Prone positioning

 

Issues:

Airway

·      Remote

·      Dependent swelling

·      Migration common

-> Secure ETT +++

-> Awake extubation

-> Check for cuff leak beforehand

Breathing

·      ↓Ventilation (chest wall compression)

·      ↓Oxygenation (↓FRC)

-> Proper table with abdomen free

-> PEEP titrated against PaO2 and compliance

Circulation

·      Abdominal compression -> IVC obstruction

o   ↓Cardiac output -> ↓mAP

o   ↑Epidural venous pressure -> ↑bleeding if spine surgery

-> Proper table with abdomen free

·      Resuscitation

o   Can’t do conventional CPR

o   Can’t apply magnet to PPM

Positioning injury

·      Face/eyes

·      Brachial plexus

·      Ulnar nerves

·      Breasts

·      Male genitals

-> Proper table with padding

-> Face/eyes: foam block for head (not horse shoe), check q30mins

-> If upper limbs extended: <90° shoulder abduction, elbows padded

-> If upper limbs by side: thumbs down (avoid excessive pronation)

-> Must inform patient of risks

Transfer injury

·      Five people minimum

·      Ensure ABC stable

·      Ensure bed and table stable

·      Disconnect both monitoring and airway

Blindness

Pattern of injury:

·      90% AION: ? hypoperfusion

·      10% central retinal artery occlusion: direct compression

·      Other: corneal injury, stroke, AACG

Risk factors:

·      Patient: elderly, male, obese, HTN, T2DM

·      Positioning: direct pressure, head down, Wilson frame

·      Surgery: ↑duration, ↑bleeding

Pathophysiology:

·      Direct compression

·      ↑Venous pressure: dependent positioning

·      ↓Arterial pressure: bleeding, anaesthetic, IVC compression

·      ↓CaO2: bleeding, haemodilution, hypoxaemia

Treatment:

·      Elevate head of bed

·      Optimise BV, BP, Hb

·      ±Acetazolamide, mannitol, frusemide

·      ±Glucocorticoid

·      ±Hyperbaric O2

Prevention:

-> Proper table with abdomen free (avoid excessive curvature)

-> Foam block for head (not horse shoe), check q30 mins

-> Minimise dependent positioning

-> Optimise oxygenation and ventilation (i.e. FiO2, PEEP)

-> Optimise circulation (fluid, blood, pressor)

-> Must inform patient about risks if expect long duration + blood loss

 

Post-op vision loss in general - DDx:

·        AION

·        PION

·        Retinal stroke

·        Cortical stroke

·        PRES

 

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