Patient Positioning Flashcards
Etiology of positioning injuries
Microvascular neuropathies-predisposition
• Blood transfusions- systemic inflammation
• Viruses
• Immunosuppression
Stretching a nerve greater than 5% will cause what? best way to prevent?
Ischemia
Have patient position themselves
What does peripheral nerve injury cause?
Disruption of nerve impulse leading to muscle weakness and impaired function
What are the mechanisms of nerve injury
Mechanical distortion of nerve membrane or myelin sheath via:
Ischemia
Stretch
Compression
Traction
Kinking
Neuropraxia
Demyelination
6 wks-3 months recovery
Good prognosis
Axonotmesis
Axonal damage
9-12 months recovery
Fair prognosis
Neurotmesis
Complete axonal transection
No regenertion or incomplete
Irreversible
What are the most favorable types of nerve injury?
Reversible…
Or
Neuropraxia
Best thing we can do in pre-op for nerve injuries
Document pre-existing nerve injuries
How do we protect patients from nerve injuries?
Proper alignment and understanding their baseline ROM
Foam/gel/cotton/bolsters/axillary rolls
Padding all bony prominences
Supine (dorsal decubitus) considerations
Support occiput
Arms next to body or <90 degrees
No skin-metal contact
No hard plastic on skin
Bend knees for lumbar support
Bony contact points!
Aortocaval syndrome
(Supine hypotensive syndrome)
When fetus or abdominal mass rests on aorta/vena cava compromising circulation
Use wedge to displace mass-this recommendation is becoming less common
Problems with Lithotomy
Hip flexion >90degrees =stretch inguinal ligaments
Compartment syndromes
Finger amputation!!
Lateral femoral cutaneous nerves
Lithotomy considerations
Protect arms! Use arm boards
Hips and knees at 90 degrees or less =legs parallel to floor
Anatomy of radial nerve compression
Lateral epicondyle of humerus
Median nerve injury etiology
Unclear
Possibly ischemia from AC IV
Ulnar nerve impairment (causes)
Pressure against elbow
Flexion-nerve is pulled over the median epicondyle/epicondylar groove
Most common nerve injured!!
Risk factors for ulnar nerve impairment
Male (70-90%)
High BMI
Hx cancer and prolonged bed rest
May have asymptomatic ulnar neuropathy at baseline
Problems with supine positioning
Arm boards- too tight or lack padding
Elbow flexion
Backache- loss of lumbar curvature=neuropathy/pain
Compartment syndrome causes :
Can happen in any extremity
-hypotension/loss of perfusion
-vascular obstruction by retractors, excessive knee/hip flexion
-compression of elevated extremity/straps
Innervation of hand diagram
Second most injured nerve
Brachial plexus
Brachial plexus neuropathy causes
Shoulder braces (steep head down)
Lateral head displacement (stretch)
Sternal retraction
Axillary trauma from humeral head (>90 degrees)
Main considerations from lateral
Dependent leg flexed to stabilize
Axillary roll to prevent venous congestion
Head neutral
Minimize pressure on bony prominences!!!
Semi-supine/prone most important thing!
Check pulses!!!
Flexed lateral position
Lateral jackknife- iliac crest is over the hinge
-opens intercostal spaces
Lateral position complications
Neck- neutral!!
Endless nerve ischemia complications?
Check body for extra leads/tape that could cause pressure
Prone position considerations
Neutral spine
Genitalia/breasts free from pressure
Eyes free from pressure
Abdomen free
POVL 5 most common risk factors
Obesity
Male
Prone (Wilson frame)
Length >6 hrs
Blood loss
Compression of globe, anemia, vasopressor use, hypotension
3 independent risk factors form ischemic optic neuropathy after spinal fusion surgery
Increased estimated blood loss
Male gender
Lower percentage colloid administration
Complications from prone positioning
Head below heart- congestion and edema
Brachial plexus- stretch and compression
Breast injuries- tissue necrosis
Abdominal compression- impaired ventilation and impedes venous return
Stoma/genitals
Complications of head elevation
Postural hypotension- no sympathetic response
Midcervical tetraplegia- hyperflexion causing paralysis below c5
Venous air embolism- highest chance with operation above the heart
Pressure difference between circle of Willis and arm
15 mmhg
Sequence of events with venous air embolism
ETCO2 drops
Hypotension
Tachycardia
Hypoxemia
What to do in Venous air embolism
Cover surgical field with saline/saline soaked dressings
100% oxygen
Vasopressors
Turn left lateral to sequester air in RV
Sciatic nerve injury cause
Over stretching in Lithotomy
Common peroneal nerve injury
Lithotomy- nerve compressed between head of fibulae and metal brace
Anterior tibial nerve injury
Plantar flexion for extended periods-sitting or prone
Femoral nerve injury
Excessive angulation during Lithotomy or compression at pelvic rim by retractors
Saphenous nerve injury
Compression against medial tibial condyle -Lithotomy
Obturator nerve injury
Excessive flexion of thigh to groin or difficult forceps delivery
Buccal branch of facial nerve injury cause
Excessive force with face mask ventilation or use of straps
Supraorbital branch injury cause
Upward force on tube after nasal intubation
Nerve injuries from Lithotomy
Sciatic
Peroneal
Femoral
Saphenous
External abdominal pressure problems (vasculature)
Impedes venous return
Increases venous pressure
Impairs ventilation
Pressure is transmitted to vena cava and communicated to the lumbar epidural veins causing congestion
Airway problem with neck flexion
Right mainstem
Shoulder braces
Don’t use when arms are extended (on boards)
Should be placed over acromioclavicular joint
If too medial or lateral will cause brachial plexus injury
DONT USE
Pathophys of compartment syndrome
Increased pressure and decreased perfusion causes neural and vascular damage in muscles with tight, fascial borders
Another term for compartment syndrome
Called reperfusion injuries because injury happens when blood flow returns after a period of ischemia
Mitigating compartment syndrome in Lithotomy
Legs should be periodically lowered if procedure lasts more than 2-3 hours
Palm position on armboards
Supinated(palm up)
Down can increase pressure over ulnar nerve
Problem with neuromuscular blocking drugs and patient positioning
Increases mobility of joints causing stretch injuries- this is why we have patients position themselves and assess function beforehand
Perineurium
Tough connective tissue that binds the fascicles into identifiable structures
Endoneurium
Loose connective tissue covering the neurolemma (Schwann cells that sheath axons)
Cross section of peripheral nerve trunk
Big lateral consideration
Minimize pressure on bony prominences
Nerve injured from arm abduction >90 degrees
Brachial plexus
