Positioning

This is the most common position for surgery, but there are many associated variations such as Trendelenburg, reverse Trendelenburg or a variation of chair positions.

Preventive measures

Protect pressure points

  • Arms either with hands supinated <90degree (prevent Brachial Plexus injury from stretch) or alongside with hands facing inward towards body
  • Pad to prevent ulnae nerve injury – hands supinated or facing inward towards body
  • Possible pillow under knees if history of back pain, which maintains lordotic curve in spine and prevents tension on sciatic nerve
  • Prevent alopecia with padding of head - increased incidence with hypothermia and hypotension
  • Heels off mattress for longer procedures

Anesthetic considerations

  • Check eyes - always tape to prevent corneal abrasion
  • Keep head in neutral position
  • Massage/reposition head during long procedures to prevent alopecia
  • CNS: blood/cerebrospinal fluid drainage are gravity dependent, valve less
    • When supine = increased ICP, which decreases cerebral perfusion pressure (CPP= MAP-ICP/or CVP)
  • FRC and total lung capacity are decreased compared to the sitting position
    • Increased intra-abdominal pressure
    • Elevated BMI - difficulty maintaining tidal volumes due to body weight pressing down on chest
  • Zone 3 (a-v-A) in dorsal portion of lungs
  • Minimal hemodynamic changes in the horizontal position