NR 340 Critical Care Exam 3 Guide

NR 340 Critical Care Exam 3 Guide Latest 2023 / 2024 Neuro Basics · Brain metabolism

• Soul source of energy for the brain is glucose. Brain needs glucose to function. Brain cannot

store it, but needs a constant supply. If glucose levels start to fall you will some changed.

• Cerebral glucose < 70 mg/dL = confusion

• Cerebral glucose < 20 mg/dL = damage

· Cerebral blood flow

· Autoregulation

• Changes in pressure

• Changes in CO2

▪ Alters cerebral blood volume with change in blood vessel size

• Ability of the blood vessel in the brain to either constrict or dilate in response to pressure or

CO2 levels

▪ Hypotension or hypoventilating causing hypercapnia BV in brain will dilate and vice versa try to send more blood and oxygen to brain.

▪ If hypertension or hypocapnia blood vessels in the brain will constrict.

▪ Systolic less than 50 or greater than 160 BV in brain lose the ability to autoregulate.

Neuro Assessment

• GCS, LOC, Memory, speech, Reflexes (babinski with brain injury) which only babies should

have if adult has it this is not good, motor response, sensation , look for aphasia, motor strength

▪ Concerned with GAS or 8 or lower

• Posturing

▪ Decorticate

· Extremities go toward the body

▪ Decerebrate

· Extremities pull away from the body, more severe, damage to brainstem – this is the worse posturing

· Cranial nerves

• 1 – Olfactory - Smell
• 2 – Optic - vison, pupil response, visual fields – PERRLA - need flashlight or pen light dim the

lights in room

• 3, 4, 6 - Oculomotor, Trochlear, Abducens - eye movement – 6 fields of gaze “EOM’S” 1 / 3

• 5,7 – Trigeminal, Facial - corneal reflex touch patients eyeball, on unresponsive patients-

corneal reflex, use gauze or cotton. Touch the eyeball – you want the person to blink as a response. Only do the corneal reflex on someone who is unresponsive.

• 8 – Acoustic – hearing - whisper test or just ask the patient questions Just talk to the patient
• 9,10 – Glossopharygeal, Vagus – swallow and gag reflex cough and gag – assess gag take a

tongue depressor. If patient is intubated use suction to assess gag reflex.

• 11 – Accessory – shoulder and neck movement
• 12 – Hypoglossal – tongue movement

· Oculocephalic Reflex (Doll’s Eyes Reflex)

• Usually absent or negative

• Only done on unconscious patients when trying to asses brainstem functioning

• Not done on if spinal cord injury is present or suspected

• Look forward and then move head side to side,

▪ Normal (negative) - eyes will move contralateral (opposite) to the direction the head moves

▪ Irregular (positive) – eyes do not move, stay fixed. (Sign of brain death)

· Oculovestibular Reflex (Cold Caloric)

• Done on unresponsive patients trying to Asses brainstem functioning. We say its normal or

abnormal.

• Must have intact tympanic membrane

• You need a 50 ml syringe and cool saline

▪ Instill 50ml of cool saline into patients ear

▪ Normal – Eyes will turn toward side you are putting water and go back to center

▪ Abnormal – Eyes do not move (brain death)

Intracranial Pressure

o Components of ICP: brain tissue, blood, CSF fluid

▪ Monro-Kellie doctrine

· Increase in any one component requires a reduction in one or both of other components to sustain normal ICP.

o Normal ICP: 0-15 mm Hg

• Cerebral Perfusion Pressure (CPP)

▪ How well brain is being profuse

▪ Dependent upon ICP and MAP (CPP = MAP – ICP) Systolic + 2(Diastolic) / 3 = 2 / 3

· Optimal is 70-100 mmHg

· If less then 70 you can develop ischemia to brain tissue.

· If under decrease BP or increase ICP

▪ If CPP is inadequate, ischemia or infarction can occur

· Increased Intracranial Pressure

• Associated with many neurological problems

• ICP 20mm Hg or greater for 5 minutes or longer

• Results from an increase in any one of the three

components:

▪ Increased Blood Volume

· Loss of Autoregulation

· Decreased Oxygenation

Increased metabolic demands, fevers, seizures can also increase intracranial pressure.

· Hypercapnia – cause blood vessels in brain to dilate sending more blood to brain which can increase pressure

· Obstruction – Ex: Tumor

▪ Increased Brain Volume

· Cerebral Edema

▪ Increased Cerebrospinal Fluid

· Hydrocephalus

• Cardinal (early) sign is changes in LOC
• Pupil changes, respiratory changes are late sign
• Herniation = he dead

▪ Brain usually comes out of foramen magnum

▪ Nurse needs to identify signs early. Prevention es muy importante.

▪ If ICP > 20 for 5 minutes or more herniation can occur.

▪ We need to know the signs to look for to prevent herniation to occur.

ICP Monitoring · Indications

• Severe head injury, severe neurologic disorder, GCS < 8, Post brain surgery, tumors, strokes

· Purpose

• Severity of brain impairment, diagnose problems, assess responsiveness to therapy,

augment our assessment

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