NA 1 > Positioning > Flashcards

Positioning Flashcards

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1
Q

Goals of positioning:

A

Optimize surgical exposure
Allow access to patient for anesthesia

Preserve CV and Pulm function

Prevent injury

Minimize blood loss

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2
Q

Supine position:

A

AKA dorsal decubitus position

Most frequently used for surgery of abdomen, head, neck, extremeties, and chest

HEAD, NECK, SPINE should be maintained at a neutral position on a small DONUT (To avoid brtachial plexus injury)

Arms should be comfortably positioned on PADDED ARMBOARDS (<90 degrees, supinated) OR tucked (Neutral position - palms facing hip

Legs must remain uncrossed to avoid pressure form superior extremity damaging SUPERFICIAL PERONEAL NERVE IN THE DEPENDENT LEG AND THE SURAL NERVE IN THE SUPERIOR LEG

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3
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4
Q

Trendenlenburg:

A

Often used as surgical position during robotic surgeries, treatment of hypotension, during central line placement

When using steep tren, shoulder braces may be used to keep patient from sliding down the bed

Initial placement in head down pos. will increase CO approx 9% in less than 1 min via an autotransfusion from lower extremities

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5
Q

What does trendenlenburg cause?

A

Increase in CENTRAL VENOUS, INTRACRANIAL, AND INTRAOCULAR PRESSURES (can cause edema in face, tongue, oropharynx, eyes)

Increase in Venous return can also shift the patient’s starling curve to the right - MAP will stay the same or increase

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6
Q

Complications of trendelenburg?

A

Shoulder braces can cause injury to brachial plexus
- If too medial - compression of plexus
- If too lateral can cause stretch of plexus
- Should be placed over acromioclavicular joint

Edema to facial structures

Unrecognized hypovolemia
- Once the patient is placed in the supine position, the blood volume will redistribute and if the patient is hypovoemic –> decrease in SV, CO, BP

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7
Q

Reverse Trendelenburg:

A

Head up position often used for laparoscopic surgeris

Reduces perfusion to the brain and may cause systemic hypotension

If using arterial monitoring during a case with reverse trendelenberg, arterial pressure transducer should be zero’ed at the Circle of Willis

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8
Q

Lithotomy

A

Legs are held in flexion and abduction above the torso via a leg holding device
- legs and hips must be elevated and lowered at the same tim e when placed in the leg-holding device to avoid hip dislocation, spinal torsion or postoperative back pain

Fingers must be watched so they dont get pinched

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9
Q

With lithotomy - acute abduction and external rotation can cause what?

A

Femoral nerve or lumbosacral plexus stretch injuries

Flexions of the hips more than 90 degrees can cause injury to the sciatic and obturator nerves as well

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10
Q

What other nerve injury is associated with lithotomy?

A

Peroneal nerve injury d/t anatomic course
- nerve crosses the knee laterally and wraps around fibular head before traveling down lower leg
- nerve can be injured by compression against the upright bar

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11
Q

Where are the arms during lithotomy?

A

Positioned at sides or abducted on arm boards
- attention should be paid to hands and fingers since they can sit close to the edge of the table

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12
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13
Q

Lateral decubitus position:

A

Patient placed in supine position for induction - then turned simulataneously to avoid stress and twisting of torso and spine

Head and neck should remain aligned with spine in a neutral position - head should be supported w pillows and not allowed to hang, tild laterally, hyperflex or hyperextend

Dependent eye and ear should remain free of pressure

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14
Q

What allows the patient to be in a stable position in lateral decubitus position?

A

Flexing the knee and hip of the dependent leg

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15
Q

The nondependent leg does what with LDP?

A

Remains straight and is supported by a pillow placed between the lower extremeties - avoiding the bony prominences from touching each other reduces compression of the inferior leg by the superior extremity

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16
Q

Where is the dependent arm positioned in LDP?

A

Positioned on padded arm board perpendicular to torso and flexed less than 90 degrees at elbow
- susceptible to compression in lateral position so an axillary roll is placed caudad to the axilla to lift the thorax and relive pressure on the shoulder
-Blood pressure should be monitored on the non-dependent arm because of compression of the dependent arm
-Pulse ox should be monitored on the dependent arm to assess for perfusion

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17
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A
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18
Q

Sittingn position:

A

Refers to any position in which torso is elevated form supine position and is higher than the legs

Lawn chair/ beach chair/ lounging

Used for shoulder sx and neuro sx

Sit patient up slowly and cycle BP frequently to assess hypotension

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19
Q

Shoulder sx and sitting position:

A

Typically placed in horseshoe headrest

  • If headrest is too tight - can cause stretch on neck and brachial plexus
    -If too loose - can cause dislodgement and cervical spine injury
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20
Q

What is the main concern for sitting position?

A

Venous air embolism is main concern

Bezold-Jarisch reflex may occur when pt is placed in sittingn position - Hypotension and bradycardia d/t decreased venous return

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21
Q

What can neck flexion cause in sitting position?

A

Obstruction of venous and lymphatic congestion that can cause edema of the face, airway, tongue, and neck

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22
Q

MAP changes ___ per inch above or below the heart

A

2mmHg

MAP of brain will be lower –> risk of hypoperfusion

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23
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24
Q

Prone position:

A

intubated on stretcher then flipped onto operating room table in prone position

D/C pt from circuit for turn then control the tube

Torso supported on frame or with rolls that extend from shoulders to iliac crest

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25
Assessing a patient's head, neck, shoulder, and arm mobility in preop is important for what with prone positioning?
How far patient can be mobilized for arm placement Arms can be tucked or placed above the head in a flexed, slightly abducted position - FA and hands should be lower than shoulders and supported with padding and pronated - <90 degrees
26
Head position with prone position:
Neutral position with a head holding device (foam or head rest) - ensure eyes and ears are free of pressure
27
If motor evoked potentials are being used in prone positioning?
B/L bite blocks should be inserted prior to turning into the prone position
28
Primary goal with prone position?
AVOID pressure on abdomen - pressure on abd can impede vnous return, increase venous pressures, and interfere with ventilation Positioning devices that allow the abdomen to hang freely allow are associated with less impedance in venous return
29
Meticulous attention should be paid to the ___ during prone position and why?
Eyes - post operative vision loss via pressure on the eye - if position causes head to be lower than the torso, venous congestion may occur and cause facial and airway edema
30
Where should the arms be placed with prone position
The arms may be positioned to the patient’s sides or placed outstretched above the head. If the arms are at the patient’s sides then they should be tucked in the neutral position. If the arms are outstretched above the head, the arms should be placed on arm boards with slight flexion at the elbows to prevent undue stretch on the nerves
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Under anesthesia, the patient typically has a decreased what?
CO and BP - d/t to myocardial depression and vasodilation from anesthetic meds
33
Blood pools in dependent body areas which reduce____ and _____
preload and stroke volume MAP is typically maintained by an increase in HR and SVR
34
In supine and lateral positions, what happens with CV system?
Minimal May see some decrease in BP with lateral position if kidney rest is causing vena cava compression
35
CV changes with sitting, prone, flexed lateral?
CO and BP decreased CO may decrease by 20% if patient is sitting at a 90 degree angle
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Lithotomy position and CV changes?
BP may appear normal or elevated (Legs above the trunk)
37
What can help the CV system compensate for position induced hemodynamic changes?
Slow assumption
38
Anesthetist may also slowly increase ____ to increase amount of time or the body has to respond to position change hemodynamics
MAC - do not get the patient to 1 MAC prior to sitting in beach chair Can also volume load
39
CV changes with trendelenburg?
Treat hypotension because it increases venous return and MAP
40
Trendelentburg + trendelenburg with lithotomy may cause:
Increase in CVP, CO, and Stroke volume A patient who is not able to compensate may be shifted to the right side of the frank-starling curve which causes the heart to struggle with the increase in volume
41
Patient's with lower extermity circulation problems may have ischemia from which positions?
Lithotomy Trendelenburg D/t hypoperfusion
42
Which positions may increase venous pressure in the head which causes swelling of the facial, pharyngeal and orbital structures?
Prone and trendelenburg
43
Effective resp gas exchange depends on balance of:
Ventilation/perfusion throufhout the lungs Gravitational effects on gas exchange and blood flow are thought to result in differences in V/Q ratio
44
In both awake and anesthetized pt's, gravity does what
Creates gradient where perfusion is favored in dependent positions of the lung and ventilation in nondependent areas
45
Posterior lung segments are better ventilated with which position?
Prone
46
What occurs with lateral position and respiratory system?
Both ventilation and perfusion are greater in the dependent lung than the non-dependent lung in SPONTANEOUSLY awake patients
47
IN MECHANICALLY VENTILATED, anesthetized patients, the ____ lung becomes _____ to ventilate and the ____ lung becomes _____ to perfuse causing a V/Q mismatch which can affect oxygenation:
Upper lung (Nondependent) Easier Dependent Easier
48
Abd viscera with prone position:
Abd contents may limit diaphragm excursion due to compressing the boyd
49
Abd viscera with lateral position:
Abd contents shift cephalad, moving the hemidiaphragm of the dependent lung upward, decreasing ventilation
50
Abd viscera sitting position:
Abd viscera remains caudal and anterior and cause less interference with diaphragmatic movement
51
Abd viscera trendelenburg:
Diaphragm displaced cephalad which causes the movement of hte diaphragm to gbe limited and decreases FRC
52
Abd viscera supin position:
FRC and TLC are significantly decreased as compared with sitting positino d/t cephalad shift of the diaphragm caused by abd viscera
53
Transection injury:
Cut via surgery or trauma
54
Compression injury:
Nerve is forced along a bony prominence or hard surface (arm board, operating room table)S
55
Stretch injury:
Force of stretching overcomes nerve elasticity, causing nerve fibers to break
56
What may be compromised with nerve injury?
Intraneural blood flow leading to nerve injury and nerve ischemia
57
Factors that contribute to nerve injury:
Incorrect surgical positioning, patient predisposition, physiologic and mechanical factors POSITIONING DEVICES - mostly evidence from isolated case reports -Tight straps/padding cause skin breakdown and nerve injury - Lateral femoral cutaneous nerve in thigh is susceptible to injury by table straps - Common peroneal nerve injury due to improer use of stirrups -Brachial plexus injury due to arm board misuse - compression injury of radial nerve due to tourniquet use
58
Length of procedure and contribution to nerve injury:
Duration of >4 hours can contribute to N injuries, postop vision loss, and compartment syndrome Weight of the body (External compression on dependent tissues ) + low perfusion
59
Anesthetic tecniques contribution to nerve injury:
Can't move in response to painful stimuli Muscle relaxant makes patient hyperflexible - pts who normally can't straighten arms or legs start to be able to, which can cause stretch injuries Hypotension from anesthetics can cause low perfusion
60
Body habitus and contribution to nerve injury:
Underweight pts may develop nerve injury due to inadequate adipose tissue Obesity can cause more pressure on dependent body parts which can lead to nerve injury - Lateral position, a patient's heavy superior extremity may interfere with perfusion of the lower extremity
61
Pre-existing conditions and contribution to nerve injury:
HTN DM PVD Peripheral neuropathies Alcoholism
62
Ulnar neuropathy:
Traverses the length of the upper extremity from medial cord of brachial plexus to its terminal branches in hand Most common peripheral nerve injury UN passes along anterior aspect of medial head of triceps muscle and posterior into the groove between the medial epicondyle and humerus and the olecranon Sheathed in cubital tunnel before passing between 2 heads of Flexor carpi ulnaris
63
When can ulnar injury occur?
When there is elbow flexion (Due to increased area between olecranon and medial epicondlye + decreased size of the tunnel) and from direct compression on the condylar groove
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Ulnar neuropathy happens most often in:
MEN Pre-existing neuropathy Prolonged hospital stays and extreme body habitus Tubercle of coronoid process is 1.5x larger in men Less adipose tissue in men than women over elbow
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Prevalence of ulnar neuropathy:
MOST frequently reported injuries after surgery Damage to UN results in inability to oppose fifth finger and diminshed sensation tot he fourth and fifth finger - clawlike shape MAY TAKE 48-72 HOURS for patients to report injury
66
Arm positioning with ulnar nerve:
Use padding, placing arms in supinated position or neutral forearm position when arms are placed on boards - Pronation may cause increase pressure over the ulnar nerve Abduction of arms < 90 degrees if arm boards are used If tucking arms, MAKE SURE arms are in neutral position with palms facing inwards In lateral position, avoid excessive flexion and/or extension
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Radial nerve injury cause:
Pressed against vertical positioning or retractor post/pole - place adequate padding between arm and pole
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What occurs with radial nerve injury?
WRIST DROP - weakness in the thumb and decreased sensation in lateral 3 1/2 fingers of dorsal surface of hand
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When do brachial plexus injuries occur?
When the patient is supine, abduction of the arms > 90 degrees stretches the plexus TURNING the head to the side with the arms abducted can cause stretching and compression of the contralateral brachial plexus When the patient is prone, inadequate support of the shoulders allows them to sag anteriorly, causing traction on the plexus - Also, extending the arms over the head may compress the plexus between the clavicle and first rib
70
Brachial plexus injury and lateral decubitus position:
External rotation, extension and lateral felxion of the head, and posterior shoulder displacement may cause injury due to excessive stretching (nondependent arm) - axillary roll placed in the axilla can cause compression of brachial plexus The dependent brachial plexus may be injured via weight of the chest that can compress the lower shoulder and axilla - An axillary roll can be placed to relieve this pressure - Axillary roll should be placed caudal to the dependent axilla
71
Steep trendelenburg and brachial plexus:
Shoulder braces palced too close to base of neck can compress neurovascular structures - should be placed distal end of the clavicle over the acromioclavicular joing
72
Sternal retractor during surgery causes what?
CLAVICLE to move posteriorly and the first rib to rotate upward, whcih can cause the brachial plexus to be pinched between the 2 Caudal placement of the sternal retractor and avoidance of excessive and prolonged asymmetric chest wall retraction
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Where does the median nerve run?
Adjacent to medial cubital and vasilic veins in the AC
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Injury to Median nerve caused by?
Laceration from IV or arterial sticks, elbow hyperextension
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Deficits from median nerve injury?
Inability to oppose thumb and little finger DIMINISHED SENSATION to palmar surface of the hand and lateral 3 1/2 fingers
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What are SCI associated with?
Neuraxial blocks in anticoagulated patients Midcervical flexion myelopathy with temporary or permanent quadriplegia may occur when the head is flexed on the neck in the sitting or prone positions - When head is flexed, SC moves anteriorly and may be compressed against the posterior vertebral body causing ischemia from a combination of stretch and compression
78
What is postoperative visual loss (POVL)?
Vision loss during non-opthalmic sx that is attributable to 5 causes: - ischemic optic neuropathy (ION) - central retinal artery occlusion (CRAO) - central retinal vein occlusion - cortical blindness - glycine toxicity
79
CRAO and ION account for ____ of all cases of POVL
80% "ION" stands for Ischemic Optic Neuropathy, which refers to a condition where the optic nerve is damaged due to insufficient blood supply, while "CRAO" stands for Central Retinal Artery Occlusion, meaning a blockage in the main artery supplying blood to the retina, causing vision loss in the central part of the eye; essentially, ION affects the optic nerve while CRAO affects the retina itself
80
ION is a result of what?
ISCHEMIA in a portion of the optic nerve (CN 2)
81
What are central retinal and posterior ciliary arteries?
End arteries that have no anastomoses with other arteries - Supply watershed areas - area that rec3eives dual blood supply from the most distal branches of 2 arteries Ocular circulation lacks autonomic innervation, but autoregulation still occurs DM and HTN can disrupt autoregulation during periods of hypotension
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Where does Anterior ION occur?
Anterior to Lamina Cribrosa
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Where does posterior ION occur?
Posterior to LAMINA cribrosa
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RF for ION with spine sx?
Male gender Wilson frame Longer operative times Greater blood loss Lower colloid to crystalloid ratio
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When will vision loss occur with ION?
24-48 hours post surgery - not associated with Pain
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What to do to reduce chance of ION?
MUST AVOID increased intraocular pressure and decreased optic nerve perfusion
87
Ocular perfusion Pressure equation (OPP)
= MAP - IOP Anything that decreases MAP can decrease ocular nerve perfusion (General anesthesia, hypotension, hemorrhage, and hypovolemia) Anything that increases IOP will decrease OPP - Head down tilt, increased abdominal and RA pressure, obstruction of jugular venous return (Steep Trendelenburg + wilson frame)
88
Central retinal artery occlusion caused by?
DECREASED blood supply to the entire retinal due to improper head positioning that leads to external pressure on the eye Can also be caused by EMBOLI that migrate to the central retinal artery
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What does CRAO present with?
UNILATERAL, PAINLESS vision loss immediately after surgery - cherry red macula on fundoscopic exam
90
RF of CRAO?
HTN CVD Increased BMI Open angle Glauc Sickle cell Horseshoe headrest
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Avoiding POVL:
PERFORM periodic eye checks in prone/lateral positions to assure no pressure is directly on the globe Keep head in a neutral position at or above the level of the heart Avoid significant hemodynamic changes
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Compartment syndrome
Tissue swelling causes damage to neural and vascular structures because of increased pressures and decreased tissue perfusion in muscles with tight, fascial borders
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Compartment syndrome occurs:
Precipitated by hypotension alongside of leg elevation (lithotomy) during longer surgeries In LONGER surgeries, the legs may need to be periodically lowered to the level of the body
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RF of compartment syndrome:
Trendelenburg Advanced age Extremes of body habitus HYPOTENSION VASOCONSTRICTORS Anemia SURGICAL TIME>2-3 hrs
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Treatment of compartment syndrome:
FASCIOTOMY
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Venous air embolism can occur:
In any position where there is negative pressure gradient btw right atrium and veins at operative site
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What happens when air enters the venous system?
travels to right ventricle and pulmonary circulation and can limit gas exchange Can cause hypotension, arrhythmias, cardiac arrest Dependent on amount of air and speed of entrainment
98
If air gets through to the Left side of the heart:
can cause micro emboli that can cause MI or stroke (PARADOXICAL EMBOLISM)
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What will venous air embolism show on ETCOW?
Causes increase in dead space - drop in ETCO2 and increase in end tidal nitrogen concentration
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What heart sound can be heard with VAE:
Mill wheel murmur through esophageal or precordial stethoscope
101
Treatment of VAE:
Flood field with saline and stop surgery 100% FiO2 IV fluids and vasoactive agents for hemodynamic compromise Left side down and trendelenburg position Aspiration through a central venous catheter
102
With NECK FLEXION, the tube will move where?
Downward and may INADVERTENTLY enter the right mainstem - can also occur with Trendelenburg
103
With NECK EXTENSION, the tube will move where?
May inadvertently DISLODGE (Extubation)
104
What is midcervical tetraplegia associated with?
HYPERFLEXION of the neck (Chin to chest) - Ischemia occurs due to stretching and compression of midcervical spinal cord (Usually C5)
105
What does midcervical tetraplegia occur in?
Sitting position --> watn to make sure there is a least 2 FINGERS between chin and chest
106
Closed claim studies reveal that the folowing are causes of liability for anesthetist:
Death 26% NERVE INJURIES 22% - ULNAR - BP - Lumbosacral nerve root - Spinal cord Permanent brain damage (9%)
NA 1
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