Positioning Flashcards
Most common cause of litigations against anesthetists
Peripheral nerve injury 16% of claims
Most commonly injured nerves?
–ulnar nerve (28%)
–brachial plexus (20%)
–lumbosacral root (16%)
–spinal cord (13%)
–Injury is less common for the sciatic, median, radial and femoral nerves.
Predisposing factors to nerve injury
- Thin or obese body habitus
- Old age
- History of vascular disease, diabetes, smoking
- Male gender
- Hypotension, hypovolemia, dehydration
- Coagulopathy or presence of hematoma near nerve
- Infection/presence of abscess near nerve
- Pre-existing generalized neuropathy
- Hereditary predisposition
- Structural anomaly/congenital abnormality
–(e.g. constriction at thoracic outlet or condylar groove, or arthritic narrowing of joint space)
•Hypothermia, especially induced
How are peripheral nerves damaged?
This outermost tissue layer is called the epineurium. Injury to the myelin sheath or axon of a nerve can lead to focal conduction block, degeneration and demyelination.
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What happens if a nerve is severely damaged, denervation?
If a nerve is severely damaged, whether by compression, stretch or other means, there is distal degeneration of the axon and, with it, the myelin, (Wallerian degeneration) over a period of 2-3 days
Three groups of Seddons Classification?
–Neurapraxia: damaged myelin with intact axon. Impulse conduction across the affected segment fails. Mild and reversible nerve injury. Recovery usually occurs in weeks to months (good prognosis)
–Axonotmesis: axonal disruption. Endoneurium and other supporting connective tissue are preserved. (variable prognosis)
–Neurotmesis: nerve is completely severed. There is complete destruction of all supporting connective tissue structures. (surgery may be required)
Five types of Sunderland’s Classification?
- Type 1: Local myelin injury (equivalent to Seddon’s ‘neurapraxia’ group). Recovery in weeks to months. (Good prognosis)
- Type 2: Disruption of axonal continuity with Wallerian degeneration. Regeneration of axon required for recovery. (Good prognosis)
- Type 3: Loss of axonal continuity and endoneurialtubes. Perineurium and epineurium preserved. Scarring can compromise recovery. (Guarded prognosis. Surgery may be required)
- Type 4: Loss of axonal continuity, endoneurial tube and perineurium damaged. Epineurium remains intact. (Poor prognosis. Surgery necessary)
- Type 5: Nerve entirely severed (equivalent to Seddon’s ‘neurotmesis’ group). (Surgery required. Prognosis poor)
Symptoms of ulnar nerve injury?
–loss of sensation of medial portion of hand
–Inability to abduct or oppose the fifth finger (claw hand)
Prevented by positioning arms in supination. Hypotension increases the risk.
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Where is the brachial plexus located?
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Diagnosis of nerve involved in brachial plexus injury
Median – “Ape hand” deformity, inability to oppose thumb
Axillary – inability to abduct the arm
Ulnar – “Claw hand” deformity
Musculocutaneous – inability to flex forearm
Radial – wrist drop
Compression of the spiral groove of the humerus can cause radial nerve injury, what are the symptoms?
–wrist drop
–weakness of abduction of thumb,
–loss of sensation in web space between thumb and index finger
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Common peroneal nerve injury
–Lateral aspect of knee is compressed against stirrup
–Adequate padding between leg and stirrup
–Better yet, rotate stirrup away from leg
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At risk- thin patients placed on a hardoperating table for a long operation
Stretching in the lithotomy position
CABG surgeries
Femoral nerve injury
Impinged under inguinal ligament from flexion and abduction of thighs
![](https://s3.amazonaws.com/brainscape-prod/system/cm/271/416/908/a_image_thumb.png?1553039572)
Saphaneous leg injury
Medial tibial condyle compressed by leg supports.
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