Positioning Flashcards

1
Q

What are some causes of nerve injury?

A
  • inadequate positioning
  • preexisting conditions
  • GA
  • extremes of body habit us
  • procedures >2hrs
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2
Q

What are some mechanisms of nerve injury?

A
  • transaction
  • compression
  • stretching
  • kinking

All = ischemia

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3
Q

Group of nerves running from neck, through shoulder, axilla, and arm

A

Brachial Plexus

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4
Q

What are the divisions of the the brachial plexus?

A
  • Roots: 5
  • Trunks: 3
  • Divisions: 3 anterior, 3 posterior
  • Cords: 3
  • Branches: 5

Randy Travis Drinks Cold Beer

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5
Q

What are the 5 roots of the brachial plexus?

A

C5, C6, C7, C8, T1

In C-spine, roots come from above vertebrae, after T1, come from below - this is why there is a C8

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6
Q

Name the 5 peripheral branches of the brachial plexus

A
  • musculocutaneous
  • axillary
  • radial
  • median
  • ulnar

*only radial, median and ulnar make it to the hand

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7
Q

Where is the lumbar plexus?

A

Runs along front of leg.

Femoral and saphenous are major branches

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8
Q

Where is the Sacral Plexus?

A
  • Runs along back of the leg

- sciatic nerve is a major branch

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9
Q

Where is the “end-point” of the dermatomes?

A

The coccyx, not the feet

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10
Q

In the anesthetized pt, describe ventilation and perfusion of lungs: dependent vs non-dependent

A
  • dependent lung has best perfusion
  • non-dependent lung has best ventilation

*creates a V/Q mismatch

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11
Q

How does GA create postural hypotension?

A

-blunts compensatory sympathetic nervous system response with abrupt position changes

Treatment

  • temporarily delay further posting changes
  • reduce agent
  • IVF to increase volume
  • pressors
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12
Q

Supine position is also called what?

A

Dorsal Recumbent

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13
Q

Cardiac and respiratory considerations of supine position

A

Cardiac

  • minimal
  • pressures from head to foot approximate mean pressure at level of the heart

Respiratory

  • FRC and total lung capacity are reduced bc ABD contents being pushed up
  • spontaneous ventilation favors posterior lung (dependent) while controlled ventilation favors anterior (non-dependent) lung
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14
Q

Pressure may change by _____mmHg for each ______cm that a given point varies in vertical height below or above the reference point of the heart

A

2 mmHg

2.5 cm

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15
Q

CV, Respiratory and Neuro consideration of trendelenburg positoin

A

Cardiovascular

  • activation of baroreceptors
    • decrease CO
    • decrease in peripheral vascular resistance
    • decrease in HR and BP

Respiratory

  • diaphragm displaced cephalad and ABD contents decreases FRC
  • movement of mediastinum towards head moves carina closer to ETT and can result in tube moving into right mainstem
  • increased V/Q mismatch

Neuro

  • increased ICP and decrease cerebral blood flow
  • increased intraocular pressure in pts with clay come
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16
Q

Consideration with reverse trendelenburg position

A

Cardiovascular
-decrease in preload, CO, and arterial pressures
Baroreceptors mediated increase in sympathetic tone, HR< and BP

Respiratory

  • FRC increased
  • easier to ventilate

Neuro
-CPP and blood flow decrease

17
Q

Consideration for lithotomy position

A

Cardiovascular

  • auto transfusion from elevation of legs above the trunk causes central blood volume to increase
  • returning legs to supine has the opposite effect decreasing volume and preload
  • effects on BP and CO depend of volume status

Respiratory
-FRC decreases

18
Q

Considerations with lateral positions

A

Cardiovascular

  • minimal changes
  • pulse ox on dependent had to assure adequate perfusion

Respiratory

  • decreased ventilation dependent lung
  • increased perfusion dependent lung
  • V/Q mismatch may manifest as unexpected arterial hypoxemia
19
Q

Consideration for sitting position

A

Cardiovascular

  • pooling of blood in lower extremities
  • venous air embolism

Respiratory
-more flavorful ventilation with less effect on lung volumes

Neuro
-decrease in cerebral blood flow and CPP

20
Q

Consideration with prone position

A

Cardiovascular

  • devices that increase ABD pressure or impede venous return via vena cava and femoral veins can contribute to decreased CO, may decrease preload, and BP
  • can cause increased difficulty with hemostasis bc vertebral venous plexuses communicate directly with ABD veins

Respiratory
-compression of ABD and thorax decreases compliance and increases work of breathing. Minimized if ABD can hang free

Neuro
-extreme rotation of head my decrease cerebral venous drainage and cerebral blood flow

21
Q

What do you do if pt has air embolism?

A

-place them in left lateral trendelenburg and try to aspirate if they have a central line

22
Q

What are types of vision damage that may occur generally due to compromise of O2 delivery to the visual pathway?

A
  • Ischemic optic neuropathy
  • Retinal artery occlusion
  • cortical blindness
23
Q

What are potential causes of blindness due to surgery?

A
  • pressure on globe
  • intra-op hypotension
  • massive blood loss
  • venous congestion due to prone position
  • prolonged surgical procedure
  • massive fluid replacement
24
Q

What is thoracic outlet syndrome?

A

-compression of brachial plexus or subclavian vessels or both due to inadequate passageway thru the thoracic outlet between the base of neck and armpit

*All pts scheduled for a prone case should be asked about their ability to work or sleep with their arms overhead

25
Q

What is the second most common post operative nerve injury?

A

Brachial plexus

26
Q

What is the most frequently damaged nerve in the lower extremity?

A

Common perineal nerve

*manifests as foot drop

27
Q

Manifestations of radial nerve injury

A

Wrist drop

-can happen if arm slips off table or pressure applied to nerve as it traverses the spiral groove of humerus

28
Q

Manifestations of saphenous nerve injury

A
  • parathesias along medial and anteromedial side of calf

- caused by pressure on inside on knee during lithotomy position

29
Q

Manifestations of sciatic nerve injury

A
  • foot drop
  • pain/numbness in lower leg, thigh, or foot
  • weakness below the knee and diminished sensation over lateral half of leg and almost all of foot

-caused by pressure in ischial tuberosity while sitting, thighs externally rotated or in lithotomy, excessive hip flexsion

30
Q

What is the most common post op peripheral neuropathy?

A

Ulnar nerve

31
Q

Manifestations of ulnar nerve injury

A
  • sensory loss of 5th digit and claw hand

- caused by compression of epicondyle of humerus and sharp edge of bed