Both surgeon and anesthesiologist share responsibility in positioning the patient appropriately for surgery. It is important that both parties are involved in the positioning so that each is aware of the potential for pressure injuries. Risk–benefit analysis should consider patient comfort, injury-risk, surgical exposure needs, and padding options.
The basic positions used in most surgeries are supine, prone, lateral, Trendelenburg, and reverse Trendelenburg with numerous variations. Additional positions include lithotomy, jackknife, lateral decubitus, beach chair, and sitting. The most common complication in any position is peripheral nerve injury. Other injuries include tape burns, blisters, skin breakdown, abrasions, and alopecia. Older patients should not be over flexed at the hips, especially in lithotomy. This can cause a sciatic nerve injury. In the prone patient, avoid eye pressure to prevent ischemic optic neuropathy, which can cause permanent blindness. Other injuries that are common in the prone position include stretch or compression injuries to the brachial plexus, ulnar nerve, and lateral femoral cutaneous nerve injury. To avoid lateral femoral cutaneous nerve injury, the anterior iliac crest should be padded. Care also needs to be taken to make sure toes are not supporting the full weight of the legs in the prone position; pillows can be used to relieve pressure.
Brachial Plexus Neuropathy
Brachial plexus neuropathy occurs with median sternotomy or prone position surgeries. Median sternotomy can place pressure on the brachial plexus during rib retraction. Minimizing rib retraction for surgical exposure prevents this injury. In the prone position, injury occurs with arms rotated cranially above the head. Positioning arms tucked at the patient’s side decreases intravenous accessibility and brachial plexus injury risk.
Symptoms associated with brachial plexus injury include paresthesia or anesthesia to the arm or hand, decreased reflexes, weakness and lack of arm, hand or wrist control. Weakness patterns depend on brachial plexus injury location and can involve the entire arm or merely a portion. With musculocutaneous nerve injury, elbow flexion and supination weakness occurs. Median nerve injury causes proximal forearm pain.
Ulnar neuropathy can be caused by external nerve compression or stretch. It is associated with the male gender, a BMI greater than 38, and prolonged bed rest. People who develop ulnar neuropathy attributed to surgical positioning may also have contralateral ulnar nerve dysfunction, suggesting preoperative dysfunction. This injury occurs with elbow flexion greater than 110 degrees. Excessive elbow flexion tightens the cubital tunnel retinaculum, which compresses the ulnar nerve. In addition, forearm pronation puts pressure on the postcondylar groove, which can also compress the nerve. Neutral or supinated arm position is recommended.
Ulnar nerve injury symptoms typically present more than 48 hours after surgery. Symptoms associated with ulnar nerve neuropathy include sensory changes to the 4th and 5th digits, and a weak grip.