Neurocritical Care

Question 1

Normal ICP

Answer 1

5-15 mmHg

7.5-20 cmH2O

Question 2

Hunt and Hess Scale

World Federation of Neurological Surgeons Scale

Fisher Scale

Answer 2

Measure of SAH Severity

H and H
1 - Asymptomatic or minimal headache and nuchal rigidity
2 - mod-severe headache and nuchal rigidity, no deficit other than CN palsy
3 - Drowsiness, confusion, or mild focal deficit
4 - Stupor, mod-severe hemiparesis, possible early decerebrate posture and vegetative disturbance
5 - Deep coma, decerebrate rigidity, moribund

WFNSS
1 - GCS 15, no motor deficit
2 - GSC 13-14, no motor deficit
3 - 13-14 w/ motor deficit
4 - GCS 7-12 w/ or w/o motor deficit
5 - GCS 3-6 w/ or w/o motor deficit

Fisher
1 - No SAH on CT
2 - Diffuse or thin vertical layer of blood <1mm thin
3 - localized clot or vertical layer >1mm thick
4 - Intracerebral or intraventricular clots w/ diffuse or no SAH

Question 3

Abnormal breathing patterns
1. Apneustic Breathing

2, Ataxic breathing

3. Cheyne-Stokes Respirations
4. Hyperventilation

Answer 3

1. B/l Pontine lesions - regular deep inspirations with an inspiratory pause followed by inadequate expiration. Associated w/ pinpoint pupils, posturing
2. Medullary lesions (breath rhythm center)- irregular respiratory pattern (gasping)
3. Forebrain impairment but intact brainstem, or severe cardiopulm disease, periodic breathing where hyperpnea alternates with apnea, and depth increases and decreases gradually
4. Midbrain lesions, uremia and hepatic failure

Question 4

ICH Score

Answer 4

Predicts 30 day outcome after ICH

1. GCS: GCS 3-4 = 2 points, GCS 5-12 = 1 point, GCS 13-15 = 0 points
2. Intraventricular: 1 point
3. ICH Volume: >30cc = 1 point
4. Infratentorial Origin: 1 point

Score of 0 = no deaths @ 30 days. Score of 5 = 100% death

Question 5

Halothane
Enflurane
Isofurane
Sevoflurane
Methoxyflurane
Nitrous Oxide

What is MAC?

Answer 5

Inhaled Anesthetics
- thane, -ane

Use:
- Anesthetics

Mech of Action:
- unknown, but causes loss of response to noxious stimuli (ex. Surgery) and increased cerebral blood flow and decreased cerebral metabolic demand

Side Effects:
- Nausea/emesis
- Cardiovascular depression
- Respiratory depression
- Halothane = hepatotoxic
- Methoxyflurane = nephrotoxic
- Enflurane = proconvulsant
- NO = diffusional hypoxia, spontaneous abortions
- All (except NO) = risk of malignant hyperthermia

NOTE: MAC
Minimum Alveolar Concentration needed to prevent 50% of patients from responding to noxious stimuli

• ↑ lipid soluability = easier crossing BBB = ↑ potency
• ↓ blood soluability = travels in blood more rapidly = faster induction and recovery

Potency = 1/MAC (less needed in lungs = more potency)

MAC decreased in the elderly and with concurrant use of opiates/sedatives

Question 6

Malignant Hyperthermia

Cause? Symptoms? Treatment?

Answer 6

Causes:
- Triggered by anesthetics or skeletal muscle relaxants
- Affected patients are normally genetically predisposed
- carry mutations in genes encoding ryanodine receptors and/or skeletal muscle L-type Ca2+ Channels

Symptoms:
- Muscle rigidity
- Hyperthermia
- Hypertension
- Acidosis
- Hyperkalemia

Treatment:
Dantrolene - acts directly on skeletal m. to decrease contractility by blocking Ca release from the sarcoplasmic reticulum

Question 7

Propofol

Answer 7

IV Anesthetic

Use:
- Induction and maintenance of anesthesia in short procedures (quick on, quick off)
- Sedation in the ICU

Action:
Potentiates GABAA activity

Side Effects:
- Cardiac depression
- Less postoperative nausea than thiopental

Propofol infusion syndrome: More common in children.

Question 8

Dexmedetomidine

Answer 8

Use:
IV sedation - Sedation, amnesia, mild analgesia without respiratory depression

MoA: alpha-2 receptor agonist