All posts by TheTraumaPro

Retained Hemothorax And Empyema

Patients with chest trauma sustain hemothorax on occasion. The trauma professional usually picks this diagnosis up in the initial evaluation and makes a decision whether or not to drain it. The parameters for this decision are not very clear, even today. But what happens when there is residual hemothorax? Should we be more aggressive in getting it out?

All this boils down to an understanding of the natural history of retained hemothorax. This kind of information can help us decide whether to be more aggressive in our efforts to remove it. The results of a multicenter study looking at this issue was published recently. They focused on patients who had a chest tube placed for management of either hemo- or pneumothorax within 24 hours of admission. Patients who had suspected retained hemothorax after tube removal received a CT scan within 14 days. The usual outcomes were studied (length of stay, complications) as well as development of empyema (purulence, acidic pleural fluid, positive Gram stain or culture).

Some interesting results:

  • 328 patients were enrolled across 20 centers. Not a lot, but one of the bigger studies to date.
  • Empyema was diagnosed in 27% of patients
  • Risk factors identified included rib fractures, ISS > 25, and performance of additional interventions for drainage
  • Patients who developed empyema stayed in the ICU and the hospital longer

Bottom line: Retained hemothorax turns into a very serious problem in a quarter of trauma patients who have a chest tube inserted. The presence of residual blood after the chest tube is removed should prompt us to figure out if it’s solid clot or liquid blood (remember the old decubitus view chest xray? They still work!). If it’s liquid, consider drainage via thoracentesis or a smaller catheter. If it’s clot, it may require more invasive techniques to drain it (VATS). If you decide to send the patient home, have them watch out for fevers, chest pain, dyspnea and other symptoms and signs of a developing complication, and make sure they report it to you promptly.

Related post:

Reference: Development of posttraumatic empyema in patients with retained hemothorax: Results of a prospective, observational AAST study. J Trauma 73(3):752-757, 2012.

When to Give Spleen Vaccines After Splenectomy for Trauma

I’ve written previously on the (f)utility of giving vaccines after splenectomy for trauma (click here to read). However, it is more or less a medicolegal standard, so pretty much everyone gives them. The big question is, when? 

Some centers give them immediately postop, some before hospital discharge, and some during their postop visit. Who is right? The argument is that major surgery produces some degree of immunocompromise. So if the vaccines are given too early, perhaps the anitbodies will not be processed as effectively, and the response to an actual bacterial challenge might not be as good.

One prospective study randomized patients to receive their pneumococcal vaccine either 1, 7, or 14 days after surgery. IgG levels were measured before vaccination and again after 4 weeks. This study found that antibody concentrations were the same in all groups. However, functional activity of the antibodies was low in the 1 and 7 day groups, and nearly normal in the 14 day group.

Following this, a rat study looked at vaccination timing followed by exposure to pneumococcus. These animals were splenectomized, then given a real or sham vaccination at 1, 7, or 42 days. They then had pneumococcus injected into their peritoneal cavity. About 70% of all rats with sham vaccination died. Only 1.5% of the vaccinated rats died, and there were no differences based on vaccination timing.

Bottom line: Neither antibody titer studies nor rat studies easily translate into recommendations for treating overwhelming post-splenectomy sepsis (OPSS) in humans. And such a study can never be done because of the rarity of this condition (less than 70 cases since the beginning of time). It really boils down to your specific population, balancing your assurance that your patient will get it against the possibility that their immune system may not react to it as much as it could. 

At our center, we give the vaccines as soon as possible postoperatively. This ensures that it is given, and erases any doubt of what might happen if the patient does not show up for their postop check.

References:

  • Immune responses of splenectomized trauma patietns to the 23-valent pneumococcal polysaccharide vaccine at 1 versus 7 versus 14 days after splenectomy. J Trauma 44(5):760-766, 1998.
  • Timing of vaccination does not affect antibody response or survival after pneumococcal challenge in splenectomized rats. J Trauma 45(4):682-697, 1998.

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Wounds: When Are They Too Old To Close?

At some point in their training, every trauma professional is taught that there is a certain period time during which a wound can be safely closed. The exact number varies, but is usually somewhere between 6 and 24 hours. After that, we are told, “bad things happen.”

Always question dogma, I say. Is this true, or is it another one of those “facts” that have been propagated through the ages? Two emergency medicine groups recently performed a meta-analysis to try to answer my question. As usual, they found that much of the published literature is not very good. Out of 418 papers in their original search, only 4 fully met their criteria (laceration repaired primarily, in the ED, with clear early vs delayed criteria.

With the exception of one study with a very limited focus, there was no correlation between wound age and infection or dehiscence after primary closure. None of the studies could reliably provide a specific time beyond which closure was destined to fail. And the use of antibiotics in some of the studies also confounded the results.

Bottom line: It is more likely that infection-prone wounds get infected, not old ones. Although leaving a wound open to heal by secondary intention usually avoids the problem, it’s a big patient dissatisfier, especially with large wounds. Since many patients don’t present to the ED until their wound is “old”, it may be reasonable to try primary closure in all but infection-prone wounds. (The meaning of that phrase is not exactly clear, but most of us know it when we see it.) 

Reference: The impact of wound age on the infection rate of simple lacerations repaired in the emergency department. Injury 43(11):1793-1798, 2012.

The EMS Second IV In Trauma

One of the critical maneuvers that EMS providers perform is establishing initial vascular access. This IV is important for administering medications and for initiating volume resuscitation in trauma patients. Prehospital Trauma Life Support guidelines state that every trauma patient should receive two large bore IV lines. But is this really necessary?

The upside of having two IVs in the field is that the EMS provider can give lots of volume. However, a growing body of literature tells us that pushing systolic blood pressure up to “normal” levels in people (or animals) with an uncontrolled source of bleeding can increase mortality and hasten coagulopathy.

The downside of placing two lines is that it is challenging in a moving rig, sterility is difficult to maintain, and the chance of a needlestick exposure is doubled. So is it worth it?

A group at UMDNJ New Brunswick did a retrospective review of 320 trauma patients they received over a one year period who had IV lines established in the field. They found that, as expected, patients with two IVs received more fluid (average 348ml) before arriving at the hospital. There was no increase in systolic blood pressure, but there was a significant increase in diastolic pressure with two lines. The reason for this odd finding is not clear. There was no difference in the ultimate ISS calculated, or in mortality or readmission.

Bottom line: This study is limited by its design. However, it implies that the second field IV is not very useful. The amount of extra fluid infused was relatively small, not nearly enough to trigger additional bleeding or coagulopathy. So if another IV does not deliver significant additional fluid and could be harmful even if it did, it’s probably not useful. Prehospital standards organizations should critically look at this old dogma to see if it should be modified.

Reference:

  • Study of placing a second intravenous line in trauma. Prehospital Emerg Care 15:208-213, 2011.