Summary of abstracts

One should always be aware of potentially devastating consequences of anaesthetic interventions, even if such disasters are uncommon. Today we briefly explore airway rupture in the setting of double lumen tube placement, and then conclude with a rare aside. You may also wish to briefly browse our editorial comment

The actual incidence of airway rupture has probably been under-reported. Red rubber tube material is more rigid.  Re-sterilised red rubber tubes have irregularities of the tube tip and are more often associated with airway damage, especially when inserted forcefully during the intubation process. A carinal hook if present can also injure the upper airway. When the poly-vinyl-chloride double lumen tubes were introduced in 1980 it was believed that these tubes did not cause airway injuries.  Reports of airway injury from the poly-vinyl-chloride double lumen tubes soon appeared however. In this article the risk factors for airway rupture with double lumen tubes, complications of double lumen lube usage and the recommendations for double lumen tube placement are discussed concisely. The medical literature published between 1972- 1998 was reviewed and where possible the foreign language publications were translated into English and one of the original investigators was contacted for additional information.

Initial over-inflation of either the tracheal or bronchial cuff at the time of tube placement may have accounted for the greatest number of injuries with red rubber double lumen tubes as well as with poly-vinyl-chloride double lumen tubes. Movement of the patient into the lateral decubitus position with both cuffs inflated increases the chances of mucosal trauma.  Red rubber double lumen tubes have low volume/ high pressure cuffs and inflate asymmetrically after multiple uses and are associated with more frequent airway injuries.

In the case of poly-vinyl-chloride double lumen tubes manufacturers recommend the removal of the stylet of the bronchial lumen as soon as the tip of the tube has passed the vocal cords.  Actually the stylet have never been implicated in any report of major airway injury. There is one report that recommends retaining of the stylet throughout the process of the tube placement.

Large and medium size red rubber double lumen tubes were associated with most of the airway injuries reported. In contrast the majority of the airway injuries with the poly-vinyl-chloride double lumen tubes are associated with the small size tubes.

Although airway injuries have been reported with all types of pulmonary surgery with both red rubber double lumen tubes as well as with poly-vinyl-chloride double lumen tubes, the most frequently reported surgery associated with such injuries is oesophageal surgery.

Airway damage can present with an air leak causing subcutaneous emphysema or cardiovascular instability from a tension pneumothorax.   Airway hemorrhage and aneurysmal dilation of the membranous wall can occur from incomplete laceration of the airway with dissection of the adventitia. The signs of injury may be delayed.

Bronchoscopy performed before extubation allows early diagnosis in the cases where airway injury is suspected as immediate surgical intervention is essential for favorable results.

Fitzmaurice and Brodsky's recommendations for the safe placement of a double lumen tube

1. Choose the largest poly-vinyl-chloride double lumen tube that will safely fit the patient’s airway.
2. Remove the bronchial stylet once the tip of the tube is past the vocal cords.
3. Be extra cautious with patients who have tracheo-bronchial wall pathological disease, leukemia, steroid therapy or  hypoperfusion.
4. Advance the double lumen tube to the appropriate distance in the bronchus (based on the patient height)
5. Inflate both cuffs slowly.
6. Use 3ml syringe to inflate the bronchial cuff.
7. Never over-inflate either cuff. 
   (Usually <3mls of air is adequate for the bronchial cuff if an appropriate size double lumen tube is selected.  If more air is needed, reassess the tube size and position.)
8. When nitrous oxide is used consider inflating both cuffs with saline or an oxygen/nitrous oxide mixture.
9. When nitrous oxide is used measure the cuff pressures intermittently. Keep the bronchial cuff pressure < 30cm of water
10. Deflate both cuffs before moving the patient
11. Deflate the bronchial cuff when lung isolation is not required.
12. During oesophageal surgery consider partial deflation of the cuff when surgical dissection is near either cuff.
13. Test the integrity of the intubated bronchus at the completion of surgery.
14. Use a fiberoptic bronchoscope to determine the extent of any suspected injury.

2.  Selecting the correct size left double-lumen tube

It is important to select the correct size of double lumen tube because most of the complications associated with double lumen tubes results from selecting too small a tube. Small double lumen tubes are more easily displaced as compared to large double lumen tubes, causing obstruction of the orifice to the upper lobe. Other problems include the over-inflation of the bronchial cuff in order to get a good seal.  Overinflation can cause herniation of the cuff in to the carina as well as airway rupture. Increased resistance to airflow during one lung ventilation with small double lumen tubes can be another problem.

Appropriate size double lumen tube selection has been done by different methods.

• Width of the left main bronchus from the chest radiograph. (Only visible in 50% of cases)
• Left bronchial diameter measured by the chest computed tomograph (CT).

The width of the trachea measured from the postero-anterior chest radiograph can be used to predict the left bronchial size and can be very helpful in selecting the appropriate size of double lumen tube quite accurately.

Jay B Brodsky et al. applied this method of selection of double lumen tube on 487 patients.  All patients were intubated successfully, the tubes functioned properly and there were no complications.

Hannallah et al by using CT scans for choosing the appropriate size double lumen tube found that in 75% of their patients they used a smaller size double lumen tube (37 or 35 French) as compared to the Brodsky series, where only 3% required a 37 or a 35 french double lumen tube

Double lumen tubes of 35 french size are seldom required for adult patients unless they have very small airways, but they can be used for larger children. Mallinckrodt also offers 32-French double lumen tube.  The author has used a 32-French BroncoCath double lumen tube in three 10 year old children with excellent results.

3.  An Oddity