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NU 568

Exam 3 - Positioning in the OR

What are the 3 goals of positioning? Maximize: surgical exposure, access to patient, recovery
Maximal access of the patient allows for what 3 things? Maintenance of ventilation/airway, administration of drugs, monitoring VS
What are 3 ways to prevent nerve injuries? Anticipate problems, proper planning, communicate abnormal findings
What are the effects of positioning injuries? Prolonged hospitalization and recovery, psychological trauma, permanent disability, increased cost
Of closed claims analysis, how many nerve injuries were CRNA related vs. not CRNA related? 68% CRNA related, 32% not CRNA related
Of the nerve injuries directly related to CRNA care, what percentage of cases were found to be inappropriate to standards of care? 52%
What are the 4 primary methods of nerve injury? Compression, stretch, transection, kinking
What are some different injuries related to compression and why do they occur? Soft tissue, nerves, and vascular structure injuries occur due to compression over an extended period of time; caused by increased tissue resistance to venous capillary outflow and decrease in pressure gradient b/w capillaries and tissue
Where do stretch injuries often occur? Superficial nerves w/a long course
Identify a scenario whereby transection injuries can occur? Surgical trauma
When do kinking nerve injuries occur? A nerve is pinched between 2 immovable structures (i.e. exaggerated lithotomy)
When do compression injuries occur? When a nerve is forced against a bony prominence or a hard surface
Describe the process of tissue ischemia. 1) decreased tissue blood flow 2)anaerobic metabolism produces and accumulates acid byproducts 3)membrane Na-K pump failure 4)increased intracellular Na leads to increased osmotic gradient and edema
What is a common component of all peripheral nerve injuries? Tissue ischemia
In an ischemic environment, decreased production of _______ leads to the failure of the Na-K pump. ATP
What are 4 causes of compartment syndrome? Prolonged operation, hypotension, extremity elevation, body habitus
What is compartment syndrome? Potentially life threatening complication causing neural and vascular damage due to swelling of the muscular compartment
What is the definitive treatment for compartment syndrome? fasciotomy
What situations may occur if compartment syndrome is not diagnosed and treated? (5) Permanent neuromuscular damage, tissue necrosis, myoglobinuria, ARF, amputation, death
What are two scenarios that lead to the development of compartment syndrome? Increased pressure and decreased tissue perfusion in muscles with tight fascial borders
When does tissue swelling typically occur? When blood flow returns following a period of ischemia
Compartment syndrome has also been dubbed a _______. Reperfusion injury
What are 4 common causes of compartment syndrome? Trauma, embolic phenomena, tumors, vascular insufficiency
What are pre-disposing perioperative factors for compartment syndrome? Tight wound closure, expanding hematoma, prolonged surgery, external compression
A higher incidence of compartment syndrome has been reported in what surgical positions? Lithotomy, lateral decubitus
What are the 2 surgical factors that contribute to nerve injuries? Positioning devices, length of surgery
A surgical length of greater than _________ hours increases the risk for nerve injury. 4
What are anesthetic factors that contribute to nerve injuries? GA, NMB, hypotensive techniques, neuraxial/peripheral blocks
Why does GA pose a risk for positioning injuries? Patient cannot verbalize or move in response to painful stimuli
What two types of drugs lend towards stretch injuries d/t increased mobility of joints? NMBs and volatile anesthetics
Name the surgical positions where gravity affects blood flow. Sitting, lithotomy, T-burg
The majority of nerve injuries are r/t what 3 factors? Block technique, needle trauma, hematoma
It (is/is not) acceptable to extend the extremities of patients with multiple contractures. Is not
The presence of paresthesia means that a medication (should/should not) be injected. should not
What does the presence of paresthesia indicate? Needle is in the nerve root
What are body habitus factors that contribute to nerve injuries? Over/under- weight, muscular
For women, a BMI < ______ is associated with increased likelihood of ulnar nerve injury. 22
What pre-existing conditions increase the risk for nerve injuries? PVD, peripheral neuropathy, smoking, subclinical ulnar nerve entrapment, thoracic outlet syndrome
A muscular body habitus is associated with what type of surgical injuries? Ulnar nerve injury and compartment syndrome
Describe the difference between under- and over- weight patients and surgical injuries. Underweight may develop decubiti or nerve damage d/t lack of adipose tissue over bone; overweight is d/t large tissue masses putting pressure on dependent body parts
Nerve injury and pre-existing neuropathies are more common in patients with what disease? diabetes
What is the most common metabolic cause of spontaneous isolated femoral neuropathy? diabetes
What are the most common upper extremity nerve injuries? Ulnar (#1) and brachial plexus (#2)
What is the most common lower extremity nerve injury? Common peroneal
Ulnar neuropathy is a well-known complication of what type of surgery? cardiac
Elbow flexion compresses the ulnar nerve in what structure? cubital tunnel
Elbow flexion stretches the cubital tunnel between what two bony structures? Medial epicondyle, olecranon
Ulnar nerve injuries are more frequently associated with (males/females), especially over the age of ______. Males; 50
Identify the vertebrae of origin for the brachial plexus. C5-C8, T1-T2
The nerve roots merge to form what 3 structures? Superior (upper), middle (middle), inferior (lower) trunks
What do the 3 nerve trunks subdivide into? 3 anterior and 3 posterior divisions
The 3 anterior and 3 posterior divisions run (anterior/posterior) to the clavicle. posterior
The patient is vulnerable to brachial plexus injuries if the arms are _______, the shoulders are _________, or the head is ________. abducted, depressed, rotated
(Supination/Pronation) increases pressure over the ulnar nerve. pronation
What are the positioning recommendations to prevent ulnar nerve injury in anesthetized patients? Use of padding, supinate arms, abduction <90 degrees with armboards
What are 5 different positioning devices? Straps, stirrups, shoulder braces, arm boards, axillary rolls
Table straps or leg holding devices are associated with what type of nerve injury? Lateral femoral cutaneous nerve (thigh)
Common peroneal nerve injury has been attributed to the use of what type of positioning device? Crutch stirrups
Brachial plexus injuries have been reported with what two positioning devices? Falling armboards, shoulder braces in steep T-burg
Leg holding devices for arthroscopy is associated with what type of nerve injury? Lateral femoral cutaneous nerve
What is the purpose of repositioning and massaging the head in the supine patient? Prevents alopecia of the occiput
What is the cause of backaches in the supine position and what can be done to prevent it? Caused by abolition of lumbosacral curve; place folded sheet or bag of IVF under the lumbar spine
Crossed legs in the supine position may lead to what two nerve injuries and in which legs? Damage to the superficial peroneal nerve in the dependent leg and damage to the sural nerve in the superior
What devices can evenly distribute body weight following lengthy procedures? Gel pads or mattresses
Armboards should be angled less than _________ degrees. 90
What direction should the thumbs be pointed if the patient's arms are resting at the sides? up
What two respiratory factors are decreased in the supine position? FRC and chest wall muscle tone
What does bending the hips and knees improve for the supine patient? venous return
Which surgical position produces the least amount of physiologic changes? supine
What are 4 drawbacks to T-burg? Doesn’t predictably improve CO in low BP/low volume patients, decreased stroke volume from viscera pressing on the heart, compresses lung bases, may increase ICP
What benefit does the prone position have over the sitting position in its use for intracranial procedures? Less risk for VAE
What are the CV effects of the prone position and why? Compression of the inferior vena cava and aorta d/t cephalad displacement of the diaphragm
What major vessels are compressed in the prone position? Inferior vena cava and aorta
Placing padding underneath the shoulders of a prone patient prevents stretching of the _________ nerve. Brachial plexus
Placing padding between the elbow and the armboard in the prone patient helps prevent ____________ nerve damage. Ulnar
Pressure on the abdomen from the prone position may cause what 3 complications? Impede venous return, increase venous pressures, inhibit diaphragmatic movement
In reference to spinal cord surgery, what is the benefit of positioning devices that allow for the abdomen to hang freely? Decreased inferior vena cava pressures, which prevents engorgement of spinal venous plexuses (epidural veins)
The ______ Table improves diaphragmatic excursion in the prone position. Jackson
How does rotation of the head negatively affect blood flow? May obstruct jugular venous drainage
What devices can be used to support the had of the prone patient w/cervical arthritis? Prone pillow or Mayfield headrest
What ocular complications are associated with the prone position? Corneal abrasions and POVL
In the absence of a Jackson Table, what can be used to relieve abdominal pressure in the prone patient? Chest rolls placed from clavicle to iliac crest
What are two variations of prone positioning? Jack-knife, kneeling
What surgical position is associated with the most significant circulatory and ventilatory effects? Lateral decubitus
Compression of which vessel may occur with lateral decubitus, especially in conjunction with a kidney rest? Inferior vena cava
Lateral decubitus is used for surgeries involving what areas of the body? Thorax and kidneys
What effect does lateral decubitus have on the lungs? Underventilation of dependent lung and increased compliance of nondependent lung
What structures compress the dependent lung in lateral decubitus? Abdominal contents and mediastinum
Lateral decubitus positioning may lead to _____ mismatch, with an increase in bloodflow to the (dependent/nondependent) lung. V/Q; dependent
What should periodically be checked in the lateral decubitus patient? Radial artery; pulse Ox on dependent hand can also assess perfusion
What are the angles for true and modified sitting positions? 90=true, 45=modified
What are the CV changes associated with the sitting position? Decreased CO, CVP, PAWP
How much does MAP decrease with sitting position? 0.75mmHg per cm of elevation
What is the most serious complication with the sitting position and why? VAE b/c of negative pressure gradient b/w R atrium and veins and the operative site
The supine and lithotomy both cause _______ displacement of the diaphragm and viscera. cephalad
What are the principle nerve injuries of the lithotomy position? Sciatic, common peroneal, femoral, saphenous, obturator
What are three steps to take in caring for the patient in lithotomy? Padding b/w metal brace and patient’s leg, elevate and lower both legs simultaneously, thigh flexion of no more than 90 degrees prior to lateral rotation of stirrups
Prolonged lithotomy of > _____ hrs may result in compartment syndrome. 4
When are peripheral nerve injuries more likely to occur during procedures requiring what type of anesthesia? GA
What are the usual causes of post-op neuropathy? Position-related compression or stretch
What are types of studies that can be done with a peripheral nerve injury? Conduction, velocity, and EMG studies
Acute injury will appear _______ days after the onset of symptoms. 18-21
How long does it take to recovery from a peripheral nerve injury? 3-12mos
What is the most common post-op neuropathy? Ulnar nerve injury
What is the prevalence of ulnar nerve injury after cardiac surgery? 38%
Bending the elbow narrows the _________ and compresses the _______ nerve. cubital tunnel; ulnar
Bending the elbow narrows the _________ and compresses the _______ nerve. Cubital tunnel; ulnar supinated; up
How does ulnar nerve injury manifest itself? 1)inability to abduct or oppose the fifth finger 2)diminished sensation over medial one and half fingers 3)atrophy of intrinsic muscles of the hand
Claw hand is associated with what type of nerve injury? Ulnar
What are two reasons the brachial plexus is prone to injury? Long superficial axillary course and proximity to movable bony structures
Name two bony structures that may cause brachial plexus injury? Clavicle and humerus
What is the second most commonly injured nerve in the upper body? brachial plexus
Shoulder braces may compress the brachial plexus between which bones? Clavicle and first rib
A compression injury of the brachial plexus may occur if a shoulder brace is not placed over the _______ joint. acromioclavicular
Which surgical position has the highest prevalence for brachial plexus injuries? Lateral decubitus
How do sternal retractors affect movement of the clavicle and 1st rib? Clavicle moves posterior, 1st rib moves up
What steps should be taken in cardiac surgery to minimize brachial plexus injury? Caudad placement of retractors and avoidance of prolonged and asymmetric chest retraction
Where should an axillary roll be placed in order to prevent brachial plexus injury? Slightly caudad, not directly underneath the axilla
The radial nerve may be injured if pressure is applied to it while it transverses the ________. Spiral groove of the humerus
What are the manifestations of radial nerve injury? (3) Wrist drop, weakened thumb abduction, decreased sensation over the dorsal surface of the thumb, 1st and 2nd fingers
The median nerve runs over what important anatomical feature? Antecubital fossa
What are the primary causes of median nerve injury? IV placement or extravasation
Sodium pentothal (is/is not) caustic to veins. is
“Ape hand” deformity is associated with what nerve injury? Median
What positions are the thumb and index finger arrested in with median nerve injury? Adduction and hyperextension
What thumb functions are lost with median nerve injury? Opposition and flexion
Where should an axillary roll be placed in order to prevent brachial plexus injury? Slightly caudad, not directly underneath the axilla
The radial nerve may be injured if pressure is applied to it while it transverses the ________. Spiral groove of the humerus
What are the manifestations of radial nerve injury? (3) Wrist drop, weakened thumb abduction, decreased sensation over the dorsal surface of the thumb, 1st and 2nd fingers
The median nerve runs over what important anatomical feature? Antecubital fossa
What are the primary causes of median nerve injury? IV placement or extravasation
Sodium pentothal (is/is not) caustic to veins. is
“Ape hand” deformity is associated with what nerve injury? Median
What positions are the thumb and index finger arrested in with median nerve injury? Adduction and hyperextension
What thumb functions are lost with median nerve injury? Opposition and flexion
Where does decreased sensation occur with median nerve injuries? Palmar aspect of the lateral 3 ½ fingers
Compression injury of the sciatic nerve occurs due to the nerve passing under the _______ muscle. Piriformis
What are the two points of fixation of the sciatic nerve and what two movements increases the distance b/w these points? Sciatic notch and fibula; external rotation of the leg or knee extension
What is the longest and widest single nerve of the human body? sciatic
What are the two branches of the sciatic nerve? Tibial and common peroneal
Sciatic nerve injury occurs due to improper placement of the patient in what surgical position? lithotomy
IM injection into the ______ could cause sciatic nerve injury. buttocks
IM injections in the OR should be placed in the ________ aspect of the _______. lateral; thigh
How is sciatic nerve injury manifested? Weakness of all skeletal muscles below the knee; diminished sensation over the lateral half of the leg and almost all of the foot
What does damage to the common peroneal nerve reflect? Compression between the head of the fibula and metal brace in the lithotomy position
What is the most frequently injured nerve in the lower body? Common peroneal
How does injury to the common peroneal nerve manifest? Foot drop, loss of dorsal extension of the toes, inability to evert the foot v
Foot drop is indicative of nerve injury to the ________. common peroneal nerve
Anterior tibial nerve injury may manifest post-op if the feet are ___________ for extended periods of time. plantar flexed
Where should a roll be placed for patients in the sitting position to prevent anterior tibial nerve injury? Under the anterior aspect of the ankle to maintain extension
What are two possible causes of a femoral nerve injury? Compression by retractor blade (laparotomy) or by excessive angulation (lithotomy)
What are the 3 manifestations of a femoral nerve injury? Decreased knee jerk, loss of hip flexion, loss of knee extension
Where does decreased sensation occur with a femoral nerve injury? Superior aspect of the thigh, medial and anterior medial side of the leg
A pelvic fracture may cause _________ nerve injury. femoral
What does the saphenous vein branch from? femoral nerve
Where does pain occur with a saphenous nerve injury? Medial knee and leg pain
Compression of the saphenous nerve against the _______ can result in injury. medial tibial condyle
How does obturator nerve injury manifest? Loss of leg adduction, decreased sensation over medial thigh
In what scenarios can an obturator nerve injury occur? Difficult forceps delivery, excessive flexion of thigh to groin
Pressure necrosis of the groin can occur with what orthopedic table? Chick Table (hip surgery)
What are high-risk surgeries for POVL? Cardiac and prone spinal surgeries
The retina supplies axons to the _____ nerve. optic
What are the 4 divisions of the optic chiasm? Intraocular, intraorbital, intracannicular, intracranial
Where do the retina and optic nerves receive their blood supply? Through the central retinal and ciliary arteries
Arteries that supply the retina and optic nerve arise from the ______. Internal carotid
What important function do retinal and ciliary arteries lack? Autoregulation in the presence of hypoperfusion
What are two pre-existing conditions that affect autoregulation and increase the risk for POVL? DM and HTN
Thrombosis of the central retinal artery, which may lead to permanent blindness, can be caused by what factors? Prone position, deliberate/accidental hypotension, increased intraocular pressure
Trauma of the appendages most often occurs with the _____. Fingers
What is the most likely cause of trauma to the fingers in patient positioning? Foot of the table is returned to horizontal position in lithotomy
Face masks can place pressure on the _________ branch of the facial nerve. Buccal
What does injury to the buccal branch of the facial nerve result in? Paresthesia of the orbicularis oris muscle
What nerve can be compressed by the ETT and how does this injury manifest? Suborbital
Decreased sensation over the forehead and pain in the eye may be due to injury of what nerve? Suborbital
Compression of what part of the mandible can cause facial nerve damage? Ascending ramus
Created by: philip.truong