Positioning Flashcards
“Res ispa loquitur”
“the thing speaks for itself”
identify major safety concerns
patterns of injury and strategies for prevention
improve patient safety by anesthesiologists working in pain management, operating rooms, labor floor, remote locations and critical care.
After induction, the patient can no longer respond to
painful stimuli with poor positioning
“most commonly associated” with positioning-related problems in anesthetized or sedated patients
Tissue stretch and compression
Stretch
> 5% of normal resting length
Kinks or decreases lumens feeding arterioles and draining venules
-Direct Ischemia: reduced arteriole blood flow
-Indirect ischemia: venous congestion
Compression
(neuropraxia or axonotmesis)
Direct pressure reduces local blood flow & cellular integrity
tissue edema, ischemia and possibly necrosis
Padding
T/F
We don’t really know “exactly” why nerve injuries happen
True
Mechanisms of Positioning Injury
Periop Inflammatory Response
-Inflammatory neuropathy
-Microvascular neuropathies
-Autoimmune disease/Viruses/immunosuppression
Radiation-induced
Systemic inflammation from drugs, transfusions of blood products
Perioperative Inflammatory Responses
-Inflammatory neuropathy
-Microvascular neuropathies
-Autoimmune Dz/Viruses/immunosuppression
Goals of Proper Positioning
Clear view & best access to surg site
Anesthesia can give drugs
reduce bleeding & resp issues
less risk pressure/nerve injury & circulation
Team Member Responsibilities
Surgeon
Optimal procedural exposure
Team Member Responsibilities
Anesthesia
-Physiologic requirements (ABC’s)
-Ongoing assessment
-Ensure patient safety
Team Member Responsibilities
Nursing
-Safe transfer
-padding and positioning aids
-Ongoing assessment
T/F
Positioning is everyone’s responsibility.
True
biggest physiologic consequence of position changes
HypoTN
you must recheck and document breath sounds when…
head, neck or whole body moves
(ETT migration possible)
You MUST document every position change, along with…
how you protected the patient
Common Perioperative Neuropathies
Ulnar Neuropathies
Brachial Plexopathies
Median Neuropathies
Radial Neuropathies
Lower Extremity Neuropathies
Most COMMON perioperative neuropathy
Ulnar Neuropathy
Key factors associated with ulnar neuropathy:
-Direct extrinsic nerve compression (often medial aspect of elbow)
-Intrinsic nerve compression (associated with prolonged elbow flexion)
-Inflammation
Risk factors for Ulnar Neuropathy
Mainly:
Male, high BMI, older, prolonged postop bed rest
Others:
Abnormal ulnar nerves before surgery (Contralateral neuropathy)
Poorly formed fibrotendinous roof of the cubital tunnel
External compression in the absence of stretch
only major peripheral nerve in the body that always passes on the extensor side of a joint
ulnar nerve
All other major peripheral nerves primarily pass on the flexion side
Flexion vs extension
We prefer extension
What happens when peripheral nerves stretched >5% of their resting length
start to lose function and can develop ischemia
> __° degree of elbow flexion stretches the ulnar nerve
(≅___° high-risk for injury)
90
110
Anatomy and Elbow flexion
Ulnar nerve passes:
behind medial epicondyle
under the aponeurosis that holds the two muscle bodies of the flexor carpi ulnaris together
Anatomy and Elbow flexion
…. is thick, especially in men
Proximal edge of aponeurosis (cubital tunnel retinaculum)
Ulnar nerve injury
Compression at nerve between …
table and medial epicondyle
Ulnar nerve injury
prevention
supination
avoid hypotension and hypoperfusion
Pad arms properly
Ulnar nerve injury
Manifested by
inability to abduct the 5th finger
Weakness / atrophy of hand muscles “claw-hand”
Numbness/tingling/pain in lateral hand on affected side
Outcomes
Sensory Only Neuropathy
40% resolve within 5 days
80% resolve within 6 months
Outcomes
Sensory & Motor Ulnar Neuropathy
20% resolve within 6 months
Many have permanent pain and dysfuction
Follow Up
Sensory - only neuropathy
Observe patient as most resolve within 5 days
persists = neurologist consult
Follow Up
both motor and sensory neuropathy
Consult neurologist ASAP
may need decompression surgery
Brachial Plexus Injury
Most common in…
patients undergoing sternotomy (especially those with internal mammary artery mobilization)
Things to think about:
Brachial plexus entrapment
Prone positioning
Anatomy of shoulder abduction
Many patients don’t notice or complain until up to 48 hours later.. why?
We’ve medicated them heavily
Brachial Plexus Injury
Patients in ___ have a higher risk than supine
prone and lateral
Brachial Plexus Entrapment
Prone and lateral position patients:
entrapped between compressed clavicles and rib cage
Prone positioning
(surrender position)
somatosensory-evoked potential changes when their arms are abducted
T/F
Shoulder Braces can cause brachial plexus injury
True
braces tight against the base of the neck
should be more laterally over the acromioclavicular joint
Proper Shoulder Brace placement
more laterally over the acromioclavicular joint
Causes of Brachial Plexus Injury
These stretch the plexus
What injury should be concerned with after a procedure using a sternal retractor?
Brachial plexus
shoulder abduction goal
avoid abduction > 90°
shoulder abduction > 90°
places the distal plexus on the extensor side of the joint and possibility of stretching the plexus
Brachial plexus injury
How it happens
Excessive external rotation or abduction of arm
Avoid:
> 90 degree abduction
arm falling off of table
Brachial plexus injury
Positions affecting it
prone:
watch flexion & abduction of arms overhead
Lateral position:
-requires a chest roll (inaccurately called an axillary roll)
-avoids compression of humerus into axilla
-avoids compression of neurovascular bundle in axilla
When a pt is in lateral position, use which method to avoid brachial plexus injury?
Chest roll
(inaccurately called an axillary roll)
Brachial Plexus Nerve Injury
Manifestations
depend on which nerves are injured
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
Long Thoracic Nerve Dysfunction
Scapular winging
Serratus anterior muscle (long thoracic nerve branches from C5-C7, ~C8)
Long thoracic nerve palsy allows the dorsal protrusion of the scapula
Traumatic in nature
Viral/inflammatory?
allows the dorsal protrusion of the scapula
Long thoracic nerve palsy
Axillary Neurovascular Injury
Abduction of the arm on the arm board > 90 degrees
Head of the humerus into the axillary neurovascular bundle
Compression and stretch injury
Compression/occlusion = decreased perfusion
Mastectomy procedures can cause which nerve injury?
Axillary Neurovascular Injury
Abduction of the arm on the arm board > 90 degrees
Axillary Neurovascular Injury
Muscular men with large biceps are susceptible to
median nerve injury if the arm is fully extended during surgery
Median Nerve Neuropathies
most common in
men between: 20 - 40 yrs.
Men with large biceps and decreased flexibility
Prevention of complete extension at the elbow contributes to
Median Nerve Neuropathies
(Creates a shortening of the median nerve over time)
Usually, motor dysfunction doesn’t readily resolve with which nerve injury?
Median Nerve Neuropathies
~80% motor dysfunction still present 2 years post injury
IVs in the antecubital fossa area are a/w which nerve injury?
Median Nerve Neuropathies
nerves become ischemic if stretched ___ of their resting length which can …
> 5%
kink penetrating arterioles & exiting venules
↓
perfusion pressure
Full extension of the elbow stretches chronically contracted ___ and promotes ischemia (at the level of the __)
median nerves
elbow
Arm Support
support/pad the forearm and hand to prevent…
full extension
Radial Neuropathies are (Less/More) common than median neuropathies
more
Radial Neuropathies
usually compression of the nerve @ mid-humerus area (arising from roots C6-8 and T1)
Surgical retractors: compress radial nerve (bars holding abdominal retraction)
Lateral position (impinged by overhead arm boards)
Unsupported arms/ poles / repeated cycling of the BP cuff
Radial nerve injury: more often by
median nerve injury: mostly due to
radial: direct compression
median: stretch
T/F
NIBP is a/w injury of the median nerve.
False
more closely a/w radial never injury
Nerve Injury Presentation
Radial, Ulnar, Median
Radial got that limp wrist 👀
Arm board use
Lower Extremity Neuropathies
Common peroneal
Sciatic nerve
Obturator nerve
Lateral femoral cutaneous nerve
Femoral nerve
Hip
Excessive flexion or abduction
Flexion: injure lateral femoral cutaneous
abduction: obturator nerves
Obturator Neuropathy
Hip abduction >30 degrees can cause strain on obturator nerve
Excessive hip flexion of thigh can cause compression
Excessive traction in abdominal Sx
Motor dysfunction is common
Inability to adduct the leg with decreased sensation over the medial side of the thigh
Obturator passes through…
through the pelvis and out the obturator foremen
Hip flexion >90 ° causes
laterally displaces anterior superior iliac spine
&
stretches inguinal ligament
T/F
Lateral Femoral Cutaneous Nerve injury results in motor disability.
False
only sensory fibers
But can have:
disabling pain
dysesthesias of the lateral thigh
Prolonged hip flexion >90° can cause ischemia of
Lateral Femoral Cutaneous Nerve
Lateral Femoral Cutaneous Nerve
1/3 of the nerve’s fibers pass through…
the inguinal ligament as it passes through the thigh (originates at L2-3)
Sciatic & its branches
-common peroneal (fibular)
-tibial nerves
cross which joints?
the hip and knee joints
Sciatic & its branches
-common peroneal (fibular)
-tibial nerves
are stretched by:
hyperflexion of the hips and extension of the knees
Sciatic Nerve is
stretched when…
external rotation of the leg
Sciatic and its branches:
common peroneal (fibular)
tibial nerves
Usually associated with direct pressure of the lateral leg, just below the knee
Peroneal Neuropathy
The peroneal nerve wraps around the…
head of the FIBula
Peroneal Neuropathy
causes
leg holders (candy canes)
-hold the leg and foot
-Impinge nerve around the head of the fibula
can cause foot drop
Pressure on Peroneal Nerve
Saphenous Nerve Injury
when the medial tibial condyle is compressed by leg supports
difficult forceps delivery or by excessive flexion of the thigh to the groin
Muscle cramps & Tightness
difficult mobility
Physiological changes related to change in body position are mostly from…
gravitational effects on cardiovascular and respiratory systems
redistribute blood within the venous, arterial, and pulmonary vasculature
(In an awake pt)
Changing from erect to supine ___ venous return and stroke volume.
What happens after?
increases
Increased preload = PNS stimulation to adapt HR & contractility
can reduce venous return (preload) when in the supine procedure
Obesity, pregnancy, and abdominal tumors
(big belly)
Starling’s Law
heart matches cardiac ejection to the dynamic changes occurring in ventricular filling and thereby regulates ventricular contraction and ejection
Jackknife position
Pulmonary changes in Supine
functional residual capacity and total lung capacity are reduced due to changes to the diaphragm
Pulm response in supine is exaggerated in
obese patients
Anesthesia and muscle relaxants further reduce __ & __ due to diaphragm position with ___
FRC & TLC
relaxation
Trendelenburg position also (increases/decreases) lung volumes.
decreases
Any position that limits movement of the diaphragm, chest wall or abdomen may:
increase atelectasis
intrapulmonary shunt
Variations of Supine
Pre-op considerations
Supine
Upper body
on back with pillow/donut under head
Arms: boards/tucked; (< 90° ); supinated (palm up)
If at side must be padded and tucked
additional padding under elbow
Check fingers
Check IV lines and SaO2 probe
Supine
Resp changes
FRC decreased by 20%
Abdominal contents limit diaphragm movement
GA decreases muscle tone
Small airways close sooner → hypoxia
VQ changes cause shunting → hypoxia
Compression of the IVC
Obesity and pregnancy problems
T/F
Supine position can contribute to alopecia
True
Pressure on occiput → alopecia
Pad back of head
Check often in long cases
Supine
lower body
Keep hips and knees slightly flexed
Blanket/ pillow under knees
Cervical, thoracic and lumbar spines should be in straight alignment
Supine
if using arm boards
Padded
palms up (supinated)
< 90-degree
Complications of Supine
Peripheral neuropathies can occur in any position
Backache
Ischemic pressure injuries
Pressure Alopecia
Pressure-Point issues
Alopecia in Supine
Prolonged compression of hair follicles
↓
hair loss
Pain and swelling where the occiput has been supporting weight
tight face mask straps
hypoTN
hypothermia
Supine pressure point issues
Hypotherm & vasoconstrictive hypoTN
Heels
Sacrum
Elbows
Check legs when patient in supine to make sure…
legs are UNCROSSED
Arm restraint too tight leads to
compresses the anterior interosseous nerve (branch of the median nerve) in the upper forearm
carpal tunnel like sydrome
Can resemble compartment syndrome in the lower extremity
anterior interosseous nerve compression (branch of the median nerve)
ex: Arm Restraint too tight
Nerve Injury and Supine Position
Brachial plexus neuropathy
Sternal retraction
Long Thoracic Nerve Injury
Axillary trauma from humeral head
Radial nerve compression
Median Nerve Dysfunction
Ulnar Nerve Neuropathy
Back pain
Compartment syndrome
chest roll is placed
caudad to the downside axilla
the chest rolls lifts the thorax enough to
relieve pressure on the axillary neurovascular bundle
Helps prevent decreases in blood flow to the hand and arm
chest roll
Decreases shoulder pain after postop
chest roll
flexed lateral decubitus
flexed lateral decubitus flexion should be
under the iliac crest
flexed lateral decubitus positioning
Chest roll
Neck neutral
Pillow between knees and flexed
Padding under ankles/feet
the flank and thorax are horizontal in what positioning
flexed lateral position
feet and legs in flexed lateral position
Feet/legs below the atria causing pooling of blood
flexed lateral position can cause
lumbar stress
flexed lateral position is used for
thoracotomy
kidney surgery positioning
Lateral jackknife with elevated kidney rest
lateral decubitus dependent lung VQ mismatch
underventilated
more perfusion
lateral decubitus non dependent lung
over ventilated
less perfusion
VQ mismatching can cause
hypoxia
lithotomy position
Patient is supine with arms extended laterally <90 °
Each lower extremity is flexed at the hip (about 90°) and knees bent parallel to the floor
in lithotomy position, extremities should be
elevated and lowered slowly and together
when is lithotomy position used most often
GYN and Urology cases
hip flexion > 90º in lithotomy position can increase
stretch of the inguinal ligaments
how should legs be moved when positioning patient in and out of lithotomy
move legs at the same time
low lithotomy
About 30-45 degrees
Reduces perfusion gradients
high lithotomy
Suspend the patient’s feet high with stirrups
Patient’s legs almost fully extended on the thighs flexed 90° or more on the trunk
significant uphill gradient for arterial perfusion to the feet
high lithotomy
high lithotomy can cause
Stretch of sciatic nerve
Compression of femoral canal by inguinal ligament
exaggerated lithotomy
Pelvis flexed ventrally on the spine, thighs forcibly flexed on trunk and lower legs aimed skyward
Associated with compartment syndrome
lithotomy can impair
impair ventilation due to upward pressure
More prominent in obese patients
most common problem with lithotomy
Nerve Injuries: Sciatic, common peroneal, femoral, saphenous and obturator
hand injury risk
lithotomy
Common peroneal nerve damage
Occurs from compression of lateral aspect of fibula head (improper padding against stirrups)
FOOT DROP
elevating and flexing simultaneously avoids
stretching of one side of the nerve
> 4 hours in lithotomy
increases risk of injury
Ischemia, edema to skin and muscles
femoral nerve injury causes
Excessive angulation of the thigh on the abdomen
Excessive traction during abdominal surgery
femoral nerve injury can cause
Decreased flexion of the hip
Decreased extension of the knee
femoral nerve injury causes loss of sensation over the
superior aspect of the thigh
medial or anteromedial side of the leg
Perfusion to an extremity is inadequate
compartment syndrome
characteristics of compartment syndrome
Characterized by ischemia, hypoxic edema, elevated tissue pressure within fascial compartments and extensive rhabdomyolysis
which positions can cause compartment syndrome
Lateral position(arm) and lithotomy (legs)
compartment syndrome is associated with
Systemic hypotension and loss of driving pressure to the extremity (elevation)
Vascular obstruction from excessive flexion, knee or pelvic retractors
External compression from straps
common factor of lithotomy for > 5 hours
compartment syndrome
prone position is used for
posterior fossa of the skull, posterior spine, buttocks and perirectal and lower extremities (Achilles)
how should arms be placed in prone position
Arms at side or “surrender position” < 90° to prevent stretching of brachial plexus
supine to prone
how is patient moved supine ➔ prone
Patient is log rolled gently so there are no abnormal movements or twisting of body parts
Chest rolls from below clavicles to iliac crest
in prone position to provide adequate lung expansion and help alleviate pressure on abdomen
prone positioning
Pillow under lower legs and ankles help flex knees and prevent pressure on toes
Head on special pillow with cut out area free of pressure on face/eyes
Head positioned to side may impair drainage on one side or neutral
Elastic stockings and active compression to minimize pooling of venous blood
prone position cardiac
Compression of abdominal viscera can cause:
- Pooling of blood in extremities
- Decreased preload, CO, BP, SV
cardiac changes in prone position
increased SVR and PVR
pulmonary changes in prone position
Decreased total lung compliance
Increased work of breathing
ETT can be dislodged
blindness from retinal ischemia
prone position
prone position eye indications
blindness from retinal ischemia
ION- Ischemic optic neuropathy
Corneal abrasions
Reverse Trendelenburg can be used for
Cholecystectomy, head and neck procedures
Shifts the abdominal contents caudad
reverse trendelenburg
May have hypotension may result in decreased venous return and perfusion to brain
reverse trendelenburg
Facilitates exposure, aids in breathing (increased FRC)
reverse trendelenburg
Causes further pressure upwards on diaphragm from abdominal contents and further decreases lung expansion
trendelenburg
Increases ICP by decreasing venous drainage
Increased IOP (pt with glaucoma)
trendelenburg
increased risk of aspiration
trendelenburg
Mendelson syndrome
aspiration of > 25cc of gastric contents with a pH of < 2.5
physiologic effects and risks associated with Trendelenburg position
Further increases translocation of blood to central compartment (along with lithotomy)
Intracranial and intraocular pressure increases
pulmonary changes in trendelenburg
Decrease in pulmonary compliance, FRC and vital capacity
What injuries can occur to the eye?
corneal abrasion is most common
Chemical injury, direct trauma (pressure and crush), blurred vision
Flexion of the head may move the endotracheal tube
toward the carina
extension of the head moves the ett
away from the carina
Sudden increases in airway pressure or oxygen desaturation may be caused by
mainstem bronchial intubation.
head down vs head up positions
sitting position is used most often for
posterior fossa, cervical spine, shoulder or neck surgery
sitting position causes pooling of blood
in the lower extremities (compression stockings)
decreases venous return and decreased cardiac output (20-40%)
sitting position
sitting position pulmonary changes
Increased lung volumes
Decreased work of breathing
awake vs anesthetized in sitting position
flexion of the head in beach chair position
Flexion of the head may obstruct the internal jugular and cause cerebral venous engorgement or hypoperfusion (swelling in the face, eyes
extension of the head in beach chair position
can impair cerebral blood flow causing cerebral ischemia, obstruction of ETT and pressure on the tongue
Cerebral vasculature dilates and constricts to maintain
constant blood flow to the brain
CPP=
MAP - ICP (or CVP)
Autoregulation occurs when MAP in between
50 and 150 m Hg
Poorly controlled HTN the CPP curve is shifted
higher to the right
BP in the arm is similar to ____________
CPP in the absence of ICP
beach chair MAP and BP in the arm
is higher than Cerebral perfusion
where is CPP monitored
at external auditory meatus (represents the base of the brain)
CPP is about
which is about 20 cm above the heart (15 mm Hg difference)
blindness and stroke due to
inaccurate BP
1 mm Hg decrease/
1.35 cm height
20 cm ~ ____________ mmHg change
15 mmHg change
sitting position potential complications
Venous air emboli
Hypotension (fluids, vasopressors, decrease agent)
Brainstem manipulations resulting in hemodynamic changes
Risk of airway obstruction
Decrease venous return (stockings or compression devices)
Macroglossia (avoid chin against chest)
midcervical tetraplegia
Hyperflexion of the neck, with or without rotation of the head
Stretching of the spinal cord resulting in compromise of the vasculature of the midcervical region
mid cervical tetraplegia paralysis below
the level of the 5th cervical vertebra
position for mid cervical tetraplegia
Sitting position
Prolonged head flexion for intracranial surgery in the supine position can cause
mid cervical tetraplegia
venous air embolism is caused by
open venous system above level of the heart
detecting venous air embolism
by listening to heart sounds with Doppler at R 2nd intercostal space
s/s of venous air embolism
sudden decrease in CO2, hypoxia, arrhythmias, hypotension and a “millwheel murmur” (usually a late sign)
venous air embolism treatment
durant’s position
face masks can cause
pressure damage over nose
facial nerve damage can occur from
fingers over mandible
Face straps can cause injury or even necrosis to
face, ears and eyes and alopecia
visual injuries
patients at risk for visual injuries
DM
Smokers
Obese
ETOH abuse
Anemic
HTN
Wilson Frame
head is lower than the heart
Potential Etiology of POVL
acute venous congestion of the optic canal
Obesity can increase
intraabdominal pressure in prone patients
how to reduce post-op vision loss
Reduce venous congestion in the optic canal
Keep head above the heart or at the same level
Colloids vs Crystalloids
Reduce intra-abdominal pressure
Limiting duration of surgery
The retinaculum stretches from ___ to the ___
the medial epicondyle
olecranon
How does elbow flexion affect the retinaculum?
stretches the retinaculum and puts a lot of stress on the nerve as it passes underneath
Radial Nerve Injury
Causes
S/S
compression against spiral groove of humerus and other object (i.e. ether screen or excessive cycling of NIBP)
wrist drop, weakness of abduction of thumb, and loss of sensation in web space between thumb and index finger
This nerve carries only sensory fibers, so no motor disability occurs
Lateral Femoral Cutaneous Nerve
But can have:
disabling pain
dysesthesias of the lateral thigh
