Exam 2 Flashcards
Standard monitors to place on patient when they are moved to OR table
pulse ox, EKG, and BP
Purpose of pre-oxygenation
increase alveolar O2 and decrease alveolar N2 (denitrogenation)
on room air what is the functional residual capacity
500mL of O2, about 2 minutes of apnea
on 100% FiO2 how long can a patient be apneic
about 6-10 minutes
what is functional residual capacity
amount of air in the lungs after exhalation
goal ETO2 of pre-oxygenation
should be 90%
how long should we preoxygenate
TV breathing for 3-5 minutes or 8 deep breaths in 60 seconds
indications for RSI
full stomach, obesity, diabetic, bowel obstruction, appendectomy, hiatal hernia w/ reflux
when does aspiration usually occur
induction and emergence
pathophysiology of aspiration pneumonitis
aspirated substance cause immediate damage
atelectasis within minutes
inflammatory response 1-2 hours after w/ pulm edema
By 24 hours secondary injuries occur
signs of aspiration
SpO2 <92%
tachypnea
tachycardia
HTN
chest Xray w/ infiltrates
alveolar-arterial gradient increase >300 on 100% O2
what monitors and devices are placed during maintenance
temperature monitoring, bair hugger, OG/NG tube, ToF monitor
appropriate MAC to render patient asleep and avoid recall
0.7-1 MAC
things to include on handoff
Surgery
Past Med Hx
how was masking?
How was intubation? View?
Meds given with intubation
Twitches/last paralytic
complications
how to eliminate inhaled anesthetic
turn off gas
increase FGF
increase ventilation
increase pressure support
amount of blockade with 1 twitch present
90%
amount of blockade with 2 twitch present
80%
amount of blockade with 3 twitch present
75%
amount of blockade with 4 twitch present
0-70%
Neostigmine numbers
dose: .025 - .075mg/kg
onset: 5-15 minute
duration: 45-90 minutes
Elimination: 50% renal 50% plasma esterase
Edrophonium numbers
Dose: .5 - 1mg/kg
Onset: 30 - 60 seconds
Duration: 5 - 20 minute
Sugammadex onset
1-3 minutes
Objective data for adequate reversal
4 twitches
TV > 5mL/kg
SpO2 > 90%
sustained tetanus >5 seconds without fade
vital capacity >15mL/kg
subjective date for adequate reversal
5 second head lift
eyes opening
constant hand grip
tongue protrusion
advantages of awake extubation
airway reflexes present
decreased aspiration risk
spontaneous ventilation
disadvantages of awake extubation
increased CV stimulation
increased coughing and straining
advantages of deep extubation
decreased CV stimulation
decreased coughing and straining
disadvantages of deep extubation
absent or depressed reflexes
increased risk of aspiration
airway obstruction
hypoventilation
calculate total body water
ICV + ECV
ICV is 2/3
ECV is 1/3
normal total body water
60% of lean body mass (42L)
primary cation of intracellular fluid
potassium
primary anion of intracellular fluid
phosphate
primary anion of extracellular fluid
Chloride
primary cation of extracellular fluid
sodium
ECF is split into what
intravascular (25%)
interstitial (75%)
what are the 2 intravascular pressures
capillary hydrostatic pressure and plasma oncotic pressure
what are the 2 interstitial pressures
interstitial fluid pressure and interstitial oncotic pressure
what is capillary hydrostatic pressure
the intravascular blood pressure driven by CO and impacted by vascular tone
what is plasma oncotic pressure
the osmotic force of colloidal proteins in the vascular space
what is interstitial fluid pressure
the hydrostatic pressure of the interstitial space
what is interstitial oncotic pressure
osmotic force of colloidal proteins within the interstitial space
what causes fluid to filter into interstitial space
increases in capillary hydrostatic pressure + increases interstitial oncotic pressure
what causes fluid to be absorbed into intravascular space
increases in plasma oncotic pressure and increases in interstitial fluid pressure
what is positive net filtration
fluid exudation into the tissues (fluid exits the capillary)
what is negative net filtration
fluid is absorbed into the vasculature
what is glycolax
the gel layer on the luminal (interior) surface of the vascular endothelium
what happens when glycolax is damaged
creates a capillary leak which causes accumulation of fluid and debris in the interstitial space and reduces tissue oxygenation
explain RAAS
renin is released due to hypotension which reacts with angiotensinogen and forms antgiotensin 1
ACE released by lungs converts angiotensin I to II
angiotensin II causes vasoconstriction and release of aldosterone
aldosterone stimulates reabsorption of water and salt in the kidneys
what is ADH and where does it work
potent vasoconstrictor and works on V1 receptor
role of Atrial natriuretic peptide
in response to increased preload, stimulates kidney to release sodium and water to reduced circulating blood volume
normal plasma osmolarity
280-290
equation for plasma osmolarity
2Na + (glucose/18) + (BUN/2.8)
advantages of crystalloids
lack allergic potential
provide immediate restoration of circulating vascular volume
preserve microcirculatory flow
decrease hormone mediated vasoconstriction
lower cost
disadvantages of crystalloids
75-80% will transfer into interstitial space due to hemodilution of plasma proteins and loss of capillary oncotic pressure
dilutional effect of coags
Normal saline can cause what
hyperchloremia and hyperchloremic metabolic acidosis
why is normal saline used widely in neurosurgical patients
hyperosmolality
why is normal saline used in patients who have anuria
less potassium in fluid than other isotonic fluids
use for 3% saline
low doses for trauma and head injury patients since it promotes volume expansion that mobilizes intracellular and interstitial fluid into the vasculature
what is the buffering agent of LR and what does it do
sodium lactate, maintains electrochemical balance and neutral pH of solution
advantages of LR
better at preserving intravascular fluid than NS
disadvantages of LR
lactate can cause gluconeogenesis
may contribute to alkalosis
mildly hypotonic so may cause transient serum hyperosmolality
contains calcium so contraindicated with blood products
why is Dextrans not used anymore
coagulopathic effects due to impairment on von willebrand factor
Dextrans osmolarity
high molecular weight (40-70kDa), hyperosmolar and have life of 6-12 hours
Gelatins molecular weight and half life
molecular weight of 30-35 kDa, half life 2-4 hours
disadvantages with gelatins
interfere with platelet function
cause nephrotoxicity
high chance to cause anaphylaxis
disadvantages of hydroxyethyl starches
can cause allergic reaction if allergic to the starchy plants
associated with coagulopathy and kidney injury
disadvantages of albumin
costly
can cause anaphylaxis
what is albumin made from
made from fractioned blood product from pooled plasma
molecular weight of albumin
65-69 kDa
calculation for maximum allowable blood loss
EBV x (initial Hct - lowest acceptable Hct) / initial Hct
4-2-1 rule
4cc/hr for first 10kg
2cc/hr for 2nd 10kg
1cc/hr for remaining kg
4-2-1 rule for 86kg patient
4cc x 10kg = 40cc
2cc x 10kg = 20cc
1cc x 66kg = 66cc
combined is 126cc/hr
what is estimated fluid deficit
maintenance fluid requirement x fasting hours
problems with 4-2-1 rule
does not account for comorbidities
what SVV indicates patient may benefit from fluid bolus
> 13%
requirements for SVV
mechanically ventilated with 7-8mL/kg TV
no arrhythmias
peep <15
hyper vs hyponatremia
hyper = shrinkage
hypo = swelling
what is the main regulator of potassium
alodsterone
EKG with hypokalemia
flattened T wave, U wave
EKG with hyperkalemia
peaked T waves, widened QRS in extreme levels
normal value of calcium
9-10.5
what is the primary regulator of calcium
parathyroid hormone
hyperparathryoid =hypercalcemia
hypocalcemia symptoms
Chvostek sign - facial spasms with touch of facial nerve
Trousseau sign - provoked carpal spasm after inflation of BP cuff
Prolonged QT
hypercalcemia symptoms
shortened QTc
hypertension
confusion/somnolence/seizure
N/V, constipation
treatment for hypercalcemia
volume expansion with NS
hypomag symptoms
fatigue, muscle weakness
Flat T wave
presence of U wave
prolonged QT
wide QRS
hypermag symptoms
depression of PNS and CNS
prolonged PR
prolonged QT
wide QRS
potentiation of NMB
hypophos symptoms
left shift oxyhem curve
hypoxia
heart blocks
seizures
come
hyperphos symptoms
same as hypocalcemia
brady
long QT
chvostek sign
trousseau sign
tetany
muscle weakness
what is hypoxis
state of insufficient oxygen to support tissues
what is hypoxemia
state of low concentration of oxygen in blood (PaO2 <80)
what is FiO2
concentration of oxygen in inspired gas
what is PaO2
partial pressure of oxygen in arterial blood
what is PAO2
partial pressure of oxygen in alveoli
what is SaO2
percent of hgb binding sites in the blood that are carrying oxygen
four factors that impact FiO2 of low flow oxygen
reservoir
oxygen flow rate
patient’s ventilation pattern
proper fit
each 1L of nasal cannula increase increases FiO2 by ____
4%
max FiO2 of nasal cannula
44%
for nasal cannula, how is FiO2 related to MV
FiO2 decreases as MV increases
simple mask FiO2 with 5-8L
35-60%
why should flows on simple mask be at least 5L
avoid rebreathing of CO2
what is FiO2 of partial rebreathing mask
60-80%
flows and FiO2 of face tent
4-8L, FiO2 30-55%
FiO2 of trach mask
up to 90%
what is absorption atelectasis
80% of gas in alveoli is nitrogen which holds alveoli open, O2 washes it out leading to collapse
high compliance causes
emphysema
neuromuscular disorders
PEEP
low compliance causes
pulm edema
ARDS
bronchoconstriction
Pneumo
insufflation of abdomen
inadequate muscle relaxation
high resistance causes
ETT kinked
airway obstruction
bronchospasm
airway edema
high gas flow (turbulence)
Low resistance causes
bronchodilators
increased lung volume
Flow volume loop for obstructive lung disease
low (flattened) peak inspiratory flow
low peak expiratory flow
failure of expiratory flow curve to reach 0 (gas trapping)
scooped out expiratory flow
what would be seen on flow volume loop with restrictive lung disease with PRESERVED compliance
loop appears normal but is small with reduced TV
what would be seen on a flow volume loop with restrictive lung disease and DECREASED compliance
reduced TV
rapid (steep) decreased in inspiratory flow
rapid (steep) expiratory flow
high peak expiratory pressure
*pulmonary fibrosis
what is seen in a flow volume loop with circuit leaks
expiratory phase not returning to original start
what is seen in flow volume loop with water/secretions
fluctuations on both curves
what pressure volume loop is used in anesthesia
dynamic pressure volume loop
Describe points of pressure volume loop
upper right point = PIP and TV
Lower left = zero volume and the set PEEP
what direction does a pressure volume loop flow
counter clockwise (inspiratory on right, expiratory on left)
how to calculate compliance
change in volume divided by change in pressure
what is normal compliance
50-100cmH2O
how does decreased compliance shift pressure volume loop
more horizontal
rotated right
how does increased compliance shift pressure volume loop
more vertical
rotated left
what does the area within the loop of pressure volume loop represent
work of breathing (hysteresis)
larger area means increased work to ventilate(increased resistance or reduced compliance)
what is peak airway pressure (Ppeak or PIP)
maximum pressure achieved during inspiration when air pushed into lungs
reflects resistance, compliance and TV
what should Ppeak (PIP) be
< 40 cmH2O
what is mean airway pressure
average pressure over whole ventilatory cycle
dynamic pressure measured by vent
optimizes oxygen
what 5 settings impact mean pressure
PIP, PEEP, rate, iTime, flow
what are the expected “Pmean” values for SV, MV, airflow obstruction, and ARDS
SV: 3-5
MV: 5-10
Obstruction: 10-20
ARDS: 15-30
what is Pplat
static pressure in alveoli achieved at end of full inspiration
should be < or = 30
what does it mean if you have high PIP and normal PP
increased airway resistance
what does it mean when you have high PIP and high PP
decreased lung compliance
what are the goals of mechanical ventilation
oxygen, ventilation, reduce work of breathing
what does PEEP do
improves oxygenation by maintaining airway pressures more than 0 during EXHALATION, preventing alveoli collapse and improving recruitment of atelectactic areas
what does PEEP do to FRC
increases
what are the aspects of protective ventilation
LOW V: 5-7mL/kg IBW
PIP < 35
Pplat: <28
Driving pressure <16
recruitment maneuvers
PEEP 5-8
Avoid FiO2 >.8
use lowest FiO2 for SpO2 88-95
what is the goal of protective ventilation
reduce overdistention and cyclic atelectasis
how do you calculate MV
TV x RR, should be 5-10L/min
what is normal TV
5-12 mL/kg of IBW
what is normal I time
1.7-2 seconds
explain maximum pressure (Pmax) set on vent
max lung pressure provider determines safe, if reached the vent will stop allow pt to exhale and alarm will sound
normal Pmax
12-100cmH20
what is Ppeak or PIP
max pressure needed to deliver TV, dependent on airway resistance and lung compliance
why use I:E 1:3 in COPD/asthma
reduces risk of air trapping
why use a 4:1 ratio
increased alveolar recruitment, increase hemodynamic effects
decrease CO2 clearance
used in severe hypoxia with poor lung compliance (ARDS)
what is constant variable in VC
tidal volume
what is dependent variable in VC
pressure, varies depending on respiratory mechanics and pt effort
recommended initial adult VC settings
TV: 5-7mL/kg IBW
RR: 6-12
I:E 1:2
PEEP: 5-10
what is constant variable in PC
pressure
what is dependent variable in PC
volume
In PC, how is TV effected if compliance increases or resistance falls
TV increases
in PC, how is TV effected if compliance decreases or resistance increases
TV decreases
in low compliance, how does PC differ from VC
in low compliance there is a higher TV compared to VC
recommended initial adult PC settings
Pressure limit: 12-20
RR: 6-12
I:E 1:2
PEEP 5-10
in VC, increased airway resistance or decreased lung resistance leads to what
PIP increases
in PC, increased airway resistance or decreased lung compliance leads to what
TV decreases
explain SIMV-VCV
initial settings mirror VC but allows patient to breath spontaneously between synchronized breaths
explain SIMV-PCV
initial settings mirror PC but allows patient to breath spontaneously between synchronized breaths
explain SIMV PCV-VG
mirrors PCV, delivers a set RR o PC breaths with guaranteed volume to them
explain PSV-Pro
spontaneously breathing patient, adds pressure to patients inspiratory effort while having apnea back up settings
explain APRV
similar to BiPAP but high CPAP during cycle
when does atelectasis develop during surgery
first 2-3 minutes
goals of lung recruitment maneuvers
reducing atelectasis
what are some lung recruitment maneuvers
manual ventilation with set inspiratory pressure 30-40 and hold pressure for 30-60 seconds
ventilator vital capacity maneuver
ventilator cycling maneuver
CPAP
PEEP
PEEP recommendations for BMI
<25: 6-7
26-30: 7-8
>30: 8-12
>40: 12-15
>50: 15
typical CPAP setting for NPPV
5-10
typical BiPAP settings for NPPV
IPAP: 8-10 max 20
EPAP: 3-5 max 10
in supine position, if the head is not in neutral position what nerve could be injured
brachial plexus
what is trendelenburg’s effect on starling curve
shift to right
complications from trendelenburg
shoulder braces can cause injury to brachial plexus, edema to facial structures, unrecognized hypovolemia
when is reverse trendelenburg commonly used and what is the complication
laparoscopic procedures
reduces perfusion to brain
why in lithotomy are the legs elevated and lowered at the same time
prevent hip dislocation, spinal torsion, or postop back pain
in lithotomy what dose acute abduction and external rotation of hips cause
femoral nerve or lumbosacral plexus stretch injuries
in lithotomy what does flexion of hips greater than 90 degrees do
injury to sciatic and obturator nerves
what are done with the legs in lateral decubitus
nondependent leg is straight, dependent leg is flexed at knee and hip
what is Bezold-Jarisch reflex
occurs when patient is in sitting position, hypotension and bradycardia from decrease in venous return
CV effects of sitting, prone, and flexed lateral positions
CO and BP decreased
when placing in different positions, what should the anesthetist do about MAC
slow increase, shouldn’t be at 1 MAC prior to sitting in beach chair
if trendelenburg increases venous return, when should precaution be taken with this
people with reduced heart function may not be able to handle the increased volume return
lateral position effect on ventilation/perfusion in both spontaneously breathing patients and mechanically ventilated
Spontaneous: dependent lung greater in ventilation and perfusion
Mechanical: nondependent (upper) better for ventilation and dependent (lower) lung better for perfusion causing V/Q mismatch
abdominal viscera effects in prone position
contents may limit diaphragm excursion due to compressing the body
abdominal viscera effects in lateral position
moves hemidiaphragm of dependent lung upward decreasing ventilation
abdominal viscera effects in sitting position
not much effect
abdominal viscera effects in trendelenburg position
diaphragm is moved cephalad which causes the movement of diaphragm to be limited and decreases FRC
abdominal viscera effects in supine position
FRC and total lung capacity are decreased
transection nerve injury
from cut
compression nerve injury
forced on bony prominence
stretch nerve injury
from stretch
conditions that can contribute to perioperative nerve injuries
HTN, DM, PVD, peripheral neuropathies, alcoholism
what is one of the most frequently reported injuries after surgery and may take 48-72 hours to report
ulnar nerve neuropathy
claw hand is from what
ulnar nerve injury
ape hand is from what
median nerve injury
wrist drop is from what
radial nerve injury
5 causes of non-ophthalmic vision loss
ischemic optic neuropathy
central retinal artery occlusion
central vein occlusion
cortical blindness
glycine toxicity
what 2 account for more than 80% of all cases of POVL
central retinal artery occlusion and ischemic optic neuropathy
vision loss from ION occurs when
24-48 hours after surgery, no pain associated
how does CRAO present
unilateral vision loss immediately after surgery
goals of MAC
sedation, amnesia, anxiolysis, and analgesia
what are the parameters of minimal sedation (anxiolysis)
normal response to verbal stimuli
unaffected airway
unaffected spontaneous ventilation
unaffected cardiovascular function
what are the parameters of moderate sedation
purposeful response to verbal or tactile stimulation
no airway intervention
adequate spontaneous ventilation
CV function usually maintained
what are the parameters for deep sedation
purposeful response after repeated painful stimuli
airway intervention may be required
spontaneous ventilation may be inadequate
CV function is usually maintained
what are the parameters of general anesthesia
unarousable
airway intervention often required
spontaneous ventilation is frequently inadequate
CV function may be impaired
fasting guidelines for MAC
same as GA
BIS target for MAC vs GA
MAC: 60-80
GA: 40-60
PaO2 equation
(FiO2 x (Patmos - PH2O)) - (PaCO2/RespQ)
levobupivacaine doses
max dose: 2mg/kg
Max total dose: 150mg
Bupivacaine doses
max dose: 2mg/kg
Max total dose: 175mg
Bupivacaine w/ epi doses
max dose: 3mg/kg
max total dose: 225mg
Ropivacaine doses
max dose: 3mg/kg
Total max dose: 200mg
lido doses
max dose: 4.5mg/kg
max total dose: 300mg
lido w/ epi doses
max dose: 7mg/kg
max total dose: 500mg
mepivacaine doses
max dose: 7mg/kg
max total dose: 400mg
prilocaine doses
max dose: 8mg/kg
max total dose: 500-600mg
procaine doses
max dose: 7mg/kg
max total dose: 350-600mg
chloroprocaine doses
max dose: 11mg/kg
max total dose: 800mg
