Positioning and nerve injury

Question 1

The awake patient has a variety of compensatory mechanisms designed to

Answer 1

minimize the hemodynamic impact of position changes

Question 2

Protective mechanisms designed to minimize the hemodynamic impact of position changes are attenuated by:

Answer 2

general anesthesia
neuraxial anesthesia
positive-pressure ventilation
PEEP
muscle relaxants

Question 3

Since blood is more likely to ____________ in the anesthetized patient, you should know how to predict how surgical positioning impacts hemodynamics

Answer 3

pool due to gravity

Question 4

Positions that increase cardiac preload include

Answer 4

Trendelenburg
lithotomy

Question 5

Positions that reduce cardiac preload:

Answer 5

reverse Trendelenburg
sitting
flexed lateral

Question 6

The _________ and __________ positions increase venous hydrostatic pressure (edema of the face, eye, and airway) and hinder cerebral venous drainage (risk of increased ICP)

Answer 6

Trendelenburg & lithotomy

Question 7

The Trendelenburg and lithotomy positions contribute to

Answer 7

unrecognized hypovolemia

Question 8

The risk of cerebral hypoperfusion is increased when the

Answer 8

brain is higher than the heart

Question 9

Interventions that promote CV stability include

Answer 9

move the patient slowly
use a lighter plane of anesthesia
IV hydration

Question 10

What 4 body positions are associated with a higher incidence of hemodynamic instability under GA?

Answer 10

prone
flexed lateral
sitting
reverse trendelenburg

Question 11

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

Answer 11

b. reduces pulmonary compliance
c. increases the risk of endobronchial intubation

Question 12

Compared to the awake spontaneously breathing patient, the anesthetized patient who is breathing spontaneously has a/an

Answer 12

decreased tidal volume
decreased FRC
increased closing volume

Question 13

If you’re concerned about airway patency before extubation as a result of edema, you can

Answer 13

perform a leak test and inspect the airway visually with direct laryngoscopy

Question 14

As a general rule, the _______ and ______ positions impair pulmonary mechanics, while ________ improve pulmonary mechanics

Answer 14

supine & Trendelenburg positions; head-up positions

Question 15

In the Trendelenburg position, the abdominal contents shift cephalad. This pushes the diaphragm towards the ETT, increasing

Answer 15

the risk of endobronchial intubation

Question 16

What positions and factors increase edema formation?

Answer 16

Prone
Trendelenburg
equipment (oral airway, esophageal temp probe)
sitting (neck flexion impairs venous drainage from head)

Question 17

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

Answer 17

d. arms tucked at sides + non-sliding mattress

Question 18

The brachial plexus is at risk for injury related to

Answer 18

stretch and compression

Question 19

Stretch injury occurs because the brachial plexus is

Answer 19

anatomically fixed at two locations

Question 20

What two locations are anatomically fixed when stretch injury to the brachial plexus occurs?

Answer 20

cervical vertebrae & axillary fascia

Question 21

The risk of stretch injury is highest when the

Answer 21

arms are abducted >90 degrees and the head is rotation to the other side

Question 22

Compression injury usually occurs when the brachial plexus is

Answer 22

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)

Question 23

___________ during cardiac surgery (median sternotomy) can compress the brachial plexus under the first rib

Answer 23

Excessive sternal retraction

Question 24

____________ should never be used for brachial plexus

Answer 24

Shoulder braces

Question 25

If shoulder races are used, they should be placed

Answer 25

at the distal end of each clavicle (over the acromion)

Question 26

To protect the brachial plexus in the prone position, assess for

Answer 26

thoracic outlet syndrome
ask the patient to clasp her hands behind her head, if pain occurs tuck the arms

Question 27

_______________ in the dependent arm is a good monitor of neurovascular compression of the brachial plexus in the lateral position.

Answer 27

A weak SpO2 signal

Question 28

Where should the retaining strap be placed on a patient in the lateral decubitus position?

Answer 28

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

Question 29

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

Answer 29

a. ulnar

Question 30

The _________ is the most commonly injured peripheral nerve.

Answer 30

ulnar nerve

Question 31

Where does the ulnar nerve emerge?

Answer 31

cubital tunnel between the humeral and ulnar heads of the flexor carpi ulnaris

Question 32

Risk factors for ulnar nerve injury include

Answer 32

poor positioning/padding
male gender (especially >50 years old)
preexisting ulnar neuropathy
extremes of body habitus (very thin or obese)
prolonged hospital stay/bedrest

Question 33

Ulnar nerve injury presents with

Answer 33

an impaired sensation of the fourth and fifth digits and the inability to ABduct the pinky finger

Question 34

Chronic ulnar nerve injury presents with

Answer 34

a claw hand (muscular atrophy)

Question 35

As with all perioperative nerve injuries, you should consider

Answer 35

a neurology consult with EMG and nerve conduction studies

Question 36

What is the common mechanism of injury of the ulnar nerve?

Answer 36

external compression (e.g. excessively tight arm strap on the forearm)
elbow flexion–> decreased cubital tunnel size–> increased pressure on the nerve

Question 37

Many cases of ulnar neuropathy don’t present until

Answer 37

> 24 hours after surgery

Question 38

Which nerve is MOST likely to be injured following traumatic IV insertion in the antecubital space?
a. ulnar
b. radial
c. median
d. axillary

Answer 38

c. median

Question 39

Median nerve injury is

Answer 39

rare

Question 40

Causes of median nerve injury include

Answer 40

IV placement in the AC
carpal tunnel syndrome
elbow hyperextension

Question 41

Median nerve injury presents with

Answer 41

reduced sensation over the palmar surface of the thumb, index finger, middle finger, and lateral aspect of the ring finger

Question 42

The patient with median nerve injury may be unable to

Answer 42

oppose the thumb

Question 43

Chronic injury to the median nerve can lead to

Answer 43

an ape hand deformity

Question 44

Where is the median nerve located?

Answer 44

next to the basilic and median cubital veins in the cubital fossa