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When using HFJV in liver tumour ablation procedures for optimizing surgical conditions, an ETT size 9 is routinely being used in our department.

In this arm an endotracheal tube of size 8 will be used. This is one size smaller than is routine when HFJV is being used for liver tumour ablation procedures in our department. Worth to note is that an endotracheal tube of size 8 is routine in all other surgical procedures, in men, during general anaesthesia.

Compare the levels of carbon dioxide and if it is related to ETT size when using size 9 (routine) or size 8 (intervention).

Entotracheal tube size

Klara Bergmark, MD

High Frequency Jet Ventilation (HFJV) can be used in liver tumour ablation to minimise breathing related movements. The jet cannula is placed freely inside an endotracheal tube (ETT) and the outflow of air is passive, moving out in the interspace between the jet cannula and the inner walls of the ETT.

This study aims to investigate whether the tube size can influence the washout of carbon dioxide using two different sizes of ETT's.

The aim of the present prospective randomised study is to compare differences in levels of carbon dioxide between two different endotracheal tube-sizes.

Background: High Frequency Jet Ventilation (HFJV) has become an important technique for ventilation during stereotactic near-diaphragm ablation to minimise breathing related movements. Thus, avoiding risks associated to movements and subsequent dislocation of the target tumour. HFJV is being increasingly used during CT-guided, percutaneous liver tumour ablation. As shown previously, breathing related movements in upper abdominal organs, are decreased significantly when compared to conventional ventilation. When HFJV is being used in the setting for tumour ablation the jet cannula is inserted into an ordinary endotracheal tube (ETT). The HFJV catheter is placed in the ETT and is during jet ventilation lying freely within the tube. Right placement is confirmed by a harmonic curve on the screen of the jet ventilator. It is of great importance that the ETT is not obstructed as this type of ventilation is dependent on passive outflow of expired air, through the tube, passing from the lungs around the catheter within the tube into the surrounding air. If the lumen around the catheter within the ETT is becoming too small, there is a risk for intrinsic PEEP built up, and subsequent risk for barotrauma, pneumothorax. The space between the catheter and the inner lumen of the ETT also governs the exhalation of gas, the passage of expired gas containing CO2 from the lung. A small inner diameter of the ETT may thus likewise increase the risk for a raise in arterial carbon dioxide. To minimise these risks, an ETT one size larger than usual can be used to lower the risk for pressure increase and improve gas exchange. One should consider the risks, even though very low, of mechanical injury in the airway when larger ETT's are being used. Previous studies on arterial blood gas in liver tumour was performed using a ETT one size larger (size 9 in men). Tadié et al showed that laryngeal injury was related to the length of intubation, the non-use of muscle relaxant drugs and the height/ETT diameter ratio. This was a study made in an ICU and all patients were intubated \>24 hrs and therefore not fully applicable to the OR-setting. Jaensson et al describe a significant lower risk for post operative sore throat (POST) using a smaller ETT size in women during elective surgery. Myles et al describe women being 1.5 times more likely to report having POST compared to men. To defend the superiority of a larger tube size further studies assessing the effect of the ETT size on the arterial CO2 tension is needed.

Methods: After written, informed consent, 26 (13 in each group) consecutive, male patients planned for liver tumour ablation with HFJV will be included in the study.

Participants will be randomized to ETT size 8 or 9. Randomisation will take place in an earlier stage with the help of a computerised randomisation generator where 26 envelopes are prepared in which the information of tube size is to be found. The envelopes are on the outside anonymous. The envelopes will be opened by the anaesthetic nurse in the operation room, who will then prepare the ETT.

An arterial line will be placed before the start of anaesthesia and a transcutaneous measuring device will be placed on the forehead of the patient. After preoxygenation, induction and ETT placement, conventional ventilation will be started and a normal tcCO2 value reached (tcCO2 4,5-5 before the start of HFJV). HFJV will have pre-set settings with the same values for all patients. Driving pressure (DP) will be 1,2 bar and frequency 220/min. Measurements from the three different methods; arterial pCO2, transcutaneous CO2 and etCO2 will then be recorded at the start of HFJV (t=0) and then every 15' until t=45 minutes of HFJV. In the case of rapidly increasing CO2, a cut off limit of 10 kPa will be used. When this level is reached, settings on the ventilator will be changed. That means increasing DP and, if needed, lower the frequency. If this does not lead to a satisfactory CO2-level HFJV has to be changed to conventional ventilation until the CO2-level is within normal limits. Any injury during intubation and post extubation stridor (PES) will be recorded. The patient will be asked for post operative sore throat (POST) and any signs of postoperative hoarseness (PH) will be noted in the protocol before leaving the post anaesthetic care unit (PACU) and also approximately 24 hrs after extubation. If symptoms still occur after 24 hrs, follow up will take place approximately 72 hrs and 96 hrs after extubation. If symptoms are still present by this point the patient will be offered a doctor's appointment.

Statistics: The power calculation was based on data from previous studies. The base-line PaCO2 among 12 male patients, at the start of HFJV, was 4.9 kPa (SD 0.5) with an increase to mean PaCO2 of 6.7 (SD 1.5) at 15 minutes with HFJV and a tube size of 9. With the hypothesis that the PaCO2 would increase to a mean of 8.0 kPa after 15 minutes of HFJV ventilation, with a tube size 8, groups of 11 patients are needed to verify the difference at a p\<0.05 with a power of 80%. To compensate for potential drop-outs, groups of 13 patients is set as the study population. Data will be presented as mean, SD, median and range where applicable. One-way ANOVA will be used on normal distributed data and ANOVA on ranks will be used on non-normal distributed data. Bonferroni's test will be used to compare differences between the different timepoints. A p-value of \<0,05 will be considered as statistically significant.

Importance of the study: This study is conducted to if the larger endotracheal tube size has benefits in gas exchange when HFJV is being used in liver tumour ablation procedures. Normally it is desirable to use as small ETT as possible as this minimises the risks for airway injury. The risks of air entrapment and even pneumothorax and raise in carbon dioxide levels are also risks that are potentially harmful for the patients and must be avoided. The small risk of using a one size larger ETT would therefore be accepted if the benefits can be shown in this study.

Patients planned for liver tumour ablation will be randomised to one of two sizes of ETT, size 8 or size 9.

The patient is not being informed what ETT-size is being used.

As men and women routinely uses two different ETT sizes and we wanted to compare two sizes within one group, this study will only focus on men.

Endotracheal Tube Size Effect on the Carbon Dioxide Washout During Jet Ventilation

Does Endotracheal Tube (ETT) Size Facilitate Carbon Dioxide Washout in Liver Tumour Ablation With High Frequency Jet Ventilation (HFJV)? - a Randomised Controlled Trial

Carbon dioxide level from an arterial line (PaCO2) in kPa will be compared from the levels at baseline to the level at 15 minutes of HFJV.

The dynamics of carbon dioxide changes obtained from an arterial line (PaCO2) in kPa, transcutaneously (tcCO2) in kPa and end tidal measurement (etCO2) in kPa registered every 15 minutes during the first 45 minutes of HFJV. That is, all values from each timepoint (15 minutes, 30 minutes and 45 minutes after the start of HFJV) will be compared to baseline.

During HFJV measure pause pressure (PP) in mbar and peak pressure in mbar .

PaO2 in kPa will also be measured and analysed during the procedure.

pH will also be measured and analysed during the procedure.

Lactate in mmol/L will also be measured and analysed during the procedure.

Saturation in percent will also be measured and analysed during the procedure.

Signs of apparent mechanical injury in the airway. Signs of apparent injury, being visible injury during intubation and post extubation stridor (PES). Post operative sore throat (POST) and any signs of postoperative hoarseness (PH)

Region Stockholm

Frequency : 120-200/min Pressure : 1-2 bars Inspiratory fraction of oxygen : 100% and 50% if Expiratory pressure : 5 -10 cmH2O

Apnea made by the anesthesiologist to the request of the radiologist.

MONSOON III™ (Acutronic Medical System AG®, SEBAC) with Double lumen catheter 12CH (Acutronic Medical System AG®, SEBAC)

Jet ventilation group

apnea made by the anesthesiologist to the request of the radiologist

Standard ventilation group

Sandra PETIOT, MD

Evaluate benefits of High Frequency Jet Ventilation compare to standard ventilation during general anesthesia in patient undergoing peri diaphragmatic percutaneous tumor ablation.

The investigators hypothesis that procedure is shorter and more accurate in High Frequency Jet Ventilation group reducing target movement induced by ventilation.

High Frequency Jet Ventilation for Percutaneous Interventional Radiology

Estimated the time for a puncture needle under High Frequency Jet Ventilation compared to the conventional mode of mechanical ventilation

University Hospital, Strasbourg, France

Respiratory Tract (Lung and Bronchial) Diseases

Pulmonary Atelectasis

Lung Diseases

Respiratory Tract Diseases

Computed tomography scans are performed every 15 minute during the first 45 minutes during general anaesthesia using high frequency jet ventilation.

On High frequency jet ventilation, Every 15 minutes, after induction of general anaesthesia, a computed tomography of the lower part of the lungs are taken (10 cm volume, with the top of the right diaphragm as the lower border)

HFJV

Atelectasis formation using HFJV during stereotactic solid organ ablations.

Primary endpoint will be to study the formation of atelectasis during HFJV. Secondary endpoint will be to study liver displacement over time. Reference groups will be found in previous published articles as referred to above.

Materials and methods: A radiological protocol has been made for the CT-scanner to take 10 cm volume Scans of the lower part of the lung. The scans will have its' lower border tangential to the top of the diaphragm. The first scan will be performed in the same session as the routine scan of the liver is performed after the patient is anesthetized. These Scans will then be repeated every 15 minute during the first 45 minutes. Arterial bloodgas analysis, transcutaneous CO2, blood pressure, saturation as well as parameters from the jet ventilator and the standard ventilator will be recorded.

The use of HFJV in abdominal surgery as well as in out-of-operating theatre environment, is not well studied. In percutaneous liver thermal ablation the patient is anesthetized and intubated on the CT-bed where the liver ablation procedure is performed. Atelectasis is formed as soon as the patient is supine. Anesthesia itself also contributes to this. In extreme cases almost half the lung can be collapsed during anaesthesia, before any surgery has taken place.

The investigators have noticed that during this specific surgery, dynamic lung compliance does not necessarily worsen during HFJV but rather being unchanged or in some cases even becoming better and want to study this further and investigate the formation of atelectasis during HFJV. There are studies where atelectasis has been measured in a similar way as in this planned study, that is, with thin axial CT-scans at representative levels of the lung. This is during conventional lung ventilation, and has not yet been studied during HFJV.

Inclusion criteria: A total of n= 25 patients planned for elective liver tumor thermal ablation will be recruited after written informed consent.

Exclusion criteria: Patients 1/ under the age of 50 years, 2/with severe, poorly controlled lung disease.

The lung images will be saved in DICOM format and the tissue density will be analysed quantitatively. For each scan, the inner contour of each hemithorax will be manually drawn, excluding the chest wall, mediastinum, pleural effusions, and regions representing partial volume effects. Liver displacement can be measured from the routine CT-scans taken before and after the procedure.

Statistical methods: Chi2-analysis will be used to calculate the percentage of atelectasis in the lung.

Power calculation: Since the rate of atelectasis formation in the study groups is not known, it is impossible to perform power calculation for this trial. This study may clarify this issue in the planning of further studies.

This study may contribute to more knowledge about HFJV and its' effect on lung physiology, it may also contribute as a generator of new hypothesis and it might be a follow up study where the effect of alveolar recruitment maneuver (ARM) is studied.

Atelectasis Formation Using HFJV During Stereotactic Solid Organ Ablations

Atelectasis Formation Using High Frequency Jet Ventilation During Stereotactic Solid Organ Ablations

Computed tomography Scans will be taken during general anaesthesia at the start of jet ventilation, t=0, and then at t=15 minutes, t=30 minutes and t=45 minutes. A total number of four scans will be performed in each study subject.

Routine CT Scans taken during surgery will be studied to calculate liver displacement over time.

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization
Endotracheal Tube Size Effect on the Carbon Dioxide Washout During Jet Ventilation	NCT05370001	Liver Tumor	Entotracheal tu...	18 Years -	Region Stockholm
High Frequency Jet Ventilation for Percutaneous Interventional Radiology	NCT02813005	Percutaneous Tu...	Jet ventilation... Standard ventil...	18 Years - 80 Years	University Hospital, Strasbourg, France
Endotracheal Tube Size Effect on the Carbon Dioxide Washout During Jet Ventilation	NCT05370001	Liver Tumor	Entotracheal tu...	18 Years -	Region Stockholm
Endotracheal Tube Size Effect on the Carbon Dioxide Washout During Jet Ventilation	NCT05370001	Liver Tumor	Entotracheal tu...	18 Years -	Region Stockholm
Atelectasis Formation Using HFJV During Stereotactic Solid Organ Ablations	NCT03378752	High Frequency ... Atelectasis	HFJV	50 Years -	Karolinska Institutet

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