positioning and nerve injury Flashcards
what positions cause frank starling relationship to go from point A to point B?
sitting
flexed lateral
venous pressure increases
hydrostatic pressure, intracranial HTN
interventions that promote CV stability
slow repositioning
lighter plane of anesthesia
IV hydration
consequences of trendelenburg positioning include
diaphragm moves cephalad
FRC reduced
p. compliance is decreased
risk of endobronchial intubation is increased
dependent and non dependent lung/region for the following positions:
sitting
supine
left lateral
right lateral
what can create edema formation
prone and trendelenburg
sitting (neck flexion and impaired drainage)
equipment (OPA, esophageal temp probe) impairs lymphatic drainage
best position to protect brachial plexus during radical prostatectomy
arms tucked at sides and non sliding mattress
do shoulder braces decrease risk of brachial plexus injury
no they increase the risk
if they HAVE to be used, they need to be placed at the distal end of each clavicle (over the acromion)
risk of brachial plexus stretch injury is highest when
arms are abducted greater than 90 degrees and head is rotated to the other side
when does compression injury of brachial plexus usually occur
when brachial plexus is compressed as it passes between clavicle and first rib (shoulder braces) or by an external force (improperly placed axillary roll)
supine position related considerations
arm abduction >90 degrees stretches brachial plexus around head of humerus
neck rotation stretches brachial plexus on contralateral side
excessive sternal retraction during cardiac surgery (median sternotomy) can compress brachial plexus under first rib
trendelenburg position related considerations
use non sliding mattress
a bean bag that envelopes the shoulders can also cause compression injury
prone position related considerations
shoulders should not be allowed to sag forward
arms should not be extended over the head
assess for thoracic outlet syndrome (in preop, ask patient to clasp hands over head. if she complains of pain, tuck arms)
lateral decubitus related position considerations
chest support (axillary roll) is placed distal (caudad) to axilla
maintain neutral neck alignment with pillow or head rest
common peroneal nerve should be padded to prevent injury from weight of leg against table
upside thigh and leg are extended and separated from lower leg with pillows
minimize risk of a circumduction of down side shoulder to minimize risk of injuring supra scapular nerve (aka dont let patient roll forward)
retaining strap placed across hip and fixed to under belly of OR table. should be placed between iliac crest and head of femur
a patient is unable to abduct his 5th finger after a prolonged stay in the ICU. which nerve sustained an injury?
ulnar n
presentation of ulnar n injury may include
impaired sensation of 4th/5th digits
inability to abduct or oppose pinky finger
chronic injury presents with claw hand (muscular atrophy)
most commonly injured peripheral nerve
ulnar n
anatomy of cubital tunnel
ulnar nerve emerges from cubital tunnel between humeral and ulnar heads of flexor carpi ulnaris
mechanism of ulnar nerve injury
external compression (excessively tight arm strap on forearm)
elbow flexion –> increased distance between medial epidondyle and olecranon, decreased cubital tunnel size, increased pressure on the ulnar n
risk factors that predispose patients to ulnar nerve injury includes
male (esp >50y)
preexisting ulnar neuropathy
extremes of body habitus
prolonged hospital stay/bedrest
cardiac surgery
most cases of ulnar neuropathy dont present until how long after surgery?
> 24h
best way to position forearm in supine position- are the following ok if the arm is abducted? at patients side?
what to do if a patient presents with postop nerve injury: sensory deficits
more common, less serious, tend to resolve on their own (5 days or less)
get a neurology consult if it lasts >5d or gets worse
prudent to consult with neurologist within first week of injury
what to do if a patient presents with postop nerve injury: motor deficits
less common, more serious, if demyelination occurs can take up too 4-6w to recover
-need PT, neurology consult, EMG and nerve conduction studies
where is the median nerve located in relation to surrounding veins
next to basilic and median veins in cubital fossa
causes of median nerve injury include
IV placed in AC space
carpal tunnel syndrome (median nerve is only nerve that passes through carpal tunnel)
elbow hyper extension
forced elbow during positioning after NMB has been administered
presentation of median nerve injury
reduced sensation over palmar surface of the thumb, index finger, middle finger, and lateral aspect of ring finger
unable to oppose thumb
chronic injury can lead to ape hand deformity
which nerve is MOST likely to be injured by an IV pole that passes against the dorsolateral aspect of the humerus?
radial nerve
where does radial nerve pass in humerus
along the spiral groove at the lateral aspect of the humerus (3 finger breadths above the lateral epicondyle)
radial nerve can be injured via
external compression via IV pole
excessive cycling of NIBP cuff
UE tourniquet
sheets are too tight on tucked arms
presentation of radial nerve injury
wrist drop
SALT pneumonic for long thoracic
serratus anterior is innervated by long thoracic (SALT)
arises from C5-7
etiologies of long thoracic nerve injuries
lateral position
trauma
preexisting neuropathy (due to a virus)
etiologies of long thoracic nerve injuries
lateral position
trauma
preexisting neuropathy (due to a virus)
presentation of long thoracic nerve injury
scapular winging
location of supra scapular nerve
anchored between cervical spine and supra scapular notch. innervates supraspinatus and infraspinatus muscles.
etiology of supra scapular nerve injury
ventral circumduction of the dependent shoulder in the lateral decubitus position can stretch the suprascapular nerve. said another way, the patient in lateral decub rolls onto their dependent arm
properly stabilizing the patient by placing a roll distal to the axilla may reduce the risk of injury
presentation of supra scapular nerve injury
dull shoulder pain
etiology of obturator nerve injury
excessive flexion of the thigh towards the groin
excessive traction during lower abdominal surgery
forceps delivery
presentation of obturator nerve injury
inability to adduct the leg
reduced sensation over medial aspect of the thigh
which nerve wraps around fibular head
common peroneal (check this)
prevention of obturator nerve injury
minimize hip flexion
etiology of femoral nerve injury
excessive traction during lower abdominal surgery
presentation of femoral nerve injury
impaired knee extension and hip flexion
reduced sensation over anterior thigh and anteromedial aspect of the leg
prevention of femoral nerve injury
avoid excessive traction during lower abdominal surgery
etiology of saphenous nerve injury
medial aspect of leg leans against supporting cradle in lithotomy position (the saphenous nerve resides near the tibia)
presentation of saphenous nerve injury
reduced sensation over anteromedial aspect of leg
prevention of saphenous nerve injury
place padding between leg and stirrup
etiology of common peroneal injury
this nerve is highly susceptible to injury when the person is placed in stirrups. this nerve wraps around the fibular head and can be compressed when the lateral aspect of the leg leans against the stirrup bar or “candy canes”
presentation of common peroneal injury
foot drop
inability to evert the foot
inability to extend toes dorsally
prevention of common peroneal injury
place padding between legs and stirrup
pad under fibular head
knees should be flexed with minimal rotation
etiology of sciatic injury
lithotomy- extreme hip flexion or external rotation of the legs
sitting- straight legs
presentation of sciatic injury
foot drop
prevention of sciatic injury
ample padding under buttocks
avoid excessive external rotation of hips
flex table at the knees
etiology of pudendal injury
nerve is compressed against a perineal post on an orthopedic fracture table
presentation of pudendal injury
loss of perineal sensation
prevention of pudendal injury
adequate padding between perineal post and the patient
what happens when patients cross their legs during surgery?
top leg- sural nerve injury
bottom leg- superficial peroneal injury
two complications most commonly associated with sitting position
mid cervical tetraplegia (hyper flexion of the neck aka chin to chest causes this. stretches mid cervical SC)
paradoxical air embolism (aka PFO. right heart–>PFO–>left heart–>systemic circulation–>CVA)
in what position is compartment syndrome most commonly seen
lithotomy
-increases leg compartment pressure and raising legs above heart reduces LE perfusion pressure. ischemia–> edema that leads to rhabdo and reperfusion injury
risk factors for LE compartment syndrome
surgical time 2-3h
increased BMI
HoTN (decreased tissue O2)
risk factors for paraplegia in the supine position
(extreme hyper extension of lumbar spine)
maximal retroflexion of OR table
raising kidney rest to its highest positon
placing large rolls under patients lumbar spine
what kind of surgery increases risk for midcervical tetraplegia (C5)
tracheal resection
benefits of prone position
improves pulmonary mechanics and venous return
decreases venous pressure
which positioning device is best for pulmonary mechanics in prone position
when compared to chest rolls and wilson frame, the jackson table is best to preserve pulmonary mechanics
tumors likely to occur in mediastinum
4 t’s
thymoma
teratoma
thyroid
terrible lymphoma
tumor in anterior mediastinum can compress these vital structures
tracheobronchial tree
p.artery
SVC (may have svc syndrome, edema of face neck and upper torso)
three key factors that worsen tracheobronchial compression
- supine position
- induction of GA
- PPV
which positions shift the frank starling curve to the left?
prone
flexed lateral
