Question 4 from the second paper of 2009 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.
Firstly, some generic material on the post-op complications of the pneumonectomy patient.
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