Patient Positioning

Question 1

Supine Position:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 1

1. Provides easy access to airway, IVs, less physiological changes
2. Pillow under head; avoid felxion or extension of neck due to brachial plexus stretch (35 degrees in sniffing position); arms abducted <90 degrees, SUPINATED; slight leg flexion (watch DVTs if pillow under knees)
3. Minimal overall; Will have initial increased VR, then increases parasympathetic compensation ( 🔽 HR, PVR) Eventual reduced VR due to pooling; careful for IVC compression in pregnant, ascites, obese
4. FRC decreases 800ml due to diaphragm displacement; decreases lung volumes, diaphragmatic excursion; use PIP to help overcome loss of chest wall tone from NMB
5. Minimal; auto regulation tight

Question 2

Trendelenburg Position:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 2

1. Can prevent air embolism; short term hypotension tx;
   upward displacement of abd cavity contents; CVC
   placement
2. Brachial plexus injury; shoulder brace lateral over
   acromioclavicular joint; reduced LE perfusion;
   face/airway
   edema; ASPIRATION RISK
3. Increases VR up to 1L; baroreceptors activates, may
   make shock worse in long term; only use short term for
   shock; increases heart workload
4. Decreases compliance, PIP, FRC; VQ mismatch at apex
   (perfusion>ventilation); risk of ASPIRATION; pulmonary
   vasculature congestion; ETT may shift to RMB
5. Increases ICP; intraocular pressure

Question 3

Reverse Trendelenburg:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 3

1. Enhances view of upper abd contents (laparoscopy,
   cholesystectomy)
2. Watch for foot drop and excessive plantar flexion
   (damages ANTERIOR TIBIAL NERVE)
3. Reduces VR; preload, CO, BP; compensatory mech
   blunted by anesthetics; increased work on heart
4. Ventilation easier; increases FRC and diaphragmatic
   excursion
5. Blood flow decrease, ICP down 20%

Question 4

Lithotomy Position:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 4

1. GYN, GU, rectal procedures; abduct legs 30-45 degrees, flex 80-100; lower legs parallel to torso, place in stirrups simultaneously to avoid torsion
2. Avoid flexion beyond 110; common perineal nerve most commonly damaged lower extremity nerve; LE compartment syndrome; move hips/legs simultaneously
3. Leg elevation increases VR; perfusion change 2 mmHg per every 2.5cm above heart; transient VR/CO increase; when take legs down, hypotension (CHECK BP)
4. Depending on amount of flexion, decreases diaphragm excursion; ⬇️ compliance, TV, VC; increase aspiration risk
5. Transient increase in blood flow

Question 5

Prone Position:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 5

1. Usually cranial surgery; Have Wilson frame (free-hanging
   abd); prepare pt on stretcher before transfer; recheck
   on line placement
2. Check breath sounds first; Neck alignment, pressure on
   eyes, nose; corneal abrasion/pressure, blindness;
   line/ET displacement; always tape eyes closed; ischemic
   optic neuropathy/intaoptical pressure
3. Thoracic outlet syndrome; IVC and aortic compression
   hypotension; ⬇️ CO and BP, especially on initial move,
   pooling in LE causes hypotension
4. VQ mismatch; post vent>perf; ant perf>vent; ⬆️ PIP,
   work of breathing, decrease compliance; have free
   chest excursion and use PPV to overcome effects
5. Obstruct venous outflow if head turned; increases ICP;
   normal ICP otherwise

Question 6

Nerve Damage:

1. Most common overall
2. Second most common
3. Most common lower extremity

Answer 6

1. Ulnar
2. Brachial Plexus
3. Common Peroneal Nerve

Question 7

Common Brachial Plexus Injury Mechanisms (5 items)

Answer 7

1. Neck extension
2. Arm abduction >90
3. Arm falling of table
4. Depressed shoulders (prone/reverse Tren)
5. Compression against thorax (lateral)

Question 8

Radial Nerve:

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 8

1. Innervates lateral aspect of UE
2. Compression usually against humerus; Surgical retractors, ether screen, BP inflation
3. Loss of extension of forearm, wrist drop (loss of hand extension), loss of sensation in lateral arm/posterior forearm

Question 9

Ulnar Nerve Compression:

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 9

1. Runs in grove between olecranon and medial epicondyle of humerus
2. Most commonly injured nerve; compression between olecranon and medial epicondyle; severe stretch (arm falling off table); compression against bed; misplaced BP inflation
3. Loss of grip, inability to abduct or feel on palmar side of 4/5th finger; atrophy (claw hand)

Question 10

Common Peroneal Nerve

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 10

1. Branch of sciatic, innervates outer calf; most common lower extremity injury
2. Compression of lateral knee (lithotomy or lateral)
3. Foot drop; inability to evert foot or dorsiflex toes

Question 11

Popliteal Nerve Injury

1. Anatomy
2. Injury Mechanisms

Answer 11

1. Branch of sciatic that innervates back of knee

2. Compression behind knee (lithotomy); especially in Knee-Crutch style stirrups

Question 12

Sciatic Nerve

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 12

1. Runs from buttock through lower limb, comes off L1 and S1
2. Excessive rotation of hips; pressure on sciatic notch (posterior buttocks)
3. Paralysis or weakness of muscles below knee; foot
   drop; lateral calf and foot numbness

Question 13

Femoral Nerve Injury

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 13

1. Runs length of internal thigh; branches from L2-L4
2. Compression at pelvic brim; excessive angulation/abduction (>45) of thighs and external rotation (lithotomy); flexion > 110 degrees
3. Loss of flexion at hip; loss of extension of knee; decreased thigh sensation

Question 14

Saphenous Nerve Injury

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 14

1. Medial aspect of the thigh and calf; branch of
   femoral nerve
2. Compression of medial aspect of leg against support bar (lithotomy)
3. Parathesia medial and antemedial part of calf

Question 15

Lower Compartment Syndrome

1. Occurrence
2. Symptoms
3. Treatment

Answer 15

1. Typically long lithotomy/lateral cases (>2-3 hours)
2. Ischemia, edema, rahbdomyolysis
3. Fasciotomy

Question 16

Thoracic Outlet Syndrome

1. Definition
2. Test

Answer 16

1. Poor circulation in vessels between upper extremities and trunk
2. Extend pt hands over head for 1 minute; check perfusion

Question 17

Lateral Position:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 17

1. Kidney, lung shoulder, hip surgery
2. Neutral head support, pressure on dependent eye/ear
   Axillary Roll placed just below axilla; knee padding to
   prevent saphenous injury, on bed to prevent common
   peroneal injury
3. Minimal; no change in CO unless VR obstructed; BP will
   be different in arms
4. VQ mismatch (see other slide)
5. Minimal unless extreme flexion

Question 18

Lateral Position VQ Mismatch:

1. Awake/Spontaneous Breathing
2. Anesthetized/ Spontaneous Breathing
3. Anesthetized/ Mechanical Ventilation

Answer 18

1. Dependent lung: better perfused and ventilated (lower lung volumes)
2. Dependent lung: better perfused, Nondependent lung: better ventilated (VQ Mismatch)
3. Dependent lung: overperfused; Nondependent lung: overventilated (worse VQ mismatch)

Question 19

Sitting Position:

1. Indications
2. Risks
3. Cardiovascular Changes
4. Respiratory Changes
5. Cranial Changes

Answer 19

1. Cranial, shoulder, humeral procedures
2. Avoid excessive neck flexion (2 FB between mandible and sternum); flexion can cause venous congestion, cervical nerve stretch, tongue swelling; ET tube kink; flex knees; support arms so no downward pulling to preven brachial plexus injury; flex knees to prevent sciatic injury
3. Pooling of blood in LE; HYPOTENSION; HR and SVR usually blunted by anesthetics; check BP often
4. Lung volumes and capacities increased; compliance increases; work of breathing decreases
5. ICP and cerebral blood flow decreased

Question 20

Venous Air Embolism

1. Risk
2. Detection

Answer 20

1. Anytime surgical field above level of heart
2. TEE (higher sensitivity) or prerecordial Doppler
   (parasternal border, 2-6 ICS)

Question 21

Venous Air Embolism Treatment (5 items)

Answer 21

1. Flood surgical field with NS, apply wax to bones, close
   any open vessels
2. D/C N20
3. Place on 100% and PEEP
4. Durant Maneuver: place pt in L Lat decubitus and
   T-berg
5. Aspirate air via CVC

Question 22

5 Nerve Injury Mechanisms

Answer 22

1. Compression
2. Stretching
3. Trans-section
4. Ischemia
5. Knotting/Kinking

Question 23

Brachial Plexus:

1. Anatomy
2. Injury Mechanisms
3. Symptoms

Answer 23

1. C5-T1; runs through vertebral foramina fasciaa, under clavicle, over first rib, to the humerus (contains ulnar, median, and radial nerve)
2. Sagging at shoulders (sitting), neck flexion/extension, lateral compression against thorax (lateral), abducting arms >90 (supine/prone)
3. Second most common injury: loss of motor control, paralysis/parathesia of UE

Question 24

Position Documentation (4 items)

Answer 24

1. Baseline ROM
2. Inta-op position
3. Use of padding, frames
4. Checks done and frequency

Question 25

OR Table: 1. Weight Limit 2. Height Limit 3. Patient Position

Answer 25

1. 136kg (300 lbs) 2. 80.7 inches (6'7") 3. Body centered under central column

Question 26

Ischemic Optic Neuropathy Risk Factors (7 items)

Answer 26

1. Prone position 2. Operaitve hypotension 3. Operative blood loss 4. Large crystaloid use 5. Anemia 6. PVD (diabetes/smoking) 7. HTN

Question 27

Venous Air Embolism Sypmtoms (6 items)

Answer 27

``` 1. Mill wheel murmur (constant, machine like murmur @ parasternal border 2-6 IC space) 2. Dysrhythmias, 3. decreased ETCO2, 4. Hypotension, 5. Desaturation, 6. Nitrogen in exhaled gas ```