Positioning Flashcards

0
Q

Who is responsible for operative positioning?

A

the anesthesia provider

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1
Q

What is the purpose of operative positioning?

A

comfort
patient safety
surgical access

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2
Q

What should the CRNA document in regards to positioning for a case?

A
baseline ROM and function
intraoperative positioning
pads/cushions used
body position
frequency of checks
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3
Q

What are the height and weight limits for a standard OR table?

A
136 kg (~300lbs)
80.7 inches
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4
Q

What are the 5 most common operative positions?

A
supine
prone
sitting
lithotomy
lateral decubitus
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5
Q

What are the advantages of the supine position?

A

access to airway
access to arms for IVs
less physiologic changes than the other positions

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6
Q

What is the benefit of placing a pillow under the head in the supine position?

A

avoids extension or flexion of the head
places the head/neck in sniffing position
doughnut pillow reduces alopecia (especially in neonates or the elderly)
no pressure on the eyes

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7
Q

How should arms be positioned in the supine position?

A

tucked - palm in, elbow padded, tuck draw sheet under patient torso

arm boards - secured to OR table, abducted <90 degrees, padded, safety strap on, hands supinated

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8
Q

How should the feet be positioned in supine position?

A

heels shouldn’t hang over the bed

heels padded

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9
Q

How should the spine be positioned in the supine position?

A

slight flexion behind the hips and knees
pillows under the knees
legs should not be crossed
SCDs on

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10
Q

What are the 5 mechanisms of nerve injury?

A
compression
kinking
ischemia
transection
stretching
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11
Q

What are some modifiable factors that put you at risk for nerve injury?

A

obesity
smoking
diabetes

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12
Q

What is the most common upper peripheral nerve injury?

A

ulnar nerve

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13
Q

How can injuries occur to the brachial plexus?

A

mostly stretch injuries

  1. neck extension or head turned too much to the side
  2. excessive abduction of the arms >90 degrees
  3. arm/arm board falling off the table
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14
Q

What symptoms would show in a brachial plexus nerve injury?

A

electric shocks or a burning sensation down the arm
numbness
weak arm function

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15
Q

How does injury to the radial nerve occur?

A

compression of the radial nerve on the lateral aspect of the humerus against surgical retractors, ether screen, “step off”, repeated BP inflation

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16
Q

Injury to the radial nerve will result in..

A

inability to flex the elbow
wrist drop
weakness in abduction of the thumb

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17
Q

How does an injury to the ulnar nerve occur?

A

compression between the olecranon of the ulna and medial epicondyle of the humerus

stretching with severe elbow flexion

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18
Q

What are the consequences of ulnar nerve injury?

A

claw hand – inability to abduct or oppose 4th and 5th finger, weak grip on the ulnar side of hand

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19
Q

How can you reduce the risk of ulnar nerve injury?

A

pad arm boards
avoid overcompression by arm straps
place BP cuff proximal to the cubital fossa
avoid prolonged flexion of the elbow

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20
Q

What are the cardiovascular effects in the supine position?

A

initially increased venous return to the heart but there is a compensatory activation of baroreceptors that decreases HR and PVR

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21
Q

Under what circumstances might venous return be impeded in the supine position?

A

abdominal/thoracic masses, obesity, pregnancy, ascites

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22
Q

What ventilatory changes occur in the supine position?

A

FRC changes +/- 800 mL

may be compounded by muscle relaxants

can be overcome with PPV

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23
Q

What cerebral changes occur in the supine position?

A

minimal changes r/t autoregulation

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24
Q

What are the benefits of trendelenburg

A

may transiently treat hypotension
may improve surgical exposure
helps prevent air embolism
facilitates placement of central line insertion

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25
Q

Describe the placement of shoulder pads

A

should be padded and placed laterally… away from the neck and near the acromioclavicular joint

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26
Q

What are the cardiovascular changes associated with trendelenburg position?

A

reduces blood flow to the lower extremities
can cause compression of the heart
increases venous return to the heart

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27
Q

What ventilatory changes are associated with trendelenburg position?

A

displacement of abdominal contents will cause decreased lung compliance, PIP increases, decreased lung volumes, V:Q mismatch, ETT displaced to the R main bronchus, risk of aspiration, airway edema

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28
Q

What are the cerebral changes associated with trendelenburg position?

A

increased ICP and increased IOP r/t vascular congestion

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29
Q

What must be considered when using a foot board with reverse trendelenburg position?

A

prolonged plantar flexion can cause anterior tibial nerve injury resulting in foot drop

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30
Q

What cardiac changes are associated with reverse trendelenburg position?

A

reduced preload, reduced CO, lower BPs, RAA activation, venous pooling in the legs

compensatory reflexes to increase SVR and HR are often blunted by anesthetics

31
Q

What ventilatory changes are associated with reverse trendelenburg?

A

ventilation becomes easier, FRC increases

32
Q

What cerebral changes occur with reverse trendelenburg?

A

ICP decreases, cerebral blood flow decreases up to 20%

33
Q

If the patient is in reverse trendelenburg, where should you place your A-line BP transducer?

A

as close to the Circle of Willis as possible

34
Q

What nerve injuries are associated with the lithotomy position?

A

femoral – r/t hip flexion
sciatic – r/t overstretching
common peroneal or saphenous – r/t calf compression

35
Q

Describe positioning for lithotomy

A

Hips flexed 80-100 degrees
Legs abducted 30-45 degrees from the midline
Lower legs parallel to the torso

36
Q

What nerves are especially at risk during the lithotomy position, particularly if you are using candy cane stirrups?

A

common peroneal nerve – the outside of the leg may compress against the metal bars

37
Q

What is the most common LE nerve injury?

A

common peroneal nerve

38
Q

What risk factors place you at increased chance of having a peripheral nerve injury r/t positioning?

A

obesity, smoking, diabetes, PVD, low BMI, prolonged surgery

39
Q

What are the symptoms of a common peroneal nerve injury?

A

foot drop, inability to evert the foot, loss of dorsal extension of the toes

40
Q

How does sciatic nerve injury occur and what are the symptoms?

A

excessive external rotation of the hips or pressure in the sciatic notch from overstretching

symptoms: weakness or paralysis of muscles below the knee, footdrop, numbness in foot or lower leg

41
Q

How does femoral nerve injury occur and what are the symptoms?

A

compression at the pelvic brim by the retractor or excessive rotation or flexion of the hip

symptoms: inability to flex the hip and extend the knee, decreased sensation over the top of the thigh

42
Q

How can saphenous nerve injury occur and what are the symptoms?

A

medial aspect of lower leg compresses against the support bar

symptoms: parasthesias to the medial aspect of the lower leg

43
Q

Discuss compartment syndrome

A

occurs when perfusion to the extremity is inadequate, resulting in ischemia and edema with extensive rhabdomyelosis

occurs with longer surgical procedures

more common in lithotomy and lateral decubitus positions

44
Q

What cardiovascular changes are associated with lithotomy position?

A

increases venous return to the heart and preload to the heart, causing transient increases in CO and BP

reduced perfusion to the lower extremities (2mm per 2.5 cm above the heart)

45
Q

What ventilatory changes are associated with the lithotomy position?

A

abdominal contents may push up and compress lung bases, reducing compliance, Vt and vital capacity.

increased risk of aspiration

46
Q

How can you combat ventilatory changes associated with lithotomy or trendelenburg position?

A

PPV

47
Q

What are the disadvantages of the prone position?

A

less access to the airway, torsion of the spinal column, hard to get the patient in a natural position

48
Q

What are important considerations for head rests?

A

watch the eyes and nose for pressure points, maintain neck alignment

49
Q

What are the most common eye injuries in the prone position?

A

corneal abrasions – direct eye trauma, swelling

treatment with antiobiotics, eye patch

50
Q

What are the most common causes of ischemic optic neuropathy?

A

edema
hypoperfusion
high IOP

51
Q

What are the risk factors for ischemic optic neuropathy?

A

HTN, obesity, smoking, diabetes, operative hypotension, large blood loss, prone position in the OR, anemia, large crystalloid use, male

52
Q

How should the arms be arranged in the prone position?

A

on arm boards by the head, abducted less than 90 degrees, extra padding around the elbow, shoulders not sagging

*may also be tucked at the sides

53
Q

What is thoracic outlet syndrome? How can it be prevented?

A

when in the prone position and the arms are elevated above the head, the clavicle moves forward and can occlude blood flow and lymphatic drainage

Prevention: check beforehand for problems by having patient place arms folded behind their head for 2 minutes and then check pulses and ask about neuropathies

54
Q

Cardiovascular changes associated with the prone position?

A

hypotension
venous pooling in the extremities
decreased preload

55
Q

What ventilatory changes are associated with the prone position?

A

V:Q mismatch (anterior better perfused, posterior better ventilated)
decreased lung compliance
increased WOB

overcome this by using rolls and PPV

56
Q

Cerebral changes associated with the prone position

A

may cause high ICP

may obstruct cerebral blood flow if the head is turned excessively

57
Q

What types of surgery would you put a patient in the lateral position for?

A

thoracic, kidney, shoulder, hip surgeries

58
Q

What special positioning is required in the lateral position?

A
  • axillary roll to support the chest and axilla
  • limit pressure on eyes and ears
  • avoid misalignment of the C-spine by keeping the head in a neutral position
  • avoid stretching of the brachial plexus
59
Q

How should arms be positioned in the lateral position?

A

dependent arm on padded arm board and perpendicular to the torso

non-dependent arm supported with pillow or suspended by arm rest

60
Q

How should the legs be positioned in the lateral position?

A

padding between the knees and flex the dependent leg to prevent saphenous nerve injury

padding on the bed for the lower leg to prevent common peroneal injury

61
Q

What are the cardiovascular changes associated with the lateral position?

A

minimal…

no change in CO unless the kidney rest compresses venous return
noninvasive BP cuff measurements will be different in the two arms

62
Q

ventilatory changes associated with the lateral position

A

V:Q mismatch

  • awake & breathing – dependent lung better ventilated and perfused
  • anesthetized but breathing – nondependent lung is ventilated and dependent is perfused
  • anesthetized and ventilated – nondependent lung is overventilated and dependent lung is overperfused ((worst mismatch))
63
Q

For what type of surgeries would you put the patient in a sitting position? Why?

A

cranial surgery, shoulder surgery, humeral surgery

facilitates drainage
excellent surgical exposure

64
Q

What are some special considerations when placing the patient in a sitting position?

A

maintain 2 FB between mandible and sternum to avoid excessive cervical flexion

avoid a bite block to prevent tongue ischemia

head will be fixed in pins

65
Q

How should you set the patient up in a sitting position?

A

arms supported and not hanging
buttocks in the break of the table
foot board padded
slightly flex knees and hips

66
Q

cardiovascular changes associated with the sitting position?

A

hypotension
blood pooling in lower extremities causing decreased preload and CO
HR and SVR may increase as compensation (blunted by anesthetics)

67
Q

What ventilatory changes are associated with the sitting position?

A

increased lung volumes, increased lung compliance, easier WOB

68
Q

cerebral changes associated with the sitting position?

A

ICP and cerebral blood flow decreased

69
Q

What are symptoms of VAE (venous air embolism?

A
wind mill heart murmur on doppler
dysrhythmias
hypotension
desaturation
decreased EtCO2
circulatory compromise
cardiac arrest
70
Q

When does VAE become a risk?

A

when surgery is performed anywhere above the heart

71
Q

What is the immediate response and treatment to VAE?

A

flood surgical field with NS or place wax over exposed bones
close any open vessels
D/C nitrous (it will expand in air spaces)
place patient on 100% O2 and add PEEP
trendelenburg position
aspirate air from RA with a catheter

72
Q

For what kind of surgeries would you place the patient in a supine position?

A

abdomen, chest, head, neck, extremities

73
Q

For what type of surgeries would you place the patient in a reverse trendelenburg position?

A

laproscopic procedures

74
Q

For what type of surgeries would you place the patient in lithotomy position?

A

gynecological, rectal, perineal procedures

75
Q

For what type of surgeries would you place the patient in the prone position?

A

spinal, rectal, some orthopedic procedures

76
Q

What are the risk factors for compartment syndrome?

A

systemic hypotension, vascular obstruction of a major extremity vessel by retractors or extreme flexion, external pressure by a poorly padded area or straps, lithotomy position, trendelenburg position, advanced age, patient hx of nerve ischemia or neuropathy , anemia, prolonged surgical time, vasoconstrictive drugs