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Resuscitate
"ABC"
Stabilize
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Resuscitation is the combination of therapies that restore physiologic stability in the patient with hemodynamic, metabolic, or other physiologic compromise secondary to head injury.
"ABC"
"ABC" is the mnemonic for "airway, breathing, and circulation" ("ABC" of resuscitation) - the top priority considerations during the resuscitation of the neurologically threatened head trauma victim.
Airway
Not every patient with altered mental status has difficulty protecting their own airway and requires endotracheal intubation. Endotracheal intubation is accomplished in the agitated patient at the cost of exam findings of movement and pain response, rendering him, from a neurological perspective, not examinable. Indicators that an agitated or stuporous patient will not adequately protect his airway (and potentially aspirate refluxed gastric contents) are snoring and puffing out of the cheeks. Patients should be intubated endotracheally whenever possible because this is less agitating and more comfortable than insertion of a nasotracheal tube in patients who are not comatose.
Breathing
Circulation
All head-injured patients should have IV access promptly established. In the absence of multitrauma with actual or possible hemorrhage fluid should be infused at a rate of approximately 75cc/hour (for adults. In children 5cc/hour for the first 10 kg body weight, plus 2cc/hour for the second 10 kg body weight, plus 1cc/hour for each kg body weight above 20). If an extracranial hemorrhagic injury is known or suspected, fluid management should be governed by considerations of systemic perfusion.
Two major concepts underlie CPP/ICP resuscitation: the first is that elevated intracranial pressure decreases cerebral perfusion according to the equation CPP = MAP - ICP where "CPP" is "cerebral perfusion pressure", "MAP" = mean arterial pressure, ICP = intracranial pressure). Second, that there is a normal range for cerebral perfusion pressure and a threshold pressure at which cerebral perfusion is so low that cellular injury results. Measures that reduce ICP with associated reduction in MAP resulting in lowering CPP towards a critical perfusion threshold of 70 mmHg are contraindicated.
The optimal fluid for infusion in the setting of head injury potentially associated with increased ICP (and decreased CPP) is iso- or hypotonic, without glucose.
Diuresis to decrease ICP should be avoided if there is any circulatory compromise either hypo- or hyper- dynamic.
ICP
The Monro Kellie hypothesis is the basis for reducing ICP by reducing the volume of: 1. brain and soft tissue, 2. intracranial circulating blood, 3. cerebrospinal fluid (CSF), or any combination of these. Soft tissue volume can be reduced by removal of tissue water with diuretics. Intravascular blood volume decreases when intracerebral blood vessels constrict in response to hyperventilation with alkalinization of the blood and CSF. The volume of the CSF compartment can be decreased directly by shunting and drainage.
TABLE: Monro Kellie Hypothesis (intracranial volume compartments)
| Compartment |
% |
Volume reduction technique |
| Parenchyma |
70 |
Diuresis |
| Blood |
5 |
Hyperventilation |
| Cerebrospinal fluid |
25 |
Drainage |
Secondary injury
After the initial mechanical trauma to cells (neurons - especially their axonal processes, glial cells - oligodendrocytes myelinate central axons, astocytes maintain the metabolic and electrical milieu interieur) and organs (brain - lobes, brainstem, spine), central nervous system injuries evolve over the first few hours and days after the mechanical trauma. Delayed, or secondary injuries result from secondary insults, primarily decreased perfusion and ischemia potentiate pathologic changes by a number of mechanisms such as generation of free radicals, cytokines, and supraphysiologic concentrations of excitatory neurotransmitters.
Minimizing secondary injuries is the objective of resuscitative measures taken to optimize cerebral arterial perfusion, as well as oxygen delivery and extraction.
Before the neurosurgeon sees him the typical trauma victim has already been "resuscitated".
The resuscitation of most civilian head trauma victims occurs in two phases: 1. Initiation in "the field" - the site of injury - usually by paramedics (sometimes with the assistance of bystanders), and 2. Completion in the Department of Emergency Medicine (DEM), by emergency medicine physicians.
Resuscitation in the field
Paramedic resuscitation of the head trauma victim in the field and during transport should be limited to measures that maintain cerebral perfusion, stop active bleeding from superficial wounds, and stabilize the cervical spine.
TABLE Paramedic resuscitation and stabilization of head trauma victims
| INTERVENTION |
RATIONALE |
| Intravenous access |
Frequent co-morbidities associated with dehydration/hypovolemia in head trauma population Anti-convulsant administration |
| Airway protection |
Loss of protective reflexes leading to aspiration common with severe head injury |
| Neck stabilization |
Protects the spinal cord from injuries due to bone dislocation and fracture |
| Hemorrhage control |
Maintain perfusion of heart, brain, and "vital organs" |
What happens in the field impacts significantly on subsequent surgical evaluation, planning, and care. The surgeon needs the information contained on the paramedic "run sheet", which in addition to mechanism of injury, vital signs, and neurologic exam, should detail any variations in the standard resuscitation protocol (with which every member of the head trauma care team should be familiar).
TABLE Paramedic "run sheet" data and significance
| RUN SHEET FIELD |
SIGNIFICANCE |
| Scene time |
Pathophysiology worse the longer hypoxic and ischemic present |
| History |
Mechanism, activity (drinking, doing drugs, etc.) at time of injury |
| Vital signs |
Evidence of Cushing's response, hypotension |
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