Positioning

Question 1

In the supine position, what is the effect seen in regards to the FRC?

Answer 1

decreases approx. 800cc; cephalad displacement of diaphragm compresses lung bases

Question 2

If possible, when a patient is in supine position… what are some position changes that can be made to improve venous return?

Answer 2

flex hips and knees to facilitate venous drainage from lower extremities, relax abdomen

Question 3

What are changes seen in circulation, pulmonary, and venous return when a patient is placed in trendelenburg?

Answer 3

circulation: abdominal viscera push against diaphragm–> compresses lung bases and pushes on heart (decreasing SV)–> may accentuate hypotension
pulmonary: lung bases compressed
venous return: should increase, but may not help the hypotension
other: may increase ICP

Question 4

What are changes seen in circulation, pulmonary, and venous return when a patient is placed in prone position?

Answer 4

circulation: compression of inferior vena cava and aorta
pulmonary: lung bases forced cephalad
venous return: hindered if vascular compression is severe
other: turning head may obstruct jugular venous drainage and vertebral artery blood flow; abdominal rolls placed under patient’s sides relieve abdominal compression and increase venous return to the heart–> eases ventilation

Question 5

What are changes seen in circulation, pulmonary, and venous return when a patient is placed in lateral decubitus (on ventilator)?

Answer 5

circulation: will decrease if kidney rest is elevated against IVC; increased to dependent lung
pulmonary: decreased ventilation of dependent lung d\t pressure on lungs and heart from abdominal viscera; increased ventilation to nondependent lung–> V\Q mismatch
venous return: should NOT pose problems
other: place axillary roll under thorax just caudal to axilla

Question 6

What are changes seen in circulation, pulmonary, and venous return when a patient is placed in sitting position?

Answer 6

circulation: venous drainage from head/neck and upper body; decrease in intrathoracic blood volume
pulmonary: no changes
venous return: from legs with elastic stockings; decreased cerebral perfusion pressure; decreased CO
other: principle hazard is air embolism

Question 7

What are changes seen in circulation, pulmonary, and venous return when a patient is placed in lithotomy position?

Answer 7

circulation: no problems unless abdominal mass is present
pulmonary: cephalad diaphragm will compress lung bases
venous return: elevation of legs together
other: peripheral nerve injury is common (sciatic, common pernoneal, femoral, saphenous, obturator all susceptible to injury)

Question 8

What is the first and second MOST common upper extremity nerve injury d\t positioning?

Answer 8

1) MOST COMMON= ulnar nerve (compression between medial epicondyle of humerus and sharp edge of OR table); stretched when pronating the arm; causes inability to abduct or oppose the fifth finger and decreased sensation over medial one and one-half fingers (ring and pinky)
2) SECOND= brachial plexus (compression between the clavicle and first rib with improperly placed shoulder braces or spreading of the sternum (stretch injury when neck is extended and head is turned away, or arm is abducted to greater than 90 degrees

Question 9

List the nerve injury associated with the following:

1) “Ape Hand”
2) “Claw Hand”
3) “Wrist Drop”

Answer 9

1) median nerve
2) ulnar nerve
3) radial nerve

Question 10

What is the MOST common nerve damaged in the lower extremity d\t positioning?

Answer 10

common peroneal nerve (branch of the sciatic; compression usually from the lithotomy position when the nerve is pressed between the head of the fibula and the metal brace–> manifests as foot drop, loss of dorsal extension of the toes, and inability to evert the foot)