Anesthetics in Epidural Blocks

Questions and Answers

What primarily influences the spread of an epidural block?

Type of anesthetic agent chosen

Duration of the anesthetic effect

Concentration of the patient’s blood

Area of injection and specific gravity of the agent (correct)

How does the volume of local anesthetic solution for an epidural block compare to that of a spinal block?

Spinal requires less volume than epidural (correct)

Both require the same volume

Volume requirement is not relevant

Epidural requires less volume than spinal

What is a distinguishing characteristic of caudal blocks in comparison to other regional blocks?

It targets the lumbar region specifically

It requires less anesthetic agent than other blocks

It involves injecting through the skin

It involves a larger space that must be filled (correct)

Which anesthetic agent is noted for its fast onset and short duration?

Chloroprocaine Signup and view all the answers

How does the addition of epinephrine affect the anesthetic agent used in epidural anesthesia?

It prolongs and intensifies the analgesic effect Signup and view all the answers

What distinguishes epidural anesthesia from spinal anesthesia in terms of muscle relaxation?

Epidural blocks may allow movement of legs and feet Signup and view all the answers

What is the typical onset time for the complete effects of an epidural block?

10 to 20 minutes Signup and view all the answers

Which of the following is NOT a factor influencing the duration and intensity of anesthesia in an epidural block?

Patient's diet prior to administration Signup and view all the answers

What is the primary purpose of spinal anesthesia?

To block the ganglia and motor nerve roots for surgical procedures Signup and view all the answers

Where is the subarachnoid space located?

Between the dura mater and the pia mater surrounding the spinal cord Signup and view all the answers

What is the typical volume of local anesthetic used for spinal anesthesia?

1 to 2 milliliters Signup and view all the answers

Which positions are typically used to prepare a patient for spinal anesthesia?

Sitting in a hunched-over position or lying in lateral fetal position Signup and view all the answers

What should an anesthetist feel to confirm correct needle placement during spinal anesthesia?

A distinct 'pop' as the needle enters the subarachnoid space Signup and view all the answers

What is the main effect of spinal anesthesia on the body?

Relaxes muscles and provides analgesia below the diaphragm Signup and view all the answers

What is the common gauge and length of the spinal needle used for spinal anesthesia?

25-gauge, 3.5-inches long Signup and view all the answers

What additional nerve is sometimes blocked during eye blocks to prevent movement?

Facial nerve Signup and view all the answers

Which of the following factors does NOT influence the distribution of local anesthetic in spinal anesthesia?

Length of the needle used Signup and view all the answers

What is the primary purpose of adding a vasoconstrictor like epinephrine to the local anesthetic agent?

To prolong the duration of anesthesia Signup and view all the answers

In what scenario would a hyperbaric anesthetic be particularly effective?

When immediate lower extremity anesthesia is desired Signup and view all the answers

What distinguishes epidural anesthesia from spinal anesthesia?

Epidural anesthesia allows for a continuous block Signup and view all the answers

Which local anesthetic agent typically provides the longest duration of anesthesia?

Bupivacaine Signup and view all the answers

What technique is NOT used to locate the epidural space during an epidural injection?

Transforaminal technique Signup and view all the answers

An anesthetist wants to ensure upper abdominal anesthesia using a lumbar epidural approach. Which positioning strategy should they consider?

Tilt the table head down post-administration Signup and view all the answers

Which anatomical area requires the administration of cervical epidural anesthesia?

Postoperative pain after cervical surgery Signup and view all the answers

How is the effectiveness of the block primarily determined after administration of the local anesthetic?

By patient's feedback on pain perception Signup and view all the answers

The term isobaric solution refers to which characteristic compared to CSF?

It has the same weight as CSF and remains stationary Signup and view all the answers

Study Notes

Spinal Anesthesia

Also known as subarachnoid block (SAB) or intrathecal block.
Achieved by injecting 1-2 milliliters of local anesthetic into the subarachnoid space, located between the dura mater and pia mater.
Primarily provides analgesia and muscle relaxation for surgeries below the diaphragm.
The spinal needle is typically inserted below the second lumbar vertebra (between L3-L4 or L4-L5).
Patient positioning is critical, often hunched-over or in a lateral fetal position to optimize access.
Correct needle placement is confirmed by a “pop” sensation and clear cerebrospinal fluid (CSF) backflow.
Onset of anesthesia is rapid, usually within 5-10 minutes.
Anesthesia level is monitored by assessing sensory response using cold or sharp stimuli.
Local anesthetic distribution in CSF is influenced by specific gravity, spinal canal curvature, and patient positioning.
Hyperbaric solutions sink, hypobaric solutions float, and isobaric solutions remain stationary in the CSF.
Intensity and duration depend on anesthetic type and dose; example agents include lidocaine (75 min-2 hrs), tetracaine, and bupivacaine (2-4 hrs).
Vasoconstrictors (e.g., epinephrine) may be added to prolong anesthesia; narcotics (e.g., morphine) enhance analgesic effects.

Epidural Anesthesia

Involves blocking nerve roots after exiting the dura, using an anesthetic agent injected into the epidural space.
The epidural space runs the full length of the spine and is accessed using an epidural needle.
Techniques include “hanging drop” or “loss-of-resistance” to locate the epidural space.
Injection can be performed in cervical, thoracic, lumbar, or caudal regions, depending on the surgical site.
Lumbar epidural is the most common, anesthetizing areas from the upper abdomen to lower legs.
Continuous epidural allows for intermittent or sustained administration of anesthetic, utilizing a catheter.
Onset is slower (10-20 minutes) compared to spinal anesthesia due to the need for diffusion into smaller nerve roots.
Requires larger volumes (10-30 milliliters) of anesthetic to fill the epidural space.
Sensory and motor block effects vary; patients may retain some ability to move their legs.
Duration and intensity are influenced by agent concentration and presence of epinephrine.
Common local anesthetic agents include chloroprocaine (fast onset, short duration), prilocaine, lidocaine, mepivacaine (intermediate onset), and bupivacaine (slow onset, long duration).
Caudal blocks involve injecting anesthetic into the epidural space via the caudal canal, requiring more anesthetic due to larger volume.

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Description

Test your knowledge on the pharmacology and technique of epidural blocks. This quiz covers the mechanism of action, onset time, and volume considerations of local anesthetics. Perfect for students or professionals in the medical field.