Patient Positioning Flashcards
Mechanism of injury for PNI
Stretching, compression, ischemia
Most common PNI
Brachial plexus
When do PNI typically present?
24-48 hr later
Advantages to supine position
Access to airway
Access to arms for IV/monitors
Hemodynamic reserve is maintained
How are arms positioned on arm boards in supine?
Secured to OR table. Abducted <90 degrees Padded Safety straps Hands supinated
How are arms tucked in supine position?
Draw sheet placed under pt hip or torso.
Elbows padded
Palm in.
Make sure IV is dripping before case starts
What 2 mechanisms can cause brachial plexus injury?
Avoid abduction >90 degrees
Avoid direct compression at neck
How can we prevent an ulnar PNI in supine position?
Hands and forearms supinated, or, neutral position w palms towards body
Proper padding at elbow
Potential complications of supine position
Pressure alopecia
Backache
PNI
Aortacabal syndrome (compression of IVC preventing blood flow returning to heart)
Trendelenburg Reasons needed
- Improves exposure during abdominal and lap sx.
- Used during central line placement to prevent air embolism
- Can help increase venous return during hypotension
CV and respiratory consequences of trendelenburg?
Increase venous return
Decrease FRC
Decrease pulmonary compliance
How does trendelenburg impact cerebral blood flow?
INCREASE intracranial vascular congestion with gravity.
Causes INCREASED ICP
DECREASED CBF
Also see intraocular pressure increase
How to prevent cephalad slide?
Anti-skid pads Flexion of knees Shoulder braces (try to NEVER use) Beanbag cradling Cross-torso straps
If using shoulder braces, where should they be positioned to minimize injury
Laterally AWAY from root of neck over the arcomioclavicular joint
Anesthestic concerns with using trendelenburg position?
Swelling of face, tongue, larynx
Stomach is above glottis
“Migration” of ETT
Purpose of reverse trendelenburg
Facilitates upper and sx (shifts abdominal contents caudad)
Anesthetic concerns for reverse trendelenburg
Caudal slipping
Decreased venous return
Cerebral perfusion pressure decrease
Lithotomy position hips flexed at? Legs abducted at?
- Hips flexed 80-100 degrees
- Legs abducted 30-45 deg from midline
- Knees flexed until lower legs parallel with torso.
- legs must be raised at SAME time
Which PNI can be caused by improper positioning of lithotomy position?
Femoral Sciatic Obturator Lateral femoral cutraneous Sphenoid Common peroneal
Concerns with use of candy can stirrups
More acute flexion of knees/hips
Injury to common peroneal nerve, femoral, sciatic
Concern of knee-crutch style lithotomy position
Popliteal nerve (tibial nerve and common peroneal nerve) Sciatic
What to watch for in lithotomy position?
Fingers! Major risk for crush injury when table is lowered if arms are tucked in
Cv consequences with lithotomy
Legs elevated increases venous return
Transient increase in co
Respiratory consequences for lithotomy
Cephalad displacement of abd contents
Decreased lung compliance
Decreased TV
Increased peak pressure
Limit for legs in air for lithotomy and why?
Legs need to be lowered if sx extends >2-3 hr.
Concerned for compartment syndrome
Decrease in arterial pressure for each cm above RA?
0.78 mmHg
At what pressure would a decompressive fasciotomy be performed?
30 mmHg
At what point is there irreversible muscle damage from compartment syndrome?
50 mm Hg
Risk factors for compartment syndrome in lithotomy
High BMI, peripheral vascular dx Hypotension Reduced cardiac output Smokers
Lateral decubitus position is used during…
Thorax sx,
Retroperitoneal sx
Hip
What do we need to pay attention to with lateral decubitus position?
Head neutral, in line with spine with pillows
Arms abducted <90
Dependent ear is flat
Dependent eye is free from material
What do we use in lateral decubitus position to decrease risk of auxiliary PNI?
Axillary roll.
Between chest wall and bed, just caudal to dependent axilla.
What do we need to be checking in dependent arm in lateral decubitus?
Pulse in dependent arm.
Know that the NIBP will be higher in dependent arm.
Padding all bony prominences
How are the legs placed in lateral decubitus
Lower leg (dependent leg) flexed with pillows between legs.
Pulmonary consequences of lateral decubitus
In mechanically ventilated, paralyzed pt- dependent lung is compressed by weight of mediastinum and cephalad pressure of abd contents.
Unanesthetized patient ventilation/perfusion in non dependent vs dependent
Non dependent lung had decreased ventilation and perfusion.
Dependent lung has increased ventilation and perfusion.
Anesthetize patient v/q in non dependent and dependent lung?
Non dependent lung has increased ventilation but decreased perfusion
Dependent lung has decreased ventilation, but increased perfusion
Ventilation/perfusion in awake and spontaneous breathing patient
Dependent (lower) lung is both better perfused and better ventilated.
LUng volumes (FRC, VC, TV decreased)
V/Q mismatch in anesthetize but spontaneous breathing
Non dependent lung between ventilated and dependent lung better perfused
V/Q mismatch in anesthetized, mechanically ventilated pt
Nondependent lung OVERventilated and dependent lung OVERperfused (wise v/q mismatch)
Prone position alternative name
Ventral decubitus
Anesthetic concerns with positioning for prone position
Thoracic outlet syndrome
PNI- posterior fossa, post spine, perirectum, lower extremities
INTUBATE IN STRETCHER!
Eye care!
Secure ETT well
You are responsible for head.
What do we do to legs in prone position?
Flex and pad legs
What do we do with face in prone position?
Can be neutral or turned to side. Do not turn head if any cervical issues, CVA hx, carotid dx etc
Positioning of arms in prone position?
Superman or tucked at sides. Arms remain <90
What do we assess immediately after turning to prone position?
Breath sounds!
Concerns for mayfield head tongs/pins
Watch for bolt slippage
Need neutral neck alignment
Eyes, nose chin free of pressure
Huge concern for prone position?
Vision loss, ischemic optic neuropathy
What can increase risk for ischemic optic neuropathy
Intraoperative hypotension Anemia Increased crystalloid use Large blood loss Long duration of sx Head down leading to increased IOP
What do we need to do to abominable in prone position?
Elevate abdomen to decrease compressure.
Increased abdominal pressure impedes venous return
Increased abdominal pressure can cause “back bleeding” from increased abdominal pressure pushing blood through epidural arteries.
What will abdominal pressure in prone position cause in regards to respiratory status?
Decreased FRC, decreased pulmonary compliance, increased peak airway pressure
Place rolls or bolsters clavicle to iliac crest.
Cardiovascular changes in prone position
IVC and aortic compression can cause hypotension
-venous pooling in lower extremities and cause hypotension
- hypotension can occur with move to prone position.
(Prolonged hypotension in addition to pressure on face/eyes may lead to blindness)
Prone position impact on cerebral blood flow?
Turning head obstructs venous drainage, may lead to increase ICP and increase cerebral volume
Excessive flexion or turning, obstructed vertebral artery flow
May cause spinal cord injury from stretch
Where do we place breast in regards to Wilson frame
Medial
Concerning populations for prone position
Morbidly obese
Respiratory compromise
Repositioning difficulty
Sitting position advantages
Excellent surgical field for post cervical spine and post fossa.
Dec blood in operative field
Reduced perioperative blood loss
Surgical disadvantages to sitting position
Venous and paradoxical air embolism
Anesthesia advantages to sitting position
Superior access to airway
Reduced facial swelling
Improved ventilation
Anesthetic concerns for sitting position
Head may be pinned/ taped
Arms need to be supported
Knees slightly flexed to reduce stretching on sciatic nerve
Feet supported and padded
Hemodynamic effects with sitting position?
Drastic effects
Pooling of blood causes hypotension.
- use IVF, Vasopressors, adjustment of anesthetic depth, leg compression devices to promote V.R.
What happens when head/neck flexed in sitting position
Impendance of blood flow
Causes hypoperfusion/venous congestion of brain
Can block ETT
Create pressure on tongue
Medcervical tetraplegia (makes someone quad by pulling/stretching of cervical spine)
Anesthesia ROB is 2 FB d/t mandible and sternum
Beach chair position advantages
Superior access to shoulder compared to lat dec position.
Better mobility/manipulation of joint
Anesthetic concerns for beach chair position
Significant Neuro and CV alterations
Decreased venous return Reduced CPP Reduced preload, CO, BP Hypotension (deliberate or permissive) Failure to compensate for height of head!
Ventilator changes with sitting position?
Lung volume and capacities increase
Compliance increase
Work of breathing easier
Mechanical and spontaneous ventilation easier
Huge risk in sitting position?
Elevation of sx field above heart and open rural sinuses might cause VAE
Signs of venous air embolism
Change in hear tones (wind mill murmur)
- can be heard via Doppler at parasternal border,
- dysrhythmia
- hypotension
- desaturation
- decreased ETCO2
- nitrogen in exhaled gas
- circulatory compromise and cardiac arrest
Treatment of VAE
Flood sx field with NS Apply wax to cut bony edges Close any open vessels D/c nitrous oxide Place on 100% o2, peep T-berg position Aspirate air from RA via a catheter.
Anesthetic considerations in sitting position
Monitor BP in reference to level of brain
- Avoid and rapidly treat hypotension or bradycardia
- Careful position of head to prevent occlusion of cerebral vessels,
- monitor CPP if available
Brachial plexus injury can be caused by:
Positioning injury
- neck extension, head turned to side/sagging sideways
- excessive abduction of arm >90 deg
- arm/arm board falls off table
- depressed sagging shoulders in prone/sitting position
- extended arms overheard in prone
- compression plexus against thorax
- shoulder braces
- sternum retractors in cardiac sx
Deficit noted in brachial plexus injury
Limp/paralyzed arm
Lack of muscle control in arm/hand/wrist
Lack of sensation in arm/hand
Ulnar nerve deficits
Inability to abduct or oppose 5th finger
Loss of grip strength- esp ulnar side
Loss of sensation palmar surface of hand 4th,5th fingers.
Eventually leads to claw hand
Radial nerve injury cause
Due to external compression of radial nerve on lateral aspect of humerus against:
- sx retractors
- ether screen
- mismatched arm board
- repeated BP inflation
Deficit of radial nerve if injured:
Loss of extension of forearm
Weakness of supination
Loss of extension of hand, wrist drop and fingers
Loss of sensation in lateral arm, posterior forearm, part of hand
Where does ulnar nerve run?
Between olecranon of ulna and medial epicondyle of humerus
What causes ulnar nerve injury?
Compression of nerve b/w olecranon of ulna and medial epicondyle of humerus (entrapment with arm extension)
Stretch with severe elbow flexion
Dislocation over medial epicondyle with pronation hand causing stretching
Compression against bed
Misplaced BP cuff
Common peroneal nerve injury cause
Compression of lateral aspect of knee against stirrup or lateral position
Common peroneal nerve injury symptoms
Foot drop
Inability to evert foot
Loss of dorsal extension of toes
Sciatic nerve injury cause
Excessive external rotation in hips
Hyperextension of knee
Pressure in sciatic notch from stretching
Sciatic nerve injury symptoms
Weakness/paralysis of muscles below knee
Numbness of foot and lateral half of calf
Foot drop
Femoral nerve injury causes
Injured with compression at pelvic brim by retractor or excessive angular ion of thigh and external rotation of hips
Femoral nerve symptoms
Loss of flexion hip and loss of extension of knee
Decreased sensation over superior aspect thighs
Saphenous nerve injury cause
Occurs when medial aspect of lower leg is compressed against support bar
Saphenous nerve injury symptoms
Parenthesis medial and antermedial side of calf
Lower extremity compartment syndrome
- Occurs when perfusion to extremity is inadequate, results in 1)ischemia
2) edema
3) extensive rhabdomyolysis
Occurs with long sx procedures >2-3 hrs
Occurs with lithotomy and lateral decubitus position
Treatment fasciotomy
Radial nerve location, etiology of nerve damage and presentation.
Passes along spiral groove at lateral aspect of humerus (3FB above lateral epicondyle)
Etiology:
- External compression IV pole
- Excessive cycling of NIBP cuff
- UE tourniquet
- Sheets too tight if arms tucked
Presentation:
Inability to extend the hand at the wrist.
Median nerve
Type of injury fairly uncommon
Etiology: IV placed in AC space Carpal tunnel syndrome Elbow hyperextension Forced elbow extension during positioning after NDNB administered
Presentation:
-Reduced sensation over palmar
surface of thumb, index finger, middle finger, lateral aspect of ring finger
-Inability to oppose thumb
Ulnar nerve location, boundaries, mechanism for injury, risk factors, presentation
Ulnar n emerges from cubical tunnel between numeral head and ulnar heads of flexor carpi ulnaris
Boundaries
1) medial epicondyle of humerus
2) olecranon process of elbow
3) cubical tunnel retinaculum
Mechanism
1) external compression
2) elbow flexion
Risk factors
1) male
2) preexisting ulnar neuropathy
3) extremes of body habitus
4) prolonged bed rest
Presentation
1) impaired sensation of 4th and 5th digit
2) inability to abduct or oppose 5th digits
Brachial plexus stretch injury
Stretch injury due to fixed anatomical locations (cervical vertebrae and axillary fascia)
Asa general rule, risk of stretch is highest when arms abducted >90 degree and head rotated to one side
Brachial compression injury
Occurs when brachial plexus compressed as it passes b/w clavicle and 1st rib or by an external force
Sternotomy retractors may compress the brachial plexus under the first rib
Brachial plexus injury presentation
Following non cardiac sx, motor deficit in upper and middle nerve roots may be experienced (median and radial nerve)
Following cardiac sx- deficit presents in lower nerve roots (ulnar nervE) and is sensory related
Obturator nerve injury etiology, presentation, prevention
Excessive flexion of thighs towards groin
Excessive traction during lower abd surgery
Forceps delivery
Presentation
Inability to ADDUCT the leg
Reduced sensation over medial aspect of thighs
Prevention
Minimize hip flexion
Femoral nerve etiology, presentation
Etiology
Excessive traction during lower abd sx
Presents
Impaired knee extension and hip flexion
Reduced sensation over anterior thigh and anterolateral aspect of leg
Saphenous etiology, prevention, presentation
Etiology- medial aspect of leg leans against supporting cradle of lithotomy position
Prevention
Place padding b/w leg and stirrups
Presentation
Reduced sensation over anteromedial aspect of leg
Common peroneal etiology, presentation, prevention
Branch of sciatic
Etiology
Highly susceptible to injury when pt placed in stirrups
Nerve wraps around fibulae head and compromised when lateral aspect of leg makes contact with stirrup bar
Presentation
Foot drop
Inability to ever foot
Inability to extend toes dorsal
Prevention
Place padding b/w leg and stirrup
Place padding under fibulae head
Knees flexed with min rotation
Sciatic nerve etiology, prevention, presentation
Etiology
External rotation of leg
External rotation of knee
Prevention
Appropriate padding under buttocks
Avoid extreme rotation of hip
Flex table at knees
Presentation
Foot drop
