lung surgery, by surgical method. PACU: Post-Anesthesia Recovery 
Unit. 
 

1.3 
Trial Interventions 
For detailed description of interventions, see section 8. 
  
Lung ultrasound (LUS) is a well-established, non-invasive method that has shown good 
agreement with CXR. The method has several advantages, such as the omittance of radiation, 
being cost and time effective and allowing the patient to be examined in his or her own bed. 
Although multiple protocols exist in many different settings [2], LUS regarding lung aeration 
and PPC’s have yet to be refined in patients undergoing lung surgery. Observational studies 
have shown that LUS performs comparable to, or even superior to CXR [4, 5, 6], yet 
randomized controlled studies are lacking. A more comprehensive description of data 
collection will be presented in section 8.2.  
 
Lung Ultrasound 
Lung ultrasound is a non-invasive method of investigating pulmonary pathology. As 
ultrasound cannot directly visualize gas, the sonographer instead must rely on specific 
signatures of artifacts that develop as pathology progresses. As the vast majority of 
pulmonary pathologies, >95%, reach the visceral pleura, they can therefore be subjected to 
semiotic interpretation [7, 8]. When extravascular fluid accumulates in the lung parenchyma, 
or when air is distributed in between the pleural membranes, these signature patterns appear, 
allowing semi-quantification and qualitative assessment of both lung aeration and the 
occurrence of air leaks. Lung ultrasound is widely used in clinical practice and has in several 
studies been proven equal to, or more sensitive and specific than comparable methods of 
investigation such as CXR [6]. 
 
Lung aeration score 
As LUS provides real-time information of pulmonary disease, it has been used to sequentially 
screen patients. Global assessment of the lungs has been strongly associated with tissue 
density and aeration. Commonly a scoring system based on loss of aeration in protocolized 
points or regions of the lung is used. Although the number of regions assessed may differ, 
scoring is based on the number and appearance of artifacts, where a reduction of artifacts 
indicates recovery from pathology [9]. A general cut-off score has not yet been defined, 
however a score > 47% of possible maximum score is indicative of poorer outcome and 
associated with more various pathologies [10]. In an observational study comparing global 

scores to those omitting posterior scores, the authors did not find any significant difference in 
diagnostic accuracy when scanning only anterolateral regions of the lungs [11].  
 
 
Pneumothorax 
As air infiltrates the space between the visceral and parietal pleura it produces a physical 
barrier for the propagating ultrasound beam. Contact with the visceral membrane during 
breathing is abolished and the sonographic image produced is characterized by a visual 
absence of pleural sliding and reverberating of the parietal pleura. Ergo, no signature of 
artifacts can be produced deeper than this. Although this sign is not exclusive to 
pneumothorax it warrants further assessment. A pneumothorax is usually limited and borders 
a region of the lung not affected by the air leak. At this border the sonographer can identify 
the transition from abolished lung sliding and present, a lung point, highly specific to 
pneumothorax [7, 11].  
 
Estimation of the size of a pneumothorax is possible with LUS. As gas accumulates in the 
least dependent areas of the pleura, this has implications for estimation of size. Supine 
patients will display an accumulation of air anteriorly and in a slightly caudal direction. As 
the pneumothorax increase in size, the lung point will move more laterally. In very large 
pneumothoraces, the entire anterior and partially lateral surface will be affected, also making 
detection of a lung point [8, 11]. Thus, any change from supine to erect position of the patient 
will shift the distribution of gas in the pleural cavity. A pneumothorax is considered small if 
the distance between the location of a lung point and chest wall is less than 2 cm, and large if 
greater than 2 cm [12], however the depth of eventual lung collapse cannot be evaluated. 
When compared to CT scan of lung collapse, a lung point anterior to the mid-axillary line 
indicated a collapse of < 10 %; on the mid-axillary line as 11–30 %, and posterior to this line 
>30 % collapse [13]. 
 
Pleural effusion 
The presence of pleural effusion can be accurately identified and reliably quantified using 
LUS. Fluid in the interpleural space creates a hypoechoic image confined between the 
diaphragm and either aerated or more commonly by the superimposed pressure collapsed 
lung parenchyma [9]. Detection of pleural effusion by ultrasound has a 93% sensitivity [7, 8, 
14, 15] and can identify as little as 5 mL. Volume can be estimated through the measured 

dimensions of the ultrasound image inserted in a simple formula. This estimated value has 
been shown to has good level of accuracy when compared to aspirated actual volume [16].   
 
Patient Satisfaction 
If in any case patients are subjected to cross-over from the investigational arms of the study 
to the control arms with routine care with CXR, a sub-group analysis will be conducted. This 
analysis will rely on a semi-quantitative questionnaire designed to encompass the dimension 
of patient satisfaction between the two methods of examination. 
 
 
1.4 
Adverse Effects of LUS 
Adverse effects of LUS are very few and considered to be minuscule. Long term exposure of 
medically indicated ultrasound can in specific instances produce tissue damage in relation to 
thermal and mechanical energy dissipation from the probe [18]. This risk is mitigated partly 
by the brief examination period, and partly from the use of relatively low frequency 
transducer and mechanical index, or output (MI). MI represents the non-thermal biological 
effects, mainly cavitation, and is recommended < 0.4 to account for the difference between 
the surface MI displayed on the ultrasound machine and in situ MI in exposed tissue. Thus, 
increasing MI should only be made in imaging requirements, to a maximum threshold of 1.9 
[19]. Furthermore, due to varying body composition in patients, an individual level of 
pressure from the probe may be applied to the patient to optimize imaging. This could lead to 
minor, transient pain in more sensitive subjects, especially in examination points adjacent to 
the operation site. 
 
As with all point-of-care examinations there is a small, but not negligible risk of transmission 
of microorganisms from the transducer. This risk is mitigated through the application of 
routine hygiene and disinfection of the machine and instruments. 
 
 
 
 
 

1.5 
Risk and Benefits 
Assessment with lung ultrasound is well-established and regarded as a safe and non-invasive 
method of examination of thousands of patients every day.  
  
 
1.6 
Ethical Justification and Trial Rationale 
Evidence suggests that LUS is a valid alternative to radiographic standards such as CXR and 
Computer Tomography (CT) for a large variety of patients. LUS is also recommended in 
international guidelines [19].  
 
Patients will be enrolled for study participation only with informed consent and will have the 
ability to withdraw their consent at any time they choose. The consenting patient will be 
provided written and oral information about the trial at a time parallel to an information 
meeting with a nurse and physician at the pre- and post-operative ward.  
 
All patient care in the trail will receive routine care apart from the method of examination. 
Post-operative routine care is based on compiled evidence and encompasses both clinical and 
diagnostic dimensions. Thus, patients in the control group will not be exposed to any 
additional risks.  
 
This study’s main investigator is a critical care specialist nurse experienced in sonography. 
The investigator reports all findings from the LUS examinations to the treating physician, or 
surgeon, who may at any point during this study requests a CXR study if the patient’s 
wellbeing is considered to be jeopardized, thus leading to crossover to control group and 
routine care with CXR. 
 
No biological material will be collected in this trial, thus no bio-bank will be formed. 
 
 
 
 
 
 

1.6.1 Ethical Conduct of the Trial 
This trial will be approved by the Regional Ethics Committee in Uppsala. The trial will 
adhere to the trial protocol, GCP and the Helsinki Declaration (Seventh Revision). If any part 
of the protocol needs to be amended, changes shall be compliant with the Ethics Committee. 
For public transparency the study will be registered on the online database 
https://clinicaltrials.gov. 
 
 
1.6.2 Disclosure of Investigator Relationship 
The principal investigators of this study are a critical care specialist nurse (S. U.) and an 
anesthetist-intensivist physician (J. J.), employed by the same clinic. The latter is a doctoral 
supervisor to the former. J. J. is to supervise the process of the study and will act as the 
secondary observer of the LUS examinations. The main doctoral supervisor (J. H-J.) and 
doctoral supervisor (J. E.) are co-authors of the study. 
 
 
1.6.3 Outcome Considerations 
A reduction in the number of performed CXR has been suggested in several prospective 
observational studies [2, 17, 21, 22]. It has also been inferred LUS has superiority in both 
sensitivity and specificity in certain aspects of lung diagnostics. Its favorable lack of ionized 
radiation makes it in the public’s interest to research the methods’ possible impact on patients 
who are routinely examined with CXR.  
 
Although a large body of research has been made on LUS over the last decade, there are still 
challenges in establishing consensus in specific outcomes. Guidelines and expert statements 
however now exist to navigate future research based on evidence and will be applied to this 
trial [19]. To the knowledge of the investigators of this trial, no prior randomised research has 
been conducted to elucidate the relationship between adult lung surgery and LUS. 
 
 
 
 
 

The rationale for choice of outcomes in this study is: 
 
1. A LUS composite of outcomes routinely monitored with CXR could possibly benefit 
patients. 
2. A protocol based on 8 regions of interest should suffice, as opposed to basing a global 
score on more regions. In emergency settings, a protocol based on 6 regions is usually 
applied [8], while other studies have included up to 28 regions. Most of studies with 
higher numbers of examined regions include posterior regions and further sectioning 
of the thorax. Although evidence suggest that adding a posterior score contribute to 
higher global scores in specific pathology, it generally seems to have a lower 
diagnostic accuracy [8, 10].  
3. The concept of limiting the number of scanned regions is based on mainly two factors 
in this trial. (1) The number of regions scanned in this trial are higher than those in 
emergency settings because of the inhomogeneity of surgical site, however no 
posterior surgery is performed, thereby omitting posterior scanning. (2) Scanning of 
an affected region refers to a point withing the specified anatomical region on the 
chest. Most disorders, however, have substantial extension and apart from certain 
signs, such as lung point in pneumothorax, an artifactual sign will also be visible 
adjacent to the probe position [8]. Another rationale is that combining the aeration 
score with the search of a lung point will lead to more extensive scans. 
 
 
 
1.7 
Trial Conduct 
This trial will be conducted according to the Helsinki Declaration in its latest revision. The 
project will be registered on to www.clinicaltrials.gov ahead of the start of the trial. No major 
deviations from or altering of the protocol will be made without further review and approval 
of the ethics committee and authorities. Enrollment to the trial will commence after the 
approval from same instances. Upon trial conclusion a manuscript with the main points of the 
protocol, including description of design, rationale and analysis plan will be submitted to a 
journal in English language. 
 
 
 

 
2 
Trial Objectives 
 
2.1 
Primary Objective 
Evaluation LUS as the primary method of examination of aeration and PPC’s during the post-
operative period. 
 
2.2 
Secondary Objectives 
• Correlation of early, or delayed removal of chest tubes, with LUS as the primary 
method of evaluation of pneumothorax. 
• Inter-observer agreement between critical care nurse specialist and anesthesiologist. 
• Evaluation of patient satisfaction. 
 
 
3 
Trial Design 
 
3.1 
Trial Design 
An investigator-initiated, single-centre, parallel-group trial of LUS versus CXR in patients 
undergoing lung surgery. 
 
3.2 
Randomisation 
1:1 randomisation will be performed through web-based randomization according to a 
computer-generated allocation sequence list. Allocation will be made to an investigational 
group, and control group, respectively. Each group will allocate in two arms depending on 
surgical method described in section 5. Each patient will be allocated with a unique 
screening-number. 
 
 
3.3 
Blinding 
The principial investigator performing the LUS will not, by self-evident reasons, be blinded 
to the randomization. The fellow researcher (J. J.) during follow-up analysis of collected 
images will be blinded to the patients’ surgery and the original LUS examination results. 
 

Blinding of type and circumstance of the surgery will also be applied in the subgroup analysis 
of patients who are subjected to crossover from investigational arm to control.  
 
 
3.4 
Participant Timeline 
The aim is to enroll patients as soon as they are identified to fulfill the inclusion criteria. 
Selected subjects will be given written and verbal information parallel to admission to the 
surgical ward by the scientist responsible for the study. Only patients who have given written 
informed consent are to be included in the study. Allocation to either LUS or CXR upon 
admittance to the pre-operative ward and will continue the allocated intervention until formal 
discharge by the treating physician.  
 
 
Pre-operative Events:  
Will take place in the surgical ward reception as part of admittance. 
• Trial information 
• Informed consent 
 
 
Peri-operative Events: Will take place in the post-operative recovery ward. 
• Lung Ultrasound or CXR 
• Physiological and Ventilatory parameters 
 
 
Post-operative Events: Will take place in the surgical ward. 
• Lung Ultrasound or CXR 
• Physiological parameters 
• Comparative CXR in the investigational group 
• Data collection from radiography records 
• Data collection from medical records 
• Inter-observer agreement study of collected LUS images 
• Sub-group analysis of Patient Satisfaction for patients subjected to cross-over, i.e., 
receiving both LUS and CXR. 

4 
Selection of Participants 
 
4.1 
Inclusion Criteria 
 
• Patients aged >18 years 
• Segmental, partial or wedge resection lung surgery, or lobectomy 
• Written informed consent 
• Available research team for measurements 
 
4.2 
Exclusion Criteria 
 
• Pregnancy 
• Re-surgery due to complications related to the original surgery 
• Need for critical care OR admittance to the ICU 
• Patient withdrawal from the study 
 
 
4.3 
Participant Discontinuation and Withdrawal 
4.3.1 Discontinuation and Withdrawal at the Choice of the Participant 
 
Subjects may at any time request to be discontinued from the study. This process will follow 
the national regulations in Sweden. 
 
Discontinuation and Withdrawal at the Choice of the Investigator 
The principal investigator may at any time withdraw a subject from the study if it is deemed 
to be in the patient’s best interest. 
 
Discontinuation and Withdrawal at the Choice of the Treating Physician 
This trials’ main investigator is a critical care specialist nurse experienced in sonography. 
The investigator reports all findings from the LUS examinations to the treating physician, or 
surgeon, who may at any point during this study requests a CXR study if the patients’ 
wellbeing is considered to be jeopardized, thus leading to crossover and exclusion of the 
subject from the study. To minimize accidental group crossover due to misinterpreted LUS 
findings, an educational effort in methodology will be implemented prior to commencing of 
the trial.    

5 
Trial Interventions 
 
5.1 
Experimental Intervention 
All patients randomized to the investigational group will receive Lung ultrasound (LUS) with 
the use of transducers of varying frequency output (5– 10 MHz) on a Philips EPIQ 7 
ultrasound machine. Examination will be performed by the principial investigator during the 
patients’ hospital stay. Since routine care with CXR differs based on the extent of surgery, 
allocation will be made in two interventional arms. The timing of examination and data 
collection is summarized in section 8.2.  
 
5.1.1 Lobectomy Intervention Arm 
Patients undergoing multiple or segmental lobectomy will receive two examinations with 
LUS in the investigational group.  
 
5.1.2 Wedge Resection Intervention Arm 
Patients undergoing multiple or single wedge resection will receive one examination with 
LUS in the investigational group. 
 
 
5.2 
Control Intervention 
Patients randomized to the control group will receive routine care with CXR. The definition 
of routine care is defined by the number of CXR examinations in the setting of optimal post-
operative care for the thoracic surgery population at the centre where this study is conducted. 
A consensus of the number of examinations with CXR was reached within the pulmonary 
surgical team and approved by the senior surgeon. Thus, as with the investigational group, 
the control group will be allocated into two arms Depending on the method of surgery. 
 
5.1.1 Lobectomy Control Arm 
Patients undergoing multiple or segmental lobectomy will receive two examinations with 
LUS in the investigational group.  
 
 
 

5.1.2 Wedge Resection Control Arm 
Patients undergoing multiple or single wedge resection will receive one examination with 
LUS in the investigational group. 
 
 
5.3 
Co-intervention 
All patients in the investigational arm will receive a CXR before discharge. The examination 
will be ordered in conjuncture with decision of patient discharge from the hospital by the 
treating or attending physician. 
 
 
 
6 
Outcomes 
 
6.1 
Primary Outcome 
The primary outcome is a reduction in CXR in patients undergoing thoracic surgery when 
LUS is the primary method of investigation for PPC. 
 
6.2 
Secondary Outcomes 
6.2.1 PPC-driven Interventions 
 
a. Variable Name: Re-insertion of Chest Tube 
Variable Description: The need for re-insertion of chest tube because of clinical 
deterioration, and/or verified clinically relevant PPC. 
 
b. Variable Name: Delayed removal of Chest Tube 
Variable Description: Number of patients in need of prolonged care with Chest 
Tube.  
 
c. Variable Name: Time to Chest Tube removal 
Variable Description: Time, in hours, to eventual removal of Chest Tube. 
 
 

 
6.2.2 Adverse Events 
 
a. Variable Name: Missed Care 
Variable Description: The number of missed diagnoses of PPC based on results from 
CXR in patients subjected to crossover. 
 
 
6.2.3 Psychometric Outcome 
 
a. Variable Name: Patient Satisfaction 
Variable Description: Sub-group analysis of the patient experience and satisfaction 
for patients receiving both LUS and CXR, measured through quantitative 
psychometric questionnaire. 
 
 
6.2.4 Inter-rater Variability Outcome 
 
a. Variable Name: Inter-rater Variability 
Variable Description: Post-hoc comparison (JJ) of ultrasound images collected by 
primary investigator (SU). Evaluation of images are recorded in separate CRF. 
 
 
 
7 
Safety 
 
 
7.1 
Definitions 
 
Adverse Events 
An Adverse Event (AE) is defined as any untoward medical occurrence in a participant 
included in this study, even if it does not have any relationship with the examination itself. 
An AE can be any unfavorable or unintended sign or abnormal finding or symptom. It is also 

regarded as an AE if patient data management is comprised resulting in breach of privacy, 
integrity, or implication of any participant in this study.  
 
 
Adverse Reaction 
An Adverse Reaction (AR) is defined as any noxious and unintended medical response to the 
examination during a clinical trial. A potential AR can be topical reaction to ultrasound gel. 
 
7.1.1 Assessment of Adverse Events 
7.1.1.1    Assessment of Intensity 
Each AE is to be classified by the investigator as mild, moderate, or severe. 
Mild: Acceptable. The subject is aware of the symptoms or signs which are tolerable. 
Moderate: Disturbing. The AE is discomfort enough to interfere with usual daily activity. 
Severe: Unacceptable. The subject is incapacity to work or to do usual daily activities. 
 
 
7.1.1.2.   Assessment of Causality 
Unlikely: The event is most likely related to an etiology other than the investigation. 
Possible: A causal relationship is conceivable and cannot be dismissed. 
Probable: Good reason and sufficient documentation to assume a causal relationship. 
 
 
7.1.2 Serious Adverse Events 
Each AE will be classified by the investigator as either serious or non-serious. Seriousness is 
not defined in medical terms, but a result or an outcome. An AE is defined as a Serious 
Adverse Event (SAE) if it: 
• results in death 
• is life-threatening 
• requires prolongation of inpatient hospitalization 
• results in persistent or significant disability or incapacity 
• other reason by the investigator deemed serious 
 
 
7.2 
Reporting 

All AEs will be recorded on a separate and designated form in the CRF. 
 
 
7.2.1    Reporting of Serious Adverse Reactions and Events 
In addition to the above mentioned, any SAE will also be reported by the investigator to the 
treating physician immediately, and to the sponsor on a separate SAE form withing 24 hours 
after the SAE has been communicated to the investigator. Follow-up information describing 
the outcome of the SAE and action taken will be reported as soon as it is available. The 
original SAE form must be filed with the CRF. 
 
 
7.3 
Risks and Issues in the Current Trial 
LUS is a well-established method of examination in clinical use.  
 
 
 
 
8 
Procedures, Assessments and Data Collection 
 
8.1 
Inclusion Procedure 
8.1.1 Screening 
All patients planned for thoracic lung surgery will be screened for eligibility of enrollment. 
The principal investigator will screen the surgical planner for candidates.  
 
 
8.1.2 Procedures for Informed Consent 
Patients eligible for trial enrollment will be given oral and written consent by the principial 
investigator as a part of the patient registration prior to pre-operative admittance to the 
surgical ward. The information will be given in a separate room and will be in compliance 
with applicable regulations. The potential participant will be offered time for consideration 
up until pre-operative admittance to the surgical ward, should the patient choose. Otherwise, 
informed consent will be collected as soon as possible. 
 

 
 
8.2 
Data Collection 
8.2.1 Method 
Radiographical data and data concerning vital parameters and ventilatory settings will be 
obtained from electric patient journal (EPJ). Data are recorded from various sources, apart 
from patients’ medical records and connected applications related to managing diagnostic 
data, e.g., radiographic or lab results. Clinical Report Forms (CRF) will be scanned and 
converted to digital copies for formatting.  
 
 
8.2.1.1   Lung Ultrasound Case Report Form 
All collection of data during the LUS examination will be collected in a specific Clinical 
Report Form (CRF). The LUS-CRF (Appendix 1) consists of six domains: Aeration Score, 
Pneumothorax, Pleural effusion, Atelectasis, Subcutaneous emphysema, and Physiological 
parameters. Collection will be made on a Philips EPIQ ultrasound machine using three 
different probes: Linear transducer L12-3 (3–12 MHz, focal depth at pleural line, maximum 
depth at 12 cm); Phased array transducer X5-1 (1–5 MHz, focal depth at costophrenic sulcus, 
maximum depth at 20 cm); and Abdominal transducer C5-1 (1–5 MHz, focal depth at 
costophrenic sulcus, maximum depth at 20 cm). Mechanical index will range from 0,4–1,2. 
 
Aeration Score 
Semi-quantitative sonographic signature pattern of artifacts indicating loss of aeration in lung 
parenchyma, i.e., inadequate lung expansion. Ranging from 0–12 scoring points, visualized in 
two anterior and lateral regions, respectively, in each hemithorax, accumulated to a global 
score [20]. Since the pleural interface is investigated, the linear probe (L12-3) will be used. 
 
Artifacts indicative of aeration loss are based on subpleural interaction of ultrasound beam, 
air and fluid accumulation in interlobular septa. This intermingling of air and water creates 
vertical comet-like artifacts (B-lines) indicative of interstitial syndrome and non-aerated lung. 
Aeration loss is scored by both quantitative and qualitative assessment of B-line number and 
the distance between each separated B-line, in four regions of respective hemithorax. Score 0 
is defined as the absence in a scanned region. Score 1 is defined as < 3 well-separated B-

lines; Score 2 as >3 coalescing B-lines; and Score 3 is ultimately defined as any subpleural 
consolidation [8, 19, 20].  
 
Pneumothorax 
Using the linear probe (L12-3), a longitudinal scan for correct intercostal placement of probe 
will be made followed by transverse scan of the pleural interface. Patterns indicating 
pneumothorax based on artifacts (abolished lung sliding, lung point, etc.) will be searched 
after in above-mentioned regions. Since the first, but not sole pathognomic sign of 
pneumothorax is abolished lung sliding, an algorithm is implemented to effectively exclude 
pneumothorax and to reach high sensitivity and specificity in correct diagnosis [7]. 
Pneumothorax is thus only confirmed when the transition between abolished normal lung 
sliding can be found, the so-called lung point. Failure to find a lung point when other signs 
indicate a pneumothorax will be recorded and reported as possible, yet unconfirmed. The 
lung point is representative for the extension and beginning of the pneumothorax in the 
current postural position (semi-recumbent, 30°). A visualized lung point will be recorded by 
anatomical reference lines such as the parasternal, mid-clavicular, anterior, mid-, and 
posterior-axillary lines [13]. 
 
 
Pleural Effusion 
Visualization of eventual pleural fluid will be made in the latero-inferior region cephalad to 
the diaphragm in semi-recumbent, 30° position, using the phased array or abdominal 
transducer (X5-1; C5-1). Estimation of volume will be measured with the ultrasound machine 
digital calipers in centimeters from chest wall, and from diaphragm to collapsed lung, 
respectively. The product of these two measurements and a factor of 70 will be used to 
estimate the effusion volume in milliliters [8]. 
 
 
Atelectasis 
A consolidation is on LUS is visualized as a tissue-like structure within the lung itself. 
Differentiating this structure from other types of consolidation (i.e., pneumonia or tumor) is 
done by qualitatively examining trapped air within partially collapsed larger bronchioles 
within the consolidation. These pockets of gas are in the case of atelectasis fixed in position 
throughout the respiratory cycle. Also called static air bronchograms are thus trapped air 

resulting from primarily resorption atelectasis [23, 24]. The choice of transducer will depend 
on which region is scanned. 
 
 
Subcutaneous Emphysema 
The presence of subcutaneous emphysema (SCE) will be diagnosed based on artifacts 
distributed superficially to the pleural interface detected by any transducer, thus hindering 
adequate propagation of the ultrasound beam [7]. 
Physiological Endpoints 
Vital parameters will be collected parallel to each examination, LUS and CXR respectively. 
These parameters include transcutaneous oxygen saturation and heart rate, respiratory rate, 
blood pressure (non-invasive and invasive when available), and oxygen demand described as 
administrated supplemental oxygen. 
 
 
8.2.1.2   Ventilatory Endpoints 
Ventilatory settings will be collected from the EPJ retrospective to surgery and will include 
ventilatory mode, tidal volume and minute ventilation, and peak or plateau pressure. 
 
 
8.2.1.3   Patient Satisfaction Endpoint 
Patients in the subgroup consisting of patients subjected to group cross-over will be handed 
semi-quantitative questionnaires before discharge from the hospital. This questionnaire will 
with a 15-item Likert-type design encompass psychometric dimensions regarding patients’ 
experiences and satisfaction with both LUS and CXR examinations. Surveyed dimensions 
will focus on patients’ attitudes toward LUS and CXR, and their perceptions of interaction 
with the clinicians performing the examinations. Patients will also be asked to assess the 
provision of care by considering various aspects of the examination process, patient 
expectations, given and understanding of information, and opinion on being examined by a 
specialist nurse rather than a physician.   
 
The possible answers in the questionnaire range from sets of satisfactory to non-satisfactory 
statements; Very satisfied, satisfied, neither, un-satisfied, and very un-satisfied. A second set 
of answers range from low to high agreement to the posed statement; strongly disagree, 

disagree, neither, agree, and strongly agree. A summated rating score will then be collected 
from each responder. A higher score is by design indicative of a more positive attitude 
toward the question being asked. To achieve this, a reverse direction of optional answers will 
be applied when questions are negatively worded. 
 
 
 
 
8.2.1.4   Chest Radiograph 
Data from CXR in the control group will be collected when all examinations have been made 
to a participant. Radiographic data will be collected from the hospital digital service for 
radiographic diagnostics along with written interpretation of the images. Clinical diagnosis 
will be based on radiologist and surgeon interpretation. 
 
CXR Endpoints 
• Patient positioning 
• Qualitative description of aeration 
• Pneumothorax (yes/no) 
o Estimated size in centimeters 
o Location 
• Pleural effusion (yes/no) 
o Location 
o Estimated size in centimeters 
• Atelectasis 
o Location 
• Subcutaneous emphysema 
o Location 
o Extension 
 
 
8.2.1.4   Inter-observer Agreement 
Appearance of LUS-artifacts are operator-dependent and therefore a degree of inter-observer 
variability could be expected. Therefore, a secondary evaluation and interpretation of 
collected LUS images will be made by a second investigator (J. J.) who is blinded to the 

primary investigators results. A statistical analysis will then be made on the inter-observer 
agreement in LUS endpoints. 
 
 
 
 
 
 
8.3 
Timing 
Appendix 4 shows and overview of the timing and variables defined in this section.  
 
Pre-operative (screening procedure) 
Subjects will be identified through the operation planning list and assessed for study 
eligibility.  
• Patient information about the study 
Collection of informed consent 
• Randomisation 
 
 
Baseline variables (not collected in the screening procedure) 
• Gender 
• Age at randomization (date of birth) 
• Date of admission to hospital 
• Prior lung resection surgery (y/n) 
• Co-morbidities 
 
 
Post-Anesthesia Recovery Unit (PACU) 
The following will be collected for patients in the lobectomy investigational and control 
arms. 
• LUS or CXR 
• Physiological parameters 
• Present air leakage in chest tube (y/n) 
• Volume of air leakage 

 
 
Post-operative Surgical Ward 
• LUS or CXR 
• Follow-up CXR for patients in the investigational g

9 
Data Handling and Record Keeping 
 
9.1 
Data Management 
All individual patient data collected from LUS examination will be recorded in the CRF and 
may be digitalized for formatting. The output files from electronic monitoring software will 
be exported individually to excel files. All files shall be collected and formatted for further 
analysis using appropriate software. Digital images and data collected from LUS 
examinations will be stored in hospital servers for digital image storage and management, 
accessible through a dedicated application (DICOM). Statistical analysis will be made by a 
statistician. 
 
9.2 
Confidentiality and Access to Data 
All original records, including informed consent, CRFs and relevant correspondence will be 
archived and coded for animosity at the trial site for 10 years. Database files and code access 
key will be accessible only to researcher connected to this trial and authorities upon request. 
 
 
 
  
10 Statistical Analysis 
 
10.1 Sample Size Estimation and Power Calculations 
10.1.1 Sample Size Estimation of the Primary Outcome 
The amount of lung surgery fitting the inclusion and exclusion criteria for this study is 
currently estimated as: 110 lobectomies, including segmental; 100 wedge resections, yearly. 
Thus around 200 patients are estimated for possible enrollment in this study. 
 
Previously published studies [2, 17, 21, 22] have shown a reduction of 30–60% in use of 
CXR. We calculate that a sample size of 55 patients per arm will be needed to provide 80% 
power (two-sided alpha level of 0,05), and to detect at least 20% reduction in the 
investigational group. 
 
 
 

10.2 Statistical Analysis 
The primary analysis of this study is designed according to the intention-to-treat principle, 
and thus analyzed to their originally assigned group. Patients who are subjected to group 
cross-over will be analyzed in a subgroup. The subgroup analysis will investigate the 
sensitivity and specificity of the interventional group endpoints, as well as agreement with 
control group outcomes. Additionally, the subgroup analysis will semi-quantitatively 
investigate patient satisfaction, when comparing the two methods of examination.  
 
 
10.2.1      Pre-planned Subgroup Analysis 
We will compare patient satisfaction as secondary outcomes in this trial for patients subjected 
to crossover from investigational to control group, regardless of reason. The rationale for this 
being an opportunity to both compare the principal outcomes of the two methods of 
examination, and to evaluate the psychometric effects of the same.  
 
 
10.2.2     Significance 
A two-sided P-value of less than 0.05 will be considered statistically significant. 
 
 
10.2.3    Interim Analysis 
An interim analysis will be conducted after patient no. 20 has been discharged from the 
hospital. This will be in accordance with the charter for independent Data Monitoring and 
Safety Committee (DMSC). 
 
 
10.2.4    Early Stopping Criteria 
The DMSC recommend pausing or stopping of the trial if the in-group differences in primary 
outcome, SARs or SAEs can be found or are suspected in the interim analysis. This will also 
apply if the continuing the trial clearly compromises patient safety. After pausing or stopping 
of the trial, a second analysis will be made based on the underlying reasons. 
 
 

10.2.5     Accountability Procedure for Missing Data/Population for Analysis 
Should less than 5 % of data be missing on either primary or secondary outcomes, a complete 
analysis will be performed without input of missing data. Missing data more than 5 % will 
warrant rational assessment of the pattern of missing data, mainly if the loss of data is 
random or not.  
 
 
 
11 Quality Control and Quality Assurance 
 
11.1 Monitoring of Intervention Group 
An interim analysis for monitoring of adverse events, including missed diagnosis, will be 
conducted when 55 patients have been enrolled in the study. All recorded data on paper CRF 
and collected digital images will be reviewed by a study monitor of the patient safety 
monitoring board. The monitor will verify data entries against existing source documents for 
accuracy and content. 
 
 
11.2 Subject Log 
A ‘subject log’ of screened and included subjects will be kept on file by the investigator 
according to the Consolidated Standards of Reporting Trials (CONSORT). This will help the 
investigator envisage an accurate ‘rate track’ and estimate the number of patients who did not 
meet inclusion criteria. Should the rate fall below appreciable levels, the investigators will be 
able to identify reasons and remedial actions could be undertaken. 
 
 
12 Legal and Organizational Aspects 
 
12.1 Finance 
The principial investigator of the trial is scheduled to part time for research as per agreement 
with the clinic where this trial is conducted. Apart from this, the trial is considered to be 
without need of further financing. 

 
 
12.1.1    Trial Funding 
This trial receives no additional funding. 
 
12.1.2    Compensation 
Patients enrolled in this trial will not be eligible for compensation. 
 
12.2 Insurance 
Participants in this trial will have insurance as part of the standard hospital care insurance in 
Sweden.  
 
 
12.3 Plan for Publication, Authorship and Dissemination 
12.3.1    Publication Authorship 
In advance of first enrollment, this trail will be registered on www.clinicaltrials.gov, along 
with the final protocol and description of design and plan for analysis. Upon completion of 
the trial, a manuscript of trial results will be submitted for peer-review publication to a 
relevant clinical journal. 
 
Listing of authors will be as follows: S. Ullmark will be the first author, J. Jakobsson the 
second, J. Engström the third, and E. Thorén the fourth. L. H-J will be the last and 
corresponding author. Authorship will be granted in accordance to the Vancouver definitions 
depending on personal input in the trial. 
 
12.4 Intellectual Property Rights 
The sponsor and main doctoral supervisor for this trial is L. Hellgren-Johansson. The 
initiative for this trial was taken by the principial investigator S. Ullmark and L. H-J together 
with doctors affiliated with the doctoral candidate (S. U.), the clinic and other ICUs at the 
hospital. Thus, no further claims to intellectual property rights are warranted. 
 
12.5 Organizational Framework 
This trial is a part of a doctoral candidate thesis for the principial investigator, Sebastian 
Ullmark.  

 
 
12.6 Trial Timeline 
Autumn/winter 2023: Ethical and formal governance approval of applications and other 
trial preparations 
January 2024: First patient enrolled 
May 2024: Preliminary time for interim analysis 
September 2024: Last patient enrolled 
Winter 2024: Data analysis and submission for publication 
 
 
 
 
 
 
 
 
 

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15 Appendices 
Appendix 1: Timing of Data Collection 
 
 
 
 
 
Surgical ward 
Surgery 
PACU 
Surgical ward 
Follow-up 
Admittance 
Pre-op 
POD 0 
2-4 hrs. after chest tube removal  
Pre-discharge 
 
In- /exclusion criteria 
 
 
 
 
 
 
 
Informed consent 
 
 
 
 
 
 
 
LUS 
 
 
 
 
 
 
 
CXR 
 
 
 
 
 
 
 
Ventilatory parameters 
 
 
 
 
 
 
 
Physiological parameters 
 
 
 
 
 
 
 
Inter-observer analysis 
 
 
 
 
 
 
 
Patient Satisfaction