CHAPTER
28
Patient Positioning and Potential Injuries
Positioning a patient for a surgical procedure is frequently a compromise between what the anesthetized patient can tolerate (structurally and physiologically) and what the surgical team requires for anatomic access (Warner ME. Patient positioning and potential injuries. In: Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Ortega R, Stock MC, eds. Clinical Anesthesia. Philadelphia: Lippincott Williams & Wilkins; 2013:803–823). There is a lack of solid scientific information on basic mechanisms of position-related complications. Notations about positions used during anesthesia and surgery, as well as brief comments about special protective measures such as eye care and pressure-point padding, are useful information to include in the anesthesia record.
I. GENERAL PRINCIPLES
A. Direct compression (especially point pressure) of neural and soft tissue may result in ischemia and tissue damage. (Despite education, padding and positioning devices injuries continue to occur.)
B. We do not yet fully understand the etiologic mechanisms of positioning issues. Inflammatory neuropathies may be an underappreciated mechanism (inflammatory response may be altered in the postoperative period or by viruses).
C. Stretch of neural tissue may be an important factor in the development of peripheral and central neuropathies.
II. SUPINE POSITIONS
A. Variations of Supine Positions (Table 28-1)
B. Complications of Supine Positions
1. Pressure alopecia results from prolonged compression of hair follicles (manifests between the 3rd and 28th postoperative day, with complete regrowth by 3 months).
2. Pressure-point Issues. Weight-bearing prominences (heels, elbows, or sacrum) should be protected against from pressure necrosis (hypothermia and vasoconstrictive hypotension may increase the risk) with padding (foam, gel). Although padding protects the skin and soft tissue from compression and ischemia, there is no evidence that this is beneficial in reducing peripheral neuropathies in the perioperative period.
TABLE 28-1 VARIATIONS IN SUPINE POSITIONS
Supine
Horizontal: The arms are padded and restrained alongside the trunk or abducted on padded arm boards; this does not place the hips and knees in a neutral position, resulting in discomfort for awake patients
Contoured: The arms are placed as for the horizontal position; the hips and knees are slightly flexed; this is a good position for routine use
Lateral uterine or abdominal mass displacement: Leftward tilt of the table or placement of a wedge under the right hip
Lithotomy
Standard: The lower extremities are flexed at the hips and knees and simultaneously elevated to expose the perineum; at the end of surgery, both legs are lowered together to minimize torsion stress on the lumbar spine
Exaggerated: This stresses the lumbar spine and restricts ventilation because of abdominal compression by the thighs
Head-Down Tilt (this should be avoid in patients with intracranial pathology)
Trendelenburg position: 30–45 degrees head-down position; this may require some means of preventing the patient from sliding cephalad; shoulder braces should be avoided if possible; this position should only be used when a unique surgical issue requires it for exposure and only for as long as needed
III. BRACHIAL PLEXUS AND UPPER EXTREMITY INJURIES (Table 28-2)
IV. ULNAR NEUROPATHY
A. Ulnar Neuropathy is characterized by an occurrence predominately in men (70%–90%), high frequency of contralateral nerve dysfunction (suggesting that many patients have asymptomatic but abnormal ulnar nerves before undergoing anesthesia), and an often-delayed appearance of symptoms (48 hours after the surgical procedure).
TABLE 28-2 BRACHIAL PLEXUS AND UPPER EXTREMITY INJURIES
Brachial plexus neuropathy: Most likely if the head is turned away from an excessively abducted arm; shoulder braces placed against the base of the neck plus steep head-down position; first rib fracture during median sternotomy
Long thoracic nerve dysfunction: Winging of the scapula reflecting serratus anterior muscle dysfunction; a viral origin should be considered
Axillary trauma from the humeral head: Abduction of the arm on an arm board to >90 degrees may thrust the head of the humerus into the axillary neurovascular bundle
Radial nerve compression: A vertical bar of screen forces the nerve against the humerus; wrist drop
Median nerve dysfunction: Isolated perioperative injuries are uncommon, and the mechanism is usually obscure, potential for injury is iatrogenic trauma to the nerve during access to vessels in the antecubital fossa
Ulnar nerve compression: Trauma occurs as the nerve passes behind the medial epicondyle of the humerus; sensory loss of the fifth finger and lateral border of the fourth finger may occur
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