Adult trauma patients are at risk for venous thromboembolism (VTE). Children seem not to be. The big question is, when do children become adults? Or, at what age do we need to think about screening and providing prophylaxis to kids? As of yet, there are no national guidelines for dealing with DVT in children.
Researchers at Johns Hopkins went to the NTDB to try to answer this question. They looked at the records of over 400,000 trauma patients aged 21 or less who were admitted to the hospital.
Here are the interesting factoids:
- Only 1,655 patients (0.4%) had VTE (1,249 DVT, 332 PE, 74 DVT+PE)
- VTE patients were older, male, and frequently obese
- VTE patients were more severely injured, with higher ISS and lower GCS
- Patients with VTE were more likely to be intubated and receive blood transfusions, and had longer hospital and ICU stays
The risk of VTE stratified by age was as follows:
Bottom line: Risk of VTE in pediatric trauma patients follows the usual injury severity pattern. But it also demonstrates a predictable age distribution. Risk increases as the teen years begin (13), and rapidly becomes adult-like at age 16. Begin your standard surveillance practices on all 16 year olds, and consider it in 13+ year olds if their injury severity warrants.
Reference: Venous thromboembolism after trauma: when do children become adults. JAMA Surgery online first October 31, 2013.
For a long time, we “knew” that pulmonary emboli were a possible and dreaded complication of deep venous thrombosis (DVT). However, we are beginning to discover that this is not always the case. The group in San Diego decided to see if there really are two different types of PE in trauma, and what that means.
Scripps Mercy Hospital, a level I trauma center, looked at 5 ½ years of their experience with adult trauma patients who were routinely screened for DVT. Any of these patients who developed a PE within 6 weeks of admission were evaluated further.
Here are the factoids:
- Duplex screening from groin to ankle was carried out twice weekly in ICU patients, and once weekly in ward patients
- Surveillance was carried out if the patient would be non-ambulatory for more than 72 hours, or were at moderate or higher risk for DVT using the ACCP guidelines
- Nearly 12,000 patients were evaluated by the trauma service and 2,881 underwent surveillance
- 31 patients (1%) developed a PE
- 12 of these 31 had DVT identified before or immediately after their PE. Clot was below-knee in 9 (!), above-knee in 2, and in the IJ in one.
- 19 patients had PE but no DVT identified (de novo PE, DNPE)
- DNPE tended to be single and peripherally located, and associated with rib fractures, pulmonary contusions, blood transfusions, and pneumonia
- DVT + PE were more often found in multiple lobes or bilaterally
Bottom line: Like most, this is not a perfect study, but it’s a really good one. It is looking more and more likely that some PEs arise de novo, without any associated DVT. These clots are more likely to be linked to some type of inflammatory process, and have a tendency toward causing more of the classic signs and symptoms of PE. There are still lots of questions to be answered, like do you need to anticoagulate the de novo PEs? But for now, no change in practice. Just be aware that these might not be as bad as they seem.
Reference: Pulmonary embolism without deep venous thrombosis: de novo or missed deep venous thrombosis? J Trauma 76(5):1270-1281, 2014.
Every trauma professional knows that DVT can be a real problem in their patients. Prophylaxis for and treatment of DVT is now well established for appropriate patients. However, the best laid plans can’t always be carried out. How many times have you had to delay, or even stop chemical prophylaxis because of an impending operation? And patients who need multiple operations may have multiple starts and stops.
Is this so called “prophylaxis interruptus” bad for the patient?
The trauma group at OHSU in Portland looked at this issue in a series of patients over a 4 year period. Any patient admitted to the trauma service who received at least one dose of prophylactic enoxaparin was eligible for inclusion. They enrolled 202 patients and studied them prospectively from admission, using a strict screening protocol. A total of 73 were trauma patients and 129 were general surgery patients. Any dosing regimen was allowed (bid, qd, renal adjustment).
Here are the factoids:
- The most common reason for a missed dose was an impending invasive procedure (~40%)
- BUT nearly a third had no recorded reason for the interruption!
- Overall incidence of DVT was 16% (!)
- A whopping 59% of patients missed at least one dose of enoxaparin
- Incidence of DVT in patients who never missed a dose was 5%
- Incidence of DVT in patients who missed any dose was 24% (!!)
- Age > 50 was another independent risk factor for DVT
Bottom line: Interrupting DVT prophylaxis (at least with enoxaparin) is bad! This was a small study, but the results were still dramatic. I am surprised, however, at the relatively small number of patients (50/year) from such a busy trauma program. This study confirms a small but growing number of studies that are beginning to suggest the same thing. There’s something that we don’t yet fully understand about DVT prophylaxis, and it appears that stopping it paradoxically creates a hypercoagulable state for a while.
What to do? First, pay attention! Make sure your patients don’t miss a dose if they don’t have to. Not a single one! And it looks like we’ll have to dust off some older papers (or generate some new ones) on the real vs perceived dangers of operating on patients on this drug. I have never been impressed that there is additional bleeding when performing the usual trauma surgical operations on patients who are receiving enoxaparin. But areas where even a small amount of bleeding can be dangerous (e.g. around the brain) will probably continue to cause problems.
Reference: Correlation of missed doses of enoxaparin with increased incidence of deep venous thrombosis in trauma and general surgery patients. JAMA Surg doi:10.1001/jamasurg.2013.3963, online first Feb 26, 2014.
Deep venous thrombosis has been a problem in adult trauma patients for some time. Turns out, it’s a problem in injured children as well although much less common (<1%). However, the subset of kids admitted to the ICU for trauma have a much higher rate if not given prophylaxis (approx. 6%). Most trauma centers have protocols for chemical prophylaxis of adult patients, but not many have similar protocols for children.
The Medical College of Wisconsin looked at trends prior to and after implementation of a DVT protocol for patients < 19 years old. They used the following protocol to assess risk in patients admitted to the PICU and to determine what type of prophylaxis was warranted:
The need for and type of prophylaxis was balanced against the risk for significant bleeding, and this was accounted for in the protocol. The following significant findings were noted:
- The overall incidence of DVT decreased significantly (65%) after the protocol was introduced, from 5.2% to 1.8%
- The 1.8% incidence after protocol use is still higher than most other non-trauma pediatric populations
- After the protocol was used, all DVT was detected via screening. Suspicion based on clinical findings (edema, pain) only occurred pre-implementation.
- Use of the protocol did not increase use of anticoagulation, it standardized management in pediatric patients
Bottom line: DVT does occur in injured children, particularly in severely injured ones who require admission to the ICU. Implementation of a regimented system of monitoring and prophylaxis decreases the overall DVT rate and standardizes care in this group of patients. This is another example of how the use of a well thought out protocol can benefit our patients and provide a more uniform way of managing them.
Reference: Effectiveness of clinical guidelines for deep vein thrombosis prophylaxis in reducing the incidence of venous thromboembolism in critically ill children after trauma. J Trauma 72(5):1292-1297, 2012.
Pregnant women get seriously injured, too. And pregnancy is an independent risk factor for deep venous thrombosis. We reflexively start at-risk patients on prophylactic agents for DVT, the most common being enoxaparin. But is it safe to give enoxaparin during pregnancy?
Studies have looked at drug levels in cord blood when the mother is receiving enoxaparin, and none has been found. No specific bleeding complications have been identified, either. So from the baby’s standpoint, administration is probably safe.
However, there are two other issues to consider. In a study looking at the use of enoxaparin for prophylaxis in women with a mechanical heart valve, 2 of 8 women (and their babies) died. Both suffered from clots that developed and blocked the valves. Most likely, the standard dose of enoxaparin was insufficient, so monitoring of anti-Factor Xa levels must be done.
The other problem lies in the multi-dose vial of Lovenox (Sanofi-Aventis). Each 100mg vial contains 45mg of benzyl alcohol, which has been associated with a fatal “gasping syndrome” in premature infants. The individual dose syringes do not have this preservative.
Bottom line: It is probably safe to give enoxaparin to pregnant women after trauma. However, it is unclear if the dose needs to be increased to achieve adequate prophylaxis. Only consider using this medication after consultation with the patient’s obstetrician, and use only the individual dose syringes. Otherwise fall back to standard subcutaneous non-fractionated heparin (even though it is a Category C drug by FDA; it is still considered the anticoagulant of choice during pregnancy).