Positioning

This position is most often used for procedures requiring access to the thorax, retroperitoneal structures, hip or shoulder. Flexion of dependent leg and hip helps keep alignment and stabilizes pt.

Padding between legs and on lateral aspect of dependent leg protects peroneal nerve.

Ensure alignment of head with spine to prevent any occlusion of carotid/vertebral arteries, compromise of perfusion to head, impairment of jugular venous drainage and thus increased intracranial pressure (if drainage blocked).

Proper arm support. Upper arm elevated to prevent compression/stretch of brachial plexus. Monitor pulse and capillary refill in dependent and nondependent arm to ensure sufficient circulation.

Neuromuscular blockers increase risk for stretch injuries due to increased mobility of joints.

Ear to be free, use donut and prevent dependent eye from pressure (retinal artery stenosis, corneal abrasion). Tape eyes prior to turning if pt is asleep.

Axillary roll (use iv fluid bag) at nipple level to prevent compression of Axillary artery and brachial plexus.

Kidney rest should lie under the dependent iliac crest.

Anesthetic considerations

  • Favors overventilation of nondependent lung due to the lateral weight of the mediastinum and cephalad pressure of abdominal contents
  • Blood flow follows gravity and goes preferentially to dependent lung tissue. This causes increased ventilation-to-perfusion mismatch and may affect gas exchange and ventilation
  • Perfusion without ventilation = shunt
  • Ventilation without blood flow/perfusion = dead space

Avoid hypotension to ensure proper tissue perfusion.

Length of procedure poses the greatest risk of injuries including the above, Rhabdomyolysis, and renal failure.