Positioning and Nerve Injury - Midterm Flashcards
What is the incidence of peripheral nerve injury?
< 1%
From the closed claims project, what are the highest top 3 claims
- Death @ 26%
- Nerve Injury @ 22%
- Permanent brain damage @ 9%
What are the most common nerve injuries?
28% Ulnar nerve (HIGHEST)
20% brachial plexus
16% lumbar sacral
15% spinal cord
Surgery > than how many hours increases the risk of nerve injury
4
What are the 4 things in a nerve injury that lead to ischemia?
Transection
Compression
Stretch
Kinking
What are the 5 consecutive nerve roots?
Reach ---------- Roots To ---------------- Trunks Drink -------------Divisions Cold -------------- Cords Beer -------------- Branches
Roots turn into trunks just beyond the lateral border of the
Scalene Muscle
Which roots make up the superior trunk
C5 and C6
Which roots make up the middle trunk
C7
Which roots make up the inferior trunk
C8 and T1
Each trunk turns into an anterior and posterior division underneath
the clavicle and under the 1st rib
Divisions –> C5-C6 –> superior trunk –>
Anterior/Posterior division of Superior trunk
Divisions –> C7 –> middle trunk –>
Anterior/posterior division of middle trunk
Divisions –> C8-T1 –> inferior trunk
Anterior/posterior division of inferior trunk
Divisions turn into cords when
the brachial plexus goes under the pectorals minor muscle
What are the 3 cords
Posterior
Lateral
Medial
In the Cords, what is C5- T1
Posterior cord
In the Cords, what is C5- C7
Lateral cord
In the Cords, what is C8- T1
Medial Cord
Cords are named per their relationship to
axillary artery
Cords turn into branches in the
axilla
How many nerves reach the hand, and which are they?
3
unlar, radial, median
If you can’t extend your hand, or you have a funny feeling on the back of the hand - you have a problem with which nerve?
Radial
The median nerve innervates the
bottom part of hand and nail beds on top of hand
If you can’t close your hand, you have a problem with which nerve?
median nerve
Which nerve innervates the shoulder and wraps around the deltoid?
Axillary nerve
Where does the musculocutaous nerve innervate?
The biceps, comes up to skin over forearm
C8 is pinky, what does that mean if it starts going numb during a spinal?
anesthesia is getting to a high level
What are the cardiac accelerators?
T1-T4
Which nerves innervate the diaphragm?
C3, C4, C5
Do macro and micro blood vessels both supply blood to nerve fibers?
yes
When the nerves come out from the cervical vertebrae, what structure do they go under?
collarbone
Very common for nerves to follow
arteries
If pinky goes numb, which nerve have I affected?
Ulnar nerve
If my pinky is going numb during a spinal anesthesia, what would that mean for HR
Pink is ulnar (C8) which is already above the cardiac accelerators, we could see bradycardia
If I lost sensation over the middle finger on the palmer side, which nerve is affected?
median nerve
Which roots make up the lumbar plexus?
L1-L5
Which major nerve runs through the groin?
Femoral Nerve
large nerve, high potential for damage
Only one branch from the femoral nerve makes it to the ankle, which one?
Saphenous branch
The sacral plexus branches from
L4 to S4 (coccyx)
Which is the major nerve coming from the sacral plexus?
Sciatic nerve
The sciatic nerve is
1/2 tibial nerve and 1/2 peroneal (fibular) nerve
splits half way down
Dermatome: T4 is
nipple line
Dermatome: T6-7 is
xiphoid process
Dermatome: T10 is
belly button
What is the purpose of an axillary roll?
When we lay patient on their side, Brachial plexus becomes compressed. We place the roll below the axilla to allow it to be free
Which nerve will tight table straps effect?
Lateral femoral cutaneous nerve
Which nerve will the candy cane stirrups effect?
Common perineal nerve
Which nerve will armbands or shoulder braces effect?
brachial plexus
Which nerve will tourniquets, BP cuffs and firm surfaces effect?
Radial nerve
length of procedure has a high correlation with what
post op vision loss
What happens when you have a loss of venous return but arteries still pumping?
Compartment syndrome
In a spontaneously breathing patient, the dependent lung has the best _______ and the best _________
Ventilation
Perfusion
(negative pressure in base of lung makes this work)
In positive pressure ventilation, the dependent lung has the best _______ and the nondependent lung has the best _______
perfusion
ventilation
In zone 1, ___>_____>_____
pA, pa> pv
in zone 1, it is _______ but not ________
ventilated but not perfused
Does zone 1 contribute to dead space ventilation?
YES
What are causes of increased zone 1?
Pulmonary HTN
excessive PEEP
excess TV
In zone 2, ___>_____>_____
pa>pA>pv
In zone 2, capillary blood flow is determined by?
Pa-PA gradient
In zone 2, flow varies with
respiration
In zone 2, ventilation =
perfusion
In zone 3, ___>_____>_____
pa>pv>pA
In zone 3, there is continuous
capillary blood flow
Zone 3 is promotional to the
arterial-venous pressure gradient
What happens with CO and BP with general anesthesia?
they decrease
Durning general anesthesia, blood pools in the dependent area, which decreases preload and stroke volume, this has more of an effect in which positions?
Less of an effect in which position?
Prone, sitting, reverse T-burg
Supine and lateral
Mean Arterial Pressure decrease by __ mm Hg per inch in height change
2 mmHg
1 in above heart = BP should be 2 mmHG lower
Since there is a 2mmHg pressure change from level of the heart, what does this mean for the brain?
Head 10-12 inches higher – BP may not be okay at the brain
A-line – level at head
General anesthesia blunts the compensatory sympathetic nervous system response that would normally minimize BP changes associated with abrupt position changes, what interventions can help this? (4)
Temporarily delay further position change
Reduce concentration of inhaled anesthetic
Administer IVF’s to increase circulating volume
Use vasopressors as indicated
In supine position: head and neck should be
midline and neutral (no extension of flexion)
In supine position: if arms at side, how should hand be placed?
thumbs up
In supine position: if arms abducted on armboard, how should hand be placed
what happen if palms the wrong way?
palms up
compress ulnar nerve
In supine position: don’t extend arms out greater than
90 degrees
Head should not be turned laterally when arms abducted because
brachial plexus stretch can occur
In the supine horizontal position, the intravascular pressures from head to foot approximate mean
pressure at level of heart
In the supine horizontal position, what 2 things are significantly reduced from a respiratory standpoint
FRC and total lung capacity
In a supine position, where is zone 1,2,3 now?
1 is along chest (anterior), 3 is along back (posterior)
When in supine position, abd contents push everything up, what could this do to your ETT?
Could mainstem
In an intubated patient, would can happen with head extension?
pull out ETT
In an intubated patient, would can happen with head flexion?
mainstem ETT
In trendelenburg position, pressures may change by 2mm Hg for each _____ cm that a given point varies in vertical height below or above the reference point of the heart
2.5
Physiologic alterations in trendelenburg position (3)
Increased CVP
Increased Intraocular pressure
Increased Intracranial pressure
Cardiovascular considerations in trendelenberg postion (3)
(activation of baroreceptors) - baroreceptors slow down because it thinks it has enough blood
Decrease in CO
Decrease in peripheral vascular resistance
Decrease in HR and BP
Respiratory considerations in trendelenberg position: Diaphragm displaced _______ and its excursion is limited by shifting of abdominal contents, decreasing the _____
cephalad
FRC
Trendelenburg position does what to the ventilation/perfusion mismatch and atelectasis?
increases
What is the head position in reverse T-burg?
head is higher than feet
What are the cardiac considerations in reverse T-Burg?
Decrease in preload, CO, and arterial pressure
Increase in sympathetic tone : increase HR and BP (baroreceptors in overdrive)
What are the respiratory considerations in reverse T-Burg? (2)
Increased FRC
Easier to ventilate
What are the neuro considerations in reverse T-Burg? (1)
Decreased CPP
Explain standard lithotomy position
Thighs flexed approximately 90* on the trunk
Knees bent to maintain lower legs nearly parallel to floor
Explain low lithotomy position
Degree of thigh elevation is approximately 30-45*
Reduces perfusion gradients to and from legs
Explain high lithotomy position
Thighs flexed 90* or more on trunk
Produces a significant uphill gradient for arterial perfusion to feet
Explain exaggerated lithotomy position
Thighs forcibly flexed on trunk
Lower legs aimed skyward
If tucking arms at the side for a lithotomy position, what must you be very careful about?
Be careful the fibers are not in break of bed. Beds are hydraulic and can cut fingers off if trapped.
When raising and lowering legs in lithotomy position, how should this be done?
legs should be raised and lowered, slowly, together
What happens if you raise or lower 1 leg at a time in lithotomy position?
causes excess stretching on opposite side
In candy cane stirrups, if the bar is pushing on the outer part of the leg, what nerve will that effect?
common perineal nerve
In candy cane stirrups, if the bar is pushing on the medial part of the leg, what nerve will that effect?
sapenous nerve
In lithotomy position, what happens to the FRC?
FRC decreases, predisposing patients to atelectasis and hypoxemia
In the lateral position, the side that is down on the table determines the name. So if left side down on table –>
left lateral position
The axilla roll is placed caudid to the axilla to avoid what?
avoid compression of the brachial plexus
How are CV changes in the lateral position?
minimal
When in the lateral kidney rest position, if bend is improper at the flank instead of the iliac crest, what can happen?
Compression of vena cava = hypotension
Where should you put the pulse Ox on a patient in the lateral position?
On the dependent arm (arm on table) to assure adequate perfusion
In the lateral position, how are the zones split up?
Top lung will be zone 1, bottom lung will be zone 3.
Increased perfusion to dependent lung
In the lateral position, how will a VQ mismatch manifest?
unexpected arterial hypoxia
What types of surgeries are sitting positions used for?
Crani
Shoulder surgery
What are other names for the sitting position?
Lawn chair, beach chair, lounging
CV considerations for sitting position
Decreased central blood volume and hypotension
Amount of decrease in hemodynamic parameters depends on the degree of elevation of torso
How does a venous air embolism happen in the sitting position?
When surgical area higher than heart, creates a negative pressure and can suck air into the vessel
What are the respiratory changes associated with sitting position?
Minimal, abd contents shifted caudid
Neuro considerations for sitting position
decreased CPP and ICP. Keep BP up!
In prone position, how often do you check eye, nose, mouth?
Every 15 minutes
What are some surgeries we use prone position?
Spine, cranial, ortho, rectal
In prone position, body typically supported at chest with frame or rolls placed ______ to chest or open frame table
parellel
Why can prone position cause a decrease in BP and CO?
Pooling of blood in the extremities and compression of abdominal muscles
Compression of abdomen and thorax decreases total lung compliance, which increases
work of breathing
If abdomen hangs free, gravity allows abdominal contents to shift _______, reducing interference with diaphragmatic movement
anteriorly
In prone postion, make sure head is neutral, extreme rotation of patient’s head may decrease
cerebral venous drainage and cerebral blood flow
How to decrease risk of POVL and coral abrasion?
Avoid pressure on eyes
Maintain MAP
Don’t let BP drop > than ___% of baseline to help prevent POVL
20
Head pins for craniotomy are very stimulating, what meds do you need to be ready with before pins are placed
propofol and fentanyl
What can happen if patient coughs while head pins in place?
If pt coughs, head can not move – body will jolt and can break neck
Mask straps can cause injury to what?
facial nerve
What is normal intra abd pressure
12-15 mmHg
If intra-abdominal pressure approaches or exceeds venous pressure, return of blood from pelvis and lower extremities is
reduced or obstructed
What causes alopecia and when does it show up?
prolonged compression of hair follicle
3-28 days post-op
An air embolism enters the right ventricle and impedes blood flow to the
pulmonary artery
To avoid aseptic necrosis of the upside femoral head, where should tape be placed?
placed between head of femur and crest of ilium
What are some causes of post op vision loss?
- Direct pressure on globe
- Intraop hypotension
- Massive blood loss
- Venous congestion in prone postion
- prolonged surgery
- Massive fluid replacement
When displacing breasts for prone position, what is the better position
Medial and cephalad displacement seems to be better tolerated
What positions is compartment syndrome most common in?
Lateral and lithotomy position
>5 hrs
Symptoms of thoracic outlet syndrome
shoulder, neck, and arm pain, numbness, or impaired circulation
What should all patients be asked when scheduled for prone surgery?
ability to work or sleep with arms elevated overhead
What is the second most common post ip nerve injury?
brachial plexus injury
What can cause a brachial plexus injury
Stretch injury ( arm extended and head turned away) (arm ABDucted >90degrees)
Compression injury between clavicle and first rib with improperly placed shoulder braces or spreading sternum
What is the most frequently damaged nerve in the lower ext?
common peroneal nerve
Where is the compression at to damage the common perineal nerve?
compression of nerve between head of fibula and metal frame used to support leg in lithotomy position
How does compression of the common peroneal nerve manifest?
foot drop
Most common upper body nerve injury
ulnar nerve
Causes of radial nerve injury
arm slips of surgical table
pressure applied to nerve as it traverses the spiral groove of humerus
Symptoms of radial nerve injury
“wrist drop” - inability to extend hand at the wrist
What should you do if you get an air embolism?
flood area with fluid, if central line - start pulling back to get air our, turn on left side
heart can take 20cc air
