Week 6- Anesthesia Monitoring, Vents, & Vent Modes Flashcards
what does tubing the goose mean? and why is it a problem?
intubating the esophagus
can cause vomiting– may need to place OG
increased airway resistance would cause what to the alpha angle of ETCO2
increased alpha angle
a incompetent inspiratory valve will cause what change to the ETCO2
altered beta angle (not as steep)
if the ETCOs waveform does not return to baseline, what should you think is the cause
desiccated CO2 absorbant
a curare cleft in the ETCO2 waveform could signify:
pt is not fully paralyzed or sedated
what are cardiac oscillations signify on ETCO2 and what should you do about them
detection of the heart beating by the lung
nothing, it is benign
typical ETCO2 waveform appearance of a person with COPD
shark fin look
what should you set the I:E ratio of someone with COPD and why
1:3
long expiratory time allows for longer exhalation
4 possible causes of exponential decrease in ETCO2
- cardiopulmonary arrest
- PE
- sudden hypotension/ massive blood loss
- cardiopulmonary bypass
what would an air leak cause a ETCO2 waveform to look like
stairs
NIBP should be ______% greater than the diameter of the limb and cover _________ of upper arm or thigh
undersized cuffs will give falsely ______ readings and oversized cuffs will give falsely __________ readings
20
2/3
high
low
the more peripheral the NIBP is, it will result in _______ systolic and _________ diastolic
higher, lower
the desired reference point for NIBP
aortic root
for every 4 inches (10cm) in height from the aortic root, the NIBP will differ by about ________ mmHg
7.5
what type of cuff is an NIBP and why
an oscillometric cuff because it measures changes in pressure as pressure becomes less and less
what causes korotkoff sounds
volatile blood flow, which can cause vibrations against the artery walls
MAP is the point at which the __________ are maximal
oscillations
standard of care: NIBP measure at least every ______ minutes
5
contraindications for NIBP (4)
- traumatic injury (from repeat NIBP, bone frx, or fistula/PICC)
- axillary lymph node dissection (could cause limb edema from repeat vascular occlusion)
- iatrogenic injury from prolonged use
- radial nerve injury
Determines adequacy of ulnar collateral flow and integrity of radial artery
When should color return
Allen’s test
<5-6 sec for return of pink color
T or F: ulnar artery is preferred location for Aline placement
F - radial artery is preferred. ulnar is much smaller
aline flush is pressurized to ~ _____ mmHg
zero point of aline
300
phlebostatic axis, 4th intercostal space (right atrium) 5 cm posterior to the sternal border
can zero a line transducer at what point to determine cerebral pressure/circle of willis
mid ear in seated position
peak of aline waveform is equivalent to …
bottom of aline waveform is equivalent to ….
systolic pressure
diastolic pressure
what does the dicrotic notch on aline waveform represent
closure of AV valves
an overdamped aline waveform will yield __________ oscillations while an underdamped aline waveform will yield ____________ oscillations
< 1.5
> 2
** normal= accurate BP 1.5- 2 oscillations
** overdamped= falsely low BP
** underdamped= falsely high BP
systolic waveform variation can signify the ____________ of patient
hydration status
some complications from A-line placement
- thrombosis
- hematoma
- bleeding
- vasospasm
- air embolism
- necrosis/ischemia
- nerve damage
- infection
- intra-arterial drug injection
the Slope of upstroke of aline waveform provides information on patient’s hemodynamic status, what does is represent
myocardial contractility
Slurred/delayed stroke of an Aline waveform is indicative of
increased afterload
CVP refers to hydrostatic pressure generated by the blood within either the _________ or the ___________ at a point adjacent to the right atrium
right atrium
great veins of the thorax
on the CVP waveform: what does the a represent
atrial contraction
on the CVP waveform: what does the c represent
tricuspid valve elevation of right atrium
on the CVP waveform: what does the x represent
downward slope of contracting right ventricle
on the CVP waveform: what does the V represent
back pressure wave from blood filing right atrium
on the CVP waveform: what does the y represent
tricuspid valve opens in early ventricular diastole
Waves order on the CVP waveform
a > c > x > v > y
the waveform of a CVP correlate to the flow and contractions states of the ________
Right atrium
main complication of placing a central line
pneumothroax
what can a-fib do to a CVP waveform
loss of a wave
prominent c wave
what can AV dissociation do to a CVP waveform
cannon a wave
what can tricuspid regurgitation do to a CVP waveform
tall systolic c-v wave and loss of x descent
what can tricuspid stenosis do to a CVP waveform
tall a wave and attetnuation of y descent
what can pericardial constriction do to a CVP waveform
tall a and v waves, steep x and y descents (M or W configuration)
what can cardiac tamponade do to a CVP waveform
dominant x descent and attenuated y descent
Standard variables measured with the PA catheter
- CVP/right atrial pressure, RV pressure, PA pressure and PAWP/left atrial
- CO
- Mixed venous oxygen saturation
- Core body temperature
CO =
SVR =
EF =
MAP =
CO = SV X HR
SVR= (MAP-CVP)/CO
EF = SV/EDV
MAP = (SBP + 2DBP)/3
T or F: Most rhythm disturbances can be detected and diagnosed with a 5-lead ECG
F - 3 lead ECG
Cardiac ischemia is best detected by monitoring with a 5-lead ECG and using both lead ___ and lead _____ (up to ___% sensitivity)
II
V5
80%
what happens to ST segment when there is supply-demand mismatch
ST-segment depression
** most common form of post-op ischemia (demand ischemia)
placement of a white lead on 5 lead EKG
RA
the periphery can be up to ___ degrees cooler than the core
3
Patients can exhibit a passive decrease of _________ degrees Celsius during anesthesia
1 to 4
t or f: neuraxial blocks can cause vasoconstriction
F- causes vasodilation
during general anesthesia, why is there an initial decrease in temperature (4 examples)
- prepping/draping
- redistribution of body heat d/t anesthesia-induced vasodilation
- vasoconstriction impaired by anesthetics
- muscle relaxants reduce heat protection–> prevents shivering
4 types of heat loss in OR
- radiation **
- conduction
- evaporation
- convection
up to 60% of heat loss in or is from
radiation heat loss
second most significant route for intraoperative heat loss
convective (30%)
what can you use to prevent heat loss in OR
baer hugger and/or warm fluids
attributes to the latent heat of vaporization of water from open body cavities and respiratory tract
evaporative heat loss ~ 8-10%
heat loss that occurs from direct contact of body tissues or fluids to a colder material
conductive ~ 5%
some major consequences of hypothermia in OR
- wound infection
- adverse cardiac events
- coagulopathy
- introp blood loss
- increased DOA of NMBD/muscle relaxants
- shivering
- increase PACU stay
- increased hospital stay
hyperthermia is a rise in body temperature of __ degrees celcius/HR
2
usual cause of hyperthermia in OR
- sepsis
- overheating d/t active warming
- MH or other syndromes
T or F: the site of temperature monitoring intraoperatively depends on the Procedure, type of anesthesia used, and the reason for the temperature monitoring
T
Gold Standard for measuring core temperature is the
pulmonary arterial blood`
Optimal position for the esophageal temperature sensor in an adult is the distal third of the esophagus to
decrease the cooling by respiratory gases in the trachea
T or F: Skin temperatures reflect central/core perfusion
F- Skin temperatures reflect peripheral perfusion rather than core body temperature
A battery-powered stimulator delivers a small electric current to a superficial nerve, usually the ulnar. Activity stimulated by the four consecutive impulses is assessed by watching or feeling for associated muscle movement.
TOF
T or F: Adequate muscle relaxation exists when 3 of 4 twitches are present
F - adequate when 2 of 4 present
Good intubating conditions exist when __ of 4 twitches remain
1
what is the TOF ratio
Comparing of T4 (4th twitch of the TOF) to T1
if you are reversing someone from paralysis and you get 4 full twitches, what % of receptors can still be blocked
75%
strong correlation with rate of larynx recovery
corrugator supercilli
50-100 Hz stimulus for 1-5 seconds
tetanic stimulation
two short burst of 50 HZ tetanic stimulation separated by 750 msec
double-burst
50 Hz tetany for 5 seconds followed by TOF starting 3 seconds later
post tetanic stimulation
processeselectroencephalographic signals to obtain a value, which reflects the LOC of the patient.
BIS monitor
A value of __represents the absence of brain activity, and ___ represents the awake state
BIS values between ___ to ____ represent adequategeneral anesthesia for a surgery
Values less than ___ represent a deep hypnotic state.
0 & 100
40 & 60
40
BIS monitor is unreliable with what two anesthetics
ketamine and N2O
limitations of BIS monitors (5)
- anesthetic agents
- age
- hypothermia
- neuro impairment
- medical device interference
modern anesthesia delivery systems are typically _________
semi-closed
T or F: Anesthesia vents are more complex than ICU vents
F
what is one of the main differences between an ICU vent and an anesthesia vent
anesthesia vent can deliver inhalational agents
Deliver precise volumes or pressures to support the patient’s breathing, and they often have advanced monitoring
Anesthesia ventilators
T or F: ICU vents are semiclosed systems
F- they are open systems
In an ICU ventilator gases are recirculated. (T/F)
False - no gases recirculated
High gas flows used in an elaborate gas-warming and humidification
(anesthesia or ICU ventilator?)
ICU ventilator
T or F: Anesthesia vents are able to remove CO2 and conserve potent inhalational agents
T
T or F: Anesthesia vents are highly customizable
F - ICU vents are highly customizable
3 modes of an anesthesia ventilator
- spontaneous
- volume control
- pressure control
in V/Q mismatching, what causes deadspace
ventilation without adequate perfusion
in V/Q mismatching, what causes shunts
perrfusion without ventilation
** deoxygenated blood bypasses alveoli and mixes oxygenated blood, resulting in decreased arterial oxygen Ventilator assumes the work of breathing.
lungs have to overcome _______ & _________
compliance and resistence
compliance has to do with the __________ of the lungs
elasticity
what initiates a breath
trigger mechanism
the trigger mechanism is the transition from ______ to _______ and begins in the ___________ phase
expiration to inspiration
inspiratory
3 main trigger methods
- time-trigger
- pressure-trigger
- flow-trigger
guarantees a minute volume and decreased work of breathing, but which is less comfortable
time-triggering
gives the patient more control over the initiation of a breath, but which can also be uncomfortable
pressure-triggering
trigger that occurs when vent detects a drop in flow
flow-triggering
refers to the variable a ventilator uses to end inspiration
cycling mechanism
typical methods of ventilator breath cycling mechanism (4)
-pressure-cycled
- volume-cycled
- time-cycled
- flow-cycled
in what type of patients is a time-cycled mechanism used
sedated or paralyzes patients
** typical of mandatory modes
what cycling mechanism is mainly used for spontaneously breathing patients and is typical of spontaneous modes
flow-cycled
the variable a ventilator uses to end inspiration
cycling
PEEP can be changed in all vent modes except?
Spontaneous
the ventilator measures the cycling mechanism variable during the _________ phase
inspiratory
** When the set parameter for this variable is achieved, the ventilator opens the expiratory valve, and expiration may begin.
the cycling mechanism changes from ______ to _______ and trigger mechanism changes from ________ to __________
inspiration to expiration
expiration to inspiration (initiates a breath)
in Volume controlled CMV; tidal volume (Vt) is controlled and independent of changes in
lung mechanics
** Vt manually to avoid atelectasis
two things you can control when using the volume control ventilator setting
- tidal volume and RR
**Rate adjusted manually for reasonable EtCO2 while monitoring PIP.
T or F: in volume control vent setting, PIP stays the same at <40 cmH2O
F: PIP varies and should be kept as low as possible (< 40 cmH2O)
threshold for potential barotrauma
40 cmH2O
in volume control, a set number of breaths/min are ______-cycled and __________-triggered
time-cycled
machine-triggered
t or f: Expiratory flow is constant in the volume control vent setting
F - Inspiratory flow is constant
T or F: you can add PEEP to most volume control vent modes
T
another name for volume control vent setting
CMV (vanilla)
** most commonly used
pressure control vent setting controls (3)
- PIP
- PEEP
- Frequency (f)
in pressure control vent setting, tidal volume varies with changes in
compliance, patient effort, and resistance
why does flow vary high at first in pressure-control mode?
to produce set PIP early
**it is less later in inspiration to maintain the set pressure through the inspiratory time (Ti).
pressure control is known as a decelerating flow (or ramp) pattern, which is thought to be beneficial in (2)
- gas exchange
- V/Q matching
pressure support vent (PSV) mode- pressure support should be adjusted tidal volumes of
6-8 mL/kg
in pressure support ventilation, what should you set the pressure at start
10-12 cmH2O
T or f: some vents require a spontaneously breathing patient for pressure support ventilation (PSV) because there is no mandatory minimum RR
T
** great for when about to wake up patient. It’s a good indicator that pt. is starting to recover from paralysis.
why is PEEP ordinarily used with PSV
to help recruit alveoli
PSV senses a patients _______ effort (volume or flow) and delivers PSV while it is present
inspiratory
useful to support Ventilation and control arterial CO2 for spontaneously breathing patients during maintenance and emergence
PSV - pressure support ventilation
