All posts by TheTraumaPro

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.

Related posts:

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.

SCIP: Importance Of Prophylactic Antibiotics In Trauma Laparotomy

Quite a lot of research has been done on the efficacy of prophylactic antibiotics in the prevention of infectious complications after surgical procedures. Antibiotics are now routinely given prior to most elective surgical procedures. In the US, the Centers for Medicare and Medicaid Services has formalized this into part of the Surgical Care Improvement Project (SCIP), which mandates the use of an appropriate antibiotic within 1 hour preop and stopping it within 24 hours postop.

But what about emergent cases, like trauma laparotomy? Ensuring timely antibiotic administration is difficult due to the rapid events leading up to the operation. And sometimes it is not clear whether a hollow viscus injury has occurred until after start of operation, so the antibiotic choice may change in the middle of the case.

Two busy urban trauma centers with high penetrating injury rates looked at one year of experience in patients undergoing trauma laparotomy. They compared surgical site infections (SSI) in patients who received SCIP-compliant antibiotic administration vs those who did not. 

Key findings:

  • Patient mix was 30% blunt, 44% gunshot, 27% stab wounds
  • There were 151 SCIP-compliant patients and 155 noncompliant ones
  • Half of the noncompliant group did not receive the appropriate antibiotic (usually Cefazolin in hollow viscus injury), and half had antibiotics given for more than 24 hours
  • SCIP-compliant patients had significantly fewer wound infections and shorter length of stay. Mortality was the same.

Bottom line: I recommend adhering to SCIP prophylactic antibiotic guidelines for trauma laparotomy. There is no reason why this subset of patients should be treated any differently, and this study presents evidence that it is beneficial. Using the SCIP guidelines in emergent surgery reinforces the usual preop routine in hospitals that have already embraced them. In general, blunt trauma patients undergoing laparotomy should receive prophylaxis that covers skin organisms. Since penetrating trauma has a much higher chance of involving the intestinal tract, broader spectrum antibiotics should be selected. In either case, use the antibiotic that has been selected for this purpose by your hospital. And be sure they are stopped during the first 24 hours.

Reference: “SCIP"ping antibiotic prophylaxis guidelines in trauma: the consequences of noncompliance. J Trauma 73(2):452-456, 2012.