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Concepts 2 > Anesthesia Effects on Respiratory System > Flashcards

Anesthesia Effects on Respiratory System Flashcards

1
Q

The supine position decreases FRC by ___

A

30%

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2
Q

The induction of GA decreases FRC by ___. Why?

A

15-20%
Loss of inspiratory muscle tone
Increased expiratory muscle tone
Diaphragm moves cephalad 4 cm
Chest wall rigidity changes
Decrease the transpulmonary pressure
Promotes alveolar collapse

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3
Q

Obesity and FRC

A

Decreases it due to:

decreased chest wall compliance &
increased airway collapsibility

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4
Q

Pregnancy and FRC

A

Decreases it due to:

Diaphragm shifts cephalad as a result of the gravid uterus
Decreased chest wall compliance

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5
Q

Neonates and FRC

A

Less alveoli leads to decreased lung compliance
Cartilaginous ribcage that is prone to collapse

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6
Q

Advanced age and FRC

A

Decreased elastic lung tissue leads to air trapping which results in increased residual volume and thus INCREASED FRC

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7
Q

Which positions increase FRC?

A

Prone, sitting, lateral

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8
Q

Paralysis and FRC

A

Decreases due to diaphragm moving cephalad which decreases lung volumes

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9
Q

Inadequate anesthesia and FRC

A

Straining leads to forceful expirations which decreases lung volumes

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10
Q

Excessive IV fluids and FRC

A

Decreases it

Fluid accumulation in dependent lung favors zone 3

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11
Q

High FiO2 and FRC

A

Decreases it

Absorption atelectasis, conversion of low V/Q unit, shunt unit

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12
Q

Reduced Pulmonary Compliance and FRC

A

Decreases it

Conditions like acute lung injury, pulmonary edema, pulmonary fibrosis, atelectasis, pleural effusion

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13
Q

Obstructive Lung Disease and FRC

A

Increases it

Air trapping increases residual volume which increases FRC

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14
Q

PEEP and FRC

A

Increases it

Recruits collapsed alveoli
Partially overcomes effects of GA
decreases venous admixture which increases PaO2

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15
Q

Sigh breaths and FRC

A

Increases it

Recruits collapsed alveoli

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16
Q

Prevention of Atelectasis happens through _____.

A

Recruitment Maneuvers

1)PEEP
2) Sigh breaths

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17
Q

How do you figure out PEEP values for different patients?

A

BMI below 25 = 6 cm H2O
BMI up to 30 = 8 cm H2O
10 cm H2O consistently reopens collapsed lung tissue

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18
Q

What are components of a sigh breath?

A

Doubling of Vt (tidal volume)
Sustained inflation of lungs to 30 cm H2O
To open all collapsed lung tissue 40 cm H2O is required
BMI > 45 will require more

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19
Q

The closing capacity is the sum of ___.

A

the closing volume and the residual volume

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20
Q

Closing capacity is normally well below ____.

A

FRC, but it rises steadily with age.

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21
Q

What is closing capacity?

A

The volume at which small airways begin to close in the dependent parts of the lungs.

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22
Q

Intrapulmonary shunting of deoxygenated blood promotes _____.

A

hypoxemia

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23
Q

Factors that Increase Closing volume

A

“CLOSE-P”
- COPD
- LV failure
- Obesity
- Extremes of age
- Pregnancy

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24
Q

General facts about V/Q Ratio

A

V/Q = alveolar ventilation/cardiac output
V/Q = (4 L/min)/(5 L/min)
V/Q are perfectly matched where the lines intersect
V > Q towards the apex
V < Q towards the base

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25
Zone 1
Dead Space: PA > Pa > Pv V/Q = ∞
26
Zone 2
Waterfall: Pa > PA > Pv V/Q = 1
27
Zone 3
Shunt: Pa > Pv > PA V/Q = 0
28
West Lung Zones
29
During anesthesia, arterial oxygenation is impaired in which patient populations?
Elderly – obese – smokers
30
Resp function during anesthesia for young to middle aged patients
Shunt 10% V/Q ratio scatter is small to moderate
31
Patients with H/O pulmonary disease
V/Q low Increase shunt
32
Respiratory Patterns with different types of anesthesia: inadequate, light, moderate, deep etc.
Inadequate Anesthesia can cause hyperventilation or breath holding. As the depth of anesthesia approaches MAC, respirations progress from irregular to a more regular pattern with an increase in Vt Moderate levels respirations increase but are shallow Deep anesthesia with halogenated agents cause rapid shallow breathing Very deep anesthesia with inhaled agents causes a “rocking boat” type of movement** Nitrous-narcotic anesthesia – slow and deep
33
Mechanisms of Hypoxemia during Anesthesia
Mechanical failure of anesthesia apparatus to deliver O2 to the patient Mechanical failure of the ETT Hypoventilation – (Decreased Vt) Decrease in FRC
34
Mechanisms of Hypoxemia during Anesthesia
35
Intraoperative conditions that cause hypoxemia
Surgical position Lithotomy – jackknife – kidney bar Massive blood loss Surgical retraction on the lung
36
Mechanisms of Hypercapnia
Hypoventilation Increased dead space ventilation Increased CO2 production Issues with CO2 absorber
37
Hypoxic Pulmonary Vasoconstriction
HPV occurs in Pulmonary Arterioles located very close to the small bronchioles & alveoli. This permits rapid & direct detection of alveolar hypoxia. 3 ways HPV works in Humans Life at High Altitudes Hypoventilation, Atelectasis, any Low V/Q state Chronic Disease
38
In response to alveolar hypoxia, the alveolar arterioles ____.
constrict, thereby decreasing shunt blood flow.
39
What inhibits the hypoxic pulmonary vasoconstriction response?
Direct-acting vasodilators inhibit HPV response, which increases shunt and decreases PaO2. Volatile Agents inhibit HPV response at higher concentrations. (> one MAC)
40
Basics of Pulse Oximetry
Two Wavelengths of light, 660nm (red) & 990nm(infrared). Infrared absorbed by Oxyhemaglobin. Red absorbed by deoxyhemoglobin. Operates based on Beer’s Law. In optics, the Beer–Lambert law is an empirical relationship that relates the absorption of light to the properties of the material through which the light is travelling.
41
When won't pulse oximetry work?
Applied to thumb Vasoconstriction Hypothermia Hypotension Methylene Blue/ Indigo Carmine Anemia of sickle cell CO Poisoning Methemoglobinemia- impairs unloading of O2
42
Basics of capnography
CO2 may be expressed as a number (capnometery). CO2 seen as a wave (capnography). Gas is sampled at two different infrared wavelengths (2600nm & 4300nm) Place sampling line as close as possible to alveolar gas. ( i.e. elbow of circuit)
43
Label the different parts of the capnography waveform
44
Basic Concepts of an ABG and the idea of compensation
Basic Concepts H+(mEq/L) = 24X [PCO2/HCO3-] Physiologic goal is to compensate to a normal pH. Compensation is not synonymous with correction Compensatory Response Respiratory system responds immediately to metabolic disorders. Kidneys provide the compensation for Respiratory disorders and begins in6 to 12 hours and requires a few days to reach maximum compensation.
45
When the primary disorder is respiratory acidosis, what is the compensation?
When ↑PCO2 (Resp. Acidosis), the compensation is ↑HCO3- .
46
When the primary disorder is respiratory alkalosis, what is the compensation?
When ↓PCO2 (Resp. Alkalosis), the compensation is ↓HCO3- .
47
When the primary disorder is metabolic acidosis, what is the compensation?
When ↓HCO3- (Met. Acidosis), the compensation is ↓PCO2.
48
When the primary disorder is metabolic alkalosis, what is the compensation?
When ↑HCO3- (Met. Alkalosis), the compensation is ↑PCO2.
49
A Primary Metabolic disorder is present if ___.
The pH and PCO2 change in the same direction, or The pH is abnormal but the PCO2 is normal.
50
The following equations will identify an associated respiratory disorder.
For Metabolic Acidosis: Expected PCO2 = 1.5(HCO3-) +8 (± 2) For Metabolic Alkalosis: Expected PCO2= 0.7(HCO3-) + 20 (± 1.5)
51
A primary respiratory disorder is present if ___.
the pH and the PCO2 change in the opposite direction.
52
The relationship between the change in PCO2 and the change in pH can be used to identify ______.
an associated metabolic disorder or an incomplete compensatory response.
53
A mixed metabolic-respiratory disorder is present if ____.
the pH is normal and the PCO2 is abnormal.
54
Anion Gap
Used to assess metabolic acidosis Unmeasured anions and cations – based on measurable anions and cations Sodium – Chloride – Bicarbonate Normal Range 8 - 16
55
Normal anion gap with metabolic acidosis
8 - 16 Loss of bicarbonate Diarrhea, isotonic saline infusion, renal tubular acidosis, acetazolamide – Addison’s disease
56
High Anion Gap Metabolic Acidosis
> 16 Excess acid Lactic acidosis Ketoacidosis (diabetic – alcoholic – starvation) Uremic (ESRD) Alcohols (ethanol) –salicylate toxicity – CO toxicity
57
Decreased Anion Gap
Decreased unmeasured anions – albumin Increased unmeasured cations – calcium – magnesium – lithium
58
Capnography waveform when ETT placed in esophagus
59
Capnography waveform when there's an inadequate seal around the ETT
60
Capnography waveform for hypoventilation
61
Capnography for hyperventilation
62
Capnography for rebreathing
63
Capnography for obstruction
64
Capnography for Curare Cleft
65
Capnography for Faulty Ventilator
66
Faulty Ventilator circuit valve - baseline elevated - allows pt to rebreathe
67
nmb wearing off aka curae clefts
68
obstruction in airway / circuit - shark fin - ett kinked - foreign body - bronchospasm
69
rebreathing - faulty expiratory valve - inadequate inspiratory flow - insufficient expiratory time - co2 absorber system malfunction
70
hyperventilation - increased RR and TV - decreased temp and metabolic rate
71
hypoventilation - deceased RR and TV - increased temp and metabolic rate
72
inadequate seal around ETT
73
esophageal ett

Concepts 2 (11 decks)

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