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671A - Anesthesia I > Week 1 - Basic Clinical Monitoring (Respiratory & Metabolic) > Flashcards

Week 1 - Basic Clinical Monitoring (Respiratory & Metabolic) Flashcards

1
Q

Cyanosis is a _________ sign of hypoxia

A

late

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2
Q

PaCO2 is based on _____________ concentration

A

hydrogen ion

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3
Q

Carbon dioxide reacts with water to produce _________

A

carbonic acid ——> hydrogen ions

reversible reaction - basis for respiratory involvement in pH balance

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4
Q

How does a colorimetric device work to monitor ventilation following intubation?

A

Exhaled CO2 reacts with water in the device to form carbonic acid - this raises the pH and changes the color on the indicator

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5
Q

What are the limitations of colorimetric devices used following intubation?

A

False positives may result from detection of CO2 from air forced into the stomach (or from the presence of carbonated beverages or antacids)

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6
Q

ETCO2 is said to be approximately _______ torr lower than arterial CO2

A

2-5

this is true for patients without cardiac or pulmonary abnormalities

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7
Q

ETCO2 has been shown to be a ________ sensitive indicator of hypoventilation than clinical observation or pulse oximetry

A

more

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8
Q

In the following capnogram, what does the segment from B to C represent?

A

Beginning of expiration

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9
Q

At which point on the capnogram is the ETCO2 measured? What is this called?

A

point D
* this is termed the Beta angle

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10
Q

How would you interpret the following capnogram?

A

There is a failure to return to baseline which indicates CO2 rebreathing

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11
Q

What effect would sustained hyperventilation have on ETCO2?

A

it would decrease
* (there is an initial increase as there is a large amount of CO2, but sustained hyperventilation causes a decrease as the blood content of CO2 is depleted)

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12
Q

What effect would sustained hypoventilation have on ETCO2?

A

it would increase
* (there is an initial decrease as exhalations are small, but over time the body compensates by removing a greater amount of CO2 with each breath)

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13
Q

In a patient with fever or sepsis, would you expect an increase or decrease in ETCO2?

A

Increase
* these states cause the body’s metabolic rate to increase - leading to greater production of CO2 at cellular level and a greater degree of CO2 removal with each exhalation

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14
Q

In a patient with pulmonary emolism, what change in ETCO2 might you expect?

A

Decrease
* this is due to a decreased delivery of CO2 to the alveoli

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15
Q

What might the following capnogram represent?

A

Asynchrony with ventilator/return of spontaneous ventilation

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16
Q

In states of __________ compliance, minimal force is needed for lung expansion

A

high

not necessarily a good thing (COPD, Emphysema)

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17
Q

When compliance is low _________ force is needed for lung expansion

A

more/higher

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18
Q

Lung _______ can be shown by a flow/volume loop

A

compliance

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19
Q

The following flow volume loop is characteristic of _________ lung disease

A

obstructive (air can’t get out)
* near normal inhalational volume and flow (bottom half of loop), but severely limited exhalational volume and flow (top half of loop)
* e.g. COPD, emphysema

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21
Q

Because oxyhemoglobin absorbs light differently than deoxyhemoglobin, oxygen saturation can be measured via ___________

A

pulse oximetry

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22
Q

In the presence of methemoglobin or carboxyhemoglobin, or a patient with sickle cell anemia, a pulse oximeter may falsely _________-estimate the true value of oxygen saturation

A

over
* methemoglobin and carboxyhemoglobin absorb light in a way similar to oxyhemoglobin - this fools the pulse oximeter into thinking that saturation is normal when the true value is low

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23
Q

The presence of dyes, such as methylene blue, alters the absorbtion of light by a pulse oximeter - this may cause a transient ___________ in measured oxygen saturation

A

decrease

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24
Q

Hypothermia is defined as a core temperature of less than _______

A

36 degrees celsius

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25
Q

How do general anesthetics alter thermoregulation?

A

Reduce shivering
Reduce vasoconstriction (normal vasoconstriction would conserve heat)

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26
Q

What are the 4 types of heat loss?

A
  • radiant
  • evaporative
  • convective
  • conductive
27
Q

What factors may place a patient at higher risk for hypothermia?

A
  • lengthy surgery
  • old age
  • lean body mass
  • combined epidural and general anesthesia
28
Q

Hypothermia may increase the risk for what perioperative complications?

A
  • wound infection/delayed healing
  • cardiovascular events (MI)
  • blood coagulation abnormalities
  • length of PACU stay
29
Q

Consider the oxyhemoglobin dissociation curve - what might cause a shift to the left?

A

Decreased:
* pCO2
* temperature

Elevated:
* pH (alkalosis)

remember - temporary or localized shifts are part of normal physiology

30
Q

Consider the oxyhemoglobin dissociation curve - what might cause a shift to the right?

A

Increased:
* pCO2
* temperature

Decreased:
* pH (acidosis)

remember - temporary or localized shifts are part of normal physiology

31
Q

A shift to the left of the oxyhemoglobin dissociation curve means that hemoglobin has ______________ affinity for oxygen

A

higher

at a constant pO2, shift to the left = higher O2 saturation

32
Q

A shift to the right of the oxyhemoglobin dissociation curve means that hemoglobin has __________ affinity for oxygen

A

lower

at a constant pO2, shift to the right = lower O2 saturation

33
Q

The following flow volume loop is characteristic of _________ lung disease

A

restrictive (minimal air in, minimal air out)
*can be caused by decreased lung compliance (e.g. pulmonary fibrosis) or chest wall movement (e.g. muscular dystrophy, pain)

PE, bronchoconstriction, pneumothorax, asthma

34
Q

The beta angle of a capnography graph increases with what 3 things?

A

Rebreathing, malfunctioning inspiratory valves, and prolonged response time compared with respiratory cycle time (especially in children)

35
Q

The beta angle of a capnography graph decreases with ___________

A

Decrease in slope of phase III

36
Q

The alpha angle of a capnography graph decreases with ______

A

COPD

37
Q

The alpha angle of a capnography graph increases what 2 things?

A

Increased peep and airway obstruction

38
Q

What 2 things can cause an increase in resistance in ventilator flow?

A

Bronchoconstriction, kinked/obstructed ET tube

39
Q

What wavelength does oxygenated Hgb absorb light

A

Red wavelength between 650-750 nm

40
Q

Infection, hyper metabolic states, and recreational drug use can cause ___________ temperatures

A

increased

41
Q

3 phases of thermoregulation?

A

Afferent thermal setting, Central regulation, and efferent responses.
(We take away efferent responses in anesthesia!)

42
Q

Examples of efferent responses to hypothermia

A

Shivering and vasoconstriction

43
Q

Examples of efferent responses to hyperthermia

A

sweating

44
Q

What type of temperature monitoring is most reflective of thermal status?

A

Core temperature.
-Blood temp via swan, tympanic, distal esophagus, and nasopharynx.

45
Q

How is variable pitch used in a pulse ox?

A

Changes in tone as the patient is desaturating. Alerts the provider of a subtle change

46
Q

How has esophageal intubation been drastically reduced?

A

Through the monitoring of EtCO2

47
Q

What are some simple ways to verify, when used with other assessments, gas exchange?

A

Movement of chest, condensation in the airway device, sense of touch to feel subtle movements of gas exchange

48
Q

When using disposable EtCO2 devices, a minimum of _____ breaths has been suggested to avoid misinterpretation

A

6

49
Q

By what method is continuous ETCO2 accomplished by?

A

Infrared analysis

50
Q

What is the difference between diverting and non-diverting sampling of CO2?

A

Diverting - Extracts gas from the sample tubing and pumps it to the monitor
Non-diverting - Measures gas directly in the breathing system

51
Q

What do phases D-E represent on the capnogram?

A

Descent to original baseline (inspiration)

52
Q

4 Phases of the capnogram

A

Phase 1 - End of inspiration and beginning of expiration
Phase 2 - Expiratory upstroke
Phase 3 - Plateau phase. Represents alveolar emptying of CO2. (longest phase)
Phase 4 - Rapid decrease in CO2, due to inspiration

53
Q

What would you interpret this capnogram as?

A

Cardiac oscillations (generally caused by pulmonary artery pulsatility)

54
Q

Why is transcutaneous CO2 monitoring not used much in the anesthesia care realm?

A

Because it does not provide immediate breath to breath verification of ET placement.

55
Q

Volume flow loops

A
56
Q

What can be the cause of decreased compliance?

A

PE, bronchoconstriction, pneumothorax, insufflation of the abdomen, inadequate muscle relaxation

57
Q

What is the most helpful test when assessing acid base balance?

A

ABG

58
Q

When does the greatest amount of heat loss occur during surgery?

A

Within the first hour

59
Q

What core temperature method is considered most ideal for many surgeries?

A

Tympanic

60
Q

Due to vasoconstriction that occurs in cold temperatures, what can be a more useful oximetry site?

A

Sites closer to central circulation
- Forehead, nose, and ear probes.

61
Q

AANA/ASA guidlines

A
62
Q

How much O2 is dissolved in the blood?

A

.003 mL of O2 per 100 mL of blood

Because we know this, we can determine the remaining amount of Hgb bound to O2

63
Q

Consider this equation
Hgb + O2 <—-> HgbO2
What does this tell us about the relationship of Hgb to O2?

A

That this is a reversible reaction. O2 is able to be bound and released from Hbg. This allows for the transfer/oxygenation of O2 to the body.

671A - Anesthesia I (22 decks)

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