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Nurse Anesthesia Summer 19 > Peripheral Nerves and OR positions > Flashcards

Peripheral Nerves and OR positions Flashcards

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1
Q

Radial Nerve

A

-passes along spiral groove at the lateral aspect of the humerus (3 fingers above lateral epicondyle)

Injury: inability to extend hand at the wrist (wrist drop)

**Compression injury
causes:
1. excessive BP cycling**
2. upper extremity tourniquet
3. external compression by an IV pole 
4. sheets wrapped to tight for tucking
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2
Q

Median Nerve

A

-comes from brachial plexus and extends down anterior arm to hand

Injury: (not common) decreased sensation in palmar surface of thumb, index finger, middle finger, lateral aspect of ring finger, inability to oppose thumb

causes:

  1. IV in AV
  2. forced elbow extension
  3. carpal tunnel syndrome
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3
Q

Ulnar Nerve

A

-from the cubital tunnel between the humeral head and ulnar heads of the flexor carpi ulnas

Injury: impaired sensation of 4th and 5th digits (ring finer and pinky), inability to abduct/ oppose pinky finger

  • *claw hand
  • usually do not present until 24 hrs postop

causes:

  1. external compression
  2. elbow flexion

predisposed risk

  • male
  • preexisting ulnar neuropathy
  • extreme body habitus (thin/ obese)
  • prolonged bedrest
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4
Q

Boundaries of cubital tunnel

A

tunnel of muscle, bone and ligament on the inside of elbow

  • medial epicondyle of humerus
  • olecranon process of the elbow
  • cubital tunnel retinaculum (creates the roof)
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5
Q

Brachial Plexus Nerve

A

Long superficial course through fixed points

  • cervical vertebrae
  • axillary fascia

Risk of injury (stretch or compression) in EVERY surgery

Injury:
Non Cardiac surgery: motor deficit in upper/ middle nerve root (median/ radial nerves)

Cardiac Surgery: sensory deficit in lower nerve root (ulnar nerve)

causes;
Stretch injury: caused by fixed anatomical location cervical vertebrae and axillary fascia ( highest risk when arms abducted greater than 90 degrees and/ or head is rotated to side

Compression injury: usually occurs as nerve passes between clavicle and 1st rib by an external force (ex. shoulder brace)
sternotomy (retractor) can compress the nerve under the first rib

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6
Q

Obturator Nerve

A

-medial compartment of thigh

Injury: inability to move leg toward body (ADDUCT), decreased sensation over medial part of thigh

causes:

  1. excessive flexion of thigh toward groin
  2. excessive traction during lower ab surgery
  3. forceps delivery
    * **minimize hip flexion
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7
Q

Femoral Nerve

A

-near femoral artery

Injury: impaired knee extension/ hip flexion, decreased sensation over the anterior
(superior) thigh

**Compression
cause:
1. compression at pelvic brim by retractors or excessive angle of thigh/ external rotation of hips

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8
Q

Saphenous Nerve

A

-medial aspect of leg

Injury: reduced sensation (parathesias) over anteroMEDIAL aspect of leg

cause: medial aspect of leg leans against the supporting cradle (lithotomy position)
* *padding between legs and stirrups

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9
Q

Common Peroneal Nerve

A

-branch of sciatic

** most frequently damaged nerve or lower extremity

Injury: foot drop, inability to evert (turn) foot, or dorsal extension of toes

Compression**

cause: LATERAL compression of knee against stirrup (lithotomy) or just LATERAL position
* *padding between legs and stirrup, padding under fibular head, knees flexed with minimal rotation

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10
Q

Sciatic Nerve

A

largest nerve in body

Injury: FOOT DROP, weakness/ paralysis of muscles below knee, numbness foot/ lateral half of calf

cause: external rotation of leg, extension of knee
* *padding under butt, avoid extreme hip rotations, flex table at knees

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11
Q

Supine

A

(Dorsal Decubitus)
-hemodynamic reserve is maintained in position (when lowering into position increase venous return aka increase BP and CO but will stabilize)

  • be careful of pressure point (back of head)
  • keep arms abducted <90 degree (decrease risk of brachial plexus injury)
  • can tuck arms at side (not too tight– radial nerve)
  • hands supinated (palm up)
  • pillows under knees, STD/ compression stockings on legs
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12
Q

Supine complications

A
  1. PNI (brachial plexus, ulnal)
  2. Pressure alopecia
  3. Aortacaval syndrome (pregnant or ab tumor compress inferior vena cava/ aorta resulting in decreased BP and blood. back to heart)
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13
Q

Trendelenburg

A

-head of the bed below level of heart (legs above heart)

gravity causes increased intracranial vascular congestion

  1. increased venous return
  2. decreased functional residual capacity (FRCO)
  3. decreased pulmonary compliance

meaning:

  • **increased ICP which decreases cerebral blood flow
  • increased intraocular pressure

risk of cephalic slide (slide toward head of bed)

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14
Q

Shoulder brace

A

extreme caution bc of risk of brachial plexus injury

-placed laterally away from root of neck over the acromioclavicular joint

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15
Q

Trendelenburg Anesthesia concerns

A
  1. swelling to face, tongue airway (check for leak before. extubation)
  2. stomach lies just above. glottis (ETT protect to protect from aspiration)
  3. cephalad movement of abdomen, diaphragm, distance between tube and carina smaller, tube can migrate and end up R main stem.
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16
Q

Reverse Trendelenburg

A
  • head above, feet below —-heart (similar to sitting position for physiologic changes)
  • decreased venous return (legs down)
  • decreased cerebral perfusion pressure (CPP) (head above heart)
17
Q

Lithotomy

A 
hips flexed (80-100 degrees)
legs abducted (30-45)

raise and lower legs into stirrups at the same time

surgeon might fold foot of b bed down to sit between pt legs***extreme caution and awareness when table back up..where are the pt hands (couch injury risk)

  • lower body nerve injuries most common (femoral, sciatic, obturator, saphenous, common peroneal and popliteal.
  • common peroneal: lateral pressure from candy can stirrups pole
  • popliteal nerve when in the knee crutch style
18
Q

Lithotomy Anesthesia Considerations

A
  • legs elevated above heart
  • cephalic displacement of ab
  • risk of compartment syndrome (legs above heart) q 2-3 hours feet n need to brought back down

CV

  • increased venous return
  • transient increase BP & CO

Resp

  • decreased lung compliance
  • decreased TV
  • increased peak pressure
19
Q

Lateral Decubitus

A
  • side lying
  • head neutral
  • arms abducted <90, one resting on top of the other (always check pulse in dependent arm)
  • concern for dependent eye and ear
  • axilla roll caudal to axilla to prevent axilla neuromuscular pressure
20
Q

Lateral Decubitus Anesthesia Considerations

A
  • V/Q mismatch (dependent lung with greater perfusion, nondependent lung with greater ventilation _
  • dependent lung compressed by weight of mediastinum and cephalad pressure of ab content
  • minimal change in blood flow unless movement of head
21
Q

V/Q mismatch

A

Awake and spont breathing person (dependent part of lungs is better perfused and ventilated, but lung volumes decreased)

Anesthetized but spont breathing (nondependent lung better ventilated and dependent lung better perfused = V/Q mismatch)

Anesthetized and mechanically vented (nondependent lung OVER ventilated and dependent lung is Over perfused = worse V/Q mismatch

22
Q

Prone

A
  • ventral decubitus
  • do everything on stretcher first, disconnect everything expect pulse ox before the flip
  • right after flip listen
23
Q

Thoracic outlet syndrome

A

test for it by having pt raise hands and clasp them behind their neck

**will complain of pain, decreased sensation

**hands by their side in prone position not superman

24
Q

Prone Anesthesia Concerns

A
  • vision loss –> ischemic optic neuropathy r/t
    1. intra op hypotension
    2. crystalloid use
    3. large blood loss
    4. head down–> increased intraoccular pressure (IOP)
    5. long surgery
    6. anemia

-avoid abdominal compression—>can impede venous return by compression of inferior vena cava (IVF) creasing CO

-Resp
external pressure on ab–> decreased FRC, decreased compliance, increased PIP

-CV
Hypotension–> decreased CO and BP

  • Inferior vena cava (IVC) & aortic compression
  • venous pooling in lower extremities

must anticipate hypotension in move to prone position

25
Q

Prone positon cardiovascular

A

HYPOTENSION..must anticipate

r/t IVC and Aortic compression, venous pooling in lower extremities

hypotension leads to decreased preload, CO and BP

prolonged hypotension not good especially in prone position bc hypotension with increased pressure on face and eye can increaser risk of blindness

26
Q

prone with head turn

A
  • turning of head obstructs venous drainage (from head) leading to increased cerebral volume and increased ICP
  • excessive turning/ flexion obstructs the vertebral artery flow

**risk of spinal cord injury from stretch

27
Q

Sitting position

A
  • *risk for air embolism
  • **maintain at least 2 fingers distance between mandible and sternum

pooling of blood–> hypotension
-IVF and vasopressors to control BP

hyperextension of head/ neck
-cervical cord injuries

flexion

  • impedes blood flow to head, hypoperfused, increased venous congestion
  • cause airway obstruction/ black ETT
  • downward pressure on tongue
28
Q

Sitting neuro and cv

A
  • decreased venous return (pooling in legs)
  • decreased CPP
  • reduced preload, CO, BP
  • loss of compensatory mechanism with anesthesia

***compensate for height of head (level transducer to circle of willis)

29
Q

conversion factor

A

1 cm rise above the heart = 0.77 mmHg

**20 cm elevation of head above heart, the drop in CPP would be (20) * (.77)= 18 mmHg drop in MAP

normal CPP 50mmHg

30
Q

sitting position ventilatory changes

A
  • lung volumes and capacities increase
  • increased lung compliance
  • easier WOB
31
Q

Venous Air Embolism

A

**risk anytime surgical site is above the heart

**indicated by decreased EtC02

  • inability of venous sinuses to collapse
  • sign: change in heart tones, new murmur, dysrhythmias, hypotension, desat, decreased EtC02, N2 in exhaled gas
32
Q

Treat Venous Air Embolism

A
  • trendelenburg position (head down)
  • flood surgical field with NS, close open vessels
  • D/C nitrous oxide
  • 100% 02
  • aspirate air
33
Q

Brachial Plexus injury

A

Stretch or compression

  • arms abducted >90 degrees or superman prone arms
  • neck extension
  • head turned to side
  • depressed sagging arms (sitting/ prone)
  • arms fall off table
  • compression by thorax (lateral)
  • shoulder braces
  • sternal retractors (cardiac)

result:
1.limb/paralyzed arm

  1. lack of muscle control in arms, hand, wrist
  2. lack of sensation in arm/ hand
34
Q

Compartment syndrome

A

-occurs with inadequate perfusion to extremity

> 2-3 hr surgery

**increased risk with lithotomy and lateral

**take legs out of stirrups q 2-3 hrs

Nurse Anesthesia Summer 19 (11 decks)

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