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Principles I Test 4
Surgical Positioning & Fire Safety
Question | Answer |
---|---|
True or False: positioning is listed as a standard the CRNA is responsible for in the AANA Standards for Nurse Anesthesia Practice. | True!!!!! |
What is the ultimate goal of positioning? | to allow optimal surgical access while minimizing potential risk to the patient |
What happens in normal positional auto regulation? | When patient lays supine venous return, preload, SV, CO, MAP are all increased. However, baroreceptors are triggered, atrial and ventricular mechanoreceptors are triggered, and atrial reflexes cause changes in RAA activity, so net result is minimal |
How do NMBs affect auto regulation in the anesthetized patient? | abolished muscle tone leads to decreased venous return and pooling, meaning lower BP and CO |
How do opioids and IV anesthetics affect auto regulation in the anesthetized patient? | decrease HR, BP, CO due to CV and CNS depression |
How do volatile anesthetics affect auto regulation in the anesthetized patient? | vasodilation and dependent pooling |
Surgical positioning should not occur until the patient is _________________ | hemodynamically stable |
What are some interventions the CRNA can implement in a patient who is hemodynamically unstable after induction but needs to be positioned for surgery to proceed? | fluids, vasopressors, trendelenberg, lightened anesthesia may be required, make sure to frequently check blood pressure (and record it!) |
MAP decreases by ________ per every inch change between the heart and a body region | 2 mmHg |
Positioning can affect ventilation and perfusion leading to _____________ | a V/Q mismatch |
Decreased lung compliance and increase resistance from shifting organs and positioning devices lead to what? | decreased functional residual capacity and lung capacity |
After any position change, what are 3 things the CRNA should check and document? | BP, ETT placement, bilateral breath sounds |
What are the 4 primary mechanisms of nerve injury during surgery? | transection, compression, stretching, kinking |
What is the one common factor to all methods of nerve injury? | ischemia |
How does pressure on a nerve ultimately lead to ischemia and damage? | pressure causes tissue edema, which increases venous pressure and decreases arterial pressure and perfusion; this is ischemia that leads to nerve injury and damage |
Straps, armboards, stirrups, shoulder braces, tourniquets, bean-bags, and rolls are all ______________ that contribute to nerve damage in the preoperative setting. | positioning devices |
Procedures lasting longer than _______ have an increased risk of nerve damage occurring. | 4 hours |
What are 3 anesthetic techniques that contribute to nerve injury in the preoperative setting? | general anesthesia (loss of pain response), NMB use (increased mobility and stretching), decreased MAP (decreased neuronal perfusion) |
Regional anesthesia can cause injury, but it is most likely due to what 3 things? | technique, hematoma, or needle trauma |
What are some patient related contributing factors to injury in the preoperative setting? | underweight, obesity, muscularity, HTN, diabetes, peripheral vascular disease, alcoholism, and smoking |
What is the most frequently reported injury after surgery and anesthesia? | ulnar nerve injury |
What is the anatomical origin of the ulnar nerve? | medial cord of the brachial plexus |
What factors predispose a patient to the incidence of an ulnar nerve injury during surgery and/or anesthesia? | male, preexisting neuropathy, prolonged hospital stay, extreme body habits |
In terms of preventing ulnar nerve injury, which arm position is better at achieving this goal: pronation or supination? | supination! supinate arm when possible. |
It is better to ensure that arms are abducted ________ | < 90 degrees |
When arms are to be tucked for surgical positioning, describe the best method of doing so. | arms should be neutral with palms inward |
Avoid extensive _______ flexion | elbow (when possible, secure arms over chest) |
________________ injury is a risk with all surgical positions but especially with arms over the head, abducted, and/or head rotated | brachial plexus |
Sternal retractors during cardiac surgery can cause what kind of nerve injury? | brachial plexus injury |
Spinal cord injury is primarily associated with __________ techniques | regional |
Hemiparesis and quadriplegia are rare but have been associated with what type of surgical positioning? | sitting position |
True or False: epidural veins do not have valves | True. this can cause venous congestion when abdominal and intrathoracic pressure increases |
To avoid hyper flexion of the neck, ________________ should be between the patients chin and chest. | 2 finger-breadths |
Radial or circumflex nerve injuries are typically associated with what two things? | ether screen or retractor pole |
Lateral position with the shoulder of the down arm circumducted leads to what type of nerve injury? | suprascapular nerve injury |
Inadequate padding in the supine or sitting position can lead to what type of nerve injury? | sciatic nerve injury |
Lithotomy position with excessive hip flexion can lead to what type of nerve injury? | obturator nerve injury |
Post operative vision loss (POVL) after non-opthalmic surgery is mainly attributed to what 5 things? | ischemic optic neuropathy, central retinal artery occlusion, central retinal vein occlusion, cortical blindness, and glycine toxicity |
Ischemic optic neuropathy and central retinal artery occlusion account for ____ of all POVL cases. | 81% |
Ischemic optic neuropathy accounts for ____ of POVL cases after prone spinal cases. | 89% |
Central retinal and posterior ciliary arteries are ____________ and are highly vulnerable to obstructed blood flow | watersheds |
What are some patient related predisposing factors to ischemic optic neuropathy resulting in POVL? | male, HTN, CV disease, obesity, diabetes |
What are some surgery related predisposing factors to ischemic optic neuropathy resulting in POVL? | spinal surgery, prone, long surgery time, high blood loss, low HCT, SBP < 100 |
What is the most common cause of ischemic optic neuropathy? | decreased perfusion with increased IOP |
How is ocular perfusion pressure (OPP) calculated? | OPP = MAP - IOP |
Patients scheduled for long spine cases should be informed of the risk of _____________ during pre-operative evaluation and consent for general anesthesia discussions. | post operative vision loss (POVL) |
What are 3 things that contribute to development of central retinal artery occlusion (CRAO)? | cardio-pulmonary bypass, hypotension, increased extra ocular pressure |
What are 5 things that contribute to development of central retinal vein occlusion (CRVO)? | HTN, CV disease, obesity, glaucoma, sickle cell anemia |
____________ results from ischemia or trauma for emboli, cardio-pulmonary bypass, or decreased perfusion. | Cortical blindness |
An L-argenine deficiency produces accumulated ammonia which leads to vision loss. This is a very rare syndrome; what is its name? | Glycine toxicity |
_____________ is typically a "repercussion injury" after a period of ischemia. | compartment syndrome |
What is the definitive treatment for compartment syndrome? | fasciotomy |
If compartment syndrome goes untreated, what are the complications? | tissue necrosis which leads to myoglobinuria and eventually ARF; could result in amputation or death from complications |
What is a well-known complication of the sitting chair position but can occur anytime the surgical site is above the right atrium? | venous air embolism (VAE) |
Up to ____ of patients have an undiagnosed PFO. | 35% |
__________________ occurs through a PFO when right atrial pressure exceeds left atrial pressure. | Paradoxical air embolism (PAE) |
Small VAEs can be absorbed, but what are the complications of large VAEs? | hypotension, dysrhythmias, CV arrest, death |
How can VAEs be aspirated? | Through a CVL placed in the right atrium at the junction of the SVC. |
This is the gold standard monitoring tool for a patient scheduled for a sitting position procedure. | TEE |
A TEE can detect emboli as small as _______ | 0.2 mL/kg |
What gas is associated with air emboli? | nitrogen |
A ____________ is equally as sensitive as a TEE at monitoring for an air embolus but cannot localize air. | precordial doppler |
Where do you place the probe for a precordial doppler? | over the 3rd - 6th intercostal space to the right of the sternum |
How can neck flexion during surgery potentially cause macroglossia or airway swelling? | neck flexion causes obstructed venous return |
Oral airways, ETTs, and esophageal stethoscopes can cause lip, tongue and airway swelling due to what? | obstructed lymphatic flow |
Edema of face, tongue and oropharynx can occur after what types of positioning? | prone, trendelenberg and sitting |
This position causes increased perfusion of posterior lung lobes, decreased functional residual capacity and carries higher risk of ulnar nerve damage. | supine position |
This position causes increased risk of aspiration, increased risk of V/Q mismatch, and decreased functional residual capacity. | trendelenberg |
This position id often used for laparoscopic procedures, decreases preload, CO, and MAP; and makes spontaneous ventilation easier. | reverse trendelenberg |
With _________ position it is important to raise and lower the legs simultaneously. | lithotomy |
In these positions it is important to monitor blood pressure at the level of the ear to ensure proper perfusion to the circle of Willis. | sitting & beach chair |
This position has been increasingly used in neuro cases due to it carrying a decreased risk of VAE. | prone |
What type of position is a Jackson Table used for? | prone |
Who always calls for the position change? | the anesthesia provider at the head of the bed! |
What are the 3 components of fire? | oxidizer, ignition source, fuel |
Most people realize that oxygen greatly enhances the rate of combustion, but many don't know that ___________ supports combustion in the same manner. | nitrous oxide |
______________ have become a common fuel source for OR fires since the CDC recommended as the preferred method for skin disinfection. | alcohol based skin preparations |