Exam 3 Flashcards
fire location %:
head, face, neck, upper chest, airway
65%
Surgeries that require “open oxygen delivery”: use less than ____% O2
less than 30% O2
standard V
positioning
standard VIII
safety
_______ position carries some degree of risk
Every position carries some degree of risk
Erect to supine leads to ___________ venous return
INCREASED venous return
Increased MAP leads to:
stimulation of _____________
baroreceptors
Stimulation of baroreceptors leads to:
_____________ HR, SV, CO (decreased SNS, increased PNS)
DECREASED HR, SV, CO
(decreased SNS, increased PNS)
Stimulation of ______ and __________ mechanoreceptors leads to:
____________ SNS to muscle and vascular beds
stimulation of atrial and ventricular mechanoreceptors leads to DECREASED SNS to muscle and vascular beds
Atrial reflexes leads to:
changes in ____ activity
RAA activity
MAP is maintained within a narrow range during postural changes in a ___________________ setting
MAP maintained in non-anesthetized setting
volatiles cause
vasodilation and dependent pooling
NMBs cause
abolished muscle tone (decreased venous return and pooling)
MAP decreases __ mmHg per _____ change between the heart and a body region
MAP decreases 2 mmHg per inch
Decreased compliance and increased resistance from shifting organs & positioning devices?
decreased FRC and lung capacity
______ position change may cause ETT migration
ANY change
what is common to all nerve injuries
ischemia (due to perfusion issues)
Length of procedure that commonly can cause nerve injury
> 4 hours
NMB leads to _____________ mobility and stretching
NMB leads to increased mobility and stretching
ulnar nerve comes from what cord
medial
ABDUCT arms _____ degrees
< less than 90 degrees
(try to keep arms closer to the body)
make sure head is turned _________ the arm that is extended
toward
venous air emboli is common with which position
sitting
AVOID hyperflexion of the neck
if necessary, use ___ fingerbreadths between chest and chin
2 fingerbreadths
Common nerve injuries
ether screen, retractor pole
radial or circumflex
Common nerve injuries
lateral position, dependent arm with shoulder circumducted
suprascapular
Common nerve injuries
inadequate padding supine or sitting
sciatic
Common nerve injuries
lithotomy stirrups, bar, knee support
Common Peroneal
Posterior tibial
Saphenous
Common nerve injuries
lithotomy with excessive hip flexion
Obturator
Common nerve injuries
traction against perineal post of fracture table
pudendal
most common postop vision loss (accounts for 89% prone, spinal cases)
Ischemic Optic Neuropathy (ION)
risk factors for Ischemic Optic Neuropathy (ION)
big back cases
prone
spinal
long cases
HTN, male, CV dx, DM, obesity
Patients should be aware of risks!
how does ION occur
watersheds are highly vulnerable
ION:
_____________ perfusion with ___________ intraocular pressure
DECREASED perfusion with INCREASED intraocular pressure
OPP ocular perfusion pressure =
MAP – intraocular pressure IOP
What does NOT cause ION
globe pressure!
what is second most common postop vision loss
Central Retinal ARTERY Occlusion (CRAO)
postop vision loss:
HYPERtension, CV disease, obesity, glaucoma, Sickle Cell anemia
Central Retinal VEIN Occlusion
postop vision loss:
CP bypass, HYPOtension, increased extraocular pressure
Central Retinal ARTERY Occlusion (CRAO)
postop vision loss:
Results from ischemia or trauma from emboli, CP bypass, decreased perfusion
Corticol blindness
postop vision loss:
L-arginine deficiency leads to accumulated ammonia leads to vision loss (very rare syndrome)
glycine toxicity
1 positional cause of compartment syndrome
lithotomy
what gas is associated with VAE
nitrogen gas
when can VAE occur (2 things)
sitting position
surgical site above right atrium (air vacuum)
patent foramen ovale in ____ of patients
1/3
paradoxical air embolism occurs through the _____ when ____>____ pressure
PFO
RA>LA
what is gold standard monitoring for VAE
TEE
what is most common monitoring for VAE
precordial doppler
3rd – 6th intercostal space, RIGHT of sternum
airway complications are usually due to what problem
lymphatic flow obstruction
airway complications are usually caused by:
ETT displacement
mainstem intubation
kinking
disconnects
esophageal stethoscopes
oral airway
pregnancy: use ______ _____________ uterine displacement
LEFT LATERAL
T-burg helps to __________ venous return during hypotension
increase venous return
when MAP is NORMAL, it leads baroreceptors to _____________ CO, PVR, HR, BP
MAP normal= decreased CO, PVR, HR, BP
shoulder braces: center above the acromioclavicular joint
should you use IMPROPER placement?
YES, use improper placement (otherwise brachial plexus risk)
reverse t-burg is often used for
laparoscopic procedures
when MAP, CO, preload is DECREASED, it leads to ___________ HR, SNS, PVR
MAP decreased= increased HR, SNS, PVR
Lithotomy
increased risk of _________ so do NOT use LMA
aspiration
often the position used for renal surgery, thoracic, ortho
lateral decubitus
use ______________ arm for pulse ox
dependent arm
issues with lateral decubitus
ears hurting
rhabdo
V/Q mismatch
what is the worst position
sitting
eye issues are common with what position
prone
position for LONG spinal procedures (scoliosis)
Jackson Table
hypothalamus uses both ________ and _________ feedback
positive AND negative feedback
requires nearly constant internal body temp
homeothermic
organism takes on the temperature of the surrounding environment
poikilothermic
what 3 body parts are part of the core temp
abdomen, thorax, head
dispersion of heat
thermolysis
(Conduction, Evaporation, Radiation, Convection)
production of heat
thermogenesis
(shivering, nonshivering, diet, BMR)
what can change body temp
o Circadian rhythm (peaks at 6pm)
o Exercise
o Food intake
o Infection
o Thyroid function
o Age
o Anesthesia, sedatives, alcohol
o Obesity (increased BMR)
temperature sensors are ___ferent
afferent
WARM temp
UNmyelinated
small
DULL pain
C fibers
COLD temp
myelinated
small
SHARP pain
A delta fibers
1st mechanism to respond during heat conservation
vasoconstriction
energy efficient
energy INefficient
shivering
2x-5x O2 consumption
newborns and premature infants ___ ____ shiver
DO NOT shiver
stimulates lipolysis with heat release
doubles heat production in infants
non-shivering thermogenesis
most important insulator against heat loss
intact skin
peaks at age 2; for each 1-degree F change, THIS changes by ___%
Basal metabolic rate
7% difference
> 36ºC
normothermia
34ºC - 35.9ºC
mild
32ºC - 33.9ºC
moderate
< 32ºC
severe
Anesthesia: induces ___________ allows core heat to flow _______________
induces vasodilation
peripherally
core compartment gets bigger
Electromagnetic heat waves emanate from all surfaces
radiation
biggest heat loss type
radiation
bair hugger/forced air convection unit: good for BOTH ____________ + ____________
both convection + radiation
Loss of heat via water loss from the skin, mucous membranes, open wound
evaporation
Loss of heat to air currents (i.e., wind)
convection
Transfer of heat between two adjacent surfaces with direct contact
conduction
2nd most common heat loss type
evaporation
3rd most common heat loss type
convection
4th most common heat loss type
conduction
____ anesthetics produce hypothermia
ALL anesthetics
how do anesthetics produce hypothermia (4 ways)
- Skeletal muscle relaxation (no shivering)
- Vasodilation
- DECREASED BMR (20%-40%)
- Impaired non-shivering thermogenesis
steep, fast drop in temp (usually 1 to 2 degrees) in the first hour
Core temp going to periphery
phase I
gradual, slower decline in temp in the next 2 to 3 hours
Continued heat loss to the environment exceeding heat production
phase II
longest, steady, equilibration state
Metabolic heat production matches heat loss
phase III
what causes the biggest drop in temp AND never reaches phase III
combined general anesthesia + epidural
anesthesia causes:
Interthreshold range __________ ____ to____ times, margins get larger
increases 10-20x
________ do NOT have thermoregulatory control
elderly!
blunted vasoconstrictor response
decreased BMR
decreased muscle mass for shivering
treatment for shivering
25 mg demerol (meperidine)
75 ug clonidine
supplemental O2
platelet ____________ is the issue for hypothermia
functioning
even _____ hypothermia increases circulating norepi by ____x
mild hypothermia (1 C)
5x
occurs at the junction of QRS-ST segments
height is directly proportional to the degree of hypothermia
80% of patients with temp <35 C
J wave=osbourne wave
what can hypothermia cause
dyshythmias
unstable angina, MI, cardiac arrest
increased PVR (acidotic)
increased blood viscocity (thick)
bradycardia in infants
J wave
hypothermia:
____x incidence of surgical wound infections
3x
____x incidence of morbid cardiac outcomes
3x
hypothermia
prolonged PACU stays (___ days)
2 days/20% increase
Drug: __________ stays hypothermic longer due to quick and profound vasodilation
propofol
Drug: _____________ gradual vasodilation, greater chance of recovery
sevoflurane
most effective means (not in the body) of heat conservation
bair hugger
give warm fluids if giving patient greater than > ___liters/hour
2 Liters/hour
greatest area of heat loss
extremities
3 benefits of hypothermia
-less trigger of malignant hyperthermia
-protection against spinal cord ischemia
-multiple sclerosis
rapid induction, quick awakening drug
used for peds, inhalation, induction
“fast on, fast off”
sevoflurane
yellow bottle
sevoflurane
blue bottle
desflurane
purple bottle
isoflurane
burnt orange bottle
halothane
Can react with CO2 absorbents to form nephrotoxic compound A
sevo
good drug for maintenance
des
Requires specially designed, electrically heated vaporizer
des
only gas that can be refilled without turning the vaporizer off
des
during induction, must combine this drug with IV agents
des
drug can cause tachycardia (caution with CAD)
des
Rapid elimination results in QUICKEST awakening
des
drug gold standard for neurosurgery
isoflurane
drug significant peripheral vasodilation can cause hypotension
iso
drug coronary artery steal syndrome: arteries dilate to the point that perfusion is an issue for other areas
iso
drug emergence is slowest on and off of all gases
halothane
drug no longer used
Major hemodynamic issues
Potent bronchodilator (so, it is good for asthma)
Causes hepatitis
Increased risk of dysrhythmias (especially with catecholamines)
halothane
NOT a volatile agent (used to SUPPLEMENT)
nitrous oxide
sympathomimetic activity
diffuses into air-filled spaces rapidly (increases pressure)
diffusion hypoxia
nitrous oxide
drug good for OB, bradycardia, hemodynamic compromise
nitrous oxide
a device for converting liquid volatile anesthetic agent into breathable vapor
vaporizer
Concentration-calibrated dials between _____ ________ and ______
between flow meters and CGO
Gaseous molecules from a substance that is LIQUID at room temp AND at 1 atm (760)
vapor
increasing temp _________ vaporization
increases
DIRECTly related
Increasing vaporization:
____________ temp of the liquid BELOW
decreases liquid below (freezing)
equilibrium pressure of a vapor above its liquid or solid
vapor pressure
when equilibrium is met at a certain temperature
saturated vapor pressure
vapor pressure is dependent only on ______ AND _______________
Dependent only on AGENT and TEMP
Temp at which vapor pressure equals atm pressure
boiling point
decreasing atm = ___________ boiling point
decreases boiling point
DIRECTLY related
Calories needed to convert 1g of liquid to vapor WITHOUT TEMP CHANGE in the remaining liquid
latent heat of vaporization
Calories needed to increase the temperature of 1g of a substance by 1°C
specific heat
you want a vaporizer with a ______ specific heat
high
Alveolar concentration that prevents movement in 50% of patients in response to surgical stimuli (incision)
MAC
MEASURED-FLOW Vaporizers: operator controls FLOW bubbled through agent from 2nd O2 flowmeter
FLOW ONLY
copper kettle
high specific heat + high thermal conductivity
copper
Carrier gas/total gas
splitting ratio
Gas entering the vaporizing chamber is carrier gas (oxygen, air, or nitrous)
variable bypass
Splitting ratio determined by: _________ resistance to FLOW (controlled by vaporizer dial) and TEMP ____________ mechanism (inside vaporizer)
FLOW + TEMP
variable bypass
internal resistance to FLOW
and TEMP compensating mechanism
TRUE OR FALSE
Saturated gas combines with fresh gas at vaporizer outlet to consistently produce final desired concentration regardless of total fresh gas flow
true
No matter how much fresh gas flow (0.5 liters vs 5 liters), and what the temp in the room is; what you have set on the dial is what is coming right from the vaporizer is the same %
2 different metals welded together; each metal responds differently to temp change
temp compensation
Vapor Blender vaporizer
electronic/TEC 6
why can des not be used with normal vaporizer
Cooling due to vaporization would overwhelm conventional vaporizer (it would freeze, be unable to maintain constant temp)
TRUE OR FALSE
NOTHING from the flow meters goes into the desflurane (no carrier gases)
true
what does T stand for on the vaporizer
transport
one central electronic control mechanism for all agents
aladdin
variable bypass (des does NOT require added heat)
what would happen?
sevoflurane (VP: 157) vaporizer was filled with isoflurane (VP: 240)?
OVER dose
SMALLER vapor pressure filled with LARGER vapor pressure
what would happen?
isoflurane (VP: 240) vaporizer was filled with isoflurane (VP: 157)?
UNDER dose
LARGER vapor pressure filled with SMALLER vapor pressure
Concentration dial increases when rotated __________________ for all vaporizers
counterclockwise
a vaporizer tilting >45° vertical may need flushing and/or recalibration to prevent overdose
tipping
breath to breath analysis should not be substituted for preventive maintenance
out of calibration
negative pressure check should be done during daily machine check
leaks
back pressure into vaporizer causes increased concentration into circuit
pumping
increased incidence of ulnar nerve injury
Male
Preexisting neuropathy
Prolonged hospital stays
Extreme body habitus (skinny or obese)
Positioning Devices Risk
Arm boards: ___________ _____
Arm boards: falling off
Positioning Devices Risk
Shoulder braces: _______ __________
Shoulder braces: steep T-burg (robotics)
Positioning Devices Risk
Sternal retractors: _________ ____________
Sternal retractors: cardiac surgery
Increasing temp:
____________ vapor pressure
increasing temp = increasing vapor pressure
DIRECTLY related
Copper Kettle
If TEMP REMAINS STABLE, 100 ml = increases anesthetic concentration by __%
1% for 100 ml
Electronic (Des) vaporizer
compensates for ______ + _____
FLOW + atm
