Prehospital management of traumatic brain injury ppt

Introduction

Traumatic Brain Injury is a leading cause of death and disability in children and adults in their most pro-ductive years1. This has devastating effect on lives of the injured individual and their families because dis-ability results in a significant loss of productivity and income potential.

Neurotrauma thus is a serious public health prob-lem that mandates continuing efforts in areas of pre-vention and treatment. Understanding the pathophysi-ology of TBI has increased remarkably in the recent past. Many guidelines were established based on evi-dence based methodology in managing and prevention of this entity2. Issues related to treating these victims in the field or at the place of injury have lagged behind prehospital advancements in medical and general trauma management. Only in the recent past few years attempts are being made to evaluate rigorously the care provided to trauma victims in the field. Equally impor-tant to the assessment and care provided is the selec-tion of the hospital destination. Whenever possible, the choice of a hospital should be predicated on selecting the most appropriate place for the patient to receive the care needed. In case of severe TBI, a facility, usu-ally a trauma center, with immediate diagnosing and intervention capabilities is the preferred direct trans-port destination which must have appropriate medical personnel, a CT scanner, an operating theatre, intrac-ranial pressure monitoring, and an intensive care unit3.

The issue of optimal prehospital care of the head injury is of prime importance in managing this rather challenging entity and this if addressed adequately and timely will reduce the associated morbidity and mortal-ity to a large extent.

The various issues which play a pivotal role in the prehospital management of the traumatic brain injury patient are as follows. Adequate training of the para-medics and associated health care workers on these is-sues will ensure a better outcome in managing this entity,

a. Hypotension and hypoxia

Early post injury episodes of hypotension and hy-poxemia greatly increase morbidity and mortality from severe head injury. Evidence suggests that one should avoid and prevent values of systolic blood pressure less than 90 mmHg and oxygen saturation of less than 90%. Strong evidence suggests that patients who had these issues corrected at the site of injury had better out-comes than who had later correction4. Early oxygen-ation and fluid therapy will ensure avoiding this issue which will go a long way in the betterment of the in-jured patient.

b. Glasgow Coma Scale

Since its introduction into clinical practice by Teasdale and Jennet in 1974, it has become the most widely used clinical measure of the severity of trau-matic brain injury. It permits a repetitive and moder-ately reliable standardized method of reporting and re-cording the ongoing neurologic evaluations even when performed by a variety of health care providers. Evi-dence suggests that initial assessment of GCS at the site of injury by the health care worker serves as an important marker in the assessment of the progress, prognosis and outcome5. As this plays a dominant role in prehospital setting assessment of the severity of the head injury we should aim in training our paramedics in the method of application of GCS and emphasize the underlying importance.

c. Pupillary size

The pupil examination is an important component of the prehospital evaluation of patients with head trauma3. Pupillary light reflex and size reflect an indi-rect evidence of the pathology inside the cranial vault. It is an indirect measure of herniation or brain stem in-jury. Dilatation and fixation of one pupil signifies her-niation, whereas bilaterally dilated and fixed pupils are consistent with brain stem injury. However, hypoxemia, hypotension, and hypothermia are also associated with dilated pupil size and abnormal reactivity making it nec-essary to resuscitate and stabilize the patient before as-sessing pupillary function. Direct trauma to the third nerve in the absence of significant intracranial injury or herniation can occur causing pupillary abnormalities, al-though this is usually associated with motor deficits.

As this forms an important component of prehospital evaluation of patients with head trauma, all efforts should be made to educate the health care worker in correctly evaluating the pupil with emphasis on pupil size and light reflex for each eye and the dura-tion of pupillary dilatation and fixation.

d. Fluid resuscitation

Fluid resuscitation in patients with TBI should be administered to avoid hypotension and /or limit hy-potension to the shortest duration possible. In adult trauma literature, hypotension is usually defined as a systolic blood pressure of < 90 mmHg and in children it is less than the fifth percentile for the age(< 65mm Hg for 0-1 year, > 75mmHg for 2-5 yrs, > 80 mm Hg for 6 -12 yrs and > 90 mmHg for 13 to 16 yrs of age).

Based on Class III evidence fluid therapy is uti-lized to support cardiovascular performance in an ef-fort to maintain adequate cerebral perfusion pressure and limit secondary brain injury6. The most commonly used resuscitation fluid for patients of head injury is isotonic crystalloid solution. It is administered in quan-tities necessary to support blood pressure in the nor-mal range. Inadequate fluid volumes or under resusci-tation can precipitate sudden hypotension and should be avoided. Hypertonic resuscitation utilizing hyper-tonic saline has been used in prehospital setting with some encouraging results but has not been well sub-stantiated7. No studies prove the efficacy of mannitol in prehospital setting8. Though hypotension stands as an important marker of outcome in head injured pa-tient there has been no clear identification of param-eters for field administration of fluid.

Preventing shock and promptly treating hypoten-sion are important components of TBI patient care. A single episode of hypotension has been shown to double mortality9. Even more important is measuring the cere-bral perfusion pressure, but these are not measured in pre hospital setting.

Vital signs such as heart rate and blood pressure are used as indirect measures of oxygen delivery in prehospital phase as well as during initial emergency department evaluation. These parameters though crude measurements, often do not correlate well with blood loss and there are no other readily available means of accurately quantifying blood loss. Autoregulation often fails following head injury, placing brain at increased risk from decrease in preload. Ideally, resuscitative intervention should begin early enough to prevent a sub-sequent drop in blood pressure.

Crystalloid fluid is utilized to augment cardiac preload, maintaining cardiac output, blood pressure and peripheral oxygen delivery. General recommendations involve the rapid infusion of 2 liters of isotonic fluid, generally Ringer′s lactate or normal saline as the initial fluid bolus in adults10. The goal of prehospital fluid re-suscitation is to support oxygen delivery and avoid hy-potension, if possible so as to avoid secondary injury.

e. Brain targeted therapy

Management of patients with TBI is directed at maintaining cerebral perfusion. Signs of cerebral her-niation include fixed dilated pupils, asymmetric pupils, extensor posturing, or neurologic deterioration.

Hyperventilation, is beneficial in the immediate management of patients demonstrating signs of cere-bral herniation, but is not recommended as a prophy-lactic measure11.

Mannitol is effective in reducing intracranial pres-sure and is recommended for control of ICP8. There is however no data to support its use in patients without signs of cerebral herniation and without ICP monitoring.

Use of lidocaine prevents increase in ICP that occur with endotracheal intubation and its use is man-datory12 in preventing these episodes of insult on an already compromised brain pressure.

f. Sedation and analgesia

These are the key components of comprehensive patient care and are important considerations in prehospital management. This is particularly true when long transport times are involved. The first step in man-aging the agitated or combative TBI patient is assess-ing and correcting hypotension, hypoxemia, hypogly-cemia and patient discomfort.

Mechanical restraints for the severely agitated patient are generally not recommended and have been associated with placing patients at risk for physical harm. Because patient cooperation is critical for a safe trans-port there are times when pharmacologic interventions, including neuromuscular blockade, are clearly indicated. Benzodiazepines and phenothiazines are commonly used drugs with range of safety in pre hospital setting.

g. Neuromuscular blockade

Studies have demonstrated the safety of using short acting neuromuscular blockade in the field to fa-cilitate intubation performed by prehospital care pro-viders1314. These agents are not without risks and their use may interfere with determining the GCS score. Con-sequently each EMS system must carefully weigh and monitor a risk/benefit analysis of the prehospital use of sedation, analgesia and neuromuscular blockade.

h. Managing hypoglycemia

Glucose is the primary fuel for neuronal function. Prevention of both hypoglycemia and hyperglycemia is important in the management of head injured patient as either way it can harm the patient. As hypoglycemia mimics TBI it is wise to test for glucose levels in field conditions rather than empirical dextrose administra-tion, however when facility for testing is not available one should recognize or suspect hypoglycemia clini-cally and administer empiric dextrose1516.

i. Hospital transport of the injured

The EMS personnel should effectively manage the head injured patient on the lines listed above and con-sider early transfer of the patient to a trauma center which is based on a number of factors - including the mechanism of injury, the type and severity of the injury and the decision regarding the choice of destination. When an integrated EMS and trauma system is in place and the EMS agencies transport a patient directly from the scene of the accident to an appropriate receiving facility, the patient is entered into a system of care that has been shown to improve overall patient outcome17. Interhospital transfers of these head injury patients are known to delay the time until neurosurgical consultation and intervention. This delay puts the patient at great risk for secondary insult to the brain.

Clearing the cervical spine in TBI

Cervical spine injury occurs in 5-10% of cases of blunt polytrauma. A missed or delayed diagnosis of cervical spine injury may be associated with perma-nent neurological sequelae. However, there is no con-sensus about the ideal evaluation and management of the potentially injured cervical spine and, despite the publication of numerous clinical guidelines, this issue remains controversial. The presence of a severe head injury increases the relative risk of a cervical spine in-jury, possibly by 8.5 times, and a focal neurological deficit by 58 times18. A Glasgow Coma Scale (GCS) score of < 8 is associated with a 50% increase in the incidence of cervical spine injury to 7.8%19. The prog-nosis in patients suffering both head and cervical injury is typically poor, with approximately 25% being dis-charged to a dedicated nursing facility with little pros-pect of recovery20.

Although the vast majority of polytrauma victims will not have a cervical spine injury, the potential im-pact on neurological outcome if these injuries are missed requires that all polytrauma victims are managed in the expectation that injury is present. The clinical evaluation of the cervical spine assesses four parameters21.

1. Glasgow Coma Scale (GCS) = 15, and the pa-tient is alert and orientated
2. No intoxicants or drugs have been consumed
3. No significant distracting injuries have occurred
4. No signs or symptoms on cervical examination:
1. No midline tenderness or pain
2. Full range of active movement
3. No referable neurological deficit

These criteria have been incorporated in Ameri-can College of Surgeons Advanced Trauma Life Sup-port (ATLS)2223 and Eastern Association for the Sur-gery of Trauma (EAST) guidelines. Unfortunately, polytrauma victims are more severely injured, one-third suffer head injury, and analgesia or sedation is typically required, therefore failing at least one precondition for clinically clearing the cervical spine.

Basic investigation

An anatomically and technically adequate film will visualize the cervical spine from the craniocervical junc-tion to the cervicothoracic junction, with adequate pen-etration to see all vertebral bony structures and soft tissue relations. The lateral cervical plain film occupies a prestigious position within ATLS guidelines)2223 be-ing one of the three initial trauma screening films (lateral cervical spine, anteroposterior chest and pelvis). How-ever, this film should never be used to ′clear′ the cervi-cal spine due to both inadequate sensitivity and the overall poor quality of emergency films, and all polytrauma patients will require a more complete as-sessment.

As a result of the limitations of a single lateral view in the diagnosis or exclusion of cervical spine injuries, the three view cervical trauma series (cervical series) has been developed. It has been incorporated into ATLS and EAST guidelines, and is widely recommended24 as being able to decrease the 15% of injuries missed by the lateral film alone. The cervical series comprisesa. Cross-table lateral view b. Open mouth odontoid view. This examines the craniocervical junction, ally the occipito-atlantal relations25 c. Anteroposterior (AP) view. Whenever possible, an open-mouth view also should be obtained. If the entire cervical spine can be visualized and is found to be normal, the collar can be removed after appropriate evaluation by a neurosur-geon or orthopedic surgeon. When in doubt, leave the collar on and a cervical CT scan can be obtained later..2223. Computerized tomography may reveal more frac-tures than plain films and may allow evaluation of the cervicothoracic and craniocervical junctions, both ar-eas traditionally poorly visualized on plain films and with high rates of concealed injury.22

Magnetic resonance imaging

Magnetic resonance imaging holds an undisputed position as the investigation of choice in evaluating spi-nal cord injuries, and has replaced conventional and CT myelography. It is recommended that any patient with a neurological deficit referable to the cervical spine should undergo plain film skeletal survey and MRI.22

Unlike plain films and CT, only MRI and dynamic fluoroscopy have the potential to directly demonstrate ligamentous pathology or instability. Since MRI is very sensitive in detecting soft tissue injury26, a number of authors advocate a normal scan as evidence of a stable cervical spine. Magnetic resonance imaging may also perform poorly at the upper cervical spine due to varia-tion in the normal appearances of the upper ligaments, encouraging false positive results.27

Limitations

One must consider the implications of routinely obtaining cervical MRI scans in a population of criti-cally ill polytrauma patients. There are a limited num-ber of scanners and typically these run during office hours. There are also severe restrictions on the avail-ability of skilled staff to transfer, manage and image such patients, with only one-third of modern MRI units providing any regular anaesthetic sessions.28 Most scanners are remote from the hospital main site and require an ambulance transfer, a process with well-rec-ognized complication rates29 The ferromagnetic envi-ronment contraindicates scanning, particularly in the presence of invasive cardio respiratory monitoring and certain orthopaedic stabilization prostheses, demand-ing significant modification of anaesthetic and monitor-ing techniques30 Finally, the cost of routinely obtaining MRI scans is likely to remain high. While MRI has an undisputed role in assessing cord injuries and neuro-logical deficits, its role in evaluating acute cervical spine trauma and mechanical stability is far from clear. There-fore, if MRI is used, it must complement plain films and CT, not replace them. The clinician must determine the likelihood of missing a cervical spine injury, particularly an isolated ligamentous injury, if the patient is mobi-lized while unconscious or obtunded, balancing this against the risks of immobilization.

In summary the health care worker should assess, stabilize and treat a TBI patient on basic resuscitation protocols that prioritize airway, breathing, and circula-tion assessment and treatment. Following this, assess the level of response and assess the GCS so as to cat-egorize the severity of injury. All patients who are non responsive to painful stimulus and whose score of GCS is 3-9 should be planned for early evacuation to a des-ignated trauma center which has facility for CT scan, operating suite and neurosurgical care.

All the rest of the category patients should seek prompt neurosurgical opinion after initial stabilization. What ever is the severity of the injury the health care worker should emphasize caution in management so as to avoid hypotension, hypoxemia and hypoglycemia at all times for an effective outcome of the injured.

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