Tag Archives: DVT

DVT Prophylaxis Interruptus Is Bad!

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.

Related posts:

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.

More On DVT In Children

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:

image

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.

Related posts:

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.

Enoxaparin And Pregnancy

Lovenox

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).

Enoxaparin And Pregnancy

Lovenox

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).

DVT Prophylaxis After Solid Organ Injury

Nonoperative management of solid organ injury is the norm, and has reduced the operative rate significantly. At the same time, the recognition that development of deep venous thrombosis (DVT) in trauma patients is commonplace creates uncertainty? Is it safe to give chemical prophylaxis with low molecular weight heparin (LMWH)? How soon after injury?

The trauma group at USC+LAC published the findings of a retrospective review of 312 patients undergoing nonoperative management for their liver, spleen or kidney injuries. They looked at chemical prophylaxis administration and its relationship to failure of nonop management of solid organ injury.

As expected, as the grade of the solid organ injury increased, so did the failure rate of nonoperative management. Administration of low molecular weight heparin, such as enoxaparin, did not increase failure rate in this study. All but one failure occurred in patients who had not yet received the injections. Likewise, two DVT and two pulmonary embolisms occurred, but only in patients who had not yet received prophylaxis. 

Bottom line: This small study offers some assurance that early prophylaxis is okay, and a few prospective studies do exist. UCSF / San Francisco General is comfortable beginning chemical prophylaxis 36 hours postop, regardless of solid organ injury. Look for more guidance on this issue in the near future. Until then, consider starting LMWH prophylaxis early to avoid complications from DVT or PE.

Reference: Thromboembolic prophylaxis with low-molecular-weight heparin in patients with blunt solid abdominal organ injuries undergoing nonoperative management: current practice and outcomes. J Trauma 70(1): 141-147, 2011.