Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
117 Cards in this Set
- Front
- Back
Bones are highly vascularized, predisposing the pt to risk for ____.
|
hemorrhage
|
|
A very high risk complication of ortho surgery is...
|
fat embolism
|
|
____ and ____ must be secured and verified after all position changes.
|
monitors and airway devices
|
|
What are the key positioning points during ortho surgery?
|
- head level, not down tilting
- free chest, abdomen w rolls - no direct eye pressure - supine, lateral, prone, modified fowlers (Beach chair) |
|
What is the target Hgb and HCT for ortho surgery?
|
- hgb > 9 mg/dl
- hct > 28% |
|
During ortho surgery, the target BP is ___% of control, and fluid losses should be replaced _____.
|
75%, aggressively (Blood PRN)
|
|
Gel pads for chest/abdomen during positioning can be adjusted to allow for..
|
- chest excursion
- large abdomen - pendulous boobies |
|
Perfusion of the lung is dependent on _____. The ____ segments have the greatest amount of perfusion.
|
posture/positioning,
gravity-dependent |
|
Describe VQ in the upright sitting position
|
- VQ mismatch
- most effective in middle lung fields (zone 2) - blood flow greater in zone 3, gas distribution initially distributed in zone 1 - with inspiration, fall in pressure will draw the greatest gas volume to more dependent areas of the lungs |
|
In some pts, changing from supine to prone positioning displaces the weight of the abdominal contents, resulting in...
|
reversal of blood flow distribution to the anterior segments -- difference in blood flow distribution is based on pressure affecting the capillaries
|
|
The pressure of the _______ can influence the resistance to blood flow through the capillaries.
|
surrounding tissues
|
|
Blood flow to areas of the lungs depends on...
|
pulmonary artery pressure, alveolar pressure, and pulmonary venous pressure
|
|
When standing, VQ match is best in zone __.
|
2
|
|
When supine, VQ match is best in zone ___.
|
3
|
|
Supine positioning leads to a ____ in FRC. Why?
|
reduction
800 mL, with abdominal contents pushing on diaphragm |
|
General anesthesia decreases FRC as much as 400 mL due to...
|
diaphragmatic relaxation
|
|
Paralysis with mechanical ventilation directs more ventilation toward the _____ areas of the lung, to improve ____.
|
gravity-dependent, VQ match
|
|
How are ventilation, perfusion and lung volumes affected by the lateral decubitus position?
|
- upper lung is zone 1, best ventilation but worst blood flow
- lower dependent lung is zone 3, best blood flow least ventilation - zone 2 is decreased - decr vital capacity and TV - mediastinum shifts toward dependent side, pushing on heart, decr venous return and CO, leads to hypotension |
|
How are ventilation, perfusion and lung volumes affected by the prone position?
|
- must maintain venous return by freeing the abdomen and avoiding vena caval occlusion
- zone 2 decr VQ match, zone 3 incr VQ match - requires greater positive pressure to ventilate - c-spine alignment and avoid eye compression |
|
What are the considerations for the sitting/beach chair position?
|
- airway is isolated (Can use ETT, LMA, or Spontaneous ventilation)
- incr hypotension - pad pressure points, align head, protect eyes |
|
What are the physiologic changes involved in moving a patient to the upright position?
|
- decr: MAP, CVP, PAWP, SV, CO, and PaO2
- incr: A-a gradient, pulm vasc resistance, total peripheral resistance |
|
Under nonanesthetized conditions, the effects of uprighting a patient are compensated for by an increase in ______ by as much as 50-80%.
|
incr SVR
|
|
During the upright position, autonomic responses are blocked by ________, which further exacerbates and compromises CO.
|
vasodilating anesthetics
|
|
Blood pressure remains unchanged or incr slightly in nonanesthetized pts in the sitting position but decreases in the _____ state.
|
anesthetized
|
|
Cerebral perfusion pressure (CPP) ______ by approximately 15% in the sitting position in non-anesthetized patients and could further ______ under anesthesia because of _______ and _______.
|
decreases, decrease,
vasodilation and impaired venous return |
|
Venous return from the cerebral circulation is usually _______ by inspiratory subatmospheric pressure during spontaneous ventilation, but this mechanism is nullified by ______.
|
increased, positive pressure ventilation
|
|
Obstruction of the _____ in the sitting position may also impede cerebral venous drainage, especially with unfavorable positions of the head and neck, such as _____ of the head.
|
internal jugular veins, flexion
|
|
Cerebral autoregulation maintains cerebral blood flow constantly between a MAP of ____.
|
50-150 mmHg
|
|
Poorly controlled HTN pts experience cerebral autoregulation shift to the ____, requiring ______ CPP/MAP to ensure adequate cerebral perfusion.
|
right, higher
|
|
What is a better lower limit for the MAP in pts with chronic HTN to maintain adequate cerebral autoregulation?
|
70-93 mmHg (mean 80 +/- 8)
|
|
Some ortho surgeons require deliberate _____ for shoulder surgery, eliminating any margin for error if BP falls further.
|
hypotension
|
|
In the supine position, BP in the arm and BP in the brain are...
|
essentially the same
|
|
In the beach chair position, BP will be _____ in the brain than at the heart or arm .The BP difference will be equal to the ______ between the heart/arm and the brain.
|
less, hydrostatic pressure gradient
|
|
What is the approximate difference in BP if the pt is positioned with the base of the brain approx 20 cm above the heart?
|
15 mmHg less in the brain
anesthetist must correct he BP readings at the arm to account for height of brain above arm! |
|
If SBP is 80-100 with a MAP of 50-80, the MAP at the base of the brain will be approx _____ lower, and at the top of the cerebral cortex approx _____ lower. This may suggest hypoperfusion to the cortex!
|
15-20 mmHg lower at brainstem
another 9 mmHg lower at top of cortex |
|
What is the critical variable in determining the diffence in BP at the cuff and in the brain?
|
vertical distance between external auditory meatus and BP cuff
|
|
Once you calculate the vertical distance between the external auditory meatus and the BP cuff, it should be converted to a ______ that must be incorporated into BP mgmt during the procedure.
|
hydrostatic pressure gradient
|
|
How is hydrostatic pressure gradient calculated?
|
0.77 mmHg decr for every 1 cm
OR 1 mmHg for every 1.25 cm |
|
The distance between the brain and site fo BP cuff on arm in the seated position will be _____ Depending on angle of sitting position and height of pt.
|
10-30 cm
|
|
If the beach chair position is combined with the use of ______, cerebral perfusion will be severely compromised!
|
deliberate hypotension
|
|
What happens if the BP cuff must be placed on the leg during a seated position case?
|
even more exaggerated difference between cuff reading and cerebral perfusion pressure
|
|
Patients in the beach chair position are at risk for intraop. _____ if borderline low BPs, as measured in arm, are used without appreciating the effect on CPP and CBF.
|
stroke
|
|
Blood pressure values during seated position of less than ____% preop resting values should be treated aggressively to enhance the margin of safety.
|
80%
|
|
Deliberate _____ should be avoided in beach chair position cases.
|
hypotension
|
|
During supination, you should be careful not to flex the non-surgical leg greater than ____ degrees, and the arms should be ....
|
no greater than 90 degrees
tape arms across body w padding |
|
What is the purpose of the axillary roll during lateral decub positioning?
|
avoids compression of the axillary artery and brachial plexus
|
|
What are the c-spine techniques during lateral decub positioning?
|
head and neck and thoracic spine should be in alignment
|
|
The torso can be positioned with ____ or ____ during lateral decub positioning.
|
bean bag or metal rod
|
|
During lateral decub positioning, it is important to monitor for pressure on the ____.
|
down ear
|
|
Increased pressure on the chest during pronation results in _____ chest wall compliance and lung expansion.
|
decreased
|
|
During pronation, there is a risk of ____ damage from excessive pressure or traction.
|
peripheral nerve damage
|
|
What must be specially protected from pressure during pronation?
|
eyes, ears, nose, breasts, genitalia
|
|
The _____ is a common table used for pronation and can be placed into 3 different shapes.
|
andrews table
|
|
This type of OR table is used for pronation and creates a nice little arch in the patients c-spine and hips.
|
jackson table
|
|
What are some considerations when choosing the anesthetic technique in an ortho case?
|
- proposed procedure and location
-length of procedure - expected EBL - postioning (prone, lateral, sitting) - coexisting medical conditions (obesity, meds) - pt preference or refusal of regional - surgeon preference, anesthetist skill level |
|
What are the advantages of regional in ortho?
|
- decr stress response
- avoids pulm irritation with COPD - decr afterload, decr bleeding - may prevent thromboembolism |
|
What are the disadvantages of regional in ortho?
|
- must pre-hydrate
- sedation to keep comfy - takes more time - may not be do-able in dementia pts - cant use if too anticoag - may not be fully effective |
|
What are some of the regional hemodynamic effects in ortho cases?
|
- decr MAP
- blood flow redistribution to larger caliber vessels - locally reduced venous pressure w epidural |
|
What are the advantages of general anesthesia with ortho cases?
|
- ease of administration
- pt comfort - control ventilation - no "Failed" generals |
|
What are the disadvantages of general anesthesia in ortho cases?
|
- myocardial and resp depr
- not protective against thromboembolism - airway control necessary - prolonged effects in elderly |
|
What are the advantages of tourniquet use in ortho cases?
|
- reduced blood loss
- bloodless surgical field (better operating conditions) |
|
What nerve is the most often injured by use of a tourniquet?
|
radial nerve bc sits next to humerus and can easily be compressed
|
|
What are the disadvantages of tourniquet use during ortho cases?
|
- potential nerve damage due to direct compression between bone and tourniquet
- ischemia of tissues - systemic metabolic acidosis - skin damage due to excessive pressure - hypo/hypertension |
|
What are the guidelines of tourniquet placement during ortho anesthesia?
|
- cuff should overlap 3-6x over a width of 50% of the extremity
- must be padded - placed by surgeon or OR nurse - pressure must be from pneumatic source - limited to 2 hr duration |
|
What are the recommended tourniquet pressures for upper vs lower extremities?
|
- 75-100 mmHg above SBP for LE (350 mmHg)
- 50-75 mmHg above SBP for UE (250 mmHg) |
|
After _____ minutes, the tourniquet should be let down for _____ minutes for reperfusion and to properly recover from inflation before putting tourniquet back up.
|
60-90 min, 10-15 min
|
|
While giving a tourniquet break, the surgeon can....
|
continue to operate or elevate the limb and apply pressure dressing to incision
|
|
Most of the time, surgeons do not want to let the tourniquet down until after the pressure dressing has been applied to....
|
decrease edema and bleeding
|
|
A _____ just distal to the cuff and padding will help protect it and the skin from betadine solution.
|
plastic drape
|
|
Describe tourniquet pain
|
- signs progressive from SNS activation
- onset 45-60 min after inflation for awake pts - suggest ischemia of tissues and nerve fibers, destruction of muscle tissues - dull, aching, burning, referred to above tourniquet - pain despite effective SAB/CLE anesthesia |
|
What may signal tourniquet pain under general anesthesia?
|
HTN, tachy
|
|
Tourniquet pain is difficult to treat...what do you do??
|
use narcotics
incr IA may not improve s/s until tourniquet deflated |
|
Why does tourniquet pain present the way it does?
|
transmission is via C fibers (may be more resistant to LA or recover faster than A delta fibers)
|
|
Although neither can truly ablate tourniquet pain, which works better? spinal or epidural?
|
spinal better
|
|
_____ neuraxial solutions provide a denser block than _____ solutions.
|
isobaric denser than hyperbaric
|
|
To treat sympathetic outflow during use of tourniquets in ortho cases, you can give what drugs?
|
hydralazine, nifedapine, labetalol
|
|
List the complications associated with tourniquet use
|
- accumulated metabolic wastes from ischemic limb causes transiet effects after release (incr ETCO2, incr O2 consumption, treat w incr ventilation, metabolic acidosis, decr core temp, decr MAP/CVP)
- pulmonary emboli d/t DVT - skin injuries - arterial spasm/vascular injury - bleeding - nerve injury (paresthesia/weakness) - compartment syndrome |
|
What are the "Evil humors" released from the extremity when tourniquet pressure is relieved?
|
- acids
- emboli of fat, air, cement - CO2 - thromboxane - myoglobin - intracellular enzymes - K - all contribute to hypotension, incr ETCO2, decr core temp, tachy, ectopy, arrest |
|
What might awake pts feel during tourniquet release?
|
dizzy, confusion, nausea, bradycardia, cold
|
|
What 3 things should you have ready when you drop a tourniquet?
|
fluids
pressors O2 |
|
Compartment syndrome
|
- true ortho emergency
- occurs following trauma or surgery, often repetitive and/or extensive muscle use of extrem - may be from casts/tight drsgs - incr pressure in closed fascial compartment causing tissue ischemia - can lead to nerve damage or muscle death - progressive, unrelenting pain - rapid onset, severe tenderness to site, pulse change is LATE sign |
|
What is the treatment for compartment syndrome?
|
fasciotomy
cant use regional for this |
|
What is polymethylmethacrylate? What's it used for?
|
- binds prosthetic w bone, bone cement
- cement mixing causes exothermic rxn ultimately expanding and causing pressure against bone surface (intermedullary pressure > 500 mmHg) |
|
Intermedullary pressures push ________ into the femoral venous channels.
|
fat, air and marrow
|
|
What are some of the clinical manifestations after placement of bone cement?
|
hypoxia
hypotension dysrhythmias pulm HTN decr CO |
|
How are the adverse effects associated with bone cement placement treated?
|
100% O2
incr fluids pressors PRN |
|
DVT and PE are most common following what types of surgeries?
|
pelvis and lower extrem surgeries
|
|
DVT and PE occurs due to _____ and _____ state.
|
venous stasis, hypercoagulable state
|
|
What are the risk factors for DVT/PE development?
|
obesity
incr age tourniquet use long immobilization |
|
What are some techniques to lower the risk of DVT/PE developmen after ortho surgery?
|
- anticoagulation post op
- SCDs - early rehab - use of regional anesthesia |
|
Fat embolism syndrome
|
- presents within 72 hrs following long bone/pelvic fx.
- s/s: pulm edema, dyspnea, hypoxia, tachycardia, mental status change/agitation/ confusion, cerebral edema, petechiae on eyes/armpits/ chest, drop in ETCO2 and PaO2 |
|
What is the treatment for fat embolism syndrome?
|
- stabilization of fracture
- 100% Fi02, CPAP - steroids if cerebral edema |
|
What sign heralds onset of fat embolism syndrome?
|
early persistent tachycardia
|
|
How is temp affected during fat embolism syndrome?
|
high spiking temps
|
|
What is the pathophysiology behind fat embolism syndrome?
|
- large fat droplets released into venous system
- droplets deposited in pulm capillary beds, travel through AV shunts to brain - microvascular lodging of droplets --> local ischemia and inflammation, release of inflammatory mediators, plt aggregation, vasoactive amines - hormonal changes caused by trauma/sepsis --> systemic release of free fatty acids/ chylomicrons, c-reactive proteins |
|
Fat embolism triad of S/S
|
dyspnea
confusion petechiae |
|
Arthroscopy
|
- used to examine interior of a joint
- minimal post op pain - decr blood loss - shortened length of stay/rehab - can do it almost any joint (access ports, fluid infused, needle muscle relaxation) - GA, LMA, ETT, SAB, other block w sedation (interscalene, axillary) |
|
Arthroplasty
|
- joint replacement (hip, knee, shoulder, ankle most common)
|
|
Hemiarthroplasty
|
partial joint replacement
|
|
What are the complications associated with arthroplasty?
|
blood loss, pain, thromboembolism, nerve injury
|
|
What is the positioning for hip surgery?
|
lateral decub
|
|
What are the anesthetic technique options for arthroplasty?
|
GA, SAB, CLE
|
|
Total Hip Arthroplasty (THA)
|
- performed in latera lposition
- avg duration 1-4 hrs - significant blood loss 1-6 units - 2 IVs, T/C - a-line, cvp - consider cell saver use - elderly population |
|
Deliberate hypotension during hip surgery may reduce blood loss by...
|
30-60 %
|
|
ORIF
|
open reducation internal fixation
- common for severely displaced fractures - requires screws, pins, external fixation - greater postop pain - GA, SAB, extremity block |
|
What are the anesthetic considerations for spine surgery ?
|
- ortho/neuro surgeons
- positioned with a specialized "Rack", pronated - hypothermia - blood loss significant - neuro monitoring |
|
SSEP
|
somatosensory evoked potentials
- continuous assmt of spinal cord fcn - monitor sensory system - IA may cause latency response and decr amplitude, use <1 MAC |
|
MEP
|
muscle evoked potentials
- motor responses fron transcranial stimulation - monitors motor pathways - NMBs affect response, ok to maintain 1-2 twitches on TOF |
|
List the types of ortho surgeries on the upper extrem?
|
- carpal tunnel release, neuromas (local bier block)
- hand surgery (local/bier/axillary, GA) - forearm to elbow (axillary block w musculocutaneous nerve block, GA, infraclavicular/supraclavicular block - risk of pneumothorax or ulnar sparing) - upper arm (interscalene/ infraclavicular/ GA) |
|
Anesthesia considerations for shoulder surgery
|
- usually performed in sitting position
- GA w or w/o regional (interscalene) - painful - brady/hypotension from vasovagal response |
|
What rare complication is associated with shoulder surgery?
|
- fluid infused through shoulder ports can infiltrate tissues of neck and cause airway obstruction
|
|
List the types of ortho surgeries in the lower extrem?
|
- foot (SAB/epidural/ ankle block/ local w MAC)
- ankle (SAB, epidural, sciatic/saphenous nerve block) - knee (SAB, epidural, formoral/lumbar plexus/ sciatic block) - hip and femoral neck fx (GA prior to moving to OR table, SAB/CLE for cooperative pts) |
|
Ortho preop assessment should include...
|
- comorbidities
- volume status (dehydration, blood loss) - arthritis (rheumatoid, osteoarthritis) - ankylosing spondylitis - pain |
|
Rheumatoid Arthritis
|
- immune-mediated condition affecting synovium (joints), chronic, progressive, inflammatory, systemic
- impaired immune system, risk of infection - CV: pericardial thickening, valvular fibrosis, conduction defects - pulmonary: effusions - heme: anemia - endo: adrenal insufficiency from steroids - pharm: nsaids and ASA - airway: potential atlantoaxial subluxation - calcified arteries, ischemic heart disease, muscle wasting, fused joints - difficulty positioning, difficult IV access - multiple joints, symmetrical involvement |
|
What are the airway concerns associated with RA pts?
|
- severe atlantoaxial subluxation
- may push odontoid (C2) into foramen magnum -- may reduce vertebral arterial blood flow, cord compression --> nerve damage or death - cricoarytenoid arthritis: hoarseness, inspiratory stridor, narrow glottic opening, use smaller ETT, post extubation monitoring |
|
Osteoarthritis
|
- degenerative disease
- articular surface wear and tear, one or more joints - most commonly hip and knee |
|
Ankylosing Spondylitis
|
- ossification of ligaments at bone attachment sites
- immobility and consolidation of joints, consider awake FOB - affects c-spine, hips, shoulders, costovertebral joints - impaired lung fcn (rigid rib cage, preO2) - risk of spinal/cervical fx (Careful positioning, while pt still awake, difficulty placing regional) |