Pathophysiology of Brain Injury Hypercarbia hypoventilation Causes cerebral

Pathophysiology of brain injury hypercarbia

This preview shows page 94 - 108 out of 152 pages.

Pathophysiology of Brain Injury Hypercarbia (hypoventilation) Causes cerebral vasodilation Results in increased blood volume Which results in increased ICP Hypotension Results in decreased CPP Which results in cerebral vasodilation Which results in increased blood volume And leads to increased ICP
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The Endless Cycle . . . With increasing ICP, this vicious cycle ensues When ICP = MAP, cerebral blood flow ceases
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Intracranial Pressure: Clinical Effects (1 of 3) Clinical effects of increased ICP will result from pressure exerted down on the brain Cerebral cortex and reticular activating system (RAS) Altered level of consciousness Hypothalamus Vomiting
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Brain stem BP increases in an effort to maintain cerebral blood flow against increasing ICP Bradycardia develops from vagal stimulation and increased BP Respirations become: Irregular, causing increased carbon dioxide (CO 2 ), or Fast (tachypnea), causing a decrease in CO 2 Intracranial Pressure: Clinical Effects (2 of 3)
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Brain stem (cont’d) Cranial nerve III (oculomotor) compression leads to unequal or unreactive pupils Abnormal posturing (flexion or extension) Seizures Herniation of the brain Intracranial Pressure: Clinical Effects (3 of 3)
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Clinical Effects of Increased ICP
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Patient Assessment: Primary Assessment Determine the mechanism of injury and the need to consider the possibility of spinal injury Is there: Airway compromise? Ventilatory compromise? Adequate oxygenation? Adequate circulation and perfusion?
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Patient Assessment Neurologic assessment for disability The complete neurologic exam consists of six components: Mental status (MS) Cranial nerves (applicable cranial nerves only) Motor function Sensory function Coordination Reflexes In most cases, only the first four are completed in the prehospital setting
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Patient Assessment: Mental Status (1 of 3) AVPU Provides an initial impression A lert Responds to V erbal stimulus Responds to P ainful stimulus U nresponsive
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Glasgow Coma Scale (GCS) The GCS should be scored after the correctible causes of altered mental status have been addressed Use the modified GCS for pediatrics Patient Assessment: Mental Status (2 of 3)
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Patient Assessment: Mental Status (3 of 3)
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Patient Assessment Assessing for symmetry of function (movement and sensation) is key Asymmetry is abnormal until proven otherwise In some people, asymmetry is a normal or baseline finding Always ask, “Is this normal for you?”
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Patient Assessment: Cranial Nerves Cranial nerves (CNs) 12 pairs Not all CNs are evaluated in the prehospital setting Most important are CNs responsible for evaluation of eye dysfunctions CN II, III, IV, and VI
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Patient Assessment: Pupils Normally equal, round, and 3 to 5 mm in size Anisocoria (unequal pupils) suggests CNS disease or traumatic injury Difference of > 1 mm is abnormal 5 10% of people are estimated to have anisocoria as a normal variant Pupils + light constrict Light in one pupil should constrict both Consensual light reflex tests CNs II and III
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