Regional Exam 1 - Anatomy & Physiology

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Questions and Answers

Which of the following is NOT a characteristic of peripheral nerves?

  • They are bundles of nerve fibers.
  • They are all similar in structure.
  • They are always myelinated. (correct)
  • They conduct impulses from one part of the body to another.

What is the basic unit of all nerves?

  • Axon
  • Neuron (correct)
  • Schwann cell
  • Myelin sheath

What is the function of the neurotransmitters released at the terminal enlargements of nociceptive afferent neurons?

  • To prevent the release of sensitizing chemicals
  • To conduct impulses to the CNS
  • To activate effector organs (correct)
  • To provide structural support for the neuron

What are the three types of fibers found in peripheral nerves?

<p>Sensory, motor, autonomic (C)</p> Signup and view all the answers

Which of the following is NOT a type of peripheral nerve based on anatomical location?

<p>Cerebral (A)</p> Signup and view all the answers

Which of the following statements accurately describes the role of the Na+/K+ pump in maintaining the resting membrane potential?

<p>The Na+/K+ pump actively transports Na+ into the cell and K+ out of the cell, contributing to the negative charge inside the cell. (B)</p> Signup and view all the answers

What is the primary function of the proteins embedded within the lipid bilayer of a nerve cell membrane?

<p>To regulate the flow of ions across the membrane, facilitating the transmission of nerve impulses. (B)</p> Signup and view all the answers

What happens during the depolarization phase of an action potential?

<p>The membrane potential becomes more positive as sodium ions flow into the cell. (B)</p> Signup and view all the answers

What is the threshold level in the context of an action potential?

<p>The minimum level of depolarization required to trigger an action potential. (D)</p> Signup and view all the answers

How do local anesthetics work to block the propagation of nerve impulses?

<p>They directly block the flow of ions through the ion channels, preventing the transmission of nerve impulses. (A)</p> Signup and view all the answers

Which ion movement is responsible for the depolarization phase of an action potential?

<p>Inward movement of sodium ($Na^+$) ions (D)</p> Signup and view all the answers

What is the primary role of the inward sodium ($Na^+$) current in the action potential?

<p>To cause the rapid depolarization phase (C)</p> Signup and view all the answers

Which of the following is TRUE regarding the repolarization phase of an action potential?

<p>It is typically followed by a hyperpolarization phase (A), It is characterized by a decrease in the membrane potential (D)</p> Signup and view all the answers

What is the relationship between the outward potassium ($K^+$) current and the rate of repolarization?

<p>A weaker outward potassium current results in a slower repolarization (B)</p> Signup and view all the answers

What is the main difference between the inward sodium ($Na^+$) current and the outward potassium ($K^+$) current in terms of their role in the action potential?

<p>The sodium current causes depolarization, while the potassium current causes repolarization (D)</p> Signup and view all the answers

Which of these local anesthetics is classified as an amide?

<p>Ropivacaine (B)</p> Signup and view all the answers

Which of the following is NOT a factor influencing plasma concentration of local anesthetics?

<p>Patient's blood type (D)</p> Signup and view all the answers

What is the maximum safe dose of bupivacaine for a 70 kg patient?

<p>210 mg (A)</p> Signup and view all the answers

Which of the following is an early sign of local anesthetic systemic toxicity (LAST)?

<p>Numbness of the tongue (D)</p> Signup and view all the answers

What is the recommended treatment for hypotension associated with spinal anesthesia?

<p>Elevation of the legs (A)</p> Signup and view all the answers

Which of the following is a common complication of spinal anesthesia?

<p>All of the above (D)</p> Signup and view all the answers

How long should a patient discontinue taking clopidogrel (Plavix) before undergoing a neuraxial block?

<p>5-7 days (D)</p> Signup and view all the answers

What is the mechanism by which spinal anesthesia causes hypotension?

<p>Decreased systemic vascular resistance (A)</p> Signup and view all the answers

What is the recommended hold time for low-dose LMWH (Lovenox) before placing or removing a neuraxial catheter?

<p>12 hours (A)</p> Signup and view all the answers

Which of the following is a true statement regarding the Bezold-Jarisch reflex?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following medications is contraindicated within 4 weeks of surgery due to its potential for bleeding complications?

<p>Tirofiban (Aggrastat) (D)</p> Signup and view all the answers

What is the recommended dose of lidocaine for a spinal anesthetic to T10?

<p>50-75 mg (B)</p> Signup and view all the answers

What is the recommended hold time for intravenous heparin (high dose >20,000 daily) before placing a neuraxial catheter?

<p>24 hours (A)</p> Signup and view all the answers

What is the typical onset of sensory block with a 3% chloroprocaine epidural?

<p>Fast (D)</p> Signup and view all the answers

Which of the following signs or symptoms is NOT typically associated with inadvertent intrathecal placement of lidocaine during a spinal injection?

<p>Increased heart rate (HR) ≥ 20–30 bpm within 30–60 seconds (B)</p> Signup and view all the answers

Which of the following medications is contraindicated in the treatment of LAST?

<p>Calcium channel blockers (A)</p> Signup and view all the answers

What is the recommended hold time for ginseng before a regional anesthesia procedure?

<p>34 hours (C)</p> Signup and view all the answers

What is the recommended initial dose for an epidural anesthetic?

<p>1-2 mL/segment to be blocked (A)</p> Signup and view all the answers

What is the purpose of a test dose for epidural anesthesia?

<p>All of the above (D)</p> Signup and view all the answers

What is the recommended hold time for dabigatran (Pradaxa) before placing a neuraxial catheter?

<p>5 days (D)</p> Signup and view all the answers

What is the recommended restarting time for low-dose LMWH after removal of a neuraxial catheter?

<p>12 hours (D)</p> Signup and view all the answers

Which of the following is a common treatment for postdural puncture headache?

<p>All of the above (D)</p> Signup and view all the answers

What is the recommended dose of intralipid for a 60 kg patient with LAST who is unresponsive to standard resuscitation procedures?

<p>90 mL (D)</p> Signup and view all the answers

Which of the following medications is associated with an increased risk of bleeding when used in conjunction with neuraxial blocks?

<p>Warfarin (B)</p> Signup and view all the answers

What is the appropriate action if blood is found in the catheter during neuraxial placement?

<p>Delay the procedure for 24 hours. (D)</p> Signup and view all the answers

What is the primary mechanism of hypotension associated with spinal anesthesia?

<p>All of the above (D)</p> Signup and view all the answers

Which local anesthetic is typically used for short-acting spinal anesthesia at a 10% concentration?

<p>Procaine (C)</p> Signup and view all the answers

Which local anesthetic is known for its rapid onset and long duration of action, particularly when administered for spinal anesthesia?

<p>Tetracaine (D)</p> Signup and view all the answers

What is the primary application of Chloroprocaine, as mentioned in the text?

<p>Epidural anesthesia for short procedures (A)</p> Signup and view all the answers

Which local anesthetic is the most widely used and has a broad range of applications, including infiltration, peripheral nerve blocks, spinal, and epidural anesthesia?

<p>Lidocaine (B)</p> Signup and view all the answers

Which local anesthetic is known for its low potency, slow onset, and short duration of action, making it less frequently utilized for peripheral nerve blocks or epidurals?

<p>Procaine (D)</p> Signup and view all the answers

Which of these local anesthetics is a hyperbaric solution that requires mixing with 10% glucose?

<p>Tetracaine (D)</p> Signup and view all the answers

What is the reason all local anesthetics have a faster onset when administered for spinal anesthesia, compared to other methods like peripheral nerve blocks?

<p>Both A and B (A)</p> Signup and view all the answers

Which local anesthetic is commonly used for urologic procedures, as mentioned in the text?

<p>Lidocaine (B)</p> Signup and view all the answers

Flashcards

Fluid Mosaic Membrane

A cell membrane structure made of phospholipid bilayer with embedded proteins.

Hydrophilic and Hydrophobic

Hydrophilic substances attract water, while hydrophobic substances repel it.

Resting Membrane Potential

The voltage potential across a cell's membrane when it's not actively firing, usually around -70mV.

Na+/K+ Pump

An active transport mechanism that moves 3 sodium ions out and 2 potassium ions into a cell.

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Depolarization and Repolarization

Depolarization is when the membrane potential becomes less negative; repolarization restores it back to resting potential.

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Nociceptive Afferent Neurons

Neurons that transmit pain signals from the body to the central nervous system.

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Peripheral Nerves

Bundles of nerve fibers outside the CNS that conduct impulses between body parts.

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Mixed Nerves

Nerves containing both sensory (afferent) and motor (efferent) fibers.

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Sensitizing Chemicals

Chemicals like bradykinin and prostaglandins released during intense pain.

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Neuron Structure

The basic unit of all nerves, including sensory and motor neurons.

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Inward Na+ current

The movement of sodium ions (Na+) into the cell during depolarization.

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Outward K+ current

The movement of potassium ions (K+) out of the cell during repolarization.

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Depolarization

The phase where the inside of the neuron becomes more positive, moving towards action potential.

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Repolarization

The return to a resting potential after depolarization by losing positive ions.

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Action potential

A rapid rise and fall in voltage across a cellular membrane due to ionic movements.

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Procaine

A local anesthetic good for skin infiltration with rapid onset but short duration.

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Chloroprocaine

An anesthetic used mainly for epidural anesthesia with rapid onset and moderate duration.

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Tetracaine

A long-acting local anesthetic used for spinal and topical anesthesia with onset in 3-5 minutes.

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Lidocaine

An amide anesthetic with a short to intermediate duration, good onset time.

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Epidural Anesthesia

A procedure for pain relief in the lower body using local anesthetics like chloroprocaine.

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Systemic Toxicity

The harmful effects that can occur when local anesthetics enter the bloodstream.

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Hypobaric and Hyperbaric Solutions

Types of spinal anesthetics differing in density to affect distribution in the CSF.

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Duration of Action

The length of time a local anesthetic can effectively block sensation.

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Inadvertent Intrathecal Placement

Accidental placement of a catheter in the subarachnoid space causing rapid spinal block.

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Rapid Spinal Block Symptoms

Weakness in the legs, hypotension, and profound sensory block below injection level.

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Inadvertent Intravascular Placement

Accidental catheter placement in a blood vessel marked by epinephrine response.

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Epinephrine As Marker

Epinephrine used to indicate intravascular injection by causing heart rate increase.

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Aspirin and NSAIDs Safety

No restrictions on neuraxial blocks for patients taking aspirin or NSAIDs.

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Clopidogrel (Plavix) Guidelines

Discontinue 5-7 days before neuraxial block; restart after 24 hours.

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Dabigatran (Pradaxa) Timing

Discontinue 5 days before neuraxial block for safety.

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IV Heparin Timing

Hold low dose heparin for 4-6 hours before neuraxial block.

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Low Molecular Weight Heparin (LMWH)

Wait 12 hours for placement and 4 hours after removal of neuraxial catheter.

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Spinal Procedure Preparation

Includes preoperative assessment, documenting deficits, and collecting necessary equipment.

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Serum Concentration Factors

Serum concentration depends on injection technique, site, and additives in local anesthetics.

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Local Anesthetic Toxicity

Systemic toxicity due to high plasma concentrations of local anesthetics can lead to severe symptoms.

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Early Signs of LAST

Initial symptoms include lightheadedness, dizziness, numbness of the tongue, and confusion.

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Late Signs of LAST

Advanced symptoms of LAST include tonic-clonic convulsions, coma, and respiratory arrest.

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Cardiovascular Effects of LA

Local anesthetics can depress myocardium and may cause arrhythmias associated with overdose.

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Cardiac Response Sequence

LA overdose can lead to hypotension from depressed cardiac output and reduced vascular resistance.

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Treatment for LAST

Management includes airway clearance, oxygenation, IV fluids for hypotension, and anticonvulsants.

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Spinal Anesthesia Drug Doses

Common drugs for spinal anesthesia include Bupivacaine (8-12 mg) and Lidocaine (50-75 mg).

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Epidural Anesthesia Initial Dose

Initial epidural dose typically is 1-2 mL per segment to be blocked.

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Post-Dural Puncture Headache (PDPH)

PDPH symptoms include severe headache, nausea, and sensitivity to light due to cerebrospinal fluid loss.

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Cauda Equina Syndrome

Neurotoxicity due to high local anesthetic concentration resulting in bowel/bladder dysfunction.

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Bezold-Jarisch Reflex

Hypotension and bradycardia resulting from decreased stretch in the left ventricle.

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Test Dose for Epidural Anesthesia

A test dose of 3-5 mL of 1.5% lidocaine is administered to avoid accidental intrathecal or intravascular placement.

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Sympathectomy Effects

Spinal anesthesia can cause hypotension and bradycardia due to sympathetic blockade.

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Study Notes

Regional Exam 1 Objectives - Anatomy and Physiology

  • Identify anatomical landmarks for neuraxial anesthesia (spinal, epidural, caudal).
    • C7: Most prominent cervical spinal process.
    • T7: Opposite the inferior angle of the scapula.
    • L4-L5: Line connecting the iliac crests (Tuffier's line).
  • Lumbar region (midline): Skin to Tuffier's line = 4-6 cm.
  • Tuffier's line = 5-6 mm (0.5 cm) thick.
  • Epidural space in the sacral region (caudal space): Sacral portion of the epidural space.
  • Needle inserted through sacrococcygeal ligament into the sacral hiatus.
  • Sacral hiatus: Notch above the coccyx, between sacral cornua.
  • Landmarks for caudal epidural space: Easier in children, more difficult/impossible in adults (calcification).

Spinal Anatomy: Midline Approach

  • Skin.
  • Subcutaneous tissue.
  • Supraspinous ligament.
  • Intraspinous ligament.
  • Ligamentum flavum.
  • Dura mater.
  • Subdural space.
  • Subarachnoid space.
  • Arachnoid mater.

Spinal Anatomy: Paramedian Approach

  • Similar to midline approach but from a paramedian position.
  • Stops at ligamentum flavum, before the dura mater.

Spinal Curvature and Neuraxial Anesthesia

  • Spinal curvature in supine position:

    • High points/apex (lordosis): C5 and L3-L5.
    • Low points/trough (kyphosis): T4-T7 and S2.

  • Scoliosis: Lateral curvature of the spine.

  • Kyphosis: Excessive posterior curve.

  • Lordosis: Hollowing of the back (in obesity/pregnancy).

Spinal Anesthesia - Factors Affecting Local Anesthetic Spread

  • Local anesthetic uptake from the subarachnoid space into neuronal tissue affected by 4 factors.
    • Concentration in CSF.
    • Dose of Local Anesthetic (LA).
    • Density of LA in relation to CSF (hypobaric, isobaric, hyperbaric).
    • Flow in CSF column.

Spinal Anesthesia - Dermatomal Levels and Clinical Relevance

  • Dermatomes: Area of skin innervated by a single spinal nerve.
  • T10: Umbilicus.
  • T6: Xiphoid process.
  • T4: Nipples.

Peripheral Nerve Anatomy

  • Peripheral nerves are bundles of nerve fibers (axons).
  • Connective tissue layers organize nerve fibers into fascicles.
  • Endoneurium: Surrounds individual nerve fibers.
  • Perineurium: Surrounds fascicles.
  • Epineurium: Covers the entire nerve.

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