Pulmonary Edema After Chest Tube Insertion
Re-expansion pulmonary edema is an uncommon event after chest tube insertion. Typically, patients have had symptoms of pneumothorax for several days, usually 3 or more. It occurs most often if a large amount of air (or blood) is evacuated at once. The patient will typically become symptomatic within an hour, with decreased oxygen saturation and subjective breathing difficulty.
Although the mechanism is not entirely clear, it appears that the small blood vessels in the lung become more permeable if they are collapsed for an extended period. Mechanical stress from rapid re-expansion further damages the vessels, allowing them to leak. This leads to oxygenation and ventilation problems if severe.
- Check the history. Most of these patients have had their pneumothorax for 3 or more days.
- Check the xray. Complete pneumothorax (or large hemothorax) puts the patient at high risk.
- Modify your chest tube insertion technique. Clamp the distal end of the tube so the pneumothorax is not evacuated suddenly as the tube goes in.
- Modify the collection system. Do not use suction initially; only set up for water seal. Clamp the tubing on the patient side. Every 10-15 minutes release the clamp and briefly let some of the air out of the chest, then reclamp. Repeat this until all air has bubbled through the water seal chamber.
- Watch your patient. If they cough excessively, start to desaturate or become dyspneic, get your respiratory adjuncts. Give higher inspired oxygen by appropriate means, and consider BiPap or CPAP. In extreme cases intubation may be needed. If the patient does not have any difficulties after about an hour, connect the collection system to suction and proceed as you normally would.
Reference: Reexpansion pulmonary edema. Ann Thoracic Cardiovasc Surg 14:205-209, 2008.
Dry Seal Chest Tube Suction Systems
The original chest tube collection system traditionally consisted of three chambers. The picture above shows the classic three bottle system (which I actually remember using during residency). On the left is the suction control bottle that determines how much suction is applied to the patient. The middle bottle provides one way flow of air out of the patient, the so-called water seal bottle. Finally, the right bottle collects any fluid from the pleural space.
Collection systems used in hospitals are much more tidy than this, wrapping all three into one modular unit. However, if you look closely you can identify parts of the system that correspond to each of the bottles.
The problem with the older systems is that they typically require water in the “water-seal” chamber to maintain one-way flow out of the patient. If this chamber is compromised by knocking the system over (see this post), air may be able to enter the patient’s chest, giving them a big pneumothorax.
Management of chest tube collection systems by EMS is tough. It’s very easy to tip the system during air or ground ambulance runs, putting the patient at risk. Some manufacturers have developed so called “dry-seal” systems that use a mechanical one-way valve to avoid this problem.
I have not been able to use one of these systems yet. Here is my take on the pros and cons:
- Pro – immune to tip-over and malfunction of the water-seal chamber
- Con – more difficult to detect an air leak. Current models require either injection of a small quantity of water, tipping the system, or converting to a water-seal system.
- Con – no literature regarding safety of this relatively new technology
Bottom line: Looks like a great idea to me, especially for EMS use. Once they get to the hospital, the unit can be changed to a water-seal system or a larger dry-seal system with the water injection port inthe dry-seal chamber.
Chest tubes are needed occasionally to help manage chest injuries. How do you decide when they are ready for removal?
Unfortunately, the literature is not very helpful in answering this question. To come up with a uniform way of pulling them, our group looked at any existing literature and then filled in the blanks, negotiating criteria that we could all live with. We came up with the following.
- No (or a minimal, stable) residual pneumothorax
- No air leak
- Less than 150cc drainage over the past 3 shifts. We do not use daily numbers, as it may delay the removal sequence. We have moved away from the “only pull tubes on the day shift” mentality. Once the criteria are met, we begin the removal sequence, even in the evening or at night.
- Has the patient ever had an air leak? If so, they are placed on water seal for 6 hours and a followup AP or PA view chest x-ray is obtained. If no pneumothorax is seen, proceed to the next step.
- Pull the tube. Click here to see a video demonstrating the proper technique.
- Obtain a followup AP or PA view chest x-ray in 6 hours.
- If no recurrent pneumothorax, send the patient home! (if appropriate)
Click here to download the full printed protocol.
How To Remove A Chest Tube
Occult pneumothorax occurs somewhere between 2% and 12% in all blunt trauma patients. Many of these pneumothoraces never progress and thus never need treatment. Is there a way that we can identify ones that are likely to get worse?
A retrospective study of 283 blunt trauma patients with occult pneumothorax was presented at the EAST Annual Scientific Assembly last January. A total of 98 of these patients underwent chest tube insertion within 7 days, and 185 patients were successfully observed.
The authors noted an inverse relationship between age and successful conservative management. Patients with more serious injuries failed expectant management more frequently. Finally, patients with more rib fractures also tended to fail.
The authors estimated the risk of failure of expectant management based on these critieria and found:
- Age > 35 – 36%
- ISS > 24 – 20%
- Rib fractures >= 4 – 53%
The risk with having none of these was 10%, and the risk with all was 75%!
The time interval for placement was also interesting. 80% of the failures requiring a chest tube occurred within 24 hours, with most occurring in the first 2 hours. The authors also found that 40% of patients who were placed on a ventilator failed.
Obviously, this is a small retrospective study and the exact criteria for placing a chest tube were not specified. Nevertheless, it provides a simple tool that allows us to keep an eye on a subset of patients who are likely to fail observation of occult pneumothorax.
Reference: Factors Predicting Failed Observation of Occult Pneumothoraces in Blunt Trauma. Selander, Med Univ of South Carolina. EAST 2010 Annual Scientific Assembly.