SPECIAL POPULATIONS

Pending Surgery

Except for brain or spine surgery, holding chemical VTE prophylaxis prior to surgery is not indicated.

1. Routinely holding pharmacological prophylaxis prior to surgery may increase VTE risk without an accompanying decrease in the risk of bleeding. Many specialties with high DVT rates are now administering chemoprophylaxis at the start of surgery. 29-32
2. A pending invasive procedure is the most common reason for a patient missing a dose of chemoprophylaxis. Every missed dose increases VTE risk. Patients that miss two to four doses are at 8.5 times higher DVT risk compared with those with no missed doses.33

Traumatic Brain Injury

1. Enoxaparin 30mg SQ twice daily remains the dosing of choice.

2. Prior to starting chemical VTE prophylaxis in TBI patients:

a. Consult a neurosurgeon.

b. Obtain CT scan of the head 24 hours post injury to assess for intracranial hemorrhage stability.

3. Prophylaxis should be withheld in the setting of progression of intracranial hemorrhage or presence of an intracranial monitor.

4. In patients with stable intracranial hemorrhage on repeat head CT, initiating chemical VTE prophylaxis 24-72 hours following traumatic brain injury does not increase the progression of intracranial hemorrhage.26,27

5. Initiating VTE chemical prophylaxis is recommended in TBI patients with a stable head CT 24 hours after injury. Even in the setting of combat related penetrating TBI, for those patients with a stable repeat head CT, initiating pharmacologic prophylaxis 24 hours after injury was safe, with similar rates of progression.34 Caution should be taken in starting chemical VTE prophylaxis 24 hours post injury and discussion with neurosurgeon is recommended for TBI patients with the following conditions:

a. Polytrauma with or at risk for coagulopathy

b. Have intracranial monitor/drain in place.

c. Have one or more of the following TBI features that are “high risk” for progression according to the Norwood-Berne criteria:

SDH > 8mm

Epidural hemorrhage > 8mm

Largest single contusion > 2cm

More than one contusion per lobe

Diffuse or scattered subarachnoid hemorrhage.

Diffuse or scattered intraventricular hemorrhage.

For these patients, chemical VTE prophylaxis is typically restarted 72 hours post-injury or from last stable CT head, or as neurosurgeon recommends. 35,36

6. Avoid interruptions in dosing for TBI patients who are started on chemical VTE prophylaxis. Interrupted dosing in this patient population causes a 600% increase in the VTE rate.37

Spine Trauma

1. Enoxaparin 30mg twice daily remains the recommended dosing.

2. Prior to starting chemical VTE prophylaxis, consult a spine surgeon.

3. Patients with traumatic spine injury or who undergo spine surgery should have VTE prophylaxis initiated within 48-72 hours after injury or after spine surgery.

a. Chemical VTE prophylaxis initiated within 48 hours of operative fixation of traumatic spine fractures does not increase the risk of bleeding, progression of neurological injury, or postoperative complications including spinal hematoma. 38

b. Delays longer than 72 hours lead to a substantial increase in VTE rate. 39

4. Patients with suspected traumatic spinal injury and neurologic deficits should have chemical VTE prophylaxis held until imaging and spinal surgical consultation are obtained.

Solid Organ Injury

1. Chemical VTE prophylaxis should be initiated in patients with moderate (AAST grades 1-3- liver, spleen, kidney) solid organ injury in the absence of:

a. Hemodynamic instability

b. Hemoglobin drops greater than 2 g/dL in less than 12 hours

c. Ongoing blood transfusion after the initial resuscitation has been completed. 24,29,40,41

2. Chemical VTE prophylaxis started within 12-24 hours of injury in this cohort decreased VTE rates without an increased risk of bleeding that required blood transfusion or intervention.42

3. There is insufficient evidence on outcomes related to patients with grade 4 and 5 injuries because these patients often undergo operative management. All Grade 4 and 5 splenic injuries should undergo splenectomy. (See JTS Blunt Abdominal Trauma, Splenectomy, and Post-Splenectomy Vaccination CPG). Initiating chemical VTE prophylaxis post-operatively, in the absence of coagulopathy or other increased risk of bleeding, is considered safe.

Patients with Indwelling Epidural and/or Paravertebral Catheters

Patients who require an epidural catheter increasingly have interruptions in pharmacologic prophylaxis, such that epidural catheter placement is now associated with an increased VTE rate, whereas previously this was not the case. 45,46,47,48 Please refer to the JTS Pain, Anxiety, and Delirium CPG for further detail.

1. The timing of administration for chemical VTE prophylaxis may need to be modified to accommodate the placement and/or removal of an epidural.43

- Regional Anesthesia Guidelines recommend a 12-hour interval between enoxaparin dose and epidural placement. After placement, resumption of prophylactic enoxaparin should begin in 12 hours. Before removing the epidural catheter, hold LMWH 12 hours prior to removal. Resumption may start 4 hours after removal. 43,44
  - The maximum recommended prophylactic dose of enoxaparin is 40mg SQ daily.
- For unfractionated heparin, a 4 to 6-hour interval is recommended before epidural placement. After placement, resumption of prophylactic heparin can begin immediately. Before removing the epidural catheter, hold heparin 4-6 hours prior to removal. Resumption may start immediately after removal.
  - The maximum recommended prophylactic dose of heparin is 5000U SQ TID.

2. Avoid missing doses of VTE prophylaxis for epidural placement, if possible.

3. In the combat casualty requiring an epidural pain catheter, modification of enoxaparin dosing to 40mg daily does not increase the incidence of venous thromboembolism.28

Pregnant Patients

1. Both unfractionated heparin and enoxaparin are considered safe in pregnancy as neither crosses the placenta. 49-51

2. Pregnant trauma patients should receive an initial dose of 30 mg of enoxaparin twice daily titrated by anti-Xa levels, (if available) targeting a peak range of 0.2 to 0.4 IU/mL or a trough range of 0.1 to 0.2 IU/mL.

Pregnancy increases renal clearance, leads to changes in weight, and induces hormonal changes that result in hypercoagulability. All these factors influence drug dosing for chemoprophylaxis.

3. For pregnant trauma patients who weigh more than 90 kg, initiating 40 mg of enoxaparin twice daily is recommended with similar anti-Xa level titration.

Pediatric Patients 17

1. There is insufficient high-quality evidence to make strong recommendations regarding the institution of chemical VTE prophylaxis in children hospitalized after trauma.
2. Based on the current recommendations of the Eastern Association for the Surgery of Trauma and the Pediatric Trauma Society, it is recommended that chemical VTE prophylaxis be considered for children older than 15 years who are at low risk of bleeding and for children younger than 15 years old who are post pubertal if they have an ISS greater than 25.
3. For prepubertal children, even with ISS greater than 25, routine chemical VTE prophylaxis is NOT recommended.

Refer to Appendix A: Prevention of Venous Thromboembolism Guidelines for specific guidance on different subsets of patients after various surgical procedures.