Introduction
Traditional model of reexpansion pulmonary edema (RPE)
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This model led to the recommendation that any volume of fluid could be removed as long as the pleural pressure was continuously measured with manometry and not allowed to fall under -20 cm. In the absence of manometry, it is recommended that we should avoid removing large volumes of fluid (variably defined as >1000 ml or >1500 ml), which could potentially lead to dangerously low pleural pressures (Daniels 2011).
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Evidence: Risk of reexpansion pulmonary edema (RPE) after large-volume thoracentesis
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Most notably, patients with RPE had slightly higher intrapleural pressure at the end of the procedure compared to patients without RPE (figure below, “closing pressure”). This argues strongly against the traditional model of RPE being due to negative intrapleural pressure “pulling” fluid into the lungs via Starling's law. These authors concluded that in the absence of manometry, pleural effusions should be drained dry unless the patient experiences vague chest discomfort.
New models of RPE: What implications do they have on thoracentesis volume?
How severe is RPE following thoracentesis if it does occur?
RPE risk in clinical context
Large-volume thoracentesis and ex vacuo pneumothorax
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Another argument to avoid large-volume thoracentesis is to reduce the risk of ex vacuo pneumothorax. This occurs if the underlying lung is unable to expand, for example due to bronchial obstruction. Thoracentesis generates a low intrapleural pressure which transiently opens a tiny hole in the lung to allow air into the pleural space (alleviating the “vacuum”). Pneumothorax ex vacuo is a benign phenomenon which rarely enlarges or leads to tension pneumothorax, and generally should not be treated with a chest tube (Heidecker 2006).
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Pneumothorax ex vacuo is rare, benign, and potentially a useful diagnostic finding. It probably doesn't make sense to limit the volume of thoracentesis to avoid this occurrence. This was explored in more detail in the last post.
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Should we stop thoracentesis if the patient starts coughing or develops chest pain?
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Guidelines and conventional wisdom
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This is an arbitrary cutoff supported by little data. The British Thoracic Society 2010 guidelines made this as a Grade C recommendation. These guidelines admitted that it is “less clear how cases at risk of RPE can be predicted at higher volumes” of fluid removed. They also admitted that “advice has generally been conservative because of the morbidity associated with RPE and a mortality rate quoted as high as 20% (Mahfood 1988).” As discussed above, evidence supporting this mortality rate is flawed. No actual evidence is provided to explain the selection of 1500 ml as the maximal safe volume:
Although the safe aspiration of much larger volumes has been documented, it is also clear that complications are uncommon when aspirating <1.5 liters. This is therefore the recommended volume to be aspirated in one attempt.
Take-home points
- Re-expansion pulmonary edema is a rare and usually mild complication of thoracentesis.
- There is no evidence that removal of a larger volume causes re-expansion pulmonary edema, although a weak correlation likely exists. It is possible that the risk of re-expansion pulmonary edema relates to the volume of the initial effusion rather than the volume removed.
- There is little evidence to support any specific cutoff for the amount of fluid which may be safely removed.
- It is reasonable to drain large effusions completely, with premature termination of the procedure if the patient develops vague chest discomfort (Feller-Kopman 2007, Soberman 2007).
- Coughing or pleuritic chest pain during fluid removal are physiologic responses to lung re-expansion and catheter irritation of the pleura. Neither requires termination of the procedure.
- Pulmcrit wee: The cutoff razor - April 15, 2024
- PulmCrit Blogitorial – Use of ECGs for management of (sub)massive PE - March 24, 2024
- PulmCrit Wee: Propofol induced eyelid opening apraxia – the struggle is real - March 20, 2024
good read. thank you for the work and enlightening us all
I just had over a liter of fluid removed from one lung. When I weighed the next morning, I was down 4 pounds. Surely that wasn’t all fluid. So, how much would one liter of fluid weigh?
ruth
a liter of water weighs about one kg (2.2lbs).
i suspect that pleural fluid weighs about the same.
tom
We took off 1.1 liters from a 91 year old last night, she began to hypotense within the hour and was dead by morning. I came here to see if there are guidelines for how much how fast to remove. I think, especially looking at the comments below, more study is needed.
very cool review and discussion, Josh.
thank you
Twice I have dern patients code and die after large volumes of effusion were drained . in each case there was sudden air hunger, huge increase in oxygen demand, difficulty with even bipap to maintain oxygenation, followed by patient coding. One brought back to code again in ICU and the other coding and dying after transfer to ICU. Another time literally moments after chest tube placement, I saw the entire drainage system completely fill in less than 60 seconds accompanied by the patient being unable to breath. That case was resolved by immediate clamping and slower drainage being initiated. However,… Read more »
That’s very unfortunate. Was re-expansion pulmonary edema confirmed? Could these cases have another pathophysiology involved: tension PTX, bleeding?
I must play devil’s advocate here. It’s very easy to remember our positive cases (particularly when there’s such dramatic negative outcomes) but when you look at large series you realize that the incidence is quite low.
Doing large volume thoracentesis is supported by our current evidence and it decreases the number of procedures needed; therefore decreasing the chances of bleeding and/or other complications every time we put a needle in the chest.
Why did you drain the fluid so rapidly ? You should know that is dangerous !
My brother has NASH. He was recently diagnosed with Stage IV liver failure/non-alcoholic liver cirrhosis. Over the past 6 weeks, he has had pleural effusions. His first and second taps went well. This past Friday, the interventional radiologists took off 4500 ml and discharged him. Later that evening, he was struggling to breathe and his Oxygen sat went down to the 60s. His wife took him to the ER – he was admitted with pneumonia in both lungs and he was treated for sepsis. Long story but is there any connection to the excessive amount of fluid that was removed.… Read more »
It is very difficult to evaluate complications that are rare, and severe, sometimes letal, by looking at a clinical course of a few hundred patients..
A few hundred in a RCT can unequivocally document usefullness or futility of evaluated treatment, but are not enough to exclude significant danger from treatment.
Very nice Clinical practice tips.
My dad has had fluid taken out of lung about 2 litres in all but he is still losing weight about 3ib a week
Brilliant precise & to the point
Just a question If the patient with a large effusion develops chest discomfort &
procedure is abandoned , after how many days can thoracocenetsis be done again?
During the second tap can we remove the same quantity of fluid or lesser than the
first attempt to prevent RPE?
Does giving oxygen during the procedure decrease possibility of RPE
Thanks
I had 1 liter drained and 7 days later had another 900ml drained. I think another thoracentesis could have been performed a lot sooner.
Once a month I get my belly drained from having liver disease
They take off me about 7 liters is that bad
How long can you go draining extra fluid off the belly
my husband had thoracentesis done which immediately filled with air. What happened to cause this?
Thank you for this nice article. Great information
Hi
I would like to know how long does a old patients need to wait after removing the liquids on his lungs? A patient that I know a tube still attached to him and doctor said they won’t remove until the liquids is clear.
Is this true?
Patient still attached to tube for a week now.
Any info thanks