Question 24

College answer

Aim: To allow the candidate to display knowledge of management of traumatic broncho-pleural fistula.
Key sources include: Papers 2014.1 Q4, 2017.2 Q3, 2019.1 Q23, CanMEDS Medical Expert.
Discussion: Alveolar or bronchopleural fistula (BPF) is a problem of significance and candidates who passed this question were able to correctly outline clinical features and list ways to assess the extent of an air leak. Examples of successful answers included descriptions of patterns of bubbling, and air leak quantification either 
clinically or using ventilator parameters (tension or expanding pneumothorax and pneumomediastinum, various ventilator infographics and measurements).
A general lack of detail regarding parts c and d was common in answers that scored fewer marks. Candidates could have improved their answers by explaining the clinical concerns with the use of PEEP. PEEP application via the ICC was commonly described by candidates but without describing the risks. Some examples of other strategies to manage a BPF included an outline of how and why to aim for spontaneous ventilation, with or without early extubation, ensuring patency connection and correct sizing of ICCs and a discussion on the advantages and disadvantages of suction. 
Answers to part d) would have improved by including (but not limited to) references to extracorporeal lung rest, bronchial occlusion devices, and various surgical options from blood patches to highly invasive surgery. Broncho-pleural fistula has appeared many times in the fellowship examination and candidates are advised to read widely around repeated topics.

Discussion

"Read widely around repeated topics" is excellent advice, and the examiners have correctly pointed out that this has appeared multiple times. In fact the last time this was repeated (in 2019) the pass rate for the question was 90%. Those SAQs were:

• Question 23 from the first paper of 2019
• Question 3 from the second paper of 2017
• Question 23 from the first paper of 2016
• Question 4 from the first paper of 2014

a) Clinical features of broncho or alveolo-pleural fistula:

• Air leak (obviously) which is not resolving over more than 24 hrs
• Pneumothorax on the CXR which is not resolving in spite of a properly placed chest drain (i.e. the lung has failed to reinflate)
• The development of worsening pneumomediastinum of subcutaneous emphysema
• Poor alveolar ventilation, i.e. the appearance of a large physiological dead space (as some  expired CO₂ escapes via the leak)

b) Methods of assessing the air leak:

• Measurement of the difference between the inspiratory and expiratory volumes (if your ventilator does that)
• Qualitatively, by looking at the pattern of bubbling, as in the Pierson article  which stratifies BPF severity according to bubble timing:
  • Bubbling during inspiration only
  • Bubbling during both inspiration and expiration
  • Bubbling during both inspiration and expiration with a detectable volume difference (at least 100-150ml leak per breath)
• Fancy drains (eg. the Thopaz system) can measure the air leak quantitatively

c)

i) Ventilator management:

• low peak inspiratory pressures, which means:
• low V_T
• low PEEP
• low resp rate
• short insp. time
• tolerate high PCO₂
• wean rapidly
• extubate early

ii) Intercostal catheter management:

• Reposition, including with CT guidance
• Resite as a larger drain
• Add another drain
• Increase the suction, OR decrease the suction (you can make an argument for either)

d) Rescue strategies for refractory leak:

• DLT, independent lung ventilation
• Bronchial stenting
• Bronchial occlusion
• Application of PEEP to the ICC
• Pleurodesis
• HFOV
• ECMO

Lois, Manuel, and Marc Noppen. "Bronchopleural fistulas: an overview of the problem with special focus on endoscopic management." CHEST Journal 128.6 (2005): 3955-3965.

Baumann, Michael H., and Steven A. Sahn. "Medical management and therapy of bronchopleural fistulas in the mechanically ventilated patient." CHEST Journal 97.3 (1990): 721-728.

Pierson, David J., et al. "Management of bronchopleural fistula in patients on mechanical ventilation." (2012) - from UpToDate.

Mueller, Michael Rolf, and Beatrice A. Marzluf. "The anticipation and management of air leaks and residual spaces post lung resection." Journal of thoracic disease 6.3 (2014): 271.

Cerfolio, Robert J., et al. "A prospective algorithm for the management of air leaks after pulmonary resection." The Annals of thoracic surgery 66.5 (1998): 1726-1730.