Positioning – Flashcards
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How is the difference in blood pressure calculated in relation to the amount of tilt relative to the heart?
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BP is calculated by adding/subtracting 2mmHg for each one inch/2.5cm above/below the heart.
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What is inhibited and what is excited when BP increases?
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The medullary vasoconstrictor center is inhibited, and the vagus nerve is excited= bradycardia, decreased workload on the heart and peripheral vasodilation.
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What happens to the pressor receptors in the case of anesthesia, disease, and injury?
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Pressor receptors are unable to compensate for changes in position/hemodynamics when the body is in a disease state.
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What type of anesthetics can cause a sympatholytic effect? What can you do to treat?
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Inhalational agents, especially when given before repositioning the patient will produce an exaggerated hypotension. Can give Neo, Ephedrine, increase IVFs)
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What changes in BP may occur from shifting from lithotomy position to supine?
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The BP may decrease after lowering the legs. Leave the BP cuff on bc the BP drop may be significant enough to treat.
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What is the chief etiology of nerve damage from positioning? What are the symptoms?
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The chief etiology of nerve damage from positioning is stretching or direct compression of the nerve. Symptoms include: pain, injury, numbness, tingling-they can be transient or permanent.
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What about GA makes it the perfect situation for nerve damage?
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-The muscle tone is lost -Patient's perceptive power is abolished since they are asleep.
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What is the most vulnerable nerve area to damage from malpositioning? What is the primary cause? How else can it be injured?
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The brachial plexus (20% of CCC)-stretching is the primary cause, if the arm is extended on an angle greater than 90 degrees the brachial plexus is stretched across the humeral-clavicular joint. Make sure you position the arm board at an angle less than 90 degrees, try to maintain the head in a midline position (not turned the opposite direction from the arm), and make sure the arm is not hanging off the table, or has fallen off the arm board. A bump under the hip can also mimic the head turning malpositioning. Suspension of the arm from an ether screen in the lateral position can produce excessive stretching.
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What may happen to injure the patient with excessive sternal retraction?
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Excessive sternal retraction may fracture the first rib and injure the plexus bundle.
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What is the most frequent site of anesthesia related peripheral nerve injury? Who is this higher in? How can this nerve be injured?
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The most commonly injured nerve is the ulnar nerve (28% of closed claim cases) Higher in males (3x higher) b/c they have more muscle mass and less adipose tissue to protect the cubital tunnel where the ulnar nerve runs, and higher in pts who have received GA. Ulnar compression nerve injury can occur if arm is pronated, if the elbow sagging over the side of the table, or if the arms are folded across the abdomen or chest.
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Should the arm be placed on the armboard with the hand pronated or supinated? If not what can happen?
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The hand should be supinated to protect the ulnar nerve-the fossa at the elbow will be free from pressure. If not, the cubital fossa is exposed more to pressure and injury. The arm should also be properly tucked.
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How does ulnar nerve damage manifest? How long after surgery can ulnar nerve injuries be reported?
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May manifest as claw hand (4th and 5th fingers clawed) and sensory deficit of the medial hand (middle part of the hand and sometimes middle finger, ring finger, and little finger) Ulnar injuries have been reported 2-7 days post op, most common is 3 days.
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What is the most common site for nerve injury related to the upper arm? Secondary to what? How does it manifest**?.
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The radial nerve, secondary to a BP cuff cycled (don't get an accurate BP unless you give time for the vessels to refill 2-3 mins) for too long or prolonged tourniquet use at a high pressure (2 hours maximum, notify surgeon per time left). Damage can also occur if radial nerve is compressed between the body and the ether screen/surgical equipment-protect with egg crate. Manifests as wrist drop, inability to extend the metacarpophalangeal joints secondary to the paralysis of the extensor muscles in the forearm.
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What is the least likely nerve to be injured in the arm?
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The median nerve is the least likely to be injured.
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What is the highest litigation payment?
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Epidural hematoma that led to permanent spinal cord injury. Epidural hematoma=emergent OR trip
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What are the most frequently damaged nerves of the lower extremities? ***
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The common peroneal and saphenous nerves are the most frequently damaged nerves of the lower extremities.
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How is the saphenous nerve (runs medially) damaged?
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If there is compression on the medial aspect of the calf, the saphenous nerve is compressed-if the legs are suspended laterally to the vertical braces/stirrups and the pressure is applied from the outside.
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How is the peroneal (runs laterally) nerve damaged? How does it manifest? ***
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When the patient is in lithotomy position, if compression is applied from inside of leg to outside-between the lithotomy stirrup and the fibula, pushing the lateral aspect of the calf against the device. Peroneal nerve damage manifests as foot drop.
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What are three other nerves can be damaged from malpositioning compression damage?
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-pudendal -femoral -obturator-sensory innervation of the medial thigh and adduction of lower extremity
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What is the primary factor to keep in mind when considering positioning in regards to respiration? What percentage of intrathoracic volume is the diaphragm responsible for?
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Mechanical interference with chest expansion is important to keep in mind. (Med student leaning on the chest or on ETT/circuit-may see an increase in PIPs, decrease in TV) Diaphragm is responsible for 60%, so any interference with its movement is the most postural influence on respiration (insufflation-check PIPs and ETCO2 prior to insufflation, trendelenberg)
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What happens to FRC when a patient is repositioned from supine to prone? Why?
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The FRC increases in the prone position bc the pressure increases alveolar expansion and because there is less pressure on the diaphragm bc when using the positioning devices, the diaphragm and abdomen have room to expand.
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What is the change in the FRC from upright and conscious to supine and anesthetized? Upright to prone?
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The FRC decreases by 44%. Upright to prone is decrease in 12%.
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In an unanesthetized spontaneously breathing patient in a lateral position which lung is better ventilated/perfused?
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The dependant lung is better ventilated and perfused d/t the increased hydrostatic pressure and weight of the viscera.
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With a paralyzed and ventilated patient which lung is better ventilated and/or perfused?
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The upper independent lung is better ventilated, but the upper lung is less perfused.
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What is the difference between men and women as far as lung compliance?
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Men have greater compliance than women when awake, but when anesthetized, men lose a greater amount of their compliance than women.
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What is the risk r/t intragastric pressure in the trendelenberg? Reverse trendelenberg?
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Trendelenberg- The intragastric pressures are increased, but if gastric contents enter the oropharnyx, the risk of aspiration is less because of the angle the stomach contents would have to turn in order to flow into the trachea is not likely to happen, the contents will flow out of the mouth. Reverse Trendelenberg/steep foot down- decrease in intragastric pressure which makes reflux/regurg less likely, but if gastric contents do flow into the oropharnyx, the risk of aspiration is increased.
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How should the patient's legs be placed in the stirrups for the lithotomy position? What nerves are at risk in the lithotomy position?
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Both legs should be put up/down into the stirrups at the same time due to risk of muscle injury. The three nerves at risk in the lithotomy position are the obturator, saphenous, and femoral nerves.
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Which position produces the greatest incidence of backache and why? What intervention takes pressure off the lower back when the patient is in the prone position?
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Lithotomy produces incidence of backache due to the stretching of the lower back muscles. Placing a pad under the ankle and allowing the feet to hang off can take the pressure off the lower back while pt is in prone position.
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What is the other name of the supine position?
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Dorsal decubitis.
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What are some points to keep in mind when placing a pt in supine position?
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-equal distribution of weight -avoid arms touching metal table -make sure thigh strap is intact over patient -tuck arms under drawsheet but not under buttocks -avoid wrinkles -place pad under head -place pad under lower back and knees to maintain normal lumbar curve -legs parallel and uncrossed
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What are the nerves that can be damaged from a patient crossing their legs in the supine position?
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-Sural nerve-runs across the back of achilles tendon -peroneal -tibial
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What nerves can be damaged during prolonged mask cases or if the head strap is too tight?
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-Optic nerve -Facial nerve
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What can happen to the vessels from hyperabduction to the arm? Why is this dangerous?
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-The subclavian and axillary vessels can be stretched under the coracoid process of the scapula or compressed and occluded between the clavical and the first rib. This is dangerous bc the radial pulse can be obliterated and an arterial thrombus can occur.
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What is the purpose of a sled?
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A sled protects the arm from mushing/falling, and the BP cuff from taking an innaccurate pressure.
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Prone: Where should the shoulder rolls be placed? What are the purpose of the shoulder rolls? How should the arms be positioned? How should the feet be positioned?
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Shoulder rolls should extend from the shoulders to the iliac crest-they improve circulation (less compression of the vena cava and the lymphatic system) and respiration (decreases intra-thoracic pressure, diaphragm hangs freely) prevent pressure on breasts and genitalia. Upper arm biceps-triceps area should be supported up to the same level as the thorax to avoid brachial plexus injury from pulling and stretching. The feet should have a dorsum support roll at the ankle.
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Ischemic Optic Neuropathy is associated with what surgeries? What patient risk factors are associated?
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Cardio pulm bypass (head is not perfused as well), radical neck dissection, abdominal and hip procedures, hypotension, large amount of fluid given, anemia, prolonged prone position. Pt risk factors are HTN, DM, smoker, or morbidly obese.
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What are three causes of pathology related to central retinal artery occlusion?
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-Direct pressure on the globe(eye itself) -low perfusion pressure in the retina -emboli
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What do you need to reassess each time you reposition the patient?
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Check BS every time you reposition the patient.
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What is the risk when turning an anesthestized pt?
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Must keep patient in alignment and the pt turned as a unit otherwise may injure the spinal cord/bony spine d/t lack of muscular support.
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What is important to document regarding to positioning?
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-"TO" the position you have put the patient in. -head/neck maintained in neutral -rolls/pads/tucked/secured/headrest -no pressure noted....Q 15 minutes -bilateral breath sounds -"positioned to patient comfort" (when placing an awake pt in prone position before anesthetizing them, ask them)
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What are important points to remember for patients in the sitting position?
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-Apply antigravity stockings -Legs flexed at both hips with the lower legs and feet at the level of the heart -arms are crossed at lap-confirm bilaterally radial pulses.
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What are complications of the sitting position?
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-venous air embolism -hypotension (esp going from supine to sitting) -streching of the sciatic nerve -brachial plexus injury -if the neck is too flexed (less than 2-3 FBs)- macroglossia, facial edema from compressed carotids, quadriplegia
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What is the normal RAP/CVP?
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2-10mmHg.
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How can a VAE occur? What are risk factors for VAE?
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...
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What is the best method to detect a VAE?
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-The precordial doppler is the best method used to detect VAE. Should always use the precordial doppler for neuro siting position. Place the precordial on the 4th IC space/over R atrium ONLY AFTER the patient is sitting up. Do testing with 1 ml of air into RA port at repeated intervals to hear the "mill wheel murmur"., will detect 90% of emboli.
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What will be seen on the Mass Spectrometer if your patient has an VAE?
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You will detect Nitrogen on the mass spec.
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What are signs/symptoms of VAE?
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-sudden profound hypotension -sudden decrease in CO due to "airlock" in RV -RV failure
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Where are the pressoreceptors located that respond to changes in body position and act to mediate blood pressure?
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Pressoreceptors are located in the carotid sinuses, aortic arch, pulmonary arteries, and other arteries and respond to changes in pressure.
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In the sitting position (and supine), what is the difference in BP between the heart and the LEs?
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The LE BP will be higher.
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1. Lumbar sacral injury percent of CCC? 2. Spinal cord?
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1. 16% CCC 2. 13% CCC
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What is the joint that the brachial plexus could be stretched across from improper positioning?
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The humeral-clavicular joint.
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Which are the most commonly damaged nerves of the lower extremity?
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-Peroneal -Saphenous -Puedendal -Femoral -Obturator
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Which two vessels can be stretched under the coracoid process of the scapula? How can the vessels occlude between two structures?
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-subclavian vessel -axillary vessel Vessels can be compressed and/or occluded between the clavicle and first rib.
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What is the point of the axillary roll?
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The axillary roll is used to prevent overstretching and compression of the dependant brachial plexus.
