The chest is one of the most commonly injured body regions. Patients are frequently found to have either air or blood in the chest, and many require a chest tube (tube thoracostomy) for these conditions. There is an art to chest tube removal, and even in 2021, the best practice has not been fully worked out.
Some believe that pulling the tube during a breath hold is best. Others do this during full expiration. Most centers confirm an uneventful tube removal with a plain chest x-ray. But the time interval after removal varies considerably.
The trauma group at the University of Tennessee – Chattanooga examined the use of chest ultrasound as the confirmatory test for residual pneumothorax after removing a chest tube. They developed an institutional practice guideline requiring a trans-thoracic ultrasound performed by a first-year resident two hours after tube removal. The interns all completed a 30-minute standard ultrasound course for training prior to beginning the study.
Two hours after tube removal, an intern performed the ultrasound (US) and interpreted it. A chest x-ray (CXR) was then ordered and the results compared.
Here are the factoids:
- A retrospective review of 46 patients was performed, but the inclusion criteria were not listed in the abstract
- Eleven of the 46 (24%) had a residual pneumothorax on CXR, and the US detected it in 12 (26%)
- Three patients had PTX on CXR, but not US
- Four patients had PTX on US, but not CXR
- None of the PTX were clinically significant, and none required tube reinsertion
- Cost of care savings was projected to be $4,000 if chest x-ray was not needed
The authors concluded that bedside ultrasound was an acceptable alternative to chest x-ray, with decreased radiation exposure and cost.
Bottom line: This is an intriguing abstract. It shows us that there might be an alternative to the standard chest x-ray confirmation after chest tube removal. It’s a very small study, so non-inferiority can’t truly be established yet. The studies are complementary since each study misses a few pneumothoraces that the other picks up.
At this point, I wouldn’t recommend switching entirely to ultrasound until we have a larger series. But I bet we will be able to in the future. Ultimately, this could reduce radiation exposure (tiny anyway for a chest x-ray) and save a small amount of money. But it will reduce x-ray department resource usage, which may be very helpful for the hospital.
Here are my questions for the authors and presenter:
- How did you select your patients? What were the selection criteria? How long did it take to accrue 46 patients? It’s important that all patients with a chest tube had the criteria applied, otherwise there is an opportunity for bias. We want to make sure that you didn’t inadvertently enroll only the patients for whom ultrasound works well.
- How much of a burden was placed on the interns who did the exam? Was the ultrasound unit nearby? Or did they have to spend 30 valuable minutes rolling it to the floor and doing the study? Radiology department resource use needs to be balanced with intern resource utilization.
- Why did you have such a high rate of residual pneumothorax after the tubes were pulled (about 25%). This seems a bit higher than what the literature reports.
- What does your protocol require when a residual pneumothorax is found? Do you have to perform another study after an additional time interval to prove that it is not getting larger? Serial ultrasound exams? Another chest x-ray? Please show us your entire guideline.
I really enjoyed this paper. I’m looking forward to hearing the nitty gritty details during the presentation.
Reference: ULTRASOUND SAFELY REPLACES CHEST RADIOGRAPH AFTER TUBE THORACOSTOMY REMOVAL IN TRAUMA PATIENTS. EAST 25th ASA, oral abstract #9.