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E1 Flashcards

1
Q

X-ray definition

A

• Classification of radiation called electromagnetic waves.

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2
Q

What do xrays produce and how

A

 Image seen on the film/CT
• Depends on amount X-Ray absorbed by the tissues
• Prior to reaching the film plate.

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3
Q

What doe xray images show and how is this accomplished

A

Shows:
• parts of our body in different shades of black and white.

Accomplished by
• Difference in radiation absorption between tissues

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4
Q

What is the general use of xrays

A
  • to diagnose numerous medical conditions

* to treat numerous medical conditions

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5
Q

Most important thing about xray assessment

A

Best predictor of
• Difficult endobronchial intubation
• Clues you into potential airway issues

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6
Q

Xray assessment can guide CRNA’s….

A

Plan of care

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7
Q

What is xray density

A
  • Degree of xray absorption

* Based on density of substance xray travels through

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8
Q

What do the black and white portions of the xray image indicate

A

Densities
Black = air filled spaces
White = dense tissue spaces

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9
Q

What are examples of black and white substances on xray

A

black:
air, fat

white:
metal, bone, calcifications, soft tissue

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10
Q

What is penetrance

A

• Helps determine if film is over or under penetrated by xrays

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11
Q

What is over penetrance

A

• Detail can be lost
 Poor differentiation of structures?
• The higher density = whiter structures
• More lucent = darker structures

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12
Q

What is under penetration

A

White imaging becomes more prominent (leads to falsely dense image)
• Opacity or consolidation
 May appear prominent (whiter)
• Can produce a false positives
• May use to identify structures behind other tissues

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13
Q

In what situation may an under penetrated image be useful

A

to identify structures behind other tissues

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14
Q

Xray benegits

A

 Noninvasive
 Painless.
 Supports medical and surgical planning.
 Identify landmarks
 Guides for insert caths, stents, treat tumors, remove blood clots.

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15
Q

Xray risks

A 
	Generally assct w/ radiation therapy
	Ionizing radiation 
	Could develop cancer
	Hair loss
	Cataract damage
	Skin burns
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16
Q

What is ionizing radiation

A

Ionizing radiation:

• form of radiation can cause tissue damage DNA damage.

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17
Q

What is ionizing radiation

A

• form of radiation can cause tissue damage DNA damage.

–The energy to create free radical and ionized molecules in tissues

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18
Q

Why does ionizing radiation occur

A

D/t driving electrons out of their stable orbits (this causes the free radicals and ionized molecules)

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19
Q

What may happen is sufficient exposure to ionizing radiation occurs

A

Tissue could be destroyed

Malignancy d/t chromosomal changes

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20
Q

Xray raduation exposure unit

A

rem

roentgen equivalent man

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21
Q

Primary source of human exposure

A

Cosmic rays

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22
Q

Primary source of human exposure and general amount

US population general exposure

A

Cosmic rays

Natural sources equate 80-200 mrems/yr???

US exposure
40 mrem/yr

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23
Q

How is exposure measured

A

dosemeter

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24
Q

Max Occupation exposure recommendations

Guideline set by who?

A

 No more than 5 rems max allowable yearly
 for ‘whole body’ occupational exposure

Office of homeland security and emergency coordination radiation safety division

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25
Q

Max recommended exposure during pregnancy

A

 Limit max exposure to 500 mrem

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26
Q

General chest xray exposure

A

~25 mrems

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27
Q

Recommended safety precautions and/or distance from pt when performing xray

A

 3-ft distance from pt recommended
 Lead aprons
 0.25 – 0.5 mm thick do the job.

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28
Q

6 ft of distance from xray provides equivalent protection to

A

Equates to
 9 inches of concrete protection
 2.5 mm lead apron

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29
Q

6 ft of distance from xray provides equivalent protection to

A

Equates to
 9 inches of concrete protection
 2.5 mm lead apron

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30
Q

What is the TWU clinical policy for pregnant women

A

Radiation exposure through radiography, CT, nuc me or fluro is generally at doses much lower than levels associated w/ fetal harm
-given that proper safety precautions are in place

  • inform program in writing
  • program will supply
  • -policy
  • -dosimetry
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31
Q

Describe the small opacity classification

A 
	can be round, irregular, or combination of the two.
	2 Primary shapes
•	Round
•	Irregular
•	Combo…

6 basic sizes.
•	ROUND (1-3)
•	Round – p = up to 1.5 mm in size.
•	Round – q = 1.5 – 3 mm in size.
•	Round – r = 3 – 10 mm in size.
  • Irregular 4-6 (easier to see on frontal xray)
  • Irregular – s = up to 1.5 mm in size.
  • Irregular – t = 1.5 mm – 3mm in size.
  • Irregular – u = 3 – 10 mm in size.
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32
Q

Difference in opacity sizing classifications

A 
	6 basic sizes.
•	ROUND
•	Round – p = up to 1.5 mm in size.
•	Round – q = 1.5 – 3 mm in size.
•	Round – r = 3 – 10 mm in size.
•	Irregular (easier to see on frontal xray)
•	Irregular – s = up to 1.5 mm in size.
•	Irregular – t = 1.5 mm – 3mm in size.
•	Irregular – u = 3 – 10 mm in size.
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33
Q

Round opacity guidelines

A
  • Round – p = up to 1.5 mm in size.
  • Round – q = 1.5 – 3 mm in size.
  • Round – r = 3 – 10 mm in size.
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34
Q

Irregular opacity guidelines

A
  • Irregular – s = up to 1.5 mm in size.
  • Irregular – t = 1.5 mm – 3mm in size.
  • Irregular – u = 3 – 10 mm in size.
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35
Q

6 description of large opacities

A 
	Diffuse Homogeneous
	Multifocal Patchy
	Lobar without Atelectasis
	Lobar with Atelectasis
	Perihilar
	Peripheral
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36
Q

6 description of large opacities

A 
	Diffuse Homogeneous
	Multifocal Patchy
	Lobar without Atelectasis
	Lobar with Atelectasis
	Perihilar
	Peripheral
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37
Q

Describe guidelines and diseases associated w/ micronodular image description

A

Corresponds to the “p” opacities
 <1.5mm
 associated with small number of dx processes.

Diseases include:
 Alveolar microlithiasis  very rare.
 IV Talc injection  drug abuse.
 Early stage pneumoconiosis seen in coal miners
 Mycobacterial, fungal disease, or sarcoidosis

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38
Q

Describe guidelines and disease associated w/ nodular image descriptions

A
  • Nodes up to 1cm in diameter.
  • Miliary (looks like millet seeds)
Disease processes included:
	TB.
	Sarcoidosis.
	Fungal Disease.
	CMV
	Pneumonias.
	Measles, Mumps, and Neoplasia.
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39
Q

What are reticular marking on xrays

A

“Fluffy,” interconnected markings

Correspond to small irregular opacities

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40
Q

What can reticular markings indicate

A

Honeycombing can indicate end-stage lung disease

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41
Q

What are 2 categories and 3 types of reticular xray patterns

A

Categories:
Acute
Chronic

Types:
• fine (ground glass)
• medium (irregular)
• course (honeycomb)

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42
Q

Describe honeycomb patterns on xray images and what do they indicate

A

An array of multilayered, stacked space that commonly collapse w/ expiration

Indicates:

  • End-Stage lung disease
  • The obliteration of small alveolar sacks that have turned into large sacks
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43
Q

What are the physiologic cause of linear lung markings on xray

A

Phys cause:

-Most likely d/t thickened interlobular septa

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44
Q

Describe the 3 types of kerley lines

A

A:
Radiate towards UPPER lodbe
-FROM hilum into lung periphery

B:

  • Result from thickening of subpleural interstitium
  • in periphery

C:
D/t thickening of the lung parencymal interstitium

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45
Q

What are 3 types of linear marking seen on xray

A
  • interlobular
  • Kerley lines (3 types)
  • Intralobular
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46
Q

What causes the appearance of Kerley lines

General characteristics of Kerley lines

A

Increased hydrostatic pressure is the cause in all cases

Characteristics:

  • NOT interconnected (like reticular)
  • Differ in length and width
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47
Q

What are cause of destructive patterns seen on lung xrays

A
  • Small lungs
  • Diffuse consolidation
  • Bronchiolectisis
  • Honeycombing
  • Bullae
  • Cysts
  • Pulm HTN
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48
Q

What is bronchiolectisis and what does it indicate

A

Chronic infections

 Permanently thick and widened bronchioles
 Allows for mucous build up

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49
Q

What are bullae and associated complications

A

 Giant fluid-illed space w/in parenchyma
 > 1cm
 Rupture = PTX

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50
Q

Characteristics of alveolar patterns on xray

A
  • Appear as “air-space”
  • ground-glass opacification
  • coalescent opacities,
  • air bronchograms.
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51
Q

List some basal lung disease processes

A 
Bronchiextasis
aspiration**
pneumonia/fibrosis
CF
asbestos
scleroderma
RA
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52
Q

List some upper lung zone diseases

A 
TB
Fungus
Sarcoidosis
Pneumoconiosis (coal miners lung)
Langerhans cell histiocystosis
ankylosing spondylitis
CF**
Radiation fibrosis
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53
Q

Describe central lung disease and associated disease processes

A

-Perihilar lung disease

-Disease processes
Sarcoidosis
lymphoma
Karposi's sarcoma**
bronchiectasis
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54
Q

List diseases that manifest in the peripheral lung zone

A

Cryptogenic organizing pna
Asbestosis
Graft v host
COVID-19**

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55
Q

What causes cor pulmonale

A

RV hypertrophy and diation r/t pulmonary HTN

D/t

  • obliterated small peripheral pulm artery branches
  • Combined w/ hypoxic vasoconstriction
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56
Q

What does cor pulmonale lead to

A

pulm HTN

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57
Q

Why is learning to read xrays important to CRNAs

A

 allows you to get a better physiological understanding of what you have to work with after you intubate the patient.

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58
Q

What do atelectasis, pulm HTN, kerly B lines, nodular markings and small___ equal

A

BAD LUNGS

difficult ventilation

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59
Q

Characteristics of cor pulmonale and what can it lead to

A

Characteristics:
Very low CO
large heart (>50% of chest)
High SVR

Lead to:
Fluid back-up
Lung compensation to improve O2

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60
Q

Anesthesia implications in pts w/ Cor pulmonale

A
  • Low FRC (VERY low O2 reserve)
  • Quicker inhalation uptake (sleep quicker)
  • Use of PPV (to inc V/P matching
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61
Q

Anesthetic implications for pts w/ pulmonary edema

A
  • Acute onset (postpone and optimize)

- Surgery could lead to prolong post-op intubation

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62
Q

Intraop treatment for pts w/ pulmonary edema

A
  • Low FRC
  • Very low O2 reserve
  • Quicker inhalation uptake
  • Sleep quicker
  • Use of PPV
  • To INC V/P matching
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63
Q

Anesthesia implications for pts w/ pulm fibrosis

A 
•Very low FRC
	Low O2 reserve 
	But good O2 uptake on induction??
•Low peak airway pressures 
	To prevent further damage
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64
Q

Anesthesia considerations for pts w/ PTX

A

• NO NITROUS (will make PTX bigger)
• 100% FiO2
• Needle decompression
 Followed by CT

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65
Q

Anesthesia considerations for pts w/ PNA

A

Acute–proceed w/ surgery if OR required

Small tidal volumes–keep airway pressures <30

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66
Q

3 primary chest xray views and how they are performed

A

 AP View/image
• The X-ray beams pass through the body from anterior to posterior.
• The pt is usually sitting or lying w/ back against the film plate.
 PA View/image
• The X-ray beams pass through the body from posterior to anterior.
• The pt is standing w/ abdomen against the plate and hands on their hips.
 Lateral View/image
• The X-ray beam pass through the body from right to left according to convention.
• The pt is standing/sitting w/ his left chest against the plate
• Both arms are lifted into the air

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67
Q

What are some clues that tell the viewer is assessing an AP and PA

A

AP image
-Scapulas are prominently visible b/c arms are down

PA image:
-Scapula edges are generally only landmark visible b/c arms up

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68
Q

What is divergence

A

images on xray are falsley larger than the actual tissue imaged

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69
Q

what are some xray modalities and their relative radiation exposure

A

CT (most)
Fluroscopy (moderate)
Radiography (conventional xray)

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70
Q

What are criteria for pre-op chest x-ray

A

Based on

  • -Physical assessment
  • -Clinically r/t the surgical procedures
  • -To assess abnormalities found on physical assessment
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71
Q

List some disease processes that may require pre-op chest xray

A
  • Chest mass, advanced COPD, suspected pulmonary edema,

* Tracheal deviation, & aortic aneurysm to list a few.

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72
Q

What is a systemic, methodical approach to interpreting chest xrays

A 
Airway
Bones
Cardiac silhouette
Diaphragm
Everything else
Foreign bodies
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73
Q

What airway landmarks should be identified on xray

A

Trachea
–midline

Carina
–At the sternal angle of Lewis

Lung fields

  • -symmetric
  • -Lung markins to edge of chest
  • —Costocondral angle defined
  • -Opacification
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74
Q

What “alterations” may be seen on a normal AP chest xray

A

Can make the heart and vasculature look enlarged

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75
Q

What cardiac landmarks should be identified on chest xray

A
  • Homogenous cardiac silhouette
  • –uniform depth = uniform opacity
  • Width of the silhouette
  • -approx 50-55% of chest width
  • Aortic knob
  • -More white indicates calcification
  • Pulmonary vasculature
  • -Indicates healthy hilum
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76
Q

What bone landmarks should be identified on chest xray

A
  • Look for symmetrical clavicles
  • -Uneven clavicles = poor position

-Shoulders should be level

  • Count 10 ribs
  • -indicates good chest expansion

-Vertebral column alignment

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77
Q

What diaphragm structures or landmarks should be identified when assessing on chest xray

A

Higher right diaphragm
–d/t liver

Look at costophrenic angles

  • -Defined = normal
  • -Blunted = Pleural effusion

Diaphragm curvature

  • -both sides should curve down
  • -Flatter diaphragm = chest expansion

Possible gastric bubble

  • -under LEFT hemidiaphragm
  • -Not always present
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78
Q

What should be considered when assess a CXR for “everything else”

A

Objects overlying the chest
–ECG leads, pulse ox, cables/wires, hair

Soft tissue artifact

  • -Breast tissue
  • -Posterior adipose tissue
  • -SQ emphysema
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79
Q

What should be considered when assess a CXR for “foreign bodies”

A
  • Central lines
  • Coins
  • Chest tube
  • NGT/OGT
  • Endotracheal tube
  • Sternal wires
  • Bullets or knives
  • PM/AICD
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80
Q

Radiologic characteristics of consolidation on CXR

A

Density to lung field/s

Loss of ascending aorta silhouette

No shifts

Air bronchogram

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81
Q

What is air bronchogram and what does it indicate on CXR

A

Definition:
Visible air-filled bronchi surrounded by fluid-filled alveoli

Indicates:
Lung consolidation
Dilated airways to consolidated areas?

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82
Q

Radiographic characteristics of pleural effusion on CXR

A

Fluid accumulates in pleural space
–Typically see defined borders

Blunt costophrenic angles

Lack of identifiable diaphragm

See next question for criteria

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83
Q

Radiologic criteria for pleural effusion include

A
  • Inc density in dependent portion
  • costophrenic angle blunting
  • unidentifiable diaphragm
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84
Q

What causes atelectasis and key characteristics seen on CXR

A

Cause:
Loss of air or surfactant in alveoli

Xray has inc density b/c of loss of lung volume

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85
Q

Types of atelectasis (don’t need to know!!)

A
  • Resorptive
  • Relaxation
  • Adhesive
  • Cicatricial
  • Round
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86
Q

CXR signs of atelectasis

A
  • Mediastinal shift (TOWARD atelectatic region)
  • Elevation of diaphragm
  • Crowding of ribs
  • Movement of fissures
  • Movement of hilum
  • Compensatory hyperinflation
  • Hemithorax asymmetry
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87
Q

Radiographic characteristics of lung fibrosis on CXR

A
  • Diffuse haziness
  • Apical cap thickening
  • Blunting of costophrenic angles
  • loss of lung volume
  • Lung fissure lines no corresponding
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88
Q

Radiographic characteristics of active TB on CXR

A

Bright circular chest cavitations

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89
Q

Radiographic characteristics of PTX on CXR

A
  • Air in pleural space w/o lung markings
  • Atelectatic lung
  • Shift of mediastinum AWAY from PTX
  • Opposite lung has PROMINENT lung/vascular markings
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90
Q

Hydropneumothorax evidence on cxr

A
  • Air and fluid within the pleural space

- Well defined horizontal fluid line that extends across the hemithorax

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91
Q

Characteristics of lung mass on cxr

A
  • Round or oval
  • Sharp/defined margins
  • Homogenous density
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92
Q

Characteristics of lung abscess on CXR

A

-air or fluid filled cavity in lung

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93
Q

Radiographic characteristics of pulmonary edema on CXR

A
  • Bilat
  • Diffuse
  • Butterfly pattern
  • Soft, fluffy lesions
  • Air bronchogram
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94
Q

Characteristics of lung blebs on CXR

A
  • Collection of air in the alveolar layer of pleura
  • -shows as circular black air markings
  • Formed by rupture of alveolar walls
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95
Q

Characteristics of sarcoidosis on CXR

A
  • Enlarged, dense connective tissue at the hilum

- Hilar nodal enlargement

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96
Q

Characteristics of emphysema on CXR

A
  • Hyperinflation
  • Hyperlucency
  • Low set and flat diaphragm
  • Tall/vertical heart
  • Barrel shape chest
  • Avascular zones
  • Extended upper lung fields
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97
Q

Causes of pleural effusion

A
  • CHF
  • Cancer Mets
  • Pancreatitis
  • PE
  • Trauma
  • Empyema
  • Collagen vascular issues (lupus, scleroderma)
  • Ovarian tumor (Meigs sx)
  • Chylothorax
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98
Q

What is hamptom’s hump/westermarks sign on CXR?

A

High density areas in the middle of the lung indicating PE and engorged pulm vasculature

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99
Q

Characteristics of CHF on CXR

A

Cardiac silhouette will be >55% of chest width

May have engorged pulm vasculature

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100
Q

Describe the discovery of xray

A

 1895–Wilhelm Roentgen
 Experimenting with e- beams in a glass tube
 Noticed that a fluorescent screen in the lab began to glow
 Put different objects between the screen and the tube including his hand…

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101
Q

What are four different types of radiation

A 
1. Electromagnetic
•	From motion of atoms
•	combine electricity and magnetism
2. Mechanical (slower)
•	Only travels through substances (not air)
3. Nuclear
•	Unstable atom nuclei
4. Cosmic (faster)
•	Sun rays 
•	Almost speed of light
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102
Q

What are the similarities and differences in xray and visible light rays?

A

Similarities

  • Both are EM energy
  • Both carried by particles called photons

Differences
-Energy level aka wavelength

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103
Q

Describe xray and radio waves wavelength vs energy level.

Are they visible or not?

A

Xray: (not visible)
wavelength = shorter
Energy = higher

Radio waves: (not visible)
wavelength = longer
Energy = lower

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104
Q

How is light emitted

A

Caused by movement of e- between orbits

  • Moving particles excite the atom
  • The e- “jumps” to higher orbit/energy level
  • When e- returns to lower orbit, energy is released in the form of a photon
  • This release = light emitted
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105
Q

Describe characteristics of xray photons

A

 Have lots of energy
 Pass through most things
 Can knock e- away from atoms or send them flying through space

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106
Q

How does the size of an atom correlate to xray absorption

A

Small atoms:

  • e- orbitals are closer and separated by low jumps in energy
  • Less energy released
  • less likely to absorb xray photons

Large atoms:

  • Greater energy differences between orbitals
  • More energy released
  • More likely to absorb xray photons
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107
Q

Example of small vs large atom tissues and how they are affected by xray photons

A

small atoms:
ex = soft tissue
less likely to absorb xray photon
not as bright white

large atoms:
ex = bones (Ca++)
more likely to absorb xray photons
brighter white

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108
Q

Describe the mechanics of how the xray machine works

A

Contains an electrode pair:
-A cathode and an anode

  • Machine is surrounded by thick shield
  • Xray photons escape machine through window in shield
  • Camera on opposite side records pattern of xray photons
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109
Q

Describe the electrode pair in relation to xray machine function

A 
Cathode (NEG)
	Filament in center
	Current heats filament (like a fluorescent lamp)
	Heat causes e- to fly off of filament
	Releasing energy

Anode (POS)
 Positively charged
 Made of tungsten
 Attracts e- across the tube

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110
Q

Describe how xray cameras record pictures

A

Camera on opposite side records the pattern of x-ray photons
• Chemical reaction on film
• DARK areas = More light exposure
• LIGHT areas = Less light exposure
• Intensity changes to beam = alter appearance
 over/under exposed picture

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111
Q

Describe the difference in darker and lighter areas of exposure on films

A

DARK areas = More light exposure
 Less dense tissues = less photons absorbed

LIGHT areas = Less light exposure
 More dense tissue = more photons absorbed

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112
Q

What are medical x-rays uses

A

Diagnostic:

  • Radiography (fx, calcifications, foreign objects, dental issues)
  • Mammography
  • Computed tomography (3D generated image)
  • Fluroscopy (real-time xray)

Therapeutic:
-Radiation therapy (much higher rad doses)

113
Q

What is ioinizing radiation and what can this lead to?

A

e- are removed from an atom

  • -creates an ion
  • -Ions have electrical charge
Leads to:
Intracellular chemical reaction
-Cell apoptosis (break down of DNA chains; cell death)
-Cancer (Mutate DNA)
-Birth defects (mutate sperm/egg cells)

RISKS ARE ADDITIVE w/ repeated exposure

114
Q

Describe the side effects of radiation therapy r/t location of irradiation.

How might this affect anesthetic plan

A

Side effects are localized to area or radiation

brain = headache, vision changes
head/neck = taste/mouth changes, dysphagia (risk for aspiration?)
pelvis/rectum = infertility, sexual and urinary changes, diarrhea (incontinence)
115
Q

How is radiation dosing measured?

What are recommended annual allowable doses?

A

Rem = measure of radiation
 Radiation dose times a weighting factor
 Nearly equivalent to Rad
 Measured as millirem (mrem) or 1/1000 of a Rem

Annual allowable doses
•	5,000 mrem whole body
•	50,000 mrem extremities
•	15,000 mrem lens of eye
•	500 mrem for pregnancy
116
Q

What are various radiation exposure sources?

A

DIRECT source

  • Primary x-ray beam
  • leakage from equipment

INDIRECT source:
-Scattered radiation (reflected off tables, pt, surfaces etc)

117
Q 
Estimated mrem exposure for each:
CXR
Coronary angiogram
Angioplasty
CT
A

CXR: 5-10 mrem
Coronary angiogram: 1,500 mrem
Angioplasty: 5,700 mrem
CT: 5,00 mrem

118
Q

Methods or protection against direct and indirect sources of radiation

A
  • Lead

- Distance

119
Q

At what doses would s/sx of radiation be present. What may that include

A

200,000 mrem = transient erythema

120
Q

At what mrem dose can lead to fetal effects

A

Fetal doses <10,000 mrem unlikely to cause effects AFTER 20 weeks

121
Q

What are principles of radiation protective measures

A

Time
Distance
Shielding

122
Q

How do time, distance and shielding affect radiation exposure.

A

Time:

  • Less time = less exposure
  • more time = MORE radiation absorption

Distance:

  • Double distance from beam … 1/4 exposure rate
  • Greater than 6 ft from pt eliminates exposure to scatter (indirect source)

Shielding:
-Lead apron, portable shields, thyroid shields, lead glasses

123
Q

Why is an angoi performed via femoral approach more desirable than via brachial approach

A

The provider is decreasing exposure time and increasing distance between themself and the xray

124
Q

The provider moves from 2 ft to 4 ft away from the pt during an xray. What are the respective mrem exposure

A

moving from 2 ft to 4 ft might change exposure from 20mrem/min to 5 mrem/min

125
Q

What is an protective measure device for radiation exposure.

Related principles for use?

A

Wearing dosimeter
• Two badges
• 1- outside the apron on the collar
• 2- inside the apron on the waist

The Don’ts
• Don’t mix up
• Don’t share dosimeters with others
• Don’t leave in car on dashboard/seat

126
Q

Describe the principles of MRI

A

Based on interactions between

  • Static magnetic fields
  • Individual atom nuclei

Magnetic field is used to orient nuclei to north-south poles

RF pulses then change the orientation of atoms which radiates energy

127
Q

How is contrast between tissue generated w/ MRI

A

Generated by amount of time to tissue relaxation when RF turned off
-time for atoms to realign in the N-S pole

128
Q

What does contrast of tissues for MRI depend on?

A
  • Various densities of H nuclei in tissues
  • Different chemical and physical properties of tissues
  • Relaxation of tissues occurs at different rates depending on tissue type
  • This leads to various grey scale colors
129
Q

What are the 2 types of MRI contrast and what are the characteristics of each

A

T1 and T2

T1:

  • Magnetic vector relaxes
  • Tissues
  • -Fat = BRIGHT
  • -Water = DARK
  • Good grey-white matter contrast
  • BEST for ANATOM

T2:

  • Axial spin relaxes
  • Tissues
  • -Fat is DARKER than water
  • Identifies tissue edema
  • BEST for PATHOLOGY (perforation, edema, Ca)
130
Q

What is the common MRI contrast material and principles for use

A

Material = Gadolinium

  • Alters magnetic properties of nearby H2O molecules
  • Enhances quality of MRI images

Use:

  • To identify obtsructions, perforations, or ruptured aneurysms
  • Best used in parts w/ high H2O content (not necessary for bone scans)
131
Q

When using gadolinium, what are common side effects or reactions.
How is it cleared?

A

Side effects: itching, rash, abnormal skin sensation (perineal itching/warmth)

Reactions: rarely severe b/c typically not IgE anaphylactic rxn

Clearance:

  • In 24 hrs w/ normal GFR
  • Give extra fluid in renal insufficiency
132
Q

How does the MRI static field affect ferro magnetic objects?

A

Attractive force:
-Objects are pulled toward center of magnet

Torque:
-Objects attempt to line up with the field

133
Q

What equipment is not compatible w/ MRI static field?

A
  • Oxygen/nitrous oxide tanks
  • Anesthesia machine
  • Monitors
  • Infusion pumps
  • Stretchers
  • Crash carts
134
Q

What are risks r/t MRI

A
  1. Projectile risk can cause serious injury to pt or staff
  2. RF energy can cause tissue/device heating (leading to skin burns i.e. from ecg leads)
  3. EM interference causes monitor artifact (poor ECG interpretation, SpO2 monitoring)
  4. Acoustic noise (125 dB, requires hearing protection)
135
Q

Anesthesia considerations for MRI

A
  • MRI requires approx 10 min per sequence
  • Any movement causes distortion
  • Pt must remain still

Thorough preop assessment:

  • Is pt able to lay still
  • Is there a potential for airway compromise w/ over-sedation (just proceed to GETA)
  • Sedation vs GETA

Populations that may require GETA:
-kids, parkinson’s pts, movement disorders, tremors, risk for airway compromise

136
Q

AANA standards of care and considerations for providing anesthesia during MRI

A
  • Airway (type or equipment and where)
  • Suction (is it compatible, where is it)
  • Emergency vent equipment
  • Minimize movement
  • Complications (what ifs)
  • MRI compatible equipment (where is IV pump, how long is tubing, how are rates changed)
  • Laryngoscope equipment MRI compatible?
137
Q

Positioning considerations for anesthesia pts in MRI

A

Head/neck scans
–Airway is inaccessible, monitor closely

Abd scans

  • -arms add artifact when at their side
  • -Arms over head
  • —Can lead to brachial plexus injury (pad and return arms to side on completion)
138
Q

What are provider and pt safety considerations when caring for MRI pts

A

Being aware of implants and devices:

  • PPM/AICDs
  • Implanted pumps
  • Rapid movement toward field (>1 m/sec) can cause dizziness, HA etc
  • Heart valves SAFE
  • Endovasc/bili stents SAFE after 8 weeks
  • Coronary stents SAFE
  • Vasc ports, IVC filters SAFE
  • Ortho implants SAFE (titanium and imbeded securly)
139
Q

What is the definition of laser

A 
Light
Amplification by
Simulated
Emission of 
Radiation
140
Q

How do lasers and ordinary light compare

A

Ordinary light

  • has MANY wavelengths
  • Spreads out in MANY directions

Laser:

  • Specific wavelength
  • Focuses, narrow beam
  • High-intensity
141
Q

What are common uses of medical lasers

A
  • Cosmetic surgeries
  • Refractive eye surgery (LASIX)
  • Dental procedures (whiten teeth)
  • General surgery
  • –resections, condyloma resections, turp/turb
  • ENT procedures
  • –sinuses, tracheal tumors, VC polyps
142
Q

What are properties of Laser radiation

A

Monochromatic:
-ALL the photons are the SAME wavelength (ONE color)

Coherence:

  • Photon travel is synchronized
  • Organized, non-random movement

Collimation:

  • Photons are parallel
  • Allows for beam to be focused in small area
143
Q

What are advantages of surgical use of laser

A
  • Precision (r/t collimation)
  • Good hemostasis
  • Rapid healing
  • Less scar formation
  • Less post-op edema/pain
  • Lower infectin rates
144
Q

What are the 3 most common lasing mediums

A

Argon
CO2
Nd:YAG

145
Q

Describe the benefits and uses of Argon, CO2 and Nd:YAG lasing mediums

A

Argon:

  • Modest tissue penetration (0.05-2mm)
  • Useful for derm, superficial procedures

CO2:

  • Minimal scatter (very collimated??)
  • Surrounding tissue damage is minimal
  • –d/t CO2 absorption by H2O which lessens heat dispersal and damage to surrounding tissues
  • Useful for VC, oropharynx

Nd:YAG:

  • Most powerful
  • Deep tissue penetration (2-6 mm)
  • Useful for tumor debulking
146
Q

What are 5 hazards of Laser use

A
  1. Atmospheric contamination
  2. Perforation of vessel or structure
  3. Embolism
  4. Inappropriate energy transfer
  5. Airway fire
147
Q

What is atmospheric contamination r/t laser plume and potential consequences?

A

Laser plume:

  • Fine particulates produced d/t vaporization of tissue
  • Possible viral transmission

Consequences:

  • SE–HA, nausea
  • Can cause–interstitial PNA, bronchiolitis, emphysema
  • May be carcinogenic
148
Q

What is the fire triad.
Examples of each component

What are 2 major sources for OR fires

A

Triad:
Ignition
-laser, electrocautery

Fuel
-drapes, paper

Oxidizer
-O2, nitrous

Sources:
ESU
Laser

149
Q

What are the most common ETT fire scenarios

A
  • Surgeon lasers through ETT burning through PVC tube
  • Tonsilectomy in peds pt w/ uncuffed tubed/t gas leak around tube
  • Using bovie to cut through trachea for tracheostomy (PVC ETT immediately on other side of trachea)
150
Q

What are airway fire safety techniques

A
  • Laser-resistant ETT (wrapped or ___)
  • Reduce accelerant (lowest FiO2 to maintain sats)
  • Wet pledgets around ETT
  • Methylene blue in cuff
  • Use scissors to cut into trachea instead of bovie
  • Remove ETT during laser procedure and reinsert prn sats
151
Q

What are fire safety techniques r/t FiO2 level

A

Use lowest FiO2 possible to maintain sats

May need to accept pt SpO2 in low 90s rather than having higher FiO2

152
Q

What is the purpose of using wet pledgets to prevent in fire safety

A

Using wet pledgets around ETT prevents gas escaping and decreases risk of airway fire

Lowers temp at site of laser

153
Q

What is the purpose of methylene blue in cuff rather than air

A

It is a visual cue for surgeon that cuff has ruptured and to cease lasering

154
Q

When surgeon is incising through trachea w/ bovie, what is a fire safety measure that can be taken to reduce airway fire

A

-Encourage surgeon to switch from bovie to scissor/scalpel to incise through trachea to avoid damage to ETT and igniting a fire

155
Q

Rational of ETT removal during laser procedures

A

Removal and reinsertion to maintain sats can decrease airway fire risk

156
Q

What are anesthesia considerations when preparing and providing anesthesia for pts in laser surgeries

A
  • Preop eval of airway
  • Mutual planning w/ surgeon
  • TIVA
  • Tooth guard?
  • Methylene blue in cuff
  • Saline gauze
  • Short, repeated pulses of laser
  • FiO2<30%, avoid nitrous
157
Q

What are important anesthesia preop assessment considerations for airway management in the pt receiving laser

A

Are any of the following present:

  • Stridor (indicating airway inflammation)
  • Flow vol loop (is obstruction evident)
  • Abnormal CT (presence of airway tumors or abnormal airway anatomy
  • Fiberoptic eval

Repeated reintubations may not be advisable in the situations

158
Q

What type of anesthesia may be provided to the pt receiving airway lasering and why

A

TIVA

-b/c gas cannot be used w/ repeated intubations

159
Q

What are considerations for gas use w/ the intermittent apnea technique vs jet ventilation

A

intermittent apnea:

  • Can’t use gas b/c ETT repeatedly removed
  • TIVA may be more appropriate

Jet ventilation
-If using gas, high flows will run through volatile quicker

160
Q

What can be used to help protect the face when performing laser procedures to face

Purpose of this technique

A

Saline gauze protection of airway/face

Purpose:
• ↓ heat to surrounding laser site
• ↓ fire changes

161
Q

What laser technique can the surgeon use to help decrease inadvertant laser related damage

A

Short, repeated pulses rather than long continuous mode

162
Q

What is ventilation

A

Spontaneous movement of air in/out of lungs

-inspired gas = IN
Expired gas = OUT

163
Q

Goal of ventilation

A

To generate flow and volume

To provide adequate alveolar ventilation w/ minimal WOB

164
Q

How is ventilation controlled/performed

A

Contraction of respiratory muscles = POWER

Phrenic nerve = Respiratory timing and intensity regulation

165
Q

What are components of dynamic respiratory mechanic

A

Resistance
Elastance
Compliance
Intertial properties

166
Q

Describe why resistance occurs in the lungs

A
  • Arises from viscous and turbulent losses associated w/:
  • -Airway tree
  • -Deformation of parenchymal and chest wall tissues
167
Q

Why does elastance exist in the lungs

A

Arises from the recoil of the lungs and chest wall (which are opposing forces)

168
Q

What is compliance

A

Ability of lung tissue to expand

Amount of pressure need to add volume

169
Q

What is the significance of inertial properties in the lungs

A

They are associated w/ acceleration of the gas column in the central lairways and motion of respiratory tissues

170
Q

How do inertial properties in the lungs affect breathing

A

Little effect on respirations except when there are sudden changes to air flow like HFJV

171
Q

How is pulmonary resistance calculated

A

R = (Ppeak - Pplat) / Vi

Vi is immediately before inspiratory pause

172
Q

What can resistance reflect about pulmonary status

A
  1. airway caliber (dec caliber = inc R)
  2. Tension w/in the alveolar surface film (surfactant; less = more R)
  3. friction w/in the pleural space
173
Q

what percent of pulmonary resistance dose lung tissue comprise

A

Approx 60% of total subglottal resistance at normal RR

174
Q

How can ETT affect resistance

A

Inc resistance esp w/ obstruction

175
Q

What can lead to ETT obstructions. How does surgery length affect this

A
  • mucous, too much humidification, surgical debris, ETT kinking
  • longer the procedure the more likely there could be an obstruction
176
Q

What is the compliance equation

A

(change vol)/(change P)

177
Q

How is compliance measured and what affects this

A

Measured in mls

Affected by lung and chest wall

178
Q

At rest, what are alv P and Pl P

A

Alv P = 0

Pl P = NEGATIVE

179
Q

What does compliance depend on and what disease inc/dec compliance

A

Depends on lung volume

Lung dx:
DEC-ARDS, pulm fibrosis, edema

INC- emphysema

180
Q

What effect does extremes in FRC have on compliance and why

A

Very high/low FRC contributes to poor compliance

b/c low FRC contributes to INC airway resistance d/t DEC airway dimensions

higher FRCs can compress small airways increasing resistance

181
Q

What is the effect on insp/exp pressure by increased resistance

A

More pressure for volume

  • -Ppeak is much higher
  • -Greater change btwn Ppeak and Pplat
182
Q

What effect does increased resistance have on air flow in the lungs

A

Inspiratory air flow is the same

Expiratory air flow is lower rate and takes longer

183
Q

What effect does increased resistance have on lung volume during respiration

A

W/ an increased pressure, volume inspired is the same.

To expire full amount of volume takes much longer

184
Q

What effect does increased elastance have on insp/exp pressures

A

Much greater Ppeak for same volume
Same difference between Ppeak and Pplat (Pr) as normal lungs.
Pplat is much higher

185
Q

What effect does increased elastance have on insp/exp air flow

A

Air flow in is the same

Air flow out is rapid and rate is fast d/t rapid recoil

186
Q

What effect does increased elastance have on insp/exp volumes

A

Volumes are the same, but expiring same volume is much quicker

187
Q

What is work of breathing

A

Energy required to inflate/deflate lungs, chest wall, or both by a specified volume

W = PV

188
Q

What is mechanical ventilation

A

Applying positive pressure >Patm to airway during insp

Main method to provide adequate ventilation to pts given MRs

Allows for greater ventilatory control by provider and expands scope of procedures that can be performed

189
Q

Historical use of ventilators date back to when?

A

1400s
1530- first bellows used
1838 - first neg pressure vent

190
Q

Describe how negative pressure ventilators worked

A

Surface of thorax exposed to sub-atmospheric pressure on inspiration

Neg P effects

  • Thoracic expansion
  • DEC pleural and alveolar pressures
  • P gradient causing air flow into lungs
191
Q

Why is negative pressure ventilation no longer used

A
  • Volume target ventilators invented

- Jet ventilation developed leading to compact intermittent pos press devices

192
Q

What were the disadvantages of negative pressure ventilation

A

Leaks
Huge and heavy
Can’t sustain high airway pressures
Pt access limited

193
Q

Describe early PP vents including problems

A
  • Pressure or volume control only
  • ZERO synchrony w/ pt breathing

Problems:

  • Relied pts spontaneous resp
  • Led to pts coughing/bucking
  • Advancement of surgical techniques requiring MR

-Driven by pneumatic rather than electric

194
Q

What were 3 advantages as ventilators developed synchrony w/ pt respiration

A

Synchrony allowed for:

  • Assuming WOB
  • Improved gas exchange
  • Resp muscle relaxation
195
Q

How do OR vents differ from ICU vents

A
  • They act like reservoir to receive and redeliver pts exhaled gases
  • Fxn in semi-closed environment
  • —Circle system, unidirectional flow and CO2 absorber
  • Must vent waste gas
  • —Scavenging sys
  • Low flow to conserve gas
  • Ability to deliver anesthetic
196
Q

Hod do ICU vents differ from OR vents

A
  • Not a reservoir
  • Open circuit
  • Vents gas to atm
  • Uses high flow
  • Humidification system
197
Q

What are benefits of the circle system

A

 Maintenance is stable
 Gas concentration stable
 Conservation of resp heat & humidity
 CO2 elimination
 Cost effective (using low flow and rebreathe)
 Less waste of anesthetic gas
 Prevent OR pollution

198
Q

What is fresh gas compensation

A

Means to prevent the FGF from changing Vt
• By measuring actual Vt
 Compared to what is programed to be delivered

Using this information to change the volume of gas delivered
 Will inc/dec to meet Vt needs

199
Q

What is fresh gas decoupling

A

Prevention of FGF affecting Vt by isolating FGF from system during inspiration
—-To prevent over-pressurization of lungs

200
Q

What is tidal volume

A

Volume of gas entering/leaving the pt during both inspiration and expiration

Vt = (min vent) / RR

201
Q

What is minute ventilation

A

Sum of Vt per minute

Vt x RR = min Vent

202
Q

What are factors that affect Vt

A
  • FGF
  • Compliance/compression volumes
  • Leaks
203
Q

How does FGF affect Vt

A

Anesthetic gas flows continuous from CGO into circuit

Fills bellows and provides the working pressure

204
Q

What must be done to ensure compliance and compression volumes don’t affect Vt

A
  • Morning machine check
  • Check machine pressures etc when changes are made to the circuit

-prevents volume loss or pressure issues

205
Q

How do leaks affect Vt

A
  • Leaks can occur around ETT or supraglottic device(LMA)
  • Vt will decrease
  • May flatten bellows
206
Q

What is the I:E time (1:2 AND 1:1) and inspiratory flow rate for a pt w/ Vt 600 ml and RR@10

A

1:2–
I = 2 sec
E = 4 sec

Inspiratory flow = 300 ml/sec

1:1
I = 3 sec
E = 3 sec
Inspiratory flow = 200 ml/sec

207
Q

Drawbacks and advantage to I:E of 1:1

A

advantage:
Allows more time for oxygenation to atelectatic regions

Disadvantage:
DEC exp time in pts that need longer exp phase

208
Q

What is the I:E ratio and how does it affect oxygenation and CO2

A

Ratio of insp phase time to exp phase time

INC I = INC O2
INC E = INC CO2 OUT

209
Q

How should the I:E ratio be adjusted to improve oxygenation and CO2 level

A

Inc inspiratory phase to improve oxygenation

Inc exp phase to blow off CO2

210
Q

What is peak pressure? When is it considered elevated?

A
  • Max pressure during the inspiratory phase time

- Elevated when >5 mmHg over Pplat

211
Q

What are causes of INC Ppeak? What does Ppeak represent?

A

Causes:
bronchospasm, asthma, secretions, ETT obstruction

Represents:
P in airways

212
Q

What is plateau pressure? What does it represent?

A
  • Pressure when there’s NO airflow at end inspiration

- Represents lung compliance and alveolar pressure

213
Q

Primary source of resistance when there is air flow vs no air flow
Which pressure do these correlate with

A

Air flow = most resistance from airways (Ppeak)

NO air flow = resistance come from alveoli (Pplat)

214
Q

What is inspiratory pause time

A

Length of time the lungs are inflated

–at a fixed pressure or volume

215
Q

What is total ventilator-controlled ventilatory support

A

Pt breathing pattern is totally replaced by ventilator

Respiratory muscles are stopped by MR/sedation

216
Q

What are the inspiratory and expiratory flow times

A

Inspiratory flow time :
time btwn beginning and end of inspiratory flow

Expiratory flow time:
Time btwn beginning and end of expiratory flow

217
Q

Describe how high vs low pressure sources control Inspiratory waveform

A

High P source:
Flow generates P >5x airway P to move air

Low P source:
Flow generates P slightly above airway P

218
Q

Purpose of flow generators for inspiratory flow

A

Constant flow generator creates reliable Vt for insp breath

  • -Regardless of pt airway P
  • -Accomplished by bellows having weight or spring inside
219
Q

What is PEEP

A

The difference between end-occlusion and pre-occlusion pressures

Occluding airway at end-expo to see rise in airway P

220
Q

What are some advantages and disadvantages to PEEP

A

Advantages:

  • To recruit alveoli
  • Improve oxygenation (inc alveoli = more surface area for gas diffusion)

diadvantages:

  • INC intrathoracic P
  • –DEC VR – DEC CO –DEC BP
221
Q

What is auto PEEP. What can cause this

A
  • Positive pressure present in alveoli at end exhalation (should be 0)
  • Caused by INC airway resistance and DEC elastic lung recoil
  • Can be caused by I:E changes
  • -w/ inverse ratio when insp time > exp time
222
Q

Describe how auto-peep occur

A
  • INC airway resistance causes air trapping in alveoli leading to POS alveolar pressures and hyperinflation
  • Can occur when I:E ratio is changed to inverse ratio (insp time > exp time)
223
Q

What pts can suffer from auto-peep and what are the implications

A

Pts affected:
COPD, ARDS, sepsis, pt w/ weak resp muscles

Implications

  • Can promote significant hemodynamic and respiratory compromise
  • Can lead to hyperinflation
  • Poor expiratory excursion causing CO2 retention
224
Q

What is the ventilator driving gas supply and considerations depending on OR setting?

A

The gas that drive the bellows
–O2, air or mix

Very high flow
–Can exhaust e-cylinders if no pipeline gases

225
Q

What are ventilator controls and alarms

A

Controls:
-Regulate flow, volume, timing and piston movement

Alarms:
Grouped by priorities based on response promptness

226
Q

What is ventilator standard 6

A

Mandates an alarm indicate when pressure and breathing system has exceeded a set limit

227
Q

What is the ventilator pressure limiting mechanism and the suggested setting

A
  • Setting designed to limit inspiratory pressure
  • To achieve desired Vt and prevent trauma

Suggested = 10 cmH2O higher than Ppeak

228
Q

What is the purpose of the pressure limiting mechanism and what can happen if set too low or high

A

Limit pressure while maintaining Vt and preventing trauma

Too low = ineffective ventilation and hypoxia
Too high = risk for bars/volutrauma

229
Q

What are the bellows assembly and bellows housing

A

Assembly:
Interface btwn breathing system and ventilator driving gases

Housing:

  • Pressure chamber w/ bellows inside, connected to breathing system
  • Clear housing that is vital in driving gases
230
Q

What is the ventilator exhaust valve and how does it work? Which type has an exhaust valve?

A
  • Valve allowing for venting of expired gases
  • Allows driving gas inside housing to exhaust to atm

Works:
Inspiration = closed
Expiration = open

Only in bellows NOT piston
b/c piston vent has NO DRIVING GAS

231
Q

What is the ventilator spill valve.

How does it work

A

aka adjustable pressure limiting valve

Valve that is isolated from the breathing sys during vent mode

INSP = closed
EXP = open to vent
232
Q

Recommendation for APL valve setting during vent mode and why

A

Set to 0/open

-to prevent in adverting delivery of large volumes of gas when vent turned back to manual mode

233
Q

Ventilator standard 6 requirement for ventilator hose connection

A

• requires that the fitting on the tubing connecting the ventilator to the breathing system be a standard 22mm male conical fitting.

234
Q

What is the ventilator PEEP valve

A

In modern vents, it’s an electrically operated valve to give peep to spontaneous or mechanically vented pts

235
Q

How are modern ventilators classified

A

Type of reservoir

  • bellows
  • piston-
  • volume reflector

Driving mechanism of the reservoir

  • pneumatic
  • mechanical
236
Q

What is the ventilator reservoir

A

The area that receives and delivers gas to the pt

237
Q

What is the volume reflector reservoir
How does it differ from bellows/piston
Possible advantages

A

Bellows replacement
-W/ partial administration of rebreathed gas via circle system

Differences:
No moving parts, constant flow, rigid bellows

Advantages
-Rigid bellows prevents large fluctuation in pressure and volume

238
Q

How does the bellows function on inspiration vs expiration

A

Inspiration:

  • Driving gas is delivered into bellows housing
  • —compresses bellows
  • —Breathing gas inside bellows flows into breathing sys

Expiration:

  • Bellow re-expands from exhaled gases from breathing system and FGF
  • Driving gas vented to atm via exhaust valve
239
Q

What does the bellows interface with

A

Breathing system and driving gas

240
Q

How are bellows reservoirs defined

A

By the direction of bellow movement on expiration

ascending vs descending

241
Q

Describe how the ascending bellows functions and safety features

A

Rises during expiration as it fills w/ exhaled gases form breathing sys and FGF

Safety features:

  • VISUAL CUE of disconnection or leaks
  • WONT FILL is disconnection
  • PARTIAL FILL is leak&raquo_space; FGF
242
Q

Describe the descending bellows function and disadvantages?

What are the essential safety features?

A

-Driving gas pushes bellows up/flat during inspiration

Disadvantage:

  • Loss of visual cues
  • Will continue to move up/down despite disconnection/leaks

Safety feature:
-Integrated CO2 apnea alarm that can’t be disabled when vent in use

243
Q

What is a very important consideration about the source of drive gas?

A

Air vs O2 and where it comes from and the consumption

If its O2 that comes from a e-cylinder then O2 could run out very fast

244
Q

How many hours of gas will an e-cylinder with 625 L run w/ a FGF of 1.5 L/m

How many hours w/ only driving gas at 5.75 L/min

A

7 hours

1.8 hrs

245
Q

How many hours of gas will an e-cylinder w/ 625 L run w/ FGF of 1.5 L/min and driving gas of 5.75 L/min?

A

less than 1.5 hrs

246
Q

How does the piston reservoir differ from bellows on inhalation and exhalation

A

Exhalation = reservoir bag NOT isolate

Inspiration = piston forces gases into breathing system

247
Q

What is and is not isolated in the piston reservoir system

A

Isolated:
the lung which collects the FGF

NOT isolated:
Reservoir bag during expiratory phase

248
Q

What type of circuit ventilators are piston vs bellow driven?

A

Piston = single circuit

Bellow = double circuit

249
Q

Why is the bellows system considered double circuit

A

b/c there is need for a drive gas circuit

250
Q

Which reservoir systems will not visual show a pt disconnect from the vent

A

Descending/hanging bellows

Piston driven

251
Q

Advantages of piston driven vent

A
  • Consumes less gas(b/c no driving gas needed)
  • Can be used w/o pipeline gas
  • Very accurate Vt delivery
252
Q

Why do piston driven vents have more accurate Vt

A

B/c piston vents don’t rely on pressure for Vt delivery like bellows do

253
Q

What are disadvantages of the piston vent

A
  • Pistons are hidden, so loss of visual cues for disconnect
  • Extremely quiet (loss of auditory cues)
  • Continue to fill even w/ circuit disconnect (leading to awareness or hypoxemia)
254
Q

Describe the assist control ventilation mode

A

Trigger = pt INSP effort

  • -vent senses negative intrathoracic pressure
  • –Vt delivered

Vent provides back-up rate to prevent hypoventilation
PEEP w/ back-up

255
Q

What will the the vent pressure waveform look like in ACV mode for a pt triggered breath vs vent triggered breath

A

Pt triggered:
NEGATIVE deflection in pressure waveform

Vent triggered:
NO negative deflection

256
Q

How would decreased compliance affect setting for ACV mode

A

Higher Vt will be required

BUT airway pressures may be TOO HIGH

257
Q

How does proportional assisted ventilation differ from ACV

A

It rewards greater negative pt triggered deflections w/ large Vt

258
Q

 Settings AC, RR 12, TV 400, FiO2 40% Peep 5. Sedated patient
 ABG pH 7.26 pCO2 60, PaO2 55, HCO3 26

How do we fix this by adjusting the ventilator

A

Increase Vt?

Increase RR?

259
Q

What is set by the vent in the PSV mode

What does pt control during PSV

A

Vent control:
I time
Ppeak delivered
Trigger

Pt control:
Initiation of each breath

260
Q

What is the greatest use of PSV?

A

When weaning from vent to overcome ETT resistance

Low-pressure PSV

  • matches ETT resistance
  • Allows pt to compensate for resistance
261
Q

What safety measures are used w/ PSV and why

How does inc PSV affect breaths

A

Safety measures:
apnea and back-up mode
b/c PSV relies 100% on pt breath initiation

INC PSV = larger breaths

262
Q

What does the vent control when in IMV mode

A

Vent:
RR
Mandatory P OR V
Insp time

263
Q

What are advantages of IMV mode

A

Pt can still produce spontaneous breaths while gettin event assistance for those breaths

Allows pt to work resp muscles while waking up

264
Q

What is a disadvantage to IMV mode and how can this occur

A

Breath stacking
–Can lead to barotrauma

Cause:
Mandatory breaths can be delivered on-top of pt initiated breaths causing over pressure in lungs

265
Q

What is set w/ SIMV mode

A

Vent sets:

  • Mandatory P or V
  • RR
  • INSP time
266
Q

What is the big difference between SIMV and IMV

A

SIMV prevents breath stacking by using sensors that monitor pts expected gas volume in the airway

This allows for mandatory breath to be delivered at the beginning or end of spontaneous breath

267
Q

How does SIMV mode coordinate breath delivery w/ spontaneous breaths at beginning and end of breaths

A

Beginning of breath
-Delivery is safe as long as there isn’t a large gas volume that could cause barotrauma

End of breath:
-Gas delivered when the volume is predictably high

268
Q

When are controlled breathing modes used and why

A

When pts are given MRs and cannot contribute to breathing effort at all

269
Q

What are the fixed, set and variable parameters for pressure control ventilation

A

FIXED:
Pressure

SET:
Ppeak, RR, I:E time

Variable:
Flow to match Ppeak

270
Q

How can compliance and resistance be inferred w/ Vt in PCV mode

A

Vt is directly proportional to lung compliance

  • low compliance = low Vt
  • High compliance = better Vt

Vt is inversely r/t airway resistance

  • low resistance = high Vt
  • High resistance = low Vt
271
Q

What are the fixed and set values for VCV mode

A

FIXED:
Volume

SET:
Vt, RR, I:E ratio

272
Q

Why is the calculated inspiratory time significant w/ VCV

A
  • b/c it is based on RR and the set I:E ratio
  • The inspiratory time is the amount of time for the Vt to be delivered
  • This FLOW during inspiration leads to the Ppeak and can cause high Ppeak
273
Q

What precautions should be considered with pts on VCV

A

Ppeak should not exceed 5 cmH2O greater than Pplat

Pt w/ high Ppeak can have barotrauma

ALWAYS watch Ppeak in this mode b/c VOL is delivered regardless of airway pressures leading to trauma

274
Q

What pts may VCV be contraindicated and why

A

Pts w/
ARDS, Fluid overload, abd distention, laparoscopies, insufflation, bronchospasm, increased secretions

Any condition or procedure that increases airway pressures in which the vent will fight against to obtain volume regardless of pressures

275
Q

Describe the VG-PVC setting and when it’s use is advantageous

A

It allows vent to change the INSP pressure based on respiratory sys compliance

This allows vent to deliver constant VOL during large changes to pressure (like in robotic procedures)

Prevents baro/volutrauma from inadvertent delivery of large pressure or volume when insufflation is removed

276
Q

What is CPAP and when is it useful

Normal setting

A

Continuous positive airway pressure throughout inspiration and expiration

Uses:
Non-invasive w/ FM
While waiting to extubate
OSA pts in recovery

Normal setting:
5-20 cmH2O

277
Q

What are advantages and disadvantages of CPAP

A

Advantages
• To recruit alveoli
• Facilitate oxygenation
• Lung compliance characteristics evident

Disadvantages
• Does intrathoracic P
• May create air-trapping in COPD pt

278
Q

MRI vents 1:19:15

A

slide 51 pg 23

Ane Principles II (3 decks)

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