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Anesthesia Principles 1 > Positioning for Anesthesia/Surgery > Flashcards

Positioning for Anesthesia/Surgery Flashcards

1
Q

CV effects of General Anesthesia

A

CO and BP decrease d/t myocardial depression and vasodilation

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2
Q

Preload and SV____ during GA

A

Decrease

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3
Q

GA effect on Venous Return

A

Decrease d/t decreased muscle tone from NMBs

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4
Q

Opioids _______HR which does what?

A

Decrease HR, CO and BP

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5
Q

GA blunts compensatory mechanisms(HR/BP) which does what?

A

Make CO and BP more susceptible to gravitational forces

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6
Q

Positions that have minimal hemodynamic changes?

A

Supine and Lateral

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7
Q

CO and BP decrease with what positions?

A

sitting, prone, and flexed lateral positions (lower extremities are dependent)

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8
Q

CV effects of Prone positioning

A

-Increase CVP
-LV volume decrease d/t decrease venous return and increase intrathoracic pressure
-Increase venous pressure in head (swelling in face, pharyngeal, orbital structures)
-possible increase ICP
-Postoperative visual loss (POVL) from increase ocular pressures

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9
Q

Lateral decubitus w/ kidney rest elevated (CV)

A

-↓ BP d/t legs being dependent
-↓ venous return d/t extreme flexion
-Kidney rest may compress the vena cava
-Kidney rest should be placed under the dependent iliac crest
-Caution with large tidal volumes and high PEEP (high intrathoracic pressures w/ a subsequent reduction in venous return, right atrial filing, and C.O)

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10
Q

Lithotomy (CV) head?

A

-↑ venous pressure in the head → swelling in face, pharyngeal, and orbital structures
-Possibly ↑ ICP

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11
Q

CO if patient raised to 90 degrees?

A

C.O ↓ 20%

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12
Q

Interventions that Promote CV Stability

A

-Move pt slowly
-lighter plane of anesthesia (MAC < 0.5) gradually increase depth
-IV hydration

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13
Q

What positions can Hypotension go unrecognized?

A

Lithotomy and Trendelenburg

Pt may get hypotensive when returned to horizontal position (decreased SV, CO, BP)

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14
Q

Pts with CAD in lithotomy and head-down tilt (CV)

A

↑ CVP, PAPA, and PCWP and ↓ C.O

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15
Q

Trendelenburg CV effects

A

may ↑ myocardial work via ↑ central blood volume, ↑ C.O and ↑ SV, pts with poor cardiac function have ↓ C.O if the ↑ in central blood volume moves them to a worse position on the frank starling curve

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16
Q

Pts with PVD have ↑ risk for ischemia in lower extremities when________

A

placed in lithotomy and Trendelenburg position

When extremities are above the level of the heart pt is at ↑ risk for compartment syndrome

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17
Q

Compared to the awake spontaneously breathing pt, a spontaneously breathing anesthetized pt has:

A

↓ tidal volume
↓ FRC
↑ closing volume

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18
Q

Sitting: LUNG Dependent/Non-Dependent

A

Dependent: Base
Non-Dependent: Apex

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19
Q

Supine: LUNG
(dependent/non-dependent)

A

Dependent: Posterior
Non-Dependent: Anterior

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20
Q

Dependent lung region (V/Q)

A

V/Q DECREASE

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21
Q

Non-Dependent lung region (V/Q) during GA

A

V/Q INCREASE

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22
Q

Prone Position
(Respiratory effects)

A

-Improved oxygenation
-More lung volume is present posteriorly and better ventilated in prone position
-Ventilation is more uniform and V/Q matching is better d/t alleviation of pressure from anterior structures on the lungs
-Increased hydrostatic pressure → edema formation

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23
Q

Lateral Decubitus (Respiratory)

A

Awake= ventilation favors dependent lung during spontaneous respiration

Anesthesia, positive pressure ventilation, paralysis: upper lung becomes easier to ventilate

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24
Q

Supine (Respiratory)
FRC and TLC?

A

FRC and total lung capacity are ↓ compared to sitting d/t cephalad shift of the diaphragm caused by the pressure of the abdominal viscera

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25
Q

Favorable for ventilation? (Respiratory)

A

-Sitting

-Neck flexion can impair venous drainage from head → edema formation

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26
Q

Trendelenburg (Respiratory)
ETT movement?

A

-↓ FRC

-Movement of the mediastinum toward the head may result in the tip of the endotracheal tube migrating into the right mainstem bronchus

-Increased hydrostatic pressure → edema formation

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27
Q

Causes of Nerve Injury

A

-Transection (surgical/trauma)

-Compression
(Nerve forced against a boney prominence or hard surface)

-Stretching

Nerves don’t tolerate being pulled. Excess stretch can damage the structure of the nerve and damage the blood flow to the nerve

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28
Q

Patient predisposition for Nerve Injury

A

-Advanced Age

-Extremes of habitus

-Comorbidities (Diabetes, Smoking, Hypertension)
-Interop (Hypotension, Hypoxia, Hypothermia
Hypovolemia)

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29
Q

Factors contributing to Nerve Injury

A

-Positioning devices

-Length of procedure
( >4hours)

-Anesthetic techniques

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30
Q

What is susceptible to stretch and compression injuries?

A

Brachial Plexus
(Keep arms Abducted less than 90°)

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31
Q

Brachial Plexus picture

A

Randy Travis Drinks Cold Beer = Roots, Trunks, Divisions, Cords, Branches

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32
Q

Sensory Distribution of Brachial Plexus (Anterior)

A
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33
Q

Sensory Distribution of Brachial Plexus (Posterior)

A
34
Q

Positions that increase Preload….

A

Trendelenburg, Lithotomy

35
Q

Positions that decrease Preload….

A

Reverse Trendelenburg, sitting, flexed lateral

36
Q

Trendelenberg and Lithotomy increase….

A

-Venous hydrostatic pressure (edema of face, eye, airway)

-increase ICP (hinders venous drainage)

37
Q

PEEP and positive-pressure ventilation (lungs)

A

Increase intrathoracic pressure and decrease venous return

38
Q

Which 4 body positions are associated with higher hemodynamic instability?

A

-Reverse T-burg
-Sitting
-Flexed lateral
-Prone

39
Q

5 anesthesia techniques that attenuate the body’s compensation for CV stability

A

-GA
-Neuraxial anesthesia
-positive-pressure ventilation
-PEEP
-Muscle relaxants

40
Q

Blood movement during T-burg and Lithotomy (F-S curve)

A

-blood shifts towards central circulation
-increase venous return
-shifts position on Frank-Starling curve to RIGHT

41
Q

The T-burg position reduces_______ and increases________.

A

-Reduces pulmonary compliance
-increases the risk of endobronchial intubation

42
Q

Picture to remember

A
43
Q

Picture to remember

A
44
Q

What locations are the brachial plexus anatomically fixed to?

A

cervical vertebrae and axillary fascia

45
Q

Highest risk position for brachial plexus STRETCH injury?

A

arms ABducted > 90 degrees and head rotated to other side

46
Q

What is common cause of compression injury for brachial plexus?

A

compression between clavicle and first rib (shoulder brace) or by external force (improperly placed axillary roll).

47
Q

Most commonly injured peripheral nerve?

A

ULNAR

Many ulnar neuropathy cases don’t present until > 24hrs after surgery

48
Q

Risk factors for ulnar injury:

A

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

49
Q

Ulnar nerve injury presentation?

A

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

Chronic= CLAW HAND

50
Q

Which deficits are more common, less serious, and tend to resolve on their own? (ULNAR)

A

Sensory

-Motor deficits are more serious and can take up to 4-6 weeks to recover

51
Q

Prone positioning recommendation (Brachial plexus)

A

-Don’t have saggy shoulders
-Keep shoulders and elbows at 90 degrees or less (NOT over the head)

52
Q

Picture to remember (arm position)

A
53
Q

Median nerve injury is _______.
How can it occur?

A

RARE

-IV placed in AC
-Elbow hyperextension
-carpal tunnel syndrome

54
Q
A
55
Q

How does median nerve injury present?

A

-reduced sensation over the palmar surface of thumb, index finger, middle finger and lateral aspect of ring finger.
-may be unable to oppose thumb

-Chronic= Ape Hand deformity

56
Q

Causes of Radial nerve injury

A

-External compression by an IV pole
-Excessive cycling of the NIBP cuff
-Upper extremity tourniquet
-Sheets that are too tight (if the arms are tucked

57
Q

Long thoracic nerve injury presents with….

A

winged scapula

58
Q

Location of Suprascapular Nerve

A

anchored between cervical spine and suprascapular notch

innervates the supraspinatus and infraspinatus muscles

59
Q

Cause of Suprascapular nerve injury

A

Ventral circumduction of the dependent shoulder in the lateral decubitus position can stretch the suprascapular nerve ( pt in lateral decubitus rolls onto their dependent arm)

presents as DULL shoulder pain

60
Q

Obturator injury presentation

A

-Inability to ADDuct the leg
-Reduced sensation over the medial aspect of the thigh

prevention: minimize hip flexion

61
Q

Femoral Nerve injury etiology, presentation and prevention

A

Etiology
Excessive traction during lower abdominal surgery

Presentation
Impaired knee extension and hip flexion
Reduced sensation over the anterior thigh and anteromedial aspect of the leg

Prevention
Surgical team should avoid excessive traction during the procedure

62
Q

Saphenousl Nerve injury etiology, presentation and prevention

A

Etiology
MEDIAL aspect of the leg leans against the supporting cradle in the lithotomy position (the saphenous n. resides near the tibia)

Presentation
Reduced sensation over the anteromedial aspect of the leg

Prevention
Place padding between leg and stirrup

63
Q

Most common lower extremity injury?

A

Common Peroneal Nerve

64
Q

Common Peroneal Nerve Etiology

A

Very susceptible when pt is in stirrups
Nerve can be compressed when the LATERAL aspect of the leg leans against the stirrup bar or “candy canes”

65
Q

Common Peroneal Nerve presentation

A

Foot drop
Inability to evert the foot
Inability to extend the toes dorsally

66
Q

Common Peroneal Nerve prevention

A

-Placing padding between the leg and stirrup
-Pad under the fibular head
-Knees should be flexed with minimal rotation

67
Q

Sciatic Nerve etiology, presentation and prevention

A

Etiology
Lithotomy- extreme hip flexion or external rotation of the legs
Sitting- Straight legs

Presentation
Foot drop

Prevention
Ample padding under the buttocks
Avoid excessive external rotation of the hips
Flex table at the knees

68
Q

Which nerves can be damaged if patients legs are crossed?

A

Top leg–> sural injury

Bottom leg–> superficial peroneal injury

69
Q

Position most common in lower extremity compartment syndrome?

A

Lithotomy

Legs are above the heart
Leg ischemia →edema→ more ischemia→ more edema

70
Q

Risk factors for lower extremity Compartment Syndrome?

A

Risk factors:
Surgical time >2-3 hrs
↑ BMI
↓ Tissue oxygenation (hypotension)

Treatment: fasciotomy

71
Q

Position most common in Air Embolism?

A

Sitting

Craniotomy done in sitting position is greatest risk for AIR EMBOLISM

72
Q

Signs and Symptoms of Venous Air Embolism

A

Air seen on TEE (most sensitive)

-“Mill wheel” murmur on precordial doppler
-Decreased EtCO2
-Increased pulmonary artery pressure
-Hypotension
-Dysrhythmias
-Pulmonary Edema
-Hypoxia
-Cyanosis

73
Q

Treatment for Venous Air Embolism

A

-100% O2
-flood surgical field with normal saline
-stop insufflation
-place patient on LEFT side (Durant maneuver)
-Aspirate air from CVC
-Hemodynamic support (pressors, inotropes, fluid)

74
Q

Paraplegia risk factors

A

Extreme hyperextension of the lumbar spine in supine position can cause paraplegia

Risk factors:
Maximal retroflexion of the OR table
Raising the kidney rest to its highest position
Placing large rolls under the patient’s lumbar spine

75
Q

Midcervical Tetraplegia is associated with?

A

hyperflexion of the neck (chin to chest)

Ischemia occurs as a result of stretching and compressing of the midcervical spinal cord (usually C5)
Most common in sitting position
Make sure you can place 2 fingers between the patients chin and chest
Can also occur postoperatively in patients who had a tracheal resection

76
Q

Post-op Vision Loss cause

A

Anterior/Posterior ischemic optic neuropathy
Most common causes of ION are decreased perfusion & increased intraocular pressure

77
Q

Post-op vision loss intraoperative factors:

A

-Prolonged surgical Procedure
-Prone Position
-Large Blood Loss/Low HCT
-Hypotension (SBP <100mmHg)

(MAP-IOP = OPP)

78
Q

Increase hydrostatic pressure –> edema formation (Airway)

A

Prone and T-burg

79
Q

Neck flexion impairs venous drainage from head–>Edema (Airway)

A

Sitting

80
Q

Equipment (oral airway, esophageal temp probe) does what?

A

impairs lymphatic drainage —->edema formation

81
Q

Long Thoracic Nerve Innervates?

A

SALT (Serratus Anterior Long Thoracic) Causes scapular winging with injury

82
Q

In a patient with a mediastinal mass, 3 ways that worsen tracheobronchial compression (airway collapse)

A
  1. Supine position
  2. GA
  3. Loss of spontaneous ventilation (need for positive-pressure ventilation)

Anesthesia Principles 1 (11 decks)

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