Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Anesthesia > Monitors > Flashcards

Monitors Flashcards

1
Q

What are the standard ASA monitors?

A 
Pulse Ox
Capnography
O2 analyzer
Vent disconnect alarms
Body temperature
EKG
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When is continuous ETCO2 monitoring required?

A

GA
Moderate sedation
Deep sedation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When is EKG monitoring required?

A

ALL anesthetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the Beer-Lambert law?

A

the intensity of transmitted light is inversely proportional to the concentration of the substance through which the light passes

More decay through more dense tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is functional saturation (SpO2)?

A

SpO2 = O2Hb / (O2Hb + RHb) x 100%

RHb = deoxyhemoglobin, 940nm
O2Hb = oxyhemoglobin, 660nm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is fractional saturation (SaO2)?

A

SaO2 = O2Hb / (O2Hb + RHb + carboxyhemoglobin (COHb), + methemoglobin (MetHb)) x 100

requires more wavelengths of light to detect different types of hemoglobin and is typically performed by a laboratory co-oximeter on an arterial blood gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

By what 2 principles does a pulse oximeter report SpO2?

A

plethysmography

absorption spectrophotometry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

With normal hemoglobin at an SpO2 of 90%, what is the PaO2?

A

60 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the x and y axes of the plethysmography waveform?

A 
y = light absorption
x = time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What factors affect pulse ox:

  1. signal strength
  2. pulse amplitude
  3. probe application
A

Signal strength - poor perfusion, high venous pressures, electromagnetic interference, or poorly applied probes.

Pulse amplitude - reduced by decreased stroke volume, hypothermia, occlusion, and/or vasopressors.

Probe application - affected by location, edema, motion, or light interference.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Pulse oximeters can’t distinguish between normal and abnormal hemoglobins. Explain what happens with:

  1. COHb
  2. MethHb
  3. SulfHb
  4. Sickle cell disease, fetal Hb
  5. Hct
A

COHb absorbs light at 660nm –> falsely elevated SpO2

MetHb absorbs light at both 660 and 940 nm –> saturation to trend towards 85%, which does not reflect the true O2Hb saturation.

SulfHb –> falsely high MetHb measurement and thus cause a falsely low SpO2.

Sickle cell –> resulting in a rightward shift of the O2Hb dissociation curve but SpO2 readings remain accurate.

Fetal hemoglobin = do not alter pulse oximetry reading

Anemia with a hematocrit underestimation error.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do the following affect SpO2 readings:

  1. indocyanine green, indigo carmine, and methylene blue
  2. Fluorescein and bilirubin
  3. bright artificial ambient light
A
  1. temporary falsely low SpO2 readings
  2. do NOT cause SpO2 changes, as they do not absorb light at 660 or 940nm.
  3. SpO2 may be falsely high when ambient light flicker frequency matching diode flashing frequency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the formula for mean arterial pressure (MAP)?

A

MAP = DBP + 1/3 (SBP-DBP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the appropriate width and length of a blood pressure cuff bladder?

A

width ~40-50% the circumference of the extremity

length - strap section should be long enough to overlap securely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What correction factor is used when the site of BP measurement is above or below the heart?

A

adding or subtracting 0.7 mmHg for each centimeter (approximately 2 mmHg for each inch) that the cuff is above or below the level of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What types of errors result in falsely elevated or falsely low blood pressure readings?

A

falsely high

  • cuff is too small
  • loosely applied
  • extremity is below the level of the heart

falsely low

  • cuff is too large
  • extremity is above the level of the heart
  • cuff is deflated too rapidly
17
Q

What blood pressure can be measured using the palpation technique?

A

Systolic blood pressure can be determined by palpating when a peripheral pulse is reestablished after it is occluded by a cuff

tends to underestimate SBP bc of the insensitivity of touch and the delay b/w flow under the cuff and distal pulsations

18
Q

Describe how an oscillometric NIBP cuff works

A

sensor detects oscillations produced by movement of the arterial wall

MAP = directly measured = maximum amplitude signal (most accurate)

systolic and diastolic pressures are calculated by various algorithms that vary from manufacturer to manufacturer from the MAP

systolic pressure = onset of oscillations
diastolic pressure = offset of oscillations

19
Q

What is the most important factor in obtaining an accurate reading from an oscillometric NIBP cuff?

A

WIDTH ~40-50% the circumference of the extremity

20
Q

As an NIBP cuff is placed progressively more distally on an extremity, what happens to the reported values for systolic and diastolic blood pressure?

A

systolic pressure increases
diastolic pressure decreases

MAP relatively unchanged

21
Q

Which reported value from an oscillometric NIBP cuff is most affected by rhythms other than normal sinus?

A

Atrial fibrillation - actual systolic, mean, and diastolic pressures vary with each heartbeat

NIBP assumes uniform pressure with each beat
Partial compensation - more frequent measurements, e.g. averaging 2 or more back-to-back measurements.

22
Q

What two wavelengths of light are most commonly used in pulse oximetry?

A 
Red light (660 nm) is well absorbed by oxyhemoglobin
Infrared light (940 nm) is well absorbed by deoxyhemoglobin
23
Q

What are some factors that can interfere with the accuracy and reliability of pulse oximetry?

A 
inaccurate at low SpO2
dyshemoglobins
dyes (methylene blue, indocyanine green, and indigo carmine)
nail polish
ambient light
light-emitting diode variability
motion artifact
low perfusion states (e.g., low cardiac output, profound anemia, hypothermia, increased systemic vascular resistance)
malpositioned sensor
venous pulsations in a dependent limb
bypassing the arterial bed
background noise
24
Q

Which dyshemoglobinemia would result in an Sp02 of 85%?

A

Methemoglobinemia

  • absorbs red and infrared wavelengths of light in a 1:1 ratio corresponding to an SpO2 of approximately 85%
  • cyanosis resolved w/in 15-30 min and substantial inc in SpO2 seen in 30-60min
25
Q

What core temperature monitors (locations) for true temperature monitoring are the best?

A 
distal esophagus
nasopharynx
ear canal/tympanic membrane
trachea
rectum
bladder
pulmonary artery

Best = PA catheter and the tympanic membrane, bladder not bad

26
Q

Why is it important to monitor the inhaled and exhaled concentrations of inhalational anesthetics?

A

enhances the safety and convenience of volatile anesthetics

Expired gas analysis –> estimate [blood] of volatile agents; = depth of anesthesia –> prevents errors by avoiding anesthesia that is “too deep” or “too light

27
Q

What is one of the biggest limitations of the mass spectrometer in respect to monitoring inhalational anesthetics?

A

very large = must be housed in a central location where it can serve multiple operating rooms

reporting delay can be considerable

28
Q

When utilizing Raman spectroscopy, what gases can be analyzed?

A 
CO2
N2O
volatile agents
O2
N2
water vapor
29
Q

When utilizing IR spectroscopy, what gases can be analyzed?

A

Asymmetric, polyatomic molecules
CO2
N2O
potent inhaled anesthetic agents (asymmetric)

30
Q

Describe how mass spectrometry works.

A

gas mixture is bombarded with electrons –> ions or ion fragments of a predictable mass and charge –> accelerated in an electric field in a vacuum –> measurement chamber, deflected on to a detector plate by a high magnetic field –> separates the fragments by their mass to charge ratio.

Each gas has a specific landing site on the detector plate where the ion impacts are proportional to the concentration of the parent gas or vapor. The processor calculates the concentration of the gases of interest.

31
Q

How does Raman spectroscopy work?

A

intense beam of light (e.g. Argon laser) into a sample of gas

Collision of a photon with a gas molecule –> photon change energy characteristics and emerge at a substantially different wavelength for the particular gas

The change in frequency –> Raman monitor to determine the type and concentration of the specific inhaled anesthetic gas or vapor

32
Q

What percentage of oxygen measured in the inspiratory limb of a breathing circuit will trigger a high intensity alarm?

A

below 18% to prevent hypoxic mixtures of gas being delivered to the patient

33
Q

What is the benefit of monitoring end tidal N2 concentration in a patient breathing spontaneously before induction of anesthesia?

A

detection of air emboli
denitrogenation prior to inducing anesthesia

No longer routinely detected - was done via mass spec

34
Q

Describe the method by which vaporizers are calibrated.

A

Refractometry

Light passes through two chambers - one w/ [volatile anesthetic] and another w/o volatile anesthetic

Slowing of light in one chamber –> a dark/light pattern that is compared to a known standard

calibrated twice per year

35
Q

What are the three major types of electrode-sensors used in blood gas analysis?

A
  1. pO2 - cathode –> anode reduction of O2 proportional to [O2]
  2. pH - change in voltage b/w electrode = [pH]
  3. pCO2
36
Q

Which blood gas analysis strategy uses temperature correction and adds CO2 to the inspired gases to maintain a pCO2 of 40 mmHg

A

pH Stat

37
Q

What is the Rosenthal Correction Factor for pH?

A

pH will DEC by 0.015 /degree increase in temperature.

pO2 will DEC 5 mmHg for each degree below 37°C.

pCO2 will DEC 2 mmHg for each degree below 37°C.

38
Q

How will air bubble, blood clotting, diluted sample affect ABG analysis?

A

Air bubble: erroneously high pO2 and low pCO2

Clot: falsely elevated potassium

Diluted sample: Na, Cl falsely elevated + decreased K, Ca, glucose, lactate, Hbg

Anesthesia (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions