Effect of the Minimum Bronchial Cuff Volume of Left-sided Double-lumen Endotracheal Tube for One-lung Ventilation on the Change of the Bronchial Cuff Pressure During Lateral Positioning in Thoracic Surgery

Study Overview
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Brief Summary
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Over-inflation of the bronchial cuff of the double-lumen tube (DLT) can cause damage to the airway mucosa and misplacement of the tube, and under-inflation may cause incomplete collapse of the non-ventilated lung and incomplete ventilation of the lung that should be ventilated. Appropriate cuff pressure is generally known to be ranged 20-30 cmH₂O, but in the study of Okubo et al., who observed the minimum bronchial cuff volume and pressure that did not cause air leakage using the method of confirming by capnography, it was possible to obtain the result that OLV was possible without air leakage even at a pressure lower than 25 cmH₂O (the generally recommended tube cuff pressure) in both men and women. In a recent study of Yamada et al., when using the capnography waveform-guided method to inflate the bronchial cuff by checking for air leakage using the capnography waveform, the bronchial cuff volume (BCV) that satisfies the air-tight seal was significantly smaller compared with a pressure-guided method to inflate the bronchial cuff with 20 cmH₂O. The minimum bronchial cuff volume (BCVmin) at which such air leakage does not occur may vary from individual to individual. It is presumed that this is because the diameter of the left main bronchus (LMB) differs from individual to individual, which causes the variation of the gap between the diameter of the LMB and the outer diameter of the DLT mounted thereon. Moreover, the previous study revealed that the lateral positioning could increase the pressure of the bronchial cuff mounted on the LMB due to the gravity-induced morphological and conformational change of the trachea. Considering these factors, the researchers hypothesized that the change in the bronchial cuff pressure (BCP) due to a positional change might vary depending on whether the bronchial cuff was inflated, that is, the initially established BCVmin. Therefore, in this study, the researchers tried to investigate the effect of BCVmin on the change of minimum bronchial cuff pressure (BCPmin) due to the positional change from the supine to lateral decubitus, by dividing the groups whose BCVmin is 0 ml or exceeds 0 ml.

Official Title
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Effect of the Minimum Bronchial Cuff Volume of Left-sided Double-lumen Endotracheal Tube for One-lung Ventilation on the Change of the Bronchial Cuff Pressure During Lateral Positioning in Thoracic Surgery: a Prospective Observational Study

Conditions
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Lung Cancer, Pneumothorax

Intervention / Treatment
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* Behavioral: Lateral positioning
* Device: Cuff pressure measurement


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients aged 18-80 and with an American Society of Anesthesiologists (ASA) physical status of 1 or 3 who are scheduled to undergo elective video-assisted thoracoscopic surgery (VATS) Exclusion Criteria: A. Need for a right-sided DLT B. An intraluminal lesion in the left main bronchus C. An anatomical problem in the tracheobronchial tree D. Patients with chronic obstructive pulmonary disease with impaired lung compliance E. Patients with interstitial lung disease with severe pulmonary dysfunction F. Patients with Body mass index (BMI) ≥ 30

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| BCVmin=0<br>This study was a prospective observational study, and the patients was divided into two groups with BCVmin=0 or BCVmin >0, according to the BCVmin which was naturally determined during anesthesia in each patient. | Behavioral: Lateral positioning<br>* After the DLT intubation, the patient is placed in lateral decubitus position<br>Device: Cuff pressure measurement<br>* The pressure of the bronchial cuff should be measured with cuff-manometer in supine position, and then measurement should be repeated after lateral positioning<br>|
| BCVmin>0<br>The patients was divided into two groups with BCVmin=0 or BCVmin >0, according to the BCVmin which was naturally determined during anesthesia in each patient. | Behavioral: Lateral positioning<br>* After the DLT intubation, the patient is placed in lateral decubitus position<br>Device: Cuff pressure measurement<br>* The pressure of the bronchial cuff should be measured with cuff-manometer in supine position, and then measurement should be repeated after lateral positioning<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The change in minimum bronchial cuff pressure (BCPmin) when changing a posture from supine to lateral decubitus, that is the diffence in BCPmin between the supine and lateral position when injecting the BCVmin of air. | The bronchial cuff pressure measured when the bronchial cuff was inflated with the smallest bronchial cuff volume without air leakage was defined as BCPmin. It should be measured at each position (supine and lateral decubitus position). To do this, the bronchial cuff should be inflated with air, increasing the volume by 0.5 ml from 0 ml, and at the same time check and measure whether air is leaking around the bronchial cuff. As a method of checking for air leakage, the investigators should check whether 80% or more of the tidal volume set on the ventilator at each stage is properly supplied to the patient while increasing the air by 0.5 ml, and whether the end-tidal carbon dioxide graph has a typical trapezoidal shape. | 1. In supine position, 2 minutes after the completion of confirming the double-lumen endotrachial tube (DLT) position via fiberoptic bronchoscope (FOB), 2. In lateral position, 2 minutes after the completion of confirming the DLT position via FOB | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The minimum bronchial cuff volume (BCVmin) | The smallest bronchial cuff volume without air leak was defined as BCVmin. It should be measured at each position (supine and lateral decubitus positon). To do this, the bronchial cuff should be inflated with air, increasing the volume by 0.5 ml from 0 ml, and at the same time check and measure whether air is leaking around the bronchial cuff. As a method of checking for air leakage, the investigators should check whether 80% or more of the tidal volume set on the ventilator at each stage is properly supplied to the patient while increasing the air by 0.5 ml, and whether the end-tidal carbon dioxide graph has a typical trapezoidal shape. | 1. In supine position, 2 minutes after the completion of confirming the DLT position via FOB, 2. In lateral position, 2 minutes after the completion of confirming the DLT position via FOB | 
| The relationship between the minimum bronchial cuff volume (BCVmin) and the gap between the diameter of patient's left main bronchus and the outer diameter of the DLT |  | In supine position, , 2 minutes after the completion of confirming the DLT position via FOB | 
| The incidence of the patients whose BCPmin when changing posture from supine to lateral decubitus | Increase or decrease of the BCPmin after positional change | 1. In supine position, 2 minutes after the completion of confirming the DLT position via FOB, 2. In lateral position, 2 minutes after the completion of confirming the DLT position via FOB | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cuff pressure, Double lumen endotracheal tube, Lateral positioning