To improve the performance of EBs, our group proposed to deliberately pass the ETT tip distally to almost touch the carina and deflect the EB balloon sideways through the Murphy eye, and have used this technique on small children with apparent success (7).
The EB was 'pre-inserted' into the ETT lumen via the Coopdech ETT connector before intubation (Figure 1); the EB balloon tip was made to emerge through the Murphy eye and the catheter was then locked at the proximal end with the blocker tube clamp (equivalent to the Tuohy-Borst type valve on the Arndt multiport adaptor).
Her laryngoscopic view was Cormack and Lehane grade 2b in spite of cricoid pressure, and initial attempts at intubation with an 8 mm ID ETT 'pre-loaded' with an intraluminal 9 Fr Coopdech catheter emerging through the Murphy eye failed.
Instead of changing to a DLT, we simply made sure that the ETT Murphy eye was facing the right, advanced the ETT to a depth just before loss of bilateral ventilation and then advanced blindly a 9 Fr Coopdech with its tip angling to the right until it emerged through the Murphy eye (a subtle resistance followed by a 'give' was felt).
Making the balloon emerge through the Murphy eye makes accidental blockade of the ETT tip even more unlikely.
5 mm ID without the EB; then pass the EB through the ETT lumen with the deflated balloon pointing towards the side to be blocked, thus allowing the balloon to emerge through the Murphy eye into the mainstem bronchus (Cases 4 and 5).
From Figure 1, one can see that tip of the EB protrudes slightly through the Murphy eye.