Question 23 from the first paper of 2016, as well as the near-identical Question 4 from the first paper of 2014 asked the candidates to "outline the principles of, and strategies for management of a persisting broncho-pleural fistula (BPF) in a mechanically ventilated patient." The examiners felt the need to comment that overall "candidates had poor knowledge of this topic." The pass rate for Question 4 was 26%, and someone managed to score 6.5 marks. Advantages and disadvantages of the management strategies were specifically asked for. More recently, Question 3 from the second paper of 2017 asked about the assessment and management of an air leak following lobectomy, which was essentially the same thing as asking about a bronchopleural fistula. Lastly, Question 23 from the first paper of 2019 was a repeat of the questions from 2014 and 2016, this time with a pass rate of 90%.
As always, the LITFL entry on bronchopleural fistulae is the ideal last-minute revision resource.
The time-rich exam candidate may wish to explore the following published literature:
These resources have been remixed and pruned to form the summary made available below:
Pathophysiology of bronchopleural fistula
- Normally, a pneumotyhorax bubbles for a while, and the the lung reinflates completely and the air leak stops as the pneumothorax is drained completely, and the lung fully re-expands.
- A bronchopleural fistula is by definition a persisting air leak into the pleural space.
- The definition of "persisting" is an air leak which continues for longer than 24 hours.
- The leak can be measured by comparing the inspiratorya nd expiratory volumes (if your ventilator does that), or by looking at the pattern of bubbling. The Pierson article stratifies BPF severity according to the latter:
- 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)
Causes of bronchopleural fistula
A good article from 2010 (Lois et al) lists the following aetiologies associated with BPF:
- Haemophilus influenzae
- Streptococcus viridans
- Staphylococcus aureus
- Pseudomona aeruginosa
- Klebsiella pneumoniae
- Nonhemolytic streptococcus
- Histoplasma capsulatum
- Gastroesophageal reflux disease with Barrett esophagus
- Boerhaave syndrome
Traumatic and iatrogenic
- Lung cancer
- Thyroid cancer
- Esophageal cancer
- Thoracic trauma with tracheobronchial tree disruption
- Post-surgical (eg. lobectomy or lung biopsy) - by far the most common cause!
- Bougie intubation
- Necrotizing lung disease associated with radiation or chemotherapy
- Ventilator-induced barotrauma
- Excessive manual ventilation
- Central line placement
- Complication of bronchoscopy
Beyond the various lung-puncturing causes, there are also perpetuating factors. For instance:
- High suction of the ICC
- High tidal volumes
- High inspiratory pressures
The management strategies are discussed below. I have attempted to synthesize the college answer to Question 4 from the first paper of 2014 with the content of the abovelisted articles.
Management Strategies for Bronchopleural Fistula
- large-bore drain
- or, multiple drains
- minimise suction
- easy and readily available
- Usually well tolerated
- Does not interfere with weaning of ventilation
- Risk of damaging more lung and creating larger leaks
- Potentially, perpetuates the fistula by negative pressure suction
- low VT
- low PEEP
- low resp rate
- short insp. time
- tolerate high PCO2
- wean rapidly
- extubate early
- easy and readily available
- Usually well tolerated
- Early extubation is the ideal step to aim for, as spontaneous negative pressure breathing is better for BPF healing than positive pressure ventilation.
- The BPF itself may frustrate weaning off ventilation
- Mandatory mode may prolong ventilation time
- Permissive hypercapnea may lead to respiratory acidosis, which is not ideal for the patient with traumatic brain injury
|Independent lung ventilation
- dual-lumen tube
- or, bronch blocker
- Isolation of one lung permits the selective low-volume low-pressure ventilation of the affected lung, and more rapid higher volume ventilation of the unaffected lung.
- PCO2 levels may be easier to control in this manner
- Technically difficult: DLT insertion is one thing; running two ventilators is another.
- There may be leak of gas and pressure from one lung to another if the seal is imperfect
- Sedation requirements will be higher, to tolerate the larger tube and the very unnatural respiratory pattern
- Local pressure effects of the DLT are also more problematic
- The affected lung can be surgically repaired. USually, this means segmental lobectomy (for alveolar leaks) or patching and oversowing of the bronchial leak
- Apparently, success rates are between 80 and 95%
- It may be impossible to find the leak intraoperatively
- It may be unfeasible to remove so much lung
- It may be impossible if there are multiple leaks
- The patient must tolerate one-lung ventilation
- This approach requires thoracotomy
- The affected bronchus can be stented over bronchoscopically, thereby blocking the leak.
- This is a minimally invasive alternative to surgical patch repair
- You need to be sure of where the leak is
- The leak must be in an accessible bronchus.
- This may not work if there are multiple leaks
- The procedure requires technical expertise
- The patient must be fit to tolerate the bronchoscopy
- Similarly to surgery, the affected pronchus is blocked with either a one-way valve or a plug. In fact, the Lois article lists options such as blood clot, cyanoacrylate glue, fibrin, lead shot, gel foam, calf bone, and various others.
- You need to be sure of where the leak is
- The leak must be in an accessible bronchus
- A major part of the lung may be sacrificed
- The atelectatic lung may develop infection
|Application of PEEP to the ICC
- The equal intra and extrathoracic PEEP decreases the leak volume
- Maintained intra-thoracic PEEP permits higher PEEP levels to be used
- Drainage is compromised
- There is a major risk of rapid tension pneumothorax
- May reduce peak pressures
- Certainly reduces tidal volume (to ~50ml)
- Thus, theoretically reduces flow across the BPD, allowing it to heal
- This is avery unnatural form of ventilation, and may be poorly tolerated
- Large amounts of sedation or paralysis will be required
- This may be the only option for severely hypoxic patients
- With ECMO, one can limit or totally abolish gas flow through the BPF
- All the risks of ECMO apply, as it is a maximally invasive therapy
- It is not widely available.
- There is little experience with this in BPF.
The air leak following lobectomy
Question 3 from the second paper of 2017 presented the candidates with a post-lobectomy patient who is extubated, and who has a significant air leak. An excellent article by Mueller & Marzluf (2014) is used here as the main guide to the discussion.
There are only two possible ways the drain could be producing an air leak:
- It's coming from the patient's lung
- It's coming from the extrathoracic air
Assessment of a post-lobectomy air leak should therefore consist of the following steps:
- Examine the patient (an ABC based primary survey, ensuring that the patient is not about to die of pneumothorax or mediastinal shift)
- Exclude drain dislodgement (examine the drain)
- Quantify the leak:
- Ask the patient to cough
- Ask the patient to speak
- Observe the quantity of bubbles.
- If bubbling is constantly happening while the patient is speaking, the leak is significant.
- If the bubbling is only present with cough and diminishes with ssutained coughing, the leak is probably small.
- CXR to confirm pneumothorax
- CT chest if the CXR is uninformative
Management options for a post-lobectomy air leak are numerous, ranging widely in their invasiveness.
- Do nothing. Keep the drain on suction and wait for it to settle down. Most do within 3 days of the surgery. Generally, about 50% of post-lobectomy patients will have some sort of air leak postoperatively, but this tends to settle down by day 3 or so. A "persistent air leak" is then defined as an air leak after Day 5, which is the average length of stay post lobectomy. In Question 3 from the second paper of 2017 the college did not give us a timeframe of how many days post-op the patient is, but the wording of the question sounds as if the patient has just returned from theatre, which would make waiting and watching a completely reasonable option. But, let's say it continues.
- Decrease the level of suction. Cerfolio et al (1998) dropped the suction down from the usual 20cm H2O down to 10cm H2O,
- Provocative chest drain clamping: the air leak may settle down more easily if the pressure in the pleural space is less negative. Clamping the drain and putting the patient on a high FiO2 may help denitrogenate the pneumothorax and allow the leak to heal.
- Permissive chest tube removal: essentially an irreversible alternative to clamping the chest drain; the advantage is that by doing this one eliminates another hole in the chest cavity which might be bringing in extrathoracic air.
- Send them home like that. Outpatient management with a chest tube and a Heimlich valve is a legitimate option for patients whose survival from cancer (or existing comorbidities) are such that further major surgery or prolonged hospital stay would be counterproductive. It may be in their best interest to get discharged with a chest drain and a palliative care referral.
- Blood patch is analogous to the same procedure performed for post-epidural CSF leaks. One ends up having to administer about 100ml of autologous blood via the chest drain. The sclerosant effect of blood is not as great as that of talc, and there is a risk of empyema. Combined with the dodgy evidence from small studies, these features make this an unpopular option
- Talc pleurodesis via the chest drain is an option for persisting air leaks. Cerfolio et al (1998) gave this to patients with an air leak around day 7 post op. 60ml of a water/talc slurry is injected via the chest drain. Alternative agents mentioned in the literature included tetracycline and silver nitrate
- Pneumoperitoneum is an option discussed by Mueller & Marzluf (2014); essentially the dome of the diaphragm on the affected side is punctured so that some gas can escape into the peritoneal cavity, thus (hopefully) obliterating the potential space in the chest cavity. It is actually a preventative measure which is most effective when performed intraoperatively, immediately following lobectomy. If not, then it is best done early, "when the lung still is mobile enough to shift to the apex of the chest cavity."
- Intrabronchial valve which is placed bronchoscopically: essentially it is a one-way valve which allows gas to escape from the cavity but not into it. This is invasive, has the potential to dislodge, and can act as a nidus for infection. Moreover, you'd need to remove it a few weeks later.
- Surgical revision is the ultimate solution for a leak which is not resolving with conservative measures in a patient suitable for surgery. The most aggressive solution (hopefulyl avoidable) would be a pneumonectomy.
Cerfolio et al (1998) give a nice algorithm:
Basically, this team would keep the drain on suction (20cm H2O) until day 2 post op, and then turn the suction off. A CXR was then performed to assess for pneumothorax. Then, if there was a pneumothorax with an air leak, they would take the level of suction down to 10cm H2O.