Multimodality Monitoring Of Head Injuries

Non-operative management of intracranial hemorrhage requires neurosurgical consultation, repeat imaging until CT scan is stable, and serial exams.

Surgical intervention may be indicated in the management of patients with severe brain injury. This includes operative care such as evacuation of space-occupying hematomas via craniectomy or craniotomy as well as placement of multimodal intracranial monitors.

INTRACRANIAL PRESSURE MONITORING

Management of severe TBI patients using information from ICP monitoring is recommended. Although long-term outcomes have not been shown to be improved with ICP monitoring, there is evidence that in-hospital and two-week post-injury mortality is improved.22 Additionally, the military trauma system may require multiple patient movements and handoffs that decrease the ability to follow neurologic exams. Therefore, ICP monitoring may detect a deterioration that would normally be detected on serial neurologic exam in a stable ICU environment.

ICP monitoring should be considered in all salvageable patients with:

- Severe TBI and abnormal CT showing one or more of the following:
  - hematoma
  - contusion
  - edema
  - herniation
  - compressed basal cisterns.25
- Severe TBI and a normal CT if 2 or more of the following are noted:
  - Age >40
  - Unilateral or bilateral posturing
  - Systolic blood pressure <90 mm Hg.25

Additionally, a low threshold for ICP monitoring should be maintained in severe TBI patients with any abnormal head CT and inability to follow serial neurologic exam such as during other surgical interventions required early after injury, long-range evacuation of intubated patients, etc.

Options for ICP monitoring:25

- External ventricular drain (ventriculostomy tube)
- Parenchymal ICP monitors. Codman ICP monitors are the only intraparenchymal device with aeromedical certification approved for U.S. Air Force aircraft.

If using antibiotic impregnated ventriculostomy, then no IV prophylactic antibiotics required. Otherwise, Ancef 1gm IV TID may be prescribed while ventriculostomy is in place (neurosurgeon’s discretion). The goal ICP is <22 mmHg.25

Cerebral Perfusion Pressure

Cerebral perfusion pressure is defined as: CPP = MAP-ICP. 22 The goal cerebral perfusion pressure (CPP) is between 60-70 mmHg when the autoregulator status of the patient is uncertain.

Brain Tissue Oxygen Monitoring

- Aeromedical evacuation may decrease continuous brain tissue oxygen (PbtO2).33,69,70 There is evidence that the combined management of PbtO2 and ICP may improve outcomes of neurologic function in patients with severe TBI.
- Consider placement of a multi-modality intra-parenchymal catheter for monitoring of both PbtO2 and ICP
- PbtO2 should be maintained greater than 20mmHg.
- Strategies for managing PbtO2 and ICP are outlined in Appendix A under Treatment Paradigms Operative Care by Neurosurgery based on CT results: Evacuation of Hematoma.

Note This monitoring capability may not be readily available, parameters have been outlined here in case these monitoring strategies are applicable in the future.