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Questions and Answers
During a proximal paravertebral nerve block for a standing laparotomy, an excessive amount of local anesthetic is inadvertently deposited ventral to the transverse process. Which of the following complications is most likely to arise from this misplacement?
During a proximal paravertebral nerve block for a standing laparotomy, an excessive amount of local anesthetic is inadvertently deposited ventral to the transverse process. Which of the following complications is most likely to arise from this misplacement?
- Development of a hematoma at the injection site, requiring surgical drainage.
- Systemic lidocaine toxicity from rapid intravascular absorption in the ventral tissues.
- Reduced efficacy of the nerve block due to diffusion away from the target nerves. (correct)
- Paresis of the hindlimb due to unintended blockade of the femoral nerve.
In comparing proximal and distal paravertebral nerve block techniques for flank anesthesia, which statement accurately differentiates a key advantage of the distal technique over the proximal?
In comparing proximal and distal paravertebral nerve block techniques for flank anesthesia, which statement accurately differentiates a key advantage of the distal technique over the proximal?
- Distal blocks widen the surgical field in the flank region by inducing scoliosis more effectively. (correct)
- Distal blocks inherently carry a lower risk of systemic toxicity due to reduced anesthetic volume needed.
- Distal blocks are technically simpler to perform, requiring fewer anatomical landmarks to identify.
- Distal blocks provide a more complete desensitization of the flank due to wider nerve coverage.
When performing an inverted 'L' block for flank anesthesia, what is the primary limitation compared to paravertebral nerve blocks in terms of achieving complete muscle relaxation for deep surgical procedures?
When performing an inverted 'L' block for flank anesthesia, what is the primary limitation compared to paravertebral nerve blocks in terms of achieving complete muscle relaxation for deep surgical procedures?
- The diffusion of anesthetic in an inverted 'L' block is unpredictable, leading to inconsistent muscle relaxation.
- Inverted 'L' blocks require significantly larger volumes of anesthetic, increasing the risk of systemic effects.
- The anatomical spread of the inverted 'L' block does not consistently encompass the deeper muscular layers of the flank.
- Inverted 'L' blocks predominantly target cutaneous nerves, offering limited muscle relaxation. (correct)
For caudal epidural anesthesia using lidocaine, the extent of the nerve block is described as 'dose (volume) dependent'. In a large animal undergoing a rectal prolapse repair, which of the following clinical signs would indicate that the volume of lidocaine administered has resulted in an undesirable cranial spread, affecting the sciatic and femoral nerves?
For caudal epidural anesthesia using lidocaine, the extent of the nerve block is described as 'dose (volume) dependent'. In a large animal undergoing a rectal prolapse repair, which of the following clinical signs would indicate that the volume of lidocaine administered has resulted in an undesirable cranial spread, affecting the sciatic and femoral nerves?
When considering the use of xylazine in combination with lidocaine for epidural anesthesia, what is the primary rationale for including xylazine, considering its mechanism of action and the desired outcome for surgical procedures?
When considering the use of xylazine in combination with lidocaine for epidural anesthesia, what is the primary rationale for including xylazine, considering its mechanism of action and the desired outcome for surgical procedures?
In a Baer block (intravenous regional limb anesthesia) using a butterfly catheter, the tourniquet's role is critical. If the tourniquet is inadvertently released prematurely immediately after lidocaine injection, what is the most significant immediate risk to the animal?
In a Baer block (intravenous regional limb anesthesia) using a butterfly catheter, the tourniquet's role is critical. If the tourniquet is inadvertently released prematurely immediately after lidocaine injection, what is the most significant immediate risk to the animal?
For dehorning procedures in goats, the text emphasizes desensitizing both the cornual branch of the zygomaticotemporal (lacrimal) nerve and the cornual branch of the infratrochlear nerve. What is the primary reason for requiring blockade of these two distinct nerves in goats compared to the single cornual nerve block sufficient for cattle?
For dehorning procedures in goats, the text emphasizes desensitizing both the cornual branch of the zygomaticotemporal (lacrimal) nerve and the cornual branch of the infratrochlear nerve. What is the primary reason for requiring blockade of these two distinct nerves in goats compared to the single cornual nerve block sufficient for cattle?
In the Peterson eye block, the needle tip is placed at the foramen orbitorotundum. What is the primary anatomical objective of targeting this foramen in the context of achieving ocular anesthesia and akinesia?
In the Peterson eye block, the needle tip is placed at the foramen orbitorotundum. What is the primary anatomical objective of targeting this foramen in the context of achieving ocular anesthesia and akinesia?
A local periorbital infiltration of lidocaine is described as an alternative to the Peterson eye block, noted for being 'easier, less complications'. However, what is a significant limitation of periorbital infiltration compared to the Peterson block in terms of its clinical effect?
A local periorbital infiltration of lidocaine is described as an alternative to the Peterson eye block, noted for being 'easier, less complications'. However, what is a significant limitation of periorbital infiltration compared to the Peterson block in terms of its clinical effect?
The Pudendal Nerve Block is indicated to facilitate evaluation and surgery of the penis by blocking motor innervation of the retractor penis muscle. If a pudendal nerve block is unilaterally successful, but the penis is still partially retracting during examination, what anatomical consideration explains this incomplete relaxation?
The Pudendal Nerve Block is indicated to facilitate evaluation and surgery of the penis by blocking motor innervation of the retractor penis muscle. If a pudendal nerve block is unilaterally successful, but the penis is still partially retracting during examination, what anatomical consideration explains this incomplete relaxation?
Flashcards
Epidural Anesthesia
Epidural Anesthesia
Anesthesia to facilitate obstetric, rectal, urinary, and reproductive surgeries in large animals.
Pudendal Nerve Block
Pudendal Nerve Block
Blocks the motor innervation of the retractor penis muscle for examination/surgery.
Dehorning anesthesia in cattle
Dehorning anesthesia in cattle
Desensitizes the cornual nerve with a ring block
Proximal Paravertebral Nerve Block
Proximal Paravertebral Nerve Block
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Distal Paravertebral Nerve Block
Distal Paravertebral Nerve Block
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Baer Block
Baer Block
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Dehorning anesthesia in goats
Dehorning anesthesia in goats
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Peterson Eye Block
Peterson Eye Block
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Study Notes
- Clinical Anesthesia - Nerve Blocks in Large Animals (VCS878 Junior Surgery)
Flank Anesthesia for Standing Laparotomy
- Performed using a proximal paravertebral nerve block.
- Landmarks for the proximal paravertebral nerve block include the transverse processes of the lumbar vertebrae T-13, L-1, and L-2.
- Nerves blocked in the proximal paravertebral block are T-13, L-1, and L-2, and both the dorsal and ventral branches of each nerve must be blocked.
- Benefits of the proximal paravertebral block include it being quick, using a small amount of lidocaine (~10ml/nerve), and scoliosis widens the surgical field in the flank region.
- Distal Paravertebral Nerve Block Landmarks are the transverse processes of Lumbar vertebrae L1, L2, and L4
- Nerves blocked are the same as the proximal paravertebral block, however, lumbar nerve two (L-2) is blocked over the lateral process L-4.
- Benefits of the distal paravertebral block include that it can usually be done with an 18 gauge, 1 ½ inch needle, preventing the need for a guide needle and longer (spinal) needle to reach the nerve.
- An inverted "L" block is an alternative technique for flank anesthesia.
- Segmental Thoraco-Lumbar Block is another method of flank anesthesia.
Epidural Anesthesia
- Used for obstetrics, rectal, urinary, and reproductive surgeries.
- Commonly used in large animal species to facilitate procedures of the "South End."
- Most common procedure being manipulation of fetuses during dystocia and other surgical interventions.
- Anesthetic is administered in the epidural space in the sacro-coccygeal region or the lumbo-sacral area.
- Care should be taken on the type of anesthetic and volume used to prevent posterior paresis/paralysis due to motor neuron blockade.
- Larger volumes of lidocaine are intentionally administered to anesthetize the posterior half of the patient for restraint and facilitate surgery in the recumbent animal.
Caudal Epidural Anesthesia
- The dose (volume) is dependent on the extent of the block.
- Larger volumes and sometimes animal conformation will allow the lidocaine to travel far enough cranially to block the sciatic and femoral nerves resulting in recumbency.
- Drugs used for caudal epidural anesthesia include: 2% Lidocaine and Xylazine (or a-2 agonists)
- Lidocaine/ a-2 combination prolongs the duration of lidocaine alone.
Lumbo-Sacral Epidural Anesthesia
Local Anesthesia of the Limb
Bier Block (Intravenous Regional Limb Anesthesia)
- A tourniquet is placed proximal to the region of the limb to be anesthetized.
- A superficial vein or the deep dorsal common digital vein can be selected for the injection of lidocaine anesthetic.
- The volume of lidocaine will diffuse out of the veins, infiltrating the surrounding tissues and anesthetizing the nerves of the limb below the tourniquet.
- Procedure is facilitated with the use of a butterfly catheter (~18 to 20 ga.) and a short extension to prevent extravascular injection when the animal moves.
- Generally, 15 to 20 cc of 2% lidocaine is administered.
- This block can be used to diagnose lameness in the foot which may not be obvious on clinical exam.
- This form of anesthesia is commonly used to facilitate treatment of conditions requiring debridement of soft tissues, horn, and bone.
Selective Regional Anesthesia of the Limb
- Due to the difficulties encountered in palpation and isolation of individual nerves in the ruminant, this form of anesthesia is usually replaced with the intravenous administration of anesthetic
Anesthesia of the Head
Anesthesia for Dehorning Procedures
- In cattle, desensitize the cornual nerve and follow with a ring block for dehorning.
- In goats, desensitize the cornual branch of the zygomaticotemporal (lacrimal) nerve and the cornual branch of the infratrochlear nerve.
- Goats are more sensitive to lidocaine toxicity, these two branches are specifically selected reducing the volume of lidocaine one would need when performing and ring block.
Anesthesia of the Eye
- Peterson Eye Block is a method of eye anesthesia.
- Local periorbital infiltration of lidocaine is an easier method with less complications.
Pudendal Nerve Block
- Facilitates evaluation and surgery of the penis by blocking the motor innervation of the retractor penis muscle.
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