Pneumonectomy and its complications have not enjoyed very much attention in the CICM fellowship exam. Historic instances of their appearance in the exam papers are limited to Question 19 from the second paper of 2018 and Question 4 from the second paper of 2009, of which the latter presents us with a situation where a post-pneumonectomy patient has come back from the operating theatre with the chest drain attached to an underwater seal tube. More on that later.
For the purposes of answering the exam questions, a good review by Mesbah et al (2015) outlines the (relatively) recent evidence in analgesia, and Slinger (2009) contains an excellent discussion of fluid management.
Perioperative assessment of the pneumonectomy patient
Surely there must be people out there who do this well enough and often enough that they would have formed some sort of guidelines. Indeed, three seconds of Googling brings forth a paywalled UpToDate article, the 2013 ACCP clinical practice guidelines (which are available for free and which the UpToDate article is based on), and the 2001 BTS guidelines with which it is in general agreement.
In summary, the tests are:
- Spirometry: FEV1 of less than 80% of predicted suggests that there will be complications
- Actual diffusing capacity: DLCO of less than 80% of expected also predicts complications
- Post-operative FEV1 (calculated): post-op FEV1 of less than 30% of predicted is associated with increased risk of mortality
- Post-operative DLCO (calculated): post-op DLCO of less than 30% of predicted is associated with increased risk of mortality
- Arterial O2 and CO2 are abbreviated as "ABG" in the college answer to Question 19 from the second paper of 2018, but in fact these parameters ae not particularly useful (for example, because of improved V\Q matching the arterial O2 may actually improve post pneumonectomy, making it a pointless preoperative risk marker).
- Exercise testing can be performed for the marginal patients. This can take the shape of stair-climbing, the "shuttle test", integrated cardiopulmonary exercise testing (which measures VO2) and the "six minute walk test" mentioned in the CICM model answer. The latter does not appear to be incorporated into any of the society guidelines for lung resection specifically, but the ATS does have a statement on how it should be used as a measure of functional status in patients with lung disease, and "lung resection" is listed as one of the indications in their (Table 1, p.112) "Indications for the six-minute walk test".
Management of the post pneumonectomy patient
For the purpose of answering Question 19 from the second paper of 2018, the exam candidate would only need to know a little about the analgesia and fluid management (which would be reasonably easy to work out from basic principles). However, one might look beyond the exam-centric focus of Φ to behold the training program as a process which produces competent intensivists, and those would probably be expected to have a more wholistic understanding of pneumonectomy management. One assumes that there's plenty of such wholistic intensivists at Liverpool Hospital, as their (publically available) post-pneumonectomy protocol is of a rather high quality. Borrowing heavily from this resource, the following management plan has been compiled:
- A: extubate early (ideally, in recovery or OT) and avoid reintubation
- B: Oxygen supplementation to maintain normal levels for the patient.
Avoid positive pressure ventilation.
Chest drains OFF suction.
- C: Monitor invasively; do not react to hypotension with fluid boluses, as pulmonary oedema may result. Liverpool ICU fluid-restrict their patients to 1500ml from Day 3.
- D: Analgesia needs to be sophisticated and multimodal:
- Regional block (paravertebral seems to be favoured over thoracic epidural- Powell et al, 2011)
- Opiate-sparing agents (eg. NSAIDs and paracetamol)
- Addition of ketamine and neuropathic pain management agents (gabapentin, tricyclic antidepressants, etc) could have an advantage
- F: Fluid management needs to reflect the changes in the pulmonary circulation:
- The right heart has suddenly increased afterload by 50-60%
- The pulmonary veins have suddenly increased pressure by 50-60%
- Increased pressure can cause capillary damage, increasing their leakiness
- The overall upshot of all these is a propensity to pulmonary oedema
- The management recommendation is to keep their fluid balance neutral or negative as much as possible
- G: NG tube placement - to remain on free drainage;
right pneumonectomy patients may develop respiratory compromise with gastric distension, as it will put pressure on the remaining lung.
Left pneumonectomy patients may be fed earlier.
- FASTHUG issues not otherwise mentioned above:
- Expect the possibility of oesophageal dysmotility, and progress diet carefully
- Sit the patient out of bed early, and mobilise them as soon as possible
Complications of pneumonectomy
- Haemorrhage: the risk seems to be about 0.1 - 3% of open procedures.
- Chest drain output in excess of 1L within 1 hour mandates a return to theatre.
- Output in excess of 200ml per hour for 2-4 hours also suggests the need for reexploration
- Atrial fibrillation: occurs in 10-20%
- Cardiac ischaemia: seems to occur in 1.2-3.8%
- Right ventricular failure: this is caused by the increased afterload.
- Post-pneumonectomy pulmonary oedema: this seems to be an issue of capillary damage due to the increased pressure, with subsequent alveolar oedema. The incidence is about 2.5-4%. This complication is avoided by maintaining a sensibly neutral fluid balance post operatively.
- Right to left shunt though a PFO: a proportion (up to 20%) of the population have one, but don't know about it; the sudden increase of right heart pressures may drive blood across the defect, creating a cyanotic heart defect.
- Cardiac Herneation: this tends to occur only with right pneumonectomy, and only when there was a surgical debridement of some of the right sided pericardium, i.e. if the tumour had involved it. The heart can herneate through the pericardial defect, kinking the greater veins and creating a picture not unlike cardiac tamponade. The cardinal features of this rare complication are the presence of a raised CVP/JVP, and the presence of heart sounds in the right side of the chest.
- "Postpneumonectomy syndrome" - the compression of the intact main bronchus due to a shift of the medistainal structures. It tends to happen more often to young people, with elastic mediastinal structures.Occasionally, it cannot be resolved with posture, and a silicone space-filling prosthesis needs to be surgically introduced into the empty hemithorax.
- Lobar torsion and gangrene: this ridiculously rare (0.02%) complication is the result of the rotation of the remaining lung on its hilum. It tends to happen after lobectomy, rather than pneumonectomy, and it tends to affect the lobectomized side, as it has space to move around. The consequences, predictably, are hideous.
- Chylothorax: the risk is between 0.7 and 2%.
- Stump breakdown and bronchopleural fistula: this complication is probably quite common, but the surgeons cannot seem to agree on what a "prolonged" air leak actually is. One surgical textbook suggests that its all OK because with watchful waiting and ongoing chest drainage "more than 90% of air leaks seemed to stop within several weeks after operation".
- Phrenic nerve damage: This is a complication of the redo procedure; it tends to happen as a consequence of adhesiolysis.
- Recurrent layngeal nerve damage: this is even more rare.
- Post-operative pneumonia or empyema: This seems to happen in up to 25% of patients. The major culprit is post-operative atelectasis.
Post-pneumonectomy chest drain care
Why is there a chest drain in the first place?
- Firstly, if there was no chest drain, you would not know about an accumulating haemothorax.
- Secondly, if there was no chest drain and the patient was turned onto the pneumonectomised side, the compression of the affected hemithorax would result in air being forced out though the thoracotomy wound, causing a sudden massive outburst of subcutaneous emphysema.
The main thing to remember is not to connect these drains to suction, or to leave them uclamped for any prolonged period of time. While the clamps are off, you need to be present in the room.
The silent hemithorax with ipsilateral tracheal deviation
Now, this chapter may not be the most effective place to put this orphan topic, but it seems to have no other home. Question 26.4 from the second paper of 2011 asks the candidate to generate three reasons as to why a distressed patient might have a silent chest with the mediastinum shifted towards the silence.
Such a list of differentials will include the following
- Right bronchial intubation
- Occlusion of a main bronchus:
- Sputum plugging
- Inhaled object
- Migrated tracheal or bronchial stent
- Large blood clot in massive haemoptysis
- Post pneumonectomy patient whose left chest drain has been left on suction.
- Phrenic nerve injury with a paralysed hemidiaphragm