- Slow onset / offset, highest degree of cardiac depression and arrhythmias - Least pungent, which is good for children

- (Barbiturate) fast acting - Side effects: decrease CBF and metabolic rate, decrease blood pressure

- Very rapid distribution and on/off; amnesia; sedative - Not an analgesic - Metabolized in liver and by plasma cholinesterase's - Side effects: hypotension, respiratory depression

Non-depolarizer - Undergoes Hoffman degradation - Can be used in liver and renal failure - Histamine release

Non-depolarizer: - Slow acting, long-lasting; renal metabolism - Most common side effect: tachycardia

Chapter 8: Anesthesia Flashcards by P H

Inhalational agents: effects

Blunt hypoxic drive
Caused unconsciousness, amnesia, some analgesia
Most have myocardial depression, increase CBF, decrease RBF

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MAC (minimum alveolar concentration)

Smallest concentration of inhalation agent at which 50% of patients will not move with incision

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Nitrous oxide (NO2)

Fast, minimal myocardial depression; tremors at induction

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Halothane

Slow onset / offset, highest degree of cardiac depression and arrhythmias
Least pungent, which is good for children

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Manifestations of halothane hepatitis

Fever, eosinophilia, jaundice, increased LFTs

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Sevoflurane

Fast, less laryngospasm and less pungent; good for mask induction

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Isoflurane

Good for neurosurgery (lowers brain oxygen consumption; no increase in ICP)

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Enflurane

Can cause seizures

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Sodium thiopental

(Barbiturate) fast acting

- Side effects: decrease CBF and metabolic rate, decrease blood pressure

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Propofol

Very rapid distribution and on/off; amnesia; sedative
Not an analgesic
Metabolized in liver and by plasma cholinesterase’s
Side effects: hypotension, respiratory depression

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Ketamine

Dissociation of thalamic / limbic systems; places patient in a cataleptic state (amnesia, analgesia).
- No respiratory depression
- Contraindicated in patients with head injury
- Good for children
Side effects: hallucinations, cathetcholamine release (increase CO2, tachycardia), increased airway secretions and increased cerebral blood flow

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Etomidate

Fewer hemodynamic changes; fast acting

- Continuous infusions can lead to adrenocortical suppression

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When is RSI indicated?

Recent oral intake
GERD
Delayed gastric emptying
Pregnancy
Bowel obstruction

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Last muscle to go down and first muscle to recover from paralytics

Diaphragm

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First to go down and last to recover from paralytics

Neck muscles and face

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Malignant hyperthermia: pathophysiology

Caused by a defect in calcium metabolism

- Calcium released from sarcoplasmic reticulum causes muscle excitation: contraction syndrome

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Malignant hyperthermia: signs

Increased end-tidal CO2…

then fever, tachycardia, rigidity, acidosis, hyperkalemia

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Malignant hyperthermia: treatment

dantrolene (10mg/kg) inhibits calcium release and decouples excitation; cooling blankets, HCO3, glucose, supportive care

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When do you NOT use succinylcholine?

Severe burns.
Neurologic injury.
Neuromuscular disorders.
Spinal cord injury. 
Massive trauma.
Acute renal failure.

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Complications of succinylcholine

Malignant hyperthermia
Hyperkalemia
Open-angle glaucoma
Atypical pseudocholinesterases

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Nondepolarizing agents: mechanism

Inhibits neuromuscular junction by competing with acetylcholine
Can get prolongation of these agents with myasthenia gravis

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Cis-atracurium

Non-depolarizer

Undergoes Hoffman degradation
Can be used in liver and renal failure
Histamine release

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Rocuronium

Non-depolarizer: Fast, intermediate duration; hepatic metabolism

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Pancuronium

Non-depolarizer:

Slow acting, long-lasting; renal metabolism
Most common side effect: tachycardia

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Neostigmine, Edrophonium: mechanism

Blocks acetylcholinesterase, increasing acetylcholine

Should be with neostigmine or edrophonium to counteract effects of generalized acetylcholine overdose

Atropine or glycopyrrolate

Local anesthestics: mechanism

Work by increasing action potential threshold, preventing Na influx. - Can use 0.5 cc/kg of 1% lidocaine.

Why are infected tissues difficult to anesthetize with local anesthetics?

Secondary to acidosis.

Length of action of local anesthetics: greatest to least

Bupivacaine > lidocaine > procaine

Side effects of local anesthetics

Tremors Seizures Tinnitus Arrhythmias (CNS symptoms occur before cardiac)

What does addition of epinephrine to local anesthetics allow?

Allows higher doses to be used, stays locally

When do you not use epinephrine with local anesthetics?

Arrhythmias, unstable angina, uncontrolled hypertension, poor collaterals (penis and ear), uteroplacental insufficiency

Two different genres of local anesthetics

Amides (all have "i" in first part of their name) | Esters

Allergic reactions: amides vs esters

Esters: increased allergic reactions due to PABA analogue

Metabolism: opioids

Metabolized by the liver and excreted via kidney

What can narcotics cause precipitate in patients on MAOIs?

Hyperpyrexic coma

Morphine: effects

Analgesia, euphoria, respiratory depression, miosis, constipation, histamine release (causes hypotension), decreased cough

Demerol: effects

Analgesia, euphoria, respiratory depression, miosis, tremors, fasciculations, convulsions

Does demerol cause histamine release?

NO.

Why avoid demerol in patients with renal failure?

Can cause seizures (buildup of normeperidine analogues)

Fentanyl

Fast acting; 80x strength of morphine (does not cross-react in patients with morphine allergy); no histamine release

Benzodiazepines: effects

Anticonvulsant. Amnesic. Anxiolytic. Respiratory depression.

Benzodiazepines: metabolized in

Liver

Versed (midazolam)

Benzo: - Short acting - Contraindicated in pregnancy - Crosses placenta

Valium (Diazepam)

Benzo: | - Intermediate acting

Ativan (lorazepam)

Benzo: | - Long acting

Flumazenil

- Competitive inhibitor - May cause seizures and arrhythmias - Contraindicated in patients with elevated ICP or status epilepticus

Epidural anesthesia

Allows analgesia by sympathetic denervation. | Vasodilation.

Epidural with morphine can cause...

Can cause respiratory depression

Epidural with lidocaine can cause...

Decreased heart rate and blood pressure

How can motor function be spared with epidural?

Dilute concentrations

Tx: acute hypotension / bradycardia with epidural

Turn epidural flow down. Fluids. Phenylephrine. Atropine

Epidural level: affect cardiac accelerator nerves

T1-5

Contraindications: epidural

Hypertrophic cardiomyopathy. | Cyanotic heart disease.

Why h-cmp and cyanotic heart disease contraindications to epidural anesthesia?

Sympathetic denervation causes decreased after load, which worsens these conditions

Spinal anesthesia

Injection into subarachnoid space, spread determined by baricity and patient position

Contraindications: spinal

Hypertrophic cardiomyopathy. | Cyanotic heart disease.

Tx: Spinal headache

Rest. Fluids. Caffeine. Analgesics. Blood patch to site if it persists > 24 hours. Headache is worse sitting up.

Associated with most postop hospital mortality

1. Pre-op renal failure | 2. CHF

May have no pain or EKG changes. Can have hypotension, arrhythmias, increased filling pressures, oliguria, bradycardia.

Postop MI

Considered high risk surgery

Most aortic, major vascular, peripheral vascular surgery

Risk: carotid endarterectomy (CEA)

Considered moderate risk surgery

Biggest risk factors for post MI

``` Age > 70. DM. Previous MI. CHF. Unstable angina. ```

MC PACU complication

nausea and vomiting.