Positioning

Question 1

Benefits of Proper Positioning

Answer 1

1. Prevents nerve damage and maintains circulation
   
   • From preventing over stretching, compression, ischemia
2. Allows better surgical access
3. Maintains homeostasis

Question 2

What are the goals of positioning

Answer 2

1. Prevent nerve injury from stretching of the nerve complexes and prevent of pressure on critical areas
2. Impediment of respiration and circulation can be avoided
3. It is essential the patient is safe at all times, appropriate padding, safety strap, alignment is important

Question 3

Things to keep in mind with positioning

Answer 3

1. Length of procedure (> than 2 hrs)
2. Surgeon’s preference
3. Position for surgery
4. Risk factors (obesity, etc.)
5. Which anesthetic is administered
6. All lines should be free to move and secured before any positioning

Question 4

Factors Affecting Compensation

Answer 4

1. Volatile anesthetics
   
   • Decrease venous return & SVR = decreasing arterial blood pressure
2. Positive-pressure ventilation
   
   • Increases mean intrathoracic pressure
   • Decreases the venous pressure gradient from peripheral capillaries to the right atrium = decreased cardiac filling & cardiac output
   • PEEP and low lung compliance states (airways disease, obesity, ascities, and light anesthesia) further increases IP = further decreased VR and CO
3. Spinal/ epidural anesthesia
   
   • significant sympathectomy across all anesthetize dermatomes - independent of GA or not
   • Decreases preload and potentially blunting cardiac response
   • Sympathetic output can be decreased even when higher spinal dermatomes not blunted

Question 5

Gas exchange effects with anesthesia

Answer 5

• Reduced Vt and FRC
• Positive Pressure W/ NMB diaphragm assumes an abnormal shape
  
  • Some V/Q mismatch - increase shunt & Adele tasks
• Positive Pressure w/o NMB
  
  • May maintain some diaphragmatic function lessening about consequence
• Regional
  
  • lose abdominal and thoracic muscle function in affected dermatomes

Question 6

Common Surgical Positions

Answer 6

1. Supine
2. Prone
3. Lateral
4. Trendelenburg (include reverse)
5. Litho to my
6. Always be sure patient is secured with a safety strap

Question 7

Supine Position

Answer 7

• The most common position
• CV most stable in this position why? - V/Q match
• Make sure patient has a safety belt on 2” above the knee
• Patient on back with arms out on arm boards with palms up. Arms are abducted < 90 degrees
• Legs uncrossed
• All pressure points padded

(Heart is level w/ everything in the body)

90 degrees is the magic #

Question 8

Complications of Supine Positioning

Answer 8

1. Most common nerve damage:
   
   • brachial plexus, radial and ulnar, perineal and tibial
2. Bony prominence that are subject to pressure sores: occiput, sacral, spine, scapula, sacrum
3. Reduction in FRC from abdominal contents moving cephalad
4. Airway obstruction and decreased tidal volume
5. Increased chance of regurgitation

Question 9

Pulmonary Concerns for the anesthetize patient in Supine

Answer 9

1. Reduced Vt
2. Reduced FRC
   
   • From standing to supine FRC decreases d/t cephalad displacement of the diaphragm
3. Increased closing volume (alveoli closing at expiration)
4. Diaphragm is displaced decrease V/Q mismatch
5. Limits movement of chest wall, diaphragm, and abdomen = increases atelectasis & intrapulmonary shunt

Question 10

Potential Complications of Supine

Answer 10

1. Nerve damage - brachial plexus
2. Backache or paraplegia
3. Perineal crush injury
4. Compartment syndrome
5. Slipping of the head from inadequate tong placement or fixation of tongs to support, or equipment failure
6. A lope is
7. Watch weight limits & consider if reversing the table

Question 11

What is the best way to prevent ulnar nerve injury?

Answer 11

Make sure the palms are up

• there is more stretching on the ulnar nerve when it is pronated d/t the pressure on the ulnar groove & spiral groove of the humerus

Question 12

What is Trendelenburg

Answer 12

Tilting the head of the patient down
- purpose is to move away the abdominal viscera from the pelvic area to give the surgeon better exposure

• increases venous return, improve exposure and prevent air embolism and facilitate cannula during central line placement
• Use a non-sliding mattress to prevent patient from sliding
• Avoid shoulder braces & bean bags

Question 13

Physiological changes with Trendelenburg

Answer 13

• Swelling of the face, conjunctiva, larynx, & tongue
  
  • Swollen airway
• Decreased pulmonary compliance
  = increased intrathoracic pressure = belly pushing against diaphragm
• May lead to reduced FRC & atelectasis,
• V/Q mismatch, raised ICP & IOP,
• Passive regurgitation (must have ETT)

Do a Test Leak!
- Sit up when extubating to facilitate drainage

Question 14

What is Reverse Trendelenburg?

Answer 14

Head up tilt

• Facilitates upper abdominal surgeries
• Make sure patient does not slip
• Head above the heart reduces perfusion to the brain
• Typical position for the laparoscopic cholecystectomy w/ a slight tilt to the Left
• Ventilation is not the problem - cardiovascular is
  
  • dumping blood in the feet = hypotension & increased risk of venous air embolism

Question 15

Physiological changes with Reverse Trendelenburg

Answer 15

1. Decreased venous return
   
   • frequent monitoring of arterial BP
2. Decreased cerebral perfusion pressure
3. Consider hydrostatic gradient on cerebral arterial & venous pressures
   
   • may require extra monitoring

Question 16

What is Lithotomy Position?

Answer 16

Patient is in the supine position with legs in the air

• Hip flexed 80 - 100 degrees
• Calves parallel with torso
• Legs are abducted 30 - 45 degrees & perineal are is exposed
• Arms are tucked to sides, placed on arm boards, or across the abdomen
  
  • Check fingers & hands at all times!!
• Adequate padding for legs and arms
• Legs should be lowered & raised simultaneously

Question 17

Physiological changes when in lithotomy position

Answer 17

1. Increased preload
2. Increased CO
3. Increased CVP
4. ICP transient
5. Decreased lung compliance (decrease FRC)
6. Decreased Vt
7. Obese abdomen or tumor may impede venous return

Question 18

What patients are more likely to experience nerve damage?

Answer 18

1. Diabetic patients
2. Obesity
3. Smokers

Question 19

What is the beach chair position

Answer 19

Sitting (cardiac chair)

• knees are slightly flexed - for balance and reduced stretching of the sciatic nerve
• Feet are supported
• Difficult to establish- requires coordination, time & effort
• Minimum of 4 people for difficult positions

Question 20

Hemodynamic effects of Beach Chair Position (2)

Answer 20

1. Prone to hypotension
   
   • Decreased venous return
   • Decreased SV & CO
2. Decreased Cerebral Perfusion Pressure

• to avoid hypotension - do not change positions fast, incremental changes, & use IV fluids, vasopressors & adjustment of anesthetic depth
• Elastic stockings are used to maintain venous return

Question 21

What are potential complications of Beach Chair (4)

Answer 21

1. Pneumocephalus
   
   • d/t head being higher than the heart
2. Postural hypotension
3. Edema of the tongue - oral airway, neck flexion, venous & lymphatic obstruction of the tongue
4. Venous Air Embolism

Question 22

What is lateral position?

Answer 22

Patient lies on the non-operative side w/ anterior & posterior support - bedding rolls or deflatable beanbag

• Dependent ear flat
• Axillary roll
• Flexed dependent leg
• Arms are usually positioned in front of the patient
  
  • the dependent arm rests on a padded arm board perpendicular to the torso
  • the non-dependent arm is often supported over folded bedding or suspended with an armrest or cradle
  • if pos., neither arm should be abducted more than 90 degrees

Question 23

In lateral position which arm should have the pulse ox & which arm should have the A-line

Answer 23

The dependent arm (arm the same side patient is laying on) should have the pulse ox to help determine the occlusion/ pressure on that side

Aline should go on the non-dependent side, (arm patient is not laying on), this side is closer to the heart and allows for a more accurate BP reading

Question 24

Hemodynamic effects of lateral position

Answer 24

1. Pulmonary
   
   • V/Q mismatch - lung is dependent
   • V/Q mismatch increases w/ one lung ventilation
2. CV
   
   • During flexion of pelvis and use of kidney rest - point of flexion should lie under the iliac crest rather than the flank or ribcage to minimize compression of the dependent lung
   • Potential for venous pooling in the lower body

Question 25

Why is prone position used

Answer 25

For posterior fossa of the skull, the posterior spine, the buttocks, and perirectal area, & the lower extremities

Question 26

Considerations for Prone Position (7)

Answer 26

• Patient to sleep on stretcher
• Log rolled, w/ head neutral - anesthesia calls the move
• Check neck mobility if turning head side to side (in pre-op)
• Typically paralyzed for turn - Team effort
• Disconnect lines and circuit
• If using mayfield pins - placement is painful (neurosurgery)
• Frequent eye checks and airway device checks
• Document, Document, Document

ERCP surgeries usually use prone with head to the side

Question 27

What monitor should you reconnect 1st after a position turn?

Answer 27

Pulse ox

Question 28

Physiological Changes in the prone position

Answer 28

1. CV
   
   • Pulse pressure slightly augmented (greater in size)
   • Incorrectly placed bolsters/pillows can impede pelvic venous return
   • Elevated intraabdominal & intrathoracic pressure = increased venous pressure to abdomen & spine vessels, including epidural veins which lack valves
   • ABD pressure may also impede venous return by compressing on the inferior vena cava, decreasing CO
2. Pulmonary
   
   • If abdomen free = excellent conditions
   • If abdomen constricted = Decreased FRC & compliance, increased peak airway pressure
3. Pendulous structures
   
   • Breasts should be placed medial to the gel bolsters (anesthesia usually responsible)
   • Genitalia should be free of compression w/ bolsters under its respective iliac crest (RN)