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