1. PATIENT POSITIONING IN NEUROANAESTHESIA.
Dr. Rahul Norawat
University College of Medical Sciences & GTB Hospital, Delhi

2. INTRODUCTION
Positioning is the joint responsibility of the surgeon & anesthesiologist.
Ideal pt. positioning involves balancing surgical comfort, against the risks related to the pt. position.
Pt. positioning & postural limitation should be considered during the PAC.

3. Positioning of neurosurgical patient:
Adequate anesthetic depth,
Hemodynamic stability,
Oxygenation,
Preservation of monitors.
Disconnection - create “blackout” state.
ASA task force general guidelines.

4. Head Positioning
Ideal position of head for Craniotomies & spine procedures based on the 2 principles:
An imaginary trajectory from the highest point at skull surface to area of interest in brain should be the shortest distance between the 2 points.
The exposed surface of the skull & an imaginary perimeter of craniotomy should be parallel to the floor.

5. Types of Craniotomies Ant. Parasagittal Frontosphenotemporal
Sub-temporal
Lat Sub-occipital
Midline Sub-occipital
Post. Parasagittal

6. Fixation of the Head
For craniotomies or burr holes, head positioned on:
Horseshoe headrest (doughnut),
Skeletally fixed with 3 (Mayfield frame) or 4-pins fixation device.

7. Application of a skeletal fixation pins
Tachycardia and hypertension
Rupture of untreated cerebral aneurysms
Local infiltration
iv anesthetic agent (propofol mg/kg)
Inhalational anesthetic
Benefits : Immobility, surgical comfort.
Risks : Bleeding, air embolism, scalp and eye laceration, pressure alopecia.

8. Head and Neck positioning: Rotation, Hyperflexion, Hyperextension
Brain stem & cervical spine ischemia.
Quadriparesis, quadriplegia & cerebral infarction.

9. Head safely rotated b/w 0-45°.
At risk Patients :
Osteophytes,
Arthritis,
Vascular atherosclerosis.
Head safely rotated b/w 0-45°.
For more rotation, a roll/pillow place under the opposite shoulder.
Maintaining 2-3 finger breadths thyromental distance during neck flexion.

10. Benefits: Surgical comfort & optimal access to the surgical area.
Risks & complications:
Postoperative discomfort & pain,
Brachial plexus injury,
Obstruction of :
Jugular veins & vertebral venous plexuses,
Cerebral lymphatic,
Vertebral or carotid arteries.
CSF flow,

11. Body Positioning Supine Position (Dorsal Decubitus)
Most frequently utilized position.
Used for :
Cranial procedures,
Carotid endarterectomies,
Ant. approaches to cervical & lumbar spine.

12. A Horizontal position : poorly tolerated.
B Lawn chair position : 15° angulation's & flexion at trunk-thigh-knee & more physiological positioning of lumbar spine, hips and knees.
C Reverse Trendelenbourg position : 10-15° repositioning from the horizontal axis.
A - horizontal position,
B - lawn chair (contoured) position,
C - reverse Trendelenbourg position.

13. Arms:
Abducted: < 90° to minimize brachial plexus injury.
Adducted
Hand & forearm:
Supinated or neutral position to reduce external pressure on spiral groove of humerus & ulnar nerve.

14. Not require special instrumentation &
Benefits:
Simplest,
Not require special instrumentation &
Not require disconnection of tracheal tube & invasive monitors.
Risks:
Head rotation or flexion for optimal surgical conditions,
Pressure alopecia,
Pressure point reaction,
Nerve injury.
cubital tunnel retinaculum (CTR)

15. Hemodynamic and Ventilation.
Every 2.5 cm change of vertical ht. from the reference point at level of the heart leads to a change of MAP by 2 mmHg in the opposite direction.
V & Q are best in dependent lungs.
Positive-pressure ventilation provides the best ventilation to non-dependent lung zones -V/Q mismatch.

16. Supine CVS Respiratory CNS Benefits Risks
       
CVS
Respiratory   
CNS
Benefits 
Risks
Supine
Compared to upright, awake and anesthetized
VR ↑, SV ↑
CO ↑, HR ↓
SVR ↓,
SBP ↔,
MAP↓↔
Compared to upright:
FRC ↓,
TLC ↓.
atelectasis of the dependent lung zones; Qs/Qt ↑,
V/Q mismatch↑      
Compared to
upright:
JVF ↑ ↔
JVR ↓ ↔
CPP ↔ ↓
CSF drainage may be impaired
The easiest position
Often needs head Flexion/ 
Extension /
Rotation,
Ulnar and 
peroneal nerve injury 
Modifications: a) Lawn-chair
b) Reverse
Trendelen
bourg
Improved VR from lower extremities.
Improved ventilation - dependent lung zones
Improved drainage –cerebral venous,
lymphatic, CSF

17. B. Lateral Position Temporal lobe craniotomy, Skull base,
Posterior fossa procedures &
Retroperitoneal approach to thoracolumbar spine.

18. B A
A - Dependent arm is hung under the operating table, an upper arm is placed on the arm board,
B - Dependent arm is positioned on the operating table and an arm board, an upper arm is placed over the trunk on the pillow.

19. Hemodynamic and Ventilation.
Park-bench position:
Modification of lat. position.
Better access to posterior fossa.
Upper arm positioned along lateral trunk & upper shoulder is taped towards table.
Hemodynamic and Ventilation.
In awake patient, Zone 3 West is occupying the dependent 18 cm of lung tissue. Lung tissue above 18 cm from bed level is not perfused.
During GA & positive pressure ventilation, the non-dependent lung zones are ventilated better - worsening V/Q mismatch.

20. CVS Respiratory CNS Benefits Risks Lateral Compared to supine,
Anesthetized
VR ↓, SV ↓,
CO↓
HR↑ ↔ 
SVR↑,
PVR↑, SBP↓,
MAP↓
supine: 
FRC ↓, TLC↓ 
Qs/Qt ↑↑  
V/Q mismatch↑↑
Atelectasis of the dependent lung 
supine:   
JVF↑↔   
with neck flexion:
JVF↓,
JVR↑,
ICP↑
Optimal approach to the temporal lobe. 
Brachial plexus injury,
Ear & eye injury,
Suprascapular nerve injury (of the dependent shoulder),
park bench
access to posterior fossa.
Stretch injuries (axillary trauma),
Decreased perfusion to the dependent arm.