A Prospective Randomised Controlled Trial To Compare The Stability Of Bronchial Blocker Between Extraluminal And Intraluminal Placement In Adult Thoracic Surgery

Bronchial blockers (BB) are the most commonly used lung isolation devices after double lumen tubes for one lung ventilation. Lesser risk of trauma to the airway is an important advantage of a BB but there is a higher intraoperative dislodgement rate which ranges from 10 - 40% during the intra operative period. Dislodgement is one of the reasons for the lower popularity of BB when compared to a Double Lumen Tube (DLT). Therefore, methods to reduce dislodgement may improve the acceptability of BB for achieving lung isolation with lesser risk of airway trauma.

Bronchial blockers may be sited via an endotracheal tube (intraluminal or coaxial) or outside it (extraluminal or para-axial) using a flexible bronchoscope (FB). While the former is the more commonly used technique, it cannot be used universally as the size of the endotracheal tube (ETT) limits its ability to accommodate both the BB and the flexible bronchoscope (FB) in certain scenarios. When both the BB and FB cannot be accommodated through the optimally sized ETT for a particular patient, extraluminal (EL) BB becomes necessary.

We theorise that ELBB would be more stable and less prone to dislodgement as the cuff of the ETT may help to maintain the position of ELBB and prevent its movement. Additionally ELBB may have a lower insertion time making it an exciting alternative to ILBB placement.

Studies comparing IL BB and EL BB in adults have reported shorter insertion times with ELBB. However, the relative risk of intra operative displacement of BB when used intraluminally versus extraluminally is scarce. Studies done to compare these two methods of placement are few and are also not powered adequately to look at BB dislodgment rate as primary objective.

Study Procedure and Methodology:

All patients will have tandard induction of anaesthesia with Inj. Propofol 2 – 3 mg/kg and Injection Fentanyl 2 μg/kg after adequate preoxygenation and  using standard ASA monitoring.  Inj Vecuronium 0.1mg/kg will be used as muscle relaxant. A sealed envelope will be opened to determine group allocation. A video laryngoscope will be used for intubation and bronchial blocker insertion. The bronchial blocker will be placed under the direct supervision of a thoracic anaesthetist. IV propofol boluses will be given to control haemodynamic response at insertion of ETT and BB at the discretion of the anaesthetist which is standard practice. If the SpO2 drops below 90%, the procedure of placement of BB will be interrupted and patient will be ventilated to achieve SpO2 of 100%. The time taken for ventilation for oxygenation will not be included in the time recorded for BB placement. However the number of times of interruption will be noted.

ELBB group

After laryngoscopy, a fixed angled tip 7F bronchial blocker (BB) will be inserted with the angled tip directed towards the side to be blocked. The depth of insertion will be around 25 cm and 27 cm mark at the incisors in female and male patients respectively. This will be followed by intubation of the trachea with a 6.0 or 6.5 ETT in females and 7.0 or 7.5 cuffed oral ETT in males as appropriate and it will be secured at the position where the proximal end of the cuff is around 0.5 cm below the vocal cords. A paediatric size flexible bronchoscope (external diameter 3.8 cm or less) will be inserted and the time of insertion will be noted. The position of the BB i.e. in trachea, in the desired bronchus or in the opposite bronchus will be noted. The BB will be manoeuvred in the desired bronchus so as to place the proximal end of the BB cuff 1 cm below the tracheal carina for left bronchus and 0.5 cm below the tracheal carina for the right bronchus and the time will be noted.

ILBB group

After layngoscopy, the trachea will be intubated with a 7.5 ETT in females and 8.0 cuffed oral ETT in males as appropriate. It will be secured at the position where the proximal end of the cuff is around 0.5 cm below the vocal cords. This will be followed by insertion of a fixed angled tip bronchial blocker (BB) such that the depth of insertion from the incisors is 25 cm in female and 27 cm in male patients respectively with the angled tip directed towards the side which is to be blocked. A paediatric size flexible bronchoscope (external diameter 3.8 cm or less) will be inserted and the time of insertion will be noted. The position of the BB i.e. in trachea, in the desired bronchus or in the opposite bronchus will be noted. The BB will be manoeuvred in the desired bronchus so as to place the proximal end of the BB cuff 1 cm  below the tracheal carina for left bronchus and 0.5 cm below the tracheal carina for the right bronchus and the time will be noted.

Failure to place a blocker: If the attending anaesthetist is unable to place the BB in 10 minutes, another thoracic anaesthetist will be called for placement. If they are unable to achieve optimum placement in 5 minutes, the patient will cross over to the other arm and data collected as described. At any point, in case of safety concerns, the attending anaesthetist can decide to change the plan to the cross over technique or a double lumen tube insertion or any other appropriate technique. This will be noted.

 Lung isolation will be achieved by inflation of the bronchial blocker cuff and one lung ventilation commenced. At change of position for surgery (lateral position for most surgeries), ventilation will be stopped and the bronchial blocker will be deflated. After final position for surgery is achieved, flexible bronchoscopy will be done in both groups to check the BB position which will be noted and BB will be repositioned if required. Thereafter, the BB position will be checked at the start of thoracotomy / thoracoscopy, at the end of procedure, before starting two lung ventilation, if loss of isolation noted by the surgeon, and at any point at the discretion of the attending anaesthetist. The dislodgement will be classified as distal or proximal depending on whether the BB has moved in or out respectively. The time taken for check bronchoscopy and repositioning of BB position will be noted.

Time taken for repositioning will be from the introduction of FB into the ETT till the correct position achieved and will be recorded. Whenever possible, an anaesthetist blinded to the study group (from the adjoining OT in the OT complex) will time the procedure. In case of unavailability, the assistant anaesthetists or technician will time the procedure.

The positions of bronchial blocker tip as seen on FB during placement and repositioning of the blockers will be recorded by clicking photos. Patients receive standard anaesthesia care during the remaining operative period irrespective of the allocated arm of the study.The photographs taken will then be assessed on a later date using a grading system by a team of thoracic anaesthetists. Photo assessment will determine whether the blocker was placed adequately or not and whether it required repositioning.Final analysis will be done to find which method of placement of BB had lesser dislodgment rate.

Safety: After removal of BB, the tracheobronchial tree will be examined by FB to look for any injuries which will be recorded.