Positioning and Associated Risks

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Positioning and Associated Risks

• Josef N Mueksch MD

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(No Transcript)
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Zero Commercial Interests
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Problems

• Often after anesthesia initiated
• Physiologic Compromise
• Blood Vessels
• Nervous Tissues
• Physical Compromise
• NDMR facilitate abnormal position
• Mac/GA facilitate uncomfortable positions

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Responsibility

• Team Effort
• Anesthesiologist Ultimately
  
  Responsible

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Why We Really Care!
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Agenda

• Positions
• Specific Nerves
• Special Cases

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Supine

• Pulmonary Effects
• FRC 800cc
• even more with NDMR
• MS Effects
• Pad Pressure Points (heels, occiput)
• Loss Lumbar Curvature
• Often Results in Post-Op Backache

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Supine

• Arm Position
• Abducted
• Supination preferred
• May place increased stress on brachial plexus
• Adducted (Tucked at side)
• Tuck under patient, NOT BED!

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Prone

• Pulmonary Effects
• Compression Abdominal Contents
• FRC even further
• PIP increases
• Consider rolls Chest Iliac Crest
• MS Effects
• Turning of head
• Arterial Venous flow
• Risk of Thromboembolism
• Pad Pressure Points (Face)

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Prone

• Arm Position
• Above Head
• Risks
• Thoracic Outlet Syndrome
• Brachial Plexus Injury
• Tucked at side

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Trendelenburg

• Neuro Effects
• Increases ICP
• CV Effects
• Does not reliable increase preload
• May worsen hypotension
• Pulmonary Effects
• FRC even further more

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Lateral Decubitus

• CV Effects
• IVC Compression
• Pulmonary Effects
• V/Q Mismatch
• Dependent Lung Hypoventilated
• Dependent Lung Hyper-perfused
• MS Effects
• Neck Position
• Avoid Traction on Brachial Plexus
• Pad Pressure Points (Between Knees)
• Arm Position
• Dependent Compress Neurovascular Bundle
• Placement of Axillary Roll
• If placed at chest level may compress artery
• Consider SPO2 on dependent Arm

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Lithotomy

• Position Itself
• 800-1000 thigh flexion with trunk
• Legs abducted 300-450
• Lift both legs together
• Avoids rotational stress on spine
• CV Effects
• Compress or occlude venous return
• Pulm Effects
• Abdominal contents pushed cephalad
• Neuro Effects
• Worsens Herniated Disc Pain
• Many Peripheral Nerve Injuries

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Sitting

• Neuro Effects
• Facilitates drainage of head
• CPP
• CV Effects
• CO
• VAE largest risk
• May completely occlude blood flow to the
  head

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Summary
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Peripheral Nerves

• Significant source of liability
• Mechanism often unknown
• Ischemia?
• Compression?
• Stretch?

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Peripheral Nerves

• What to do?
• Neurology Consult
• EMG Studies
• Denervation takes 18-21 days
• If present post-op, maybe already existed
• Recovery?
• Takes 3-12 months
• If at all!

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Peripheral Nerves

• Ulnar Nerve
• Occurs at elbow more often in males
• Thought secondary to pronation
• Severe Flexion also causes
• Cubital Tunnel Entrapment Syndrome
• Thicker FCU retinaculum
• Overzealous BP Cuff/Tourniquet
• Manifestations
• Diminished Sensation 4th and 5th digits
• Claw Hand

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Peripheral Nerves

• Radial Nerve
• Compression against humerus
• Overzealous BP Cuff/Tourniquet
• Metal Drape Bar (heart room)
• Manifestations
• Decreased sensation over lateral 3 fingers
• Wrist Drop
• Weak Thumb ab/adduction

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Peripheral Nerves

• Median Nerve
• Unlikely

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Peripheral Nerves

• Sciatic Nerve
• Stretch Injury
• Knee extension and external rotation
• Often in lithotomy position
• Direct Injury
• Needle
• Inject upper outer quadrant
• Manifestations
• Foot Drop

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Peripheral Nerves

• Common Peroneal Nerve
• Compression against Fibula
• Candy Canes
• Tourniquet
• Manifestations
• Foot Drop
• Mimics sciatic nerve
• (It is part of sciatic nerve!)

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Peripheral Nerves

• Saphenous Nerve
• Compression against Fibula
• Candy Canes
• Tourniquet
• Manifestations
• Decreased Sensation medial leg

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Peripheral Nerves

• Femoral Nerve
• Compression against pelvic brim
• Laparotomy retractor
• Excessive thigh flexion
• Lithotomy position
• Manifestations
• Loss knee jerk
• Decreased sensation
• Superior thigh
• Anteriormedial leg

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Peripheral Nerves

• Obturator Nerve
• Forceps delivery
• Excessive thigh flexion
• Manifestations
• Inability to Adduct
• Decreased sensation medial thigh

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Non-Neural

• Skin
• Pressure necrosis
• Eyes
• Compression Thrombosis BLIND!
• Increased with hypotension
• Corneal Abrasion
• Appendages
• Caught in bed
• Compressed

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Sternal Retraction

• Neuro Effects
• Brachial Plexus Stretch Injury
• Often Ulnar distribution

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Blood Supply

• Loss of blood supply leads to
• Ischemia
• Hypoxic Edema
• Rhabdomyolysis
• leading to
• Compartment Syndrome

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Anesthesia Mask

• Facial Nerve
• Prolonged force behind mandible
• Supraorbital Nerve
• Circuit resting on patient
• Pressure Necrosis
• Prolonged mask placement with strap
• Often in mask cases

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References

• Baby Miller
• Chapter 15 pgs 196-208
• Fausts Anesthesiology Review
• Chapter 198 pgs 480-1
• Morgan and Mikhail
• Chapter 46
• Millers Anesthesia
• Chapter 28

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Any Questions
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