Reexpansion pulmonary edema following thoracentesis

Another pulmonary case! This time around it is a case report about what didn't happen...reexpansion pulmonary edema.

We had a pleasant 39 year old female with a PMH of RA on adalimumab and recurrent metastatic breast cancer presenting with dyspnea due to a large right sided pleural effusion. We're talking the entire right lung opacified on the CXR. We knew the etiology of the effusion to be malignant so we were mainly performing a therapeutic thoracentesis. The post-thora CXR showed a small improvement in aeration in the apex of the right lung. That's it. WHY DIDN'T WE TAKE MORE OFF? We actually removed 2 whole liters.

Important points to address here:

1.  What is reexpansion pulmonary edema?

• After thoracentesis the lung can quickly fill back up with fluid - in an alveolar filling pattern (hence reexpansion pulmonary edema, not reexpansion pleural effusion). 
• The pulmonary edema can range from radiographic changes only to full on ARDS requiring intubation.
• This typically comes on quickly, within 1 hour after the procedure. 
• Presentation includes dyspnea, tachypnea, cough, hypoxia, chest pain and hypotension

2.  Is it bad?

• MORTALITY UP TO 20%

3.  Pathophys?

• There are several postulated mechanisms, all of which likely contribute, including:
• Reperfusion and oxidative stress/oxygen free radicals
• Histologic changes and vascular permeability from lung expansion and damage
• Increased hydrostatic pressure from reperfusion with negative pleural pressure

4.  How can we prevent it?

• This is where the evidence gets dicey...there have been multiple small studies to try and predict how negative the pleural pressure can get, how much can be taken off, etc. but there is no consensus
• Most authors agree that taking off no more than 1.5 - 1.8 liters reduces the risk to acceptable levels
• One sign of potential early edema and lung reexpansion/friction of the visceral and parietal pleura is coughing and chest pain, so some authors suggest that if they haven't had these signs you are ok to continue
• In our patient we removed 2 liters as she had no symptoms of coughing or pain until that point
• In our institution generally we stick to 1.5 - 1.8 liters from what I have seen, IR and Pulm will both go up to 2 liters occasionally but NEVER more than 2 liters

5.  Let's say we didn't prevent it...

• Oops! Happens in less than 1% of cases but happens nonetheless
• Treatment is supportive - oxygen, occasionally PEEP in the form of CPAP/BiPAP or intubation and mechanical ventilation
• Diuretics vs IVF vs pressors - this just depends on the hemodynamics and overall clinical picture

Key Points

• This is a rare, preventable and potentially fatal complication of thoracentesis
• Our best guess - stick to 1.5 - 1.8 liters off at one time
• They deserve close monitoring the first hour after the procedure - watch out for dyspnea, tachypnea, hypoxia, cough, chest pain and hypotension

To find out more:

http://www.respiratorycasereports.com/article/S2213-0071(14)00046-X/fulltext

http://www.uptodate.com/contents/noncardiogenic-pulmonary-edema#H14

http://www.nejm.org/doi/full/10.1056/NEJMicm1309844