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)