Portex endobronchial double lumen tube

                                

Endobronchial Tubes

Endobronchial tubes are used in thoracic surgery. Double lumen tubes all have cuffed endobronchial portions and tracheal cuffs. The endobronchial parts are curved to the left or right. They are passed blindly and their position should be confirmed bronchoscopically. The main disadvantage of right sided tubes concerns the short length of the right main bronchus before giving off the upper lobe bronchus (risk of occlusion). Thus left-sided tubes are usually preferred, even for right sided-surgery, because the risk of inadequate ventilation of the right upper lobe if incorrectly positioned.

Indications for one-lung ventilation (OLV)

The indications for one-lung ventilation are divided into two groups: absolute and relative. The decision to use an endobronchial blocker is clinical and should be based on a consideration of risk verses benefit. Double-lumen tubes and endobronchial blockers function differently. Double-lumen endotracheal tubes isolate ventilation, separating the right and left pulmonary units using two separate endotracheal tubes. An endobronchial blocker blocks ventilation to a pulmonary segment. Endobronchial blockers are balloon tipped catheters that are placed in the portion of the trachea that is to be blocked (usually the right or left main stem bronchus). Ventilation to the pulmonary unit is blocked when the balloon is inflated. Endobronchial blockers are a preferable choice for patients optimally managed with single-lumen endotracheal tubes rather than conventional double-lumen tubes.

 

Insertion of endobronchial tubes

The tube is held with the bronchial curve concave anteriorly (as with normal ETT). As the tip is passed through the larynx the tube is rotated 900 to direct the endobronchial part to the intended side. The tube is then connected to the breathing circuit via a double catheter mount.

Checking the tube position

Manual ventilation is commenced with the tracheal cuff inflated. Air entry should be equal on both sides and there should be no leak around the tracheal cuff.
The tracheal side of the adapter is then clamped and the tracheal port is opened distal to the clamp. The bronchial cuff is inflated so as to just eliminate air leak from the tracheal lumen. Breath sounds should be heard only on the side of endobronchial intubation.
The tracheal limb is then unclamped, the tracheal port closed and the bronchial limb of the adapter is clamped and the bronchial port opened to air. Breath sounds should only be heard on the contralateral side.

Fibreoptic bronchoscopy down the tracheal lumen should reveal the carina and the top edge of the blue bronchial cuff should be just visible in the intended main stem bronchus. When a right sided tube is used the fibrescope should be used to visualize the orifice of the right upper lobe bronchus.
                                                                  
The Double Lumen Tube with final position in the left main bronchus with the bronchial and tracheal cuffs inflated.

Management of Hypoxia under OLV

Manoeuvres are directed at minimizing atelectasis in the ventilated lung and shunt in the non-ventilated lung. Set initial tidal volume at 10ml/kg and adjust respiratory rate to maintain normocapnia. Use FIO2 of 0.5 initially and increase to 1.0 if required.

ensure proper tube position (auscultate, bronchoscopy); suction at regular intervals.
Apply CPAP to the non-ventilated lung to expand it just enough so as not to interfere with the surgery, thus reduce shunt.
Apply PEEP to the ventilated lung may reduce atelectasis but oxygenation may deteriorate due to increase in shunt through the other lung.
oxygenation can be insufflated into the non-ventilated lung via a suction catheter. Alternatively, the non-ventilated lung can be inflated briefly with 100% oxygen at intervals.

Persistent hypoxia that does not respond to the above manoeuvres must be treated with resumption of two-lung ventilation with 100% O2. Failing this, clamping of the pulmonary artery (of the surgical lung) should improve oxygenation.