Bb Monitors 2

Front 1

How do you determine if there is atrial hypertrophy on EKG?

Back 1

if p wave in V1 is greater than 3mm or biphasic you should suspect atrial hypertrophy

Front 2

What is frequency and wavelength?

Back 2

frequency=number of cycles/s;
wavelength=distance traveled by sound during one cycle

Front 3

How does the frequency and wavelengh change if an object is moving toward the observer?

Back 3

wavelength is shorter and frequency is higher

Front 4

How does the frequency and wavelengh change if an object is moving away from the observer?

Back 4

wavelength is longer frequency is lower

Front 5

What factors increase frequency on EEG?

Back 5

1. hyperoxia,
2. hypercarbia (mild),
3. hypoxia (initial),
4. sz,
5. barbs,
6. valium,
7. inhalational agents <1MAC,
8. N2O,
9. ketamine

Front 6

What factors decrease the frequency and increase the amplitute on EEG?

Back 6

1. hypothermia,
2. hypocarbia (mod to severe),
3. hypoxia (mild),
4. barbs-moderate dose,
5. etomidate,
6. narcotics,
7. inhalational agents>1MAC

Front 7

What factors decrease the frequency and decrease the amplitude on EEG?

Back 7

1. hypoxia-severe,
2. hypercarbia severe,
3. hypothermia,
4. hypotension,
5. barbs large doses

Front 8

What factors can cause electrical silence on EEG?

Back 8

1. brain death,
2. severe hypothermia,
3. severe hypoxia,
4. barb-coma dose,
5. isoflurane 2MAC

Front 9

What patients cannot be taken into the MRI scanner?

Back 9

pacemaker or aneurysm clips

Front 10

What does capnography rely on for measurement?

Back 10

infrared absortion and represents an evaluation of the CO2 waveform
-it is a function of molecular weight

Front 11

Describe the segments of a normal capnograph.

Back 11

-AB: beginning of exhalation when tracheal dead space empties of its CO2 free gas
-BC: period of continued exhalation when increasing amounts of CO2 rich respiratory gas mixes with dead space gas and results in an increasing CO2
-CD: near the end of exhalation, "alveolar plateau" representing nearly constant CO2 rich alveolar gas
-D: highest value of CO2, the PETCO2
-DE: inhalation

Front 12

Sudden drop to zero with capnography.

Back 12

technical defect, ie circuit disconnect

Front 13

Sudden increase in CO2 waveform

Back 13

release of a tourniquet
injection of sodium bicarb

Front 14

Gradual increase in CO2 waveform

Back 14

1. decreased minute ventilation,
2. prolapse of the expiratory valve
3. exhaustion of soda lime
4. insufficient fresh gas flow
5. malignant hyperthermia
6. thyroid storm

Front 15

What is most central to expired gas analysis?

Back 15

infrared analysis

Front 16

How is mass spectrometry performed?

Back 16

-concentrations of gas particles in the blood are determined by analysis of molecular mass to charge ratio
-After being ionized by a beam of electrons, a gas molecule is accelerated by an electric field and then shot into a magnetic field where radius curvature depends upon mass of the molecule
-the lightest ions are deflected first and this provides a way to ID compounds and measure concentrations

Front 17

How is infrared absorption performed?

Back 17

infrared light is passed through a gas sample in a chamber, and gas concentrations are derived based upon the intensity of transmitted light
-capable of measuring all anesthetic agents as well as CO2 and N2O
-notable exception is Oxygen

Front 18

How is oxygen analyzed?

Back 18

It does not absorb infrared light and must be measured by electrochemical or paramagnetic analysis

Front 19

What is the preferred method to analyze oxygen concentration?

Back 19

paramagnetic analysis
-magnetic field can be use to determine the concentration of oxygen in a gas mixture
-last longer and respond quicker than electrochemical cells

Front 20

How can oxygen concentrations be determined by electrochemical determinations?

Back 20

Through the use of a Clark electrode which requires an applied voltage or galvanic cells
-response time is slow

Front 21

What are the 2 types of capnometers?

Back 21

1. mainstream - less complicated, faster response rate, incorporate the infrared sensor into the circuit very close to the ET
2. sidestream - fixed volume of gas is continuously sampled from the circuit

Front 22

When will erroneous measurements of CO2 be taken?

Back 22

if sampling rate exceeds the expiratory flow rate and causes inspired gas to be sampled

Front 23

3 indirect apnea monitors

Back 23

1. impedance pneumography - MC; electrodes are placed on each side of thoracic cavity and low intensity alternating current is passed between them; small decreases in impedance are sensed as respiration
2. pressure sensitive pad - transducers sense body motion and convert it to electrical signals
3. pneumatic abdominal sensor - pressure changes by expansion and contraction during respiration are detected as breaths

Front 24

What are the 3 direct apnea monitors?

Back 24

1. thermistors - detect passage of cool air of inspiration and warm air of expiration
2. proximal airway pressure sensors
3. carbon dioxide

Front 25

How does pulse oximetry work?

Back 25

-It involves transillumination of tissue with 2 frequencies of light
-1 frequency is 940 nanometers and corresponds to 100% saturation (and absorption of less red light)
-other frequency is 660 nm and corresponds to 50% Hgb saturation and is called the isobestic point (and corresponds to the absorption of more red light)

Front 26

Explain color difference between oxygenated hgb and deoxyhemoglobin.

Back 26

-oxygenated hgb absorbs less red light than deoxyhgb accounting for its red color (ie less red light absorbed so more red light is deflected which explains why it has a red appearance)

Front 27

What are the 4 technical limitations of pulse oximetry?

Back 27

1. No or very low pulse present - hypotension, hypothermia, hypovolemia
2. Hemoglobin variants present - Carboxyhemoglobin false elevates reading, Met-hgb and indocyanine green have sat of 85%
3. Severe anemia present - Hgb <3-5 gm/dl
4. Venous pulsations - RV failure or TR produce false values

Front 28

What is transcutaneous oxygen monitoring (TCOM)? What concept is it based upon?

Back 28

A noninvasive way to measure tissue oxygenation
-Based on the fact that capillary PO2 may approximate arterial PO2 in areas of the skin where local blood flow exceeds the amount necesary for local tissue needs
-especially holds if the local area is warmed

Front 29

PtcO2 is what percentage of actual arterial oxygen tension?

Back 29

80%

Front 30

How is the TCOM electrode placed?

Back 30

It is attached to the skin, which is warmed to 40-45 degree C
-this provides local vasodilation
-oxygen from capillaries can then diffuse through the skin into a Clark type electrode for direct measurement

Front 31

What are the limitations of TCOM?

Back 31

1. Erroneus in present of peripheral vasoconstriction
2. Erroneus in present of decreased CO
3. Erroneus in thick, usually adyult skin, better in infants
4. Sudden decreases in PO2 are not detected - conjunctival probes partly lessen problem
5. Skin burns result from prolonged application - should not be placed for >2-3 hrs

Front 32

What are the 2 types of oxygen monitors?

Back 32

1. paramagnetic analysis
2. electrochemical analysis - diffusion of oxygen through an electrolyte solution creates an electric current which is proportional to concentration

Front 33

Describe this arterial waveform.

Back 33

This is critical dampening which is considered optimal. Will see one positive and negative deflection with flush test.

Front 34

Describe this arterial waveform.

Back 34

This is considered over dampened or hyporesonant. Will see no positive or negative deflections with flush test.

Front 35

Describe this arterial waveform.

Back 35

This is considered underdampened or hyperresonant. Will see > 1 positive and negative deflection with flush test.

Front 36

What if an arterial transducer is 15 cm higher than the right atrium?

Back 36

It would generate a pressure 15 cm H2O lower than actual BP
15/1.36 = 11 mmHg lower than actual BP

Front 37

What if an arterial transducer is 10 cm below the right atrium?

Back 37

It generates a pressure that is 10 cmH20 higher than actual BP
10/1.36 = 7.35 mmHg higher than actual BP

Front 38

What is MAP equation?

Back 38

MAP = (SBP + 2(DBP))/3

Front 39

What is the reason for the difference in measured systolic BP with an appropriately sized BP cuff and an arterial catheter?

Back 39

arterial - radial artery
cuff - brachial artery
-As the arterial pulse wave form travels distally from the aortic valve, SBP is exaggerated relative to more proximal arteries bc of 1) incident and reflected wave amplication and 2) a decrase in overall compliance in the smaller arteries compared with the aorta
-Radial systolic BP is higher than aortic SBP, but mean BP and DBP are similar

Front 40

What is now the standard method of BP cuff readings? How does this work?

Back 40

Oscillometric method
-Cuff is inflated above SBP and there are no oscillations (pulsations transmitted to the cuff by movement of the arterial wall)
-as the cuff is deflated, an abrupt incrase in the magnitude of oscillations is the SBP
-oscillation magnitude increases to a peak and then falls rapidly and the point at which there is no longer an alteration in the magnitude of oscillations is the DBP

Front 41

Specifically, how are the values for the SBP and DBP derived using the oscillometric method?

Back 41

Derived by using various formulas that examine the rate of change of pulsation
-SBP - the point at which pulsations are increasing and are 25-50% of maximum
-DBP placed at the point of 80% decline of pulse amplitude.

Front 42

How is MAP derived using the oscillometric method?

Back 42

Identified as the cuff pressure at the point of largest oscillation

Front 43

What are the indications for CVP monitoring?

Back 43

1. major surgery with major fluid shifts - either acutely or over several hours of surgery
2. aspiration of air emboli
3. insertion of transvenous pacing wires
4. admin of vasoactive substances such as dopamine

Front 44

What is the x descent?

Back 44

- starts with atrial relaxation
- continues as the RV contracts during systole which pulls the floor of the atrium downward
- during ventricular systole blood continues to flow into the RA from the vena cavae

Front 45

What is the y descent?

Back 45

Tricuspid valve opens early in diastole, blood int he RA flows passively into the RV and RA pressure falls again

Front 46

What are contraindications to CVP monitoring?

Back 46

1. local infection
2. placement in the surgical field
-Coagulopathies are not an absolute CI

Front 47

Why is there a higher incidence of pneumothorax with left vs right sided central lines?

Back 47

left pleural apex arises higher

Front 48

Why does pulmonary htn disrupt the relationship between CVP and wedge pressure?

Back 48

pulmonary artery diastolic pressure is normally about 1-4 mmHg higher than wedge pressure to maintain forward flow
- in the presence of pulmonary htn, blood flow is obstructed, lowering filling pressures on the left side of the heart
- pulmonary vascular resistance increases with loss of vasculature increasing pulmonary vascular resistance and causing elevation of pulmonary artery diastolic pressure

Front 49

Above what HR do right and left sided filling pressures not correlate?

Back 49

HR >120 bc diastolic filling time is shortened and pressures do not plateau

Front 50

What are PA catheters primarily used for?

Back 50

To monitor preload and afterload to reduce myocardial O2 consumption