It's 3:00 AM and you want to do a thoracentesis?

Today in our Grand Morning Report, we discussed a common clinical dilemma that many Senior Medical Residents (SMR) face on call across the city:

This patient has a pleural effusion and it's 3:00 AM, should I perform a thoracentesis?

I would argue that there is really only one absolute, emergency indication to perform a thoracentesis on call (overnight) as an SMR covering the GIM service.

This being the old adage, "never let the sun set on an empyema".

If an SMR suspects empyema clinically, for example imaging confirms a loculated pleural effusion and the patient is febrile, than I believe the sun should not set, or in the case of our SMR's overnight, the sun should not rise before that pleural effusion is sampled and sent for culture.

This may require calling interventional radiology or thoracic surgery to provide assistance.

In my practical experience as an SMR at Sunnybrook Hospital, all that is needed overnight is an adequate sample to perform the necessary tests, mainly a sterile specimen for culture and gram stain, and to perform basic biochemistry (pH, cell count, protein, LDH).  This usually amounts to a 20 cc specimen, and no more.

Time... it is a precious commodity on call!

Practically on call, there is very little time to do a full therapeutic thoracentesis and drain off 1000 mL of fluid, so once the diagnostic sample is obtained, I would finalize the procedure and move on to the rest of your clinical duties.

It would not be an ideal scenario to be called to attend a Code Blue, while you are in the midst of draining off a large pleural effusion, and a needle is in the patient's back.

But... What if the patient is in respiratory distress and I feel that removing the fluid will alleviate their symptoms?

I would argue that the risks of performing a therapeutic thoracentesis overnight far outweigh the potential benefit.  If a patient is in such significant respiratory distress, that you want to insert a needle into their pleural cavity, they most likely will not have a significant clinical change from taking off 1000 mL of fluid.  

A unilateral pleural effusion is often not the only cause of the respiratory distress.  It usually takes an insult to both lungs to cause significant respiratory distress in most patients.  It is probably the presence of the underlying disease process such as pneumonia, congestive heart failure, malignancy, or pulmonary embolus that may be causing both the pleural effusion, and  the respiratory distress.

My suggestion in this circumstance would be to treat the underlying cause, such as giving lasix to a patient with CHF and a pleural effusion, provide supplemental oxygen (such as optiflow, or BiPAP), and if they are truly in respiratory distress, then these patients should be in a monitored setting (ICU or step down unit) as they will most likely require intubation or ventilatory support.  If it is patient discomfort that is the major problem, than providing symptom relief along with supplemental oxygen should be the way to go overnight.

What is the risk of performing a thoracentesis overnight?

Most of the literature points out that a bedside thoracentesis without the use of an ultrasound at the best of times carries a risk of pneumothorax between 4 - 30%, and approximately half of these patients will require insertion of a chest tube (Jones et. al, 2003).  Overnight, when an SMR has time constraints, and is fatigued this number is likely on the higher side.

Even with the use of ultrasound, the rates of pneumothorax were 2.5% among experienced interventional radiologists.

I love point of care ultrasound, but I am not an experienced interventional radiologist!

The Bottom Line:  

The last thing you want to do to a patient at 3:00 AM with significant respiratory distress is cause a pneumothorax as this may significantly worsen an already unstable situation.

The safe SMR knows when to subject a patient to a significant risk of harm, but more importantly knows when not to perform a procedure (especially overnight when there is very little support around).

If you're not ruling out empyema, don't stick a needle into the chest.  If the case is particularly challenging, call thoracic surgery or interventional radiology for assistance.  If the patient is unstable, call the ICU and if they are symptomatic, treat the symptoms and wait until the heavy cavalry arrives in the morning, and their is enough support around to safely perform the thoracentesis and deal with any serious complications.

A great reference on the rates of pneumothorax in the ultrasound era.  See reference below!

Ultrasound-Guided Thoracentesis: Is it a safer method? Jones, et. al. CHEST. 2003. 123: 418-423.