Positioning #2

Question 1

What cardiovascular changes would you anticipate in lithotomy position?

Answer 1

• Elevation of legs increases venous return/increases preload to heart with a transient increase in CO and BP
• perfusion to lower extremities is reduced
  
  • perfusion pressure changes 2 mmhg for each 2.5 cm that a given point varies in vertial height above or below the heart
• After legs are put down, venous blood will pool in them. Always check BP after putting legs down

Question 2

What ventilatory changes would you anticipate in lithotomy position?

Answer 2

• Depending on the degree of hip flexion, abdominal contents may push up on the diaphragm and impede excursion
  
  • reducing lung compliance
  • decreasing TV and VC
  • increases risk of aspiration

Question 3

What cerebral changes would you anticipate when putting your pt in lithotomy position?

Answer 3

• transient increase in cerebral venous blood flow and increase in intracranial pressure with legs elevated

Question 4

What is the Wilson frame?

Answer 4

• frame used to prone a patient; it is open under abdomen and chest to allow for ventilation

Question 5

What is a jackson table?

Answer 5

• special table used if position changes are needed during the procedure
• *the human rotisserie

Question 6

What are the different options for head rests when pt is prone?

Answer 6

• head rest with mirror
• horseshoe headrest
  
  • watch eyes, nose, bony structures of face
  • make sure head and neck are aligned
• Mayfield head tongs/pins (pictured)
  
  • watch for bolt slippage
  • want natural neck alignment
  • eyes, nose, and chin are free with nothing touching them

Question 7

How is a patient put into prone position?

Answer 7

• While patient is still on the stretcher:
  
  • induction/intubation
  • line placement
  • NGT/OGT, esoph stethescope, bit block
  • foley
  • good eye protection
• secure everything
• Consider disconnecting the monitors
• Turn pt to prone postion onto OR table (you in charge of head/neck/airway
• Once turned, check breath sounds again
  
  • make sure monitors are on and working
  • check IV and art line
• Check for excessive pressure on eyes, nose, chin, upper extremities, breasts, genitals, etc
• Chest and hips should be supported to allow for free abdomen for diaphragmatic movement and increased venous return

Question 8

How do you position the head in prone position?

Answer 8

• Head may be turned to side if they have adequate mobility
  
  • caution: obstruction of jugular venous drainage and vertebral artery flow
• Head supported face down with its weight on bony structures
• Neck should be in neutral alignment, not excessive flexion or extension
• Eyes, nose, ears should all be free of pressure

Question 9

What are the risks for the eyes in prone position?

What are the risk factors for blindness in the OR?

Answer 9

• Corneal abrasions
  
  • direct trauma, dry eye, or swelling
  • treatment is antibiotic ointment, eye patch
• Blindness
  
  • ischemic optic neuropathy
    
    • via central vein or artery obstruction
    • via sustained, direct pressure on the eye/retina
  • visual changes/ partial or complete blindness
  • Risk factors include prone position, operative hypotension, large operative blood loss, large crystalloid use, anemia, smoker, diabetic, patients with vascular pathology or HTN, males
  • Caution in spinal surgery and cardiac surgery

Question 10

What do you do with the extremeties in prone position?

Answer 10

• Arms:
  
  • on boards by the head
  • abducted less than 90 degrees
  • extra padding at elbow
  • prevent shoulder from sagging
  • watch for thoracic outlet syndrome
    
    • or tuck arms at sides
• legs:
  
  • slightly flexed
  • compression socks/SCD

Question 11

What CV changes would you expect with a proned patient?

Answer 11

• IVC and Aortic compression- hypotension
• Venous pooling in lower extremities- hypotension
  
  • leads to decreased preload, CO, and BP
• Hypotension associated with the move to prone position must be anticipated, monitored, and treated as necessary.
  
  • prolonged hypotension in addition to pressure on the face/eyes may lead to blindness!!

Question 12

What ventilatory changes would you expect in a proned patient?

Answer 12

• V:Q mismatch
  
  • posterior would have ventilation > perfusion
  • anterior would have perfusion > ventilation
• Cephaled displacement of diaphragm
  
  • decreases lung compliance
  • increased peak airway pressures
  • increased WOB
• **Use rolls/bolsters to free chest
• PPV overcomes compression effects

Question 13

What cerebral blood flow changes would you anticipate in a proned patient?

Answer 13

• Turning head obstructs venous drainage leading to increased cerebral volume and ICP
• Excess flexion or turning can obstruct vertebral artery flow
• spinal cord injury can be caused by stretch

Question 14

What is lateral decubitus position used for?

What special accomodations does it require?

Answer 14

• Used for:
  
  • thoracotomy
  • kidney
  • shoulder
  • hip surgery
• Requires special positioning of:
  
  • head support- neutral position
    
    • avoid misalignment of cervical spine or stretch of brachial plexus
  • Limited pressure on dependent eye and ear
  • axillary roll placed caudad to and outside of lower axilla (pic on front of card)

Question 15

What should you do with the extremeties when positioning your patient laterally?

Where does the safety strap go?

Answer 15

• Arms:
  
  • dependent arm on a padded arm board perpendicular to torso
  • Non-dep arm supported over folded bedding or suspended with armrest
• Legs:
  
  • padding between knees and flexed dependent leg (to avoid saphenous nerve injury)
  • padding on bed (to avoid common peroneal nerve injury)
• Anterior/posterior support- bean bag/hip posts
• Safety strap- between head of femur and iliac crest

Question 16

What cardiovascular changes would you expect when you postion your patient laterally?

Answer 16

• Minimal changes
• no change to CO unless venous return is obstructed
  
  • if the kidney rests against the vena cava
• Non-invasive BP cuff measurements will be different in the two arms
  
  • higher in dep
  • lower in non-dep

Question 17

What ventilatory changes would you expect in your laterally positioned pt?

Answer 17

• V/Q mismatch
• If awake and spontaneously breathing:
  
  • dependent lung is both better perfused and better ventilated
  • lung volumes (FRC, VC, TV) decrease
• Anesthetized but spontaneously breathing
  
  • Non-dep lung better ventilated and dep lung better perfused (V/Q mismatch)
• Anesthetized, mechanically ventilated:
  
  • Non-dep lung overventilated and dep lung over perfused (worse V/Q mismatch)

Question 18

What changes to cerebral blood flow would you anticipate in a pt positioned laterally?

Answer 18

• Minimal change unless there is extreme flexion

Question 19

When is the sitting position used?

Answer 19

• Used for:
  
  • cranial surgery
  • shoulder
  • humoral
• Facilitates venous drainage
• excellent surgical exposure

Question 20

How should you position the head when placing your patinet in sitting position?

Answer 20

• Head should be fixed in pins or taped in place
• avoid excessive cervical flexion (want at least two finger breadths between mandible and sternum)
  
  • obstructs outflow causing hypoperfusion or venous congestion in the brain
  • stretches cervical nerve roots
  • can obstruct ETT
  • can place pressure on the tongue (swelling)
• Avoid rigid bite-block that can cause tongue eschemia
• watch spinal alignment

Question 21

How can you ensure your patient is well positioned in sitting position?

Answer 21

• Arms should be supported- avoid traction pulling down on shoulders
• Buttocks should be positioned in the break of the table
• Flex knees and hips- decrease stretch of sciatic nerve
• compression socks/SCD
• feet supported and padded

Question 22

What cardiovascular changes would you anticipate for a pt in sitting position?

Answer 22

• Pooling of blood in lower extremeties decreases preload, CO, and BP
  
  • HYPOTENSION!!
• HR and SVR increase as a compensatory measure (blunted by anesthetics)
• Treatment: IVF, vasopressors, adjustments of ansethetic depth, compression socks/devices

Question 23

What ventilatory changes would you anticipate in a patient in sitting position?

Answer 23

• Lung volumes and capacities increase
• compliance increases
• WOB is easier
• Mechanical and spontaneous breathing is easier in this position

Question 24

What changes to CBF would you anticipate in a pt in sitting postition?

Answer 24

• Cerebral blood flow decreased
• ICP decreased
• watch positioning which can impede arterial and venous blood flow, causing hypoperfusion or venous congestion of the brain
• zero art line at circle of willis

Question 25

What is a major risk associated with the sitting position?

Answer 25

* Venous air embolism is a risk **any time the surgical site is above the level of the heart** * VAE prevents venous sinuses from being able to collapse * can be a lethal complication * Signs of VAE: * change in heart tones (wind mill murmor) * new murmor * dysrhythmias * hypotension * desaturation * decreased ETCO2 * nitrogen in exhaled gas * circulatory compromise * cardiac arrest * detected with TEE or precordial doppler

Question 26

Where would you hear the wind mill murmor associated with VAE?

Answer 26

* Heard via doppler placed at the parasternal border * 2nd-6th intercostal space

Question 27

How is VAE treated?

Answer 27

* Flood surgical field with NS, apply wax to cut bony edges, close any open vessles * D/C nitrous * place on 100% FiO2, peep * t-berg position * aspirate air from right atrium via a catheter