/study / lectures / General Principles
Patient Positioning + Position-Related Injuries
TEXTGeneral Principles · 8 min read
Where the hands meet the gel pad is where lawsuits start. Brachial plexus, ulnar, peroneal, sciatic injuries — all preventable with deliberate setup.
After this lesson you can
2 min read7 sections- Identify positioning-related injuries by site.
- Pad pressure points correctly.
- Avoid POVL in prone/sitting cases.
- Document positioning + checks.
Supine — most common injuries
Mechanism: forearm pronated + elbow flexed compresses ulnar nerve at cubital tunnel.
- arms supinated (palms up) or neutral
- padded elbow
- abduction ≤90°
Brachial plexus stretch from arm abduction >90° + lateral head rotation.
Heel/sacral pressure ulcers in long cases.
Posterior alopecia from prolonged scalp pressure.
Lithotomy
Femoral nerve from hip hyperflexion + abduction + external rotation.
Sciatic from prolonged hip flexion.
Compartment syndrome of lower legs in long lithotomy (>4 hr) — perfusion pressure drops in elevated legs.
Lower legs sequentially (one at a time) to prevent sudden venous return shift and hypotension.
Pad popliteal fossa.
Prone
- long surgery (>6 hr)
- large blood loss
- hypotension
- steep head-down
- direct eye pressure
- head-neutral on Mayfield/Prone-view
- document eye checks q15 min
- avoid direct globe pressure
- keep MAP ≥
70 mmHg - head ≥ heart
ETT/airway dislodgement, abdominal/chest compression compromising ventilation + venous return, breast/genital compression.
Mark pulses pre-prone.
Lateral decubitus
Down eye/ear pressure.
Down peroneal nerve at fibular head.
Suprascapular nerve from arm position.
Hemodynamic: V/Q mismatch (dependent lung gets perfusion but reduced ventilation under GA), worse with OLV.
Sitting (beach chair)
1 mmHg.NIBP at arm under-reads brain MAP by 15-20 mmHg.
Maintain MAP appropriate for brain level (use arterial line zeroed at tragus, or add correction).
Venous air embolism risk — surgical site above heart with open venous channels; precordial Doppler + capnogram drop is the alert.
Quadriplegia from neck flexion + chin-on-chest (two-finger gap rule).
Steep Trendelenburg (robotic + laparoscopic)
Shoulder braces cause brachial plexus injury — avoid; use non-slip mattress + crossed arms tucked.
Recheck airway pressures + ETT depth after positioning.
Limit duration where possible.
Documentation + the timeout
Document pre-induction symmetry, padding placement, intraop position checks q1-2 hr, postop nerve exam.
- 'arms abducted ≤90°
- palms supinated
- elbows padded
- heels offloaded
- eyes taped and free of pressure.' Co-sign with surgeon for non-standard positions
⚠ Common pitfalls
- Prone with eye pressure — POVL; horseshoe headrest must be used correctly with periodic eye checks.
- Arms abducted >90° — brachial plexus stretch injury.
- Lithotomy >2 hr — compartment syndrome of the legs; release periodically.
- Pressure-pad-skip in long cases — pressure ulcers in elderly + diabetic.
💎 Clinical pearls
- POVL risk factors: prone, long case, anemia + hypotension, eye pressure. Prevention: head neutral, no globe pressure, normal MAP + Hb.
- Brachial plexus protection: arms tucked or abducted ≤90° with palms supine.
- Lithotomy nerve injury: peroneal (sole of foot drop), saphenous (medial calf numbness).
- Document positioning in the anesthesia record — both initial and any changes during case.
Recap
- POVL risk factors: prone, long case, anemia + hypotension, eye pressure. Prevention: head neutral, no globe pressure, normal MAP + Hb.
- Brachial plexus protection: arms tucked or abducted ≤90° with palms supine.
- Lithotomy nerve injury: peroneal (sole of foot drop), saphenous (medial calf numbness).
- Document positioning in the anesthesia record — both initial and any changes during case.
Mark each section done to complete the module.