Positioning and nerve injury Flashcards
The awake patient has a variety of compensatory mechanisms designed to
minimize the hemodynamic impact of position changes
Protective mechanisms designed to minimize the hemodynamic impact of position changes are attenuated by:
general anesthesia
neuraxial anesthesia
positive-pressure ventilation
PEEP
muscle relaxants
Since blood is more likely to ____________ in the anesthetized patient, you should know how to predict how surgical positioning impacts hemodynamics
pool due to gravity
Positions that increase cardiac preload include
Trendelenburg
lithotomy
Positions that reduce cardiac preload:
reverse Trendelenburg
sitting
flexed lateral
The _________ and __________ positions increase venous hydrostatic pressure (edema of the face, eye, and airway) and hinder cerebral venous drainage (risk of increased ICP)
Trendelenburg & lithotomy
The Trendelenburg and lithotomy positions contribute to
unrecognized hypovolemia
The risk of cerebral hypoperfusion is increased when the
brain is higher than the heart
Interventions that promote CV stability include
move the patient slowly
use a lighter plane of anesthesia
IV hydration
What 4 body positions are associated with a higher incidence of hemodynamic instability under GA?
prone
flexed lateral
sitting
reverse trendelenburg
The Trendelenburg position (select 2):
a. moves the diaphragm caudad
b. reduces pulmonary compliance
c. increases the risk of endobronchial intubation
d. increases functional residual capacity
b. reduces pulmonary compliance
c. increases the risk of endobronchial intubation
Compared to the awake spontaneously breathing patient, the anesthetized patient who is breathing spontaneously has a/an
decreased tidal volume
decreased FRC
increased closing volume
If you’re concerned about airway patency before extubation as a result of edema, you can
perform a leak test and inspect the airway visually with direct laryngoscopy
As a general rule, the _______ and ______ positions impair pulmonary mechanics, while ________ improve pulmonary mechanics
supine & Trendelenburg positions; head-up positions
In the Trendelenburg position, the abdominal contents shift cephalad. This pushes the diaphragm towards the ETT, increasing
the risk of endobronchial intubation
What positions and factors increase edema formation?
Prone
Trendelenburg
equipment (oral airway, esophageal temp probe)
sitting (neck flexion impairs venous drainage from head)
The surgical team is positioning a patient for a robotic-assisted laparoscopic radical prostatectomy. What is the BEST position to protect the brachial plexus?
a. arms tucked at sides + should braces placed near the acromion
b. arms abducted 90 degrees+ non-sliding mattress
c. arms abducted 90 degrees + shoulder braces placed at the midpoint of the clavicle
d. arms tucked at sides + non-sliding mattress
d. arms tucked at sides + non-sliding mattress
The brachial plexus is at risk for injury related to
stretch and compression
Stretch injury occurs because the brachial plexus is
anatomically fixed at two locations
What two locations are anatomically fixed when stretch injury to the brachial plexus occurs?
cervical vertebrae & axillary fascia
The risk of stretch injury is highest when the
arms are abducted >90 degrees and the head is rotation to the other side
Compression injury usually occurs when the brachial plexus is
compressed as it passes between the clavicle and first rib (e.g. shoulder braces) or by an external force (e.g. improperly placed axillary roll)
___________ during cardiac surgery (median sternotomy) can compress the brachial plexus under the first rib
Excessive sternal retraction
____________ should never be used for brachial plexus
Shoulder braces
If shoulder races are used, they should be placed
at the distal end of each clavicle (over the acromion)
To protect the brachial plexus in the prone position, assess for
thoracic outlet syndrome
ask the patient to clasp her hands behind her head, if pain occurs tuck the arms
_______________ in the dependent arm is a good monitor of neurovascular compression of the brachial plexus in the lateral position.
A weak SpO2 signal
Where should the retaining strap be placed on a patient in the lateral decubitus position?
across the hip and fixed to the underbelly of the OR table
should be placed between the iliac crest and the head of the femur
a second strap can be placed over the thorax or shoulders
A patient is unable to abduct his fifth digit after a prolonged stay in the ICU. Which nerve sustained an injury?
a. ulnar
b. median
c. radial
d. long thoracic
a. ulnar
The _________ is the most commonly injured peripheral nerve.
ulnar nerve
Where does the ulnar nerve emerge?
cubital tunnel between the humeral and ulnar heads of the flexor carpi ulnaris
Risk factors for ulnar nerve injury include
poor positioning/padding
male gender (especially >50 years old)
preexisting ulnar neuropathy
extremes of body habitus (very thin or obese)
prolonged hospital stay/bedrest
Ulnar nerve injury presents with
an impaired sensation of the fourth and fifth digits and the inability to ABduct the pinky finger
Chronic ulnar nerve injury presents with
a claw hand (muscular atrophy)
As with all perioperative nerve injuries, you should consider
a neurology consult with EMG and nerve conduction studies
What is the common mechanism of injury of the ulnar nerve?
external compression (e.g. excessively tight arm strap on the forearm)
elbow flexion–> decreased cubital tunnel size–> increased pressure on the nerve
Many cases of ulnar neuropathy don’t present until
> 24 hours after surgery
Which nerve is MOST likely to be injured following traumatic IV insertion in the antecubital space?
a. ulnar
b. radial
c. median
d. axillary
c. median
Median nerve injury is
rare
Causes of median nerve injury include
IV placement in the AC
carpal tunnel syndrome
elbow hyperextension
Median nerve injury presents with
reduced sensation over the palmar surface of the thumb, index finger, middle finger, and lateral aspect of the ring finger
The patient with median nerve injury may be unable to
oppose the thumb
Chronic injury to the median nerve can lead to
an ape hand deformity
Where is the median nerve located?
next to the basilic and median cubital veins in the cubital fossa
