Mod10: Anesthesia for Orthopedic Surgery - Positioning

Question 1

_{Anesthesia for Orthopedic Surgery}

Anesthetic Challenges

Answer 1

Minor

^{Finger - Knee arthroplasty}

Major

^{Spinal fusion for scoliosis - Hemipelvectomy}

Variety of patients

^{Neonate with CHD - Young healthy adult}

^{Elderly with CAD, COPD, DM, OSA}

_{206 bones in body}

_{Vast range of patients – neonate with Congenital Heart disease, Elderly pt with multi-organ failure, and at the very least, CAD in almost all patients of advanced age.}

_{Providing anesthesia for orthopedic surgery requires knowledge of a wide range of procedures, as well as competence to care for a diverse group of patients.}

_{Example of some of the more straightforward procedures are: repair of a minor finger injury or a knee arthroplasty (more commonly known as a knee “replacement”)}

_{Examples of more complex or major orthopedic surgical procedures include: a spinal fusion for scoliosis or a hemipelvectomy}

_{Patients can vary in age and comorbidities. For example, at CHOG, you may be caring for a young neonate with a congenital heart defect. In a trauma center, you may provide anesthesia for a young, otherwise healthy patient with a major pelvic fracture following a MVA. Another example would be an elderly patient with a hip fracture who has CAD, along with a number of other comorbidities, such COPD, DM, and/or OSA}

Question 2

_{Anesthesia for Orthopedic Surgery}

Special Anesthetic Considerations

Answer 2

Positioning

Pneumatic tourniquet

Bone cement

Fat embolism

Venous air embolism

Thromboembolic event

Large blood loss

_{Some special anesthetic considerations specific to orthopedic procedures include: positioning, pneumatic tourniquet, bone cement (polymethylmethacrylate), fat emboli, thromboembolic events, and the potential for large blood loss}

Question 3

_{Anesthesia for Orthopedic Surgery}

Most common Positions:

Answer 3

Prone

^{spine cases (e.g. PCF, lumbar and thoracic fusions, laminectomies}

Beach chair (semi-sitting)

^{Shoulder arthroscopy or Total shoulder arthroplasty}

Lateral

^{Some hip surgeries; some thoracic and lumbar spine cases}

Supine

^{with HOB down (knee surgeries – knee scope or total knee arthroplasty) – usually have leg holder for leg}

_{Positioning will depend on access needed and surgeon preference}

Question 4

_{Anesthesia for Orthopedic Surgery}

Prone Position

^{used for:}

Answer 4

Spine cases

(e.g. PCF, lumbar and thoracic fusions, laminectomies)

Question 5

_{Anesthesia for Orthopedic Surgery}

Beach chair (semi-sitting) Position

^{used for:}

Answer 5

Shoulder arthroscopy

or

Total shoulder arthroplasty

Question 6

_{Anesthesia for Orthopedic Surgery}

Lateral Position

^{used for:}

Answer 6

Some Hip surgeries

Some Thoracic and Lumbar spine cases

Question 7

_{Anesthesia for Orthopedic Surgery}

Supine (with HOB down) Position

^{used for:}

Answer 7

Knee surgeries

Knee scope or total knee arthroplasty

_{usually have leg holder for leg}

Question 8

_{Anesthesia for Orthopedic Surgery}

Positioning

^{extreme variations:}

Answer 8

Wilson frame

Fracture table (Chick)

Jackson table

_{Positioning will depend on access needed and surgeon preference}

Question 9

_{Anesthesia for Orthopedic Surgery}

Spontaneously breathing patients under GA

^{Altered pulmonary function d/t Positioning}

Answer 9

Decreased Vt and FRC

Increased closing volume

^{(i.e. their small airways are more prone to collapse)}

Diaphragm displaced unevenly

^{(due to loss of muscles tone)}

^{_{[Review Miller Chapter 19]​}}

Question 10

_{Orthopedic Surgery - Altered pulmonary function d/t Positioning}

Patients under GA with spinals and epidurals

Answer 10

Loss of abdominal and thoracic muscles function

at the affected dermatome level

Question 11

_{Orthopedic Surgery - Altered pulmonary function d/t Positioning​}

Diaphragm function

^{Patients only having a neuraxial anesthetic without GA nor NMB:}

Answer 11

Normal

Question 12

_{Orthopedic Surgery - Altered pulmonary function d/t Positioning​}

Atelectasis d/t general anesthesia

^avoidable?

Answer 12

Unavoidable

Question 13

_{Orthopedic Surgery - Altered pulmonary function d/t Positioning​}

Minimizing atelectasis during GA

^how?

Answer 13

Set an appropriate Vt for the patient

Add PEEP

Give sigh breaths

Use recruitment maneuvers (”Valsalva”) from time to time to try to re-open collapsed alveoli

(delivery of sustained pressure 30-40 cmH20 – for several seconds => just know you will have a drop in BP d/t decreased venous return)

=> This may not be appropriate for all patients

=> i.e. if you are battling hypotension, might not be the time to do this

Question 14

_{Orthopedic Surgery - Altered pulmonary function d/t Positioning​}

Positioning that impairs diaphragmatic, chest wall or abdominal movement

^{lead to:}

Answer 14

Further increase the risk for atelectasis and intrapulmonary shunt

Positions that cause gastric contents to be pushed cephalad or compressed => decreased FRC and TLV

May see increased Peak Airway Pressures

=> Smaller VT => Atelectasis => Decrease SpO2 reading

Question 15

_{Orthopedic Surgery - Altered pulmonary function d/t Positioning​}

How to Prevent or Treat pulmonary function alterations?

Answer 15

Make sure abdomen is free of pressure.

May need to give NMBs and/or change to PCV and adjust other vent settings

Prone position actually can improve respiratory function

Under GA, prone position is more favorable than supine in relation to lung volumes and oxygenation

Question 16

_{Orthopedic Surgery - Positioning and CV Function}

Altered CV functions

Answer 16

VR

Arterial tone

Autoregulation

_{Risk for hemodynamic compromise with position change (because the body’s mechanisms of autoregulation/adjustment are inhibited)}

Question 17

_{Orthopedic Surgery - Positioning and CV Function}

Causes of Altered CV functions

Answer 17

GA

Muscle relaxation

PPV

Neuraxial blockade

Question 18

_{Orthopedic Surgery - Positioning and CV Function}

Awake patient lies down in a supine position

^{CV changes:}

Answer 18

Improved VR

Increased CO

Increase in right heart filling pressure

Decrease in HR (Baroreceptor-mediated)

Vasodilation (there are also mechanoreceptors and arterial reflexes involved in this autoregulation)
Ultimately the body normalizes (autoregulates) the HR and BP back to baseline)

Question 19

_{Orthopedic Surgery - Positioning and CV Function}

Patient under anesthesia in a supine position

^{Autoregulation:}

Answer 19

Compromised

Patients hemodynamically labile just after induction or just after a position changed

Monitor BP frequently and treat appropriately

This is especially important to remember when the surgical team is rushing to get the patient positioned right after induction or when you have flipped your patient to a prone or lateral position

Remember to hook all of your monitors back up after your airway management (i.e. hooking circuit back up and making sure you haven’t lost your airway)

Question 20

_{Orthopedic Surgery - Positioning and CV Function}

CV effects of Sitting position or Rev. T-burg

Answer 20

BP can drop significantly when changing from a supine to sitting position

Consider sitting patient up in increments

Be ready to treat with volume and/or pressors
May need to turn INH agent down

Question 21

_{Orthopedic Surgery - Positioning and CV Function}

CV effects of Extreme flexion of neck

Answer 21

Can inhibit venous and arterial blood flow

=> decreased cerebral perfusion and increased cerebral venous congestion

Can impair respiratory mechanics

ETT can become obstructed; with flexion
=> maintain 2 FB between chin and sternum

Question 22

_{Orthopedic Surgery - Positioning and CV Function}

CV effects of Prone position

Answer 22

If the lower extremities are kept level with the torso

=> hemodynamic stability is preserved

If legs lowered or if OR bed is tilted L or R

=> VR will decrease or increase accordingly

Question 23

_{Orthopedic Surgery - Positioning and CV Function}

CV effects of Lateral position

Answer 23

There is potential for a decrease in VR if kidney rest isn’t properly placed

=> should be placed under the iliac crest

=> prevents compression of the IVC and to prevent impaired ventilation of the dependent lung

Do not place under flank or lower costal margin

Monitor pulse ox in dependent arm

=> a decrease in saturation may be an early sign that blood flow to axillary neurovascular structures is compromised or inadequate

Question 24

_{Orthopedic Surgery - Effects of positioning}

Effects of Lateral Position and V/Q Mismatch

^{in an wake, spontaneously breathing patient:}

Answer 24

V/Q ratio is not greatly changed

Dependent lung => better ventilated and better perfused

Question 25

_{Orthopedic Surgery - Effects of positioning} **Effects of Lateral Position and V/Q Mismatch** ^{Once the patient is anesthetized and mechanically ventilated:}

Answer 25

**Pulmonary function** is **compromised** *Non-dependent lung (Up lung)* = better ventilated, but poorly perfused **Dependent lung (Down lung)** = poorly ventilated, but blood flow increases to this lung (gravity) =\> so better perfused

Question 26

_{Orthopedic Surgery - Effects of positioning} **Nerve injury** results when:

Answer 26

Nerves are compressed, stretched, or lack adequate blood flow Injury can also occur as the result of direct trauma (laceration during surgery; injury from needle during nerve block placement)

Question 27

_{Orthopedic Surgery - Effects of positioning} **Most common** nerve injuries:

Answer 27

**Ulnar nerve** damage _{is complex, involves a number of factors, can’t always be prevented; exact etiology is not fully understood; damage can be temporary or permanent}

Question 28

_{Orthopedic Surgery - Effects of positioning} **Second most common** nerve injuries:

Answer 28

**Brachial plexus** injury results from stretching and compression; associated with abducting the arm \> 90 degrees, rotation of the head from L to R (laterally), asymmetrical sternal retraction for dissection of the internal mammary artery during open heart surgery

Question 29

_{Orthopedic Surgery - Effects of positioning} How to prevent **Brachial Plexus** injury?

Answer 29

Keep **head** midline, **arms** at side, mildly flex **elbows**, and **forearms** should be supinated

Question 30

_{Orthopedic Surgery - Effects of positioning} Potential causes of **Postoperative visual loss**:

Answer 30

Ischemic Optic Neuropathy (primarily) and Central retinal arterial occlusion

Question 31

_{Orthopedic Surgery - Effects of positioning} Perioperative factors a/w **Postoperative visual loss**:

Answer 31

Extensive periods of hypotension, long surgeries in the prone position, excessive blood loss, excessive administration of crystalloid, anemia or hemodilution, increased IO or venous pressure from the prone position Hyperglycemia, hypothermia, repeat spine surgery in prone position, preop donation of blood leading to a low Hct, smoking, obesity

Question 32

_{Orthopedic Surgery - Effects of positioning} Perioperative factors a/w **corneal abrasion/injury** and **Prevention/Treatment:**

Answer 32

Swelling of eyes during prone cases is associated with corneal abrasion/injury; carefully tape the eyes, lacrilube; watch out for dangling objects (lanyard with badge, stethoscope); remind patients not to rub the eyes; be very careful and aware of eyes when changing positions

Question 33

_{Orthopedic Surgery - Effects of positioning} Effects of **Rheumatoid Arthritis**

Answer 33

Joint pain and inflammation, can affect other organs Frequent fatigue, low grade fever, anorexia, muscle/joint aches, stiffness; check cervical ROM; may need C-Mac or Glidescope; can have patient position themselves prior to induction and not deviate from that position during induction

Question 34

_{Orthopedic Surgery - Effects of positioning} How should pt with **Decreased ROM** (e.g. Osteoarthritis) be positionned?

Answer 34

According to patient’s ROM Decreased ROM: Osteoarthritis =\> Systemic symptoms are not present. Localized joint pain. Position patients according to their comfort and safety Sometimes patients are contractured, and you have to position according to patient’s ROM

Question 35

_{Orthopedic Surgery - Effects of positioning} **Which patients are induced** on the **stretcher or bed?**

Answer 35

**Trauma** and/**pain** _{may prohibit movement from stretcher to bed} **Prone cases** _{(usually induce on stretcher)}

Question 36

_{Orthopedic Surgery - Effects of positioning} **Safety** considerations with **stretcher or bed at induction**

Answer 36

Still need to bring the patient to top of the bed, position the head and neck in the sniffing position, maximize your ability to access the patient Bring machine to you, etc. May even have to move the OR bed over and out of way, so that the patient is in a SAFE position for induction This may involve removing or adjusting parts of the bed. No matter how much of a rush you or the surgeon is in, as long as the patient is not coding ;), move the patient to a position that is SAFE and IDEAL for induction

Question 37

Orthopedic Surgery - Effects of positioning For a SAB for hip fx

Answer 37

may have to place **SAB** with patient in **lateral position** Make landmarks as usual; Hook patient up to monitors, O2 as necessary; **Aim for belly button,** can throw you off placing lateral position

Question 38

_{Orthopedic Surgery - Effects of positioning} Considerations for **Versed, fentanyl or other anxiolytics, narcotics**

Answer 38

AS TOLERATE many of these patients are fragile, elderly, lots of comorbidities; overall patient morbidity goes up with hip fracture in and of itself in the elderly; some may have already had narcotics; consider holding versed in elderly because of PCD