E1 Flashcards
(278 cards)
1
Q
X-ray definition
A
• Classification of radiation called electromagnetic waves.
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.
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
4
Q
What is the general use of xrays
A
- to diagnose numerous medical conditions
* to treat numerous medical conditions
5
Q
Most important thing about xray assessment
A
Best predictor of
• Difficult endobronchial intubation
• Clues you into potential airway issues
6
Q
Xray assessment can guide CRNA’s….
A
Plan of care
7
Q
What is xray density
A
- Degree of xray absorption
* Based on density of substance xray travels through
8
Q
What do the black and white portions of the xray image indicate
A
Densities
Black = air filled spaces
White = dense tissue spaces
9
Q
What are examples of black and white substances on xray
A
black:
air, fat
white:
metal, bone, calcifications, soft tissue
10
Q
What is penetrance
A
• Helps determine if film is over or under penetrated by xrays
11
Q
What is over penetrance
A
• Detail can be lost
Poor differentiation of structures?
• The higher density = whiter structures
• More lucent = darker structures
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
13
Q
In what situation may an under penetrated image be useful
A
to identify structures behind other tissues
14
Q
Xray benegits
A
Noninvasive
Painless.
Supports medical and surgical planning.
Identify landmarks
Guides for insert caths, stents, treat tumors, remove blood clots.
15
Q
Xray risks
A
Generally assct w/ radiation therapy Ionizing radiation Could develop cancer Hair loss Cataract damage Skin burns
16
Q
What is ionizing radiation
A
Ionizing radiation:
• form of radiation can cause tissue damage DNA damage.
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
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)
19
Q
What may happen is sufficient exposure to ionizing radiation occurs
A
Tissue could be destroyed
Malignancy d/t chromosomal changes
20
Q
Xray raduation exposure unit
A
rem
roentgen equivalent man
21
Q
Primary source of human exposure
A
Cosmic rays
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
23
Q
How is exposure measured
A
dosemeter
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
25
Max recommended exposure during pregnancy
Limit max exposure to 500 mrem
26
General chest xray exposure
~25 mrems
27
Recommended safety precautions and/or distance from pt when performing xray
3-ft distance from pt recommended
Lead aprons
0.25 – 0.5 mm thick do the job.
28
6 ft of distance from xray provides equivalent protection to
Equates to
9 inches of concrete protection
2.5 mm lead apron
29
6 ft of distance from xray provides equivalent protection to
Equates to
9 inches of concrete protection
2.5 mm lead apron
30
What is the TWU clinical policy for pregnant women
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
31
Describe the small opacity classification
```
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.
32
Difference in opacity sizing classifications
```
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.
```
33
Round opacity guidelines
* Round – p = up to 1.5 mm in size.
* Round – q = 1.5 – 3 mm in size.
* Round – r = 3 – 10 mm in size.
34
Irregular opacity guidelines
* Irregular – s = up to 1.5 mm in size.
* Irregular – t = 1.5 mm – 3mm in size.
* Irregular – u = 3 – 10 mm in size.
35
6 description of large opacities
```
Diffuse Homogeneous
Multifocal Patchy
Lobar without Atelectasis
Lobar with Atelectasis
Perihilar
Peripheral
```
36
6 description of large opacities
```
Diffuse Homogeneous
Multifocal Patchy
Lobar without Atelectasis
Lobar with Atelectasis
Perihilar
Peripheral
```
37
Describe guidelines and diseases associated w/ micronodular image description
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
38
Describe guidelines and disease associated w/ nodular image descriptions
* Nodes up to 1cm in diameter.
* Miliary (looks like millet seeds)
```
Disease processes included:
TB.
Sarcoidosis.
Fungal Disease.
CMV
Pneumonias.
Measles, Mumps, and Neoplasia.
```
39
What are reticular marking on xrays
"Fluffy," interconnected markings
| Correspond to small irregular opacities
40
What can reticular markings indicate
Honeycombing can indicate end-stage lung disease
41
What are 2 categories and 3 types of reticular xray patterns
Categories:
Acute
Chronic
Types:
• fine (ground glass)
• medium (irregular)
• course (honeycomb)
42
Describe honeycomb patterns on xray images and what do they indicate
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
43
What are the physiologic cause of linear lung markings on xray
Phys cause:
| -Most likely d/t thickened interlobular septa
44
Describe the 3 types of kerley lines
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
45
What are 3 types of linear marking seen on xray
- interlobular
- Kerley lines (3 types)
- Intralobular
46
What causes the appearance of Kerley lines
| General characteristics of Kerley lines
Increased hydrostatic pressure is the cause in all cases
Characteristics:
- NOT interconnected (like reticular)
- Differ in length and width
47
What are cause of destructive patterns seen on lung xrays
- Small lungs
- Diffuse consolidation
- Bronchiolectisis
- Honeycombing
- Bullae
- Cysts
- Pulm HTN
48
What is bronchiolectisis and what does it indicate
Chronic infections
Permanently thick and widened bronchioles
Allows for mucous build up
49
What are bullae and associated complications
Giant fluid-illed space w/in parenchyma
> 1cm
Rupture = PTX
50
Characteristics of alveolar patterns on xray
* Appear as “air-space”
* ground-glass opacification
* coalescent opacities,
* air bronchograms.
51
List some basal lung disease processes
```
Bronchiextasis
aspiration**
pneumonia/fibrosis
CF
asbestos
scleroderma
RA
```
52
List some upper lung zone diseases
```
TB
Fungus
Sarcoidosis
Pneumoconiosis (coal miners lung)
Langerhans cell histiocystosis
ankylosing spondylitis
CF**
Radiation fibrosis
```
53
Describe central lung disease and associated disease processes
-Perihilar lung disease
```
-Disease processes
Sarcoidosis
lymphoma
Karposi's sarcoma**
bronchiectasis
```
54
List diseases that manifest in the peripheral lung zone
Cryptogenic organizing pna
Asbestosis
Graft v host
COVID-19**
55
What causes cor pulmonale
RV hypertrophy and diation r/t pulmonary HTN
D/t
- obliterated small peripheral pulm artery branches
- Combined w/ hypoxic vasoconstriction
56
What does cor pulmonale lead to
pulm HTN
57
Why is learning to read xrays important to CRNAs
allows you to get a better physiological understanding of what you have to work with after you intubate the patient.
58
What do atelectasis, pulm HTN, kerly B lines, nodular markings and small___ equal
BAD LUNGS
| difficult ventilation
59
Characteristics of cor pulmonale and what can it lead to
Characteristics:
Very low CO
large heart (>50% of chest)
High SVR
Lead to:
Fluid back-up
Lung compensation to improve O2
60
Anesthesia implications in pts w/ Cor pulmonale
- Low FRC (VERY low O2 reserve)
- Quicker inhalation uptake (sleep quicker)
- Use of PPV (to inc V/P matching
61
Anesthetic implications for pts w/ pulmonary edema
- Acute onset (postpone and optimize)
| - Surgery could lead to prolong post-op intubation
62
Intraop treatment for pts w/ pulmonary edema
* Low FRC
* Very low O2 reserve
* Quicker inhalation uptake
* Sleep quicker
* Use of PPV
* To INC V/P matching
63
Anesthesia implications for pts w/ pulm fibrosis
```
•Very low FRC
Low O2 reserve
But good O2 uptake on induction??
•Low peak airway pressures
To prevent further damage
```
64
Anesthesia considerations for pts w/ PTX
• NO NITROUS (will make PTX bigger)
• 100% FiO2
• Needle decompression
Followed by CT
65
Anesthesia considerations for pts w/ PNA
Acute--proceed w/ surgery if OR required
Small tidal volumes--keep airway pressures <30
66
3 primary chest xray views and how they are performed
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
67
What are some clues that tell the viewer is assessing an AP and PA
AP image
-Scapulas are prominently visible b/c arms are down
PA image:
-Scapula edges are generally only landmark visible b/c arms up
68
What is divergence
images on xray are falsley larger than the actual tissue imaged
69
what are some xray modalities and their relative radiation exposure
CT (most)
Fluroscopy (moderate)
Radiography (conventional xray)
70
What are criteria for pre-op chest x-ray
Based on
- -Physical assessment
- -Clinically r/t the surgical procedures
- -To assess abnormalities found on physical assessment
71
List some disease processes that may require pre-op chest xray
* Chest mass, advanced COPD, suspected pulmonary edema,
| * Tracheal deviation, & aortic aneurysm to list a few.
72
What is a systemic, methodical approach to interpreting chest xrays
```
Airway
Bones
Cardiac silhouette
Diaphragm
Everything else
Foreign bodies
```
73
What airway landmarks should be identified on xray
Trachea
--midline
Carina
--At the sternal angle of Lewis
Lung fields
- -symmetric
- -Lung markins to edge of chest
- ---Costocondral angle defined
- -Opacification
74
What "alterations" may be seen on a normal AP chest xray
Can make the heart and vasculature look enlarged
75
What cardiac landmarks should be identified on chest xray
- 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
76
What bone landmarks should be identified on chest xray
- Look for symmetrical clavicles
- -Uneven clavicles = poor position
-Shoulders should be level
- Count 10 ribs
- -indicates good chest expansion
-Vertebral column alignment
77
What diaphragm structures or landmarks should be identified when assessing on chest xray
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
78
What should be considered when assess a CXR for "everything else"
Objects overlying the chest
--ECG leads, pulse ox, cables/wires, hair
Soft tissue artifact
- -Breast tissue
- -Posterior adipose tissue
- -SQ emphysema
79
What should be considered when assess a CXR for "foreign bodies"
* Central lines
* Coins
* Chest tube
* NGT/OGT
* Endotracheal tube
* Sternal wires
* Bullets or knives
* PM/AICD
80
Radiologic characteristics of consolidation on CXR
Density to lung field/s
Loss of ascending aorta silhouette
No shifts
Air bronchogram
81
What is air bronchogram and what does it indicate on CXR
Definition:
Visible air-filled bronchi surrounded by fluid-filled alveoli
Indicates:
Lung consolidation
Dilated airways to consolidated areas?
82
Radiographic characteristics of pleural effusion on CXR
Fluid accumulates in pleural space
--Typically see defined borders
Blunt costophrenic angles
Lack of identifiable diaphragm
See next question for criteria
83
Radiologic criteria for pleural effusion include
- Inc density in dependent portion
- costophrenic angle blunting
- unidentifiable diaphragm
84
What causes atelectasis and key characteristics seen on CXR
Cause:
Loss of air or surfactant in alveoli
Xray has inc density b/c of loss of lung volume
85
Types of atelectasis (don't need to know!!)
- Resorptive
- Relaxation
- Adhesive
- Cicatricial
- Round
86
CXR signs of atelectasis
- Mediastinal shift (TOWARD atelectatic region)
- Elevation of diaphragm
- Crowding of ribs
- Movement of fissures
- Movement of hilum
- Compensatory hyperinflation
- Hemithorax asymmetry
87
Radiographic characteristics of lung fibrosis on CXR
- Diffuse haziness
- Apical cap thickening
- Blunting of costophrenic angles
- loss of lung volume
- Lung fissure lines no corresponding
88
Radiographic characteristics of active TB on CXR
Bright circular chest cavitations
89
Radiographic characteristics of PTX on CXR
- Air in pleural space w/o lung markings
- Atelectatic lung
- Shift of mediastinum AWAY from PTX
- Opposite lung has PROMINENT lung/vascular markings
90
Hydropneumothorax evidence on cxr
- Air and fluid within the pleural space
| - Well defined horizontal fluid line that extends across the hemithorax
91
Characteristics of lung mass on cxr
- Round or oval
- Sharp/defined margins
- Homogenous density
92
Characteristics of lung abscess on CXR
-air or fluid filled cavity in lung
93
Radiographic characteristics of pulmonary edema on CXR
- Bilat
- Diffuse
- Butterfly pattern
- Soft, fluffy lesions
- Air bronchogram
94
Characteristics of lung blebs on CXR
- Collection of air in the alveolar layer of pleura
- -shows as circular black air markings
- Formed by rupture of alveolar walls
95
Characteristics of sarcoidosis on CXR
- Enlarged, dense connective tissue at the hilum
| - Hilar nodal enlargement
96
Characteristics of emphysema on CXR
- Hyperinflation
- Hyperlucency
- Low set and flat diaphragm
- Tall/vertical heart
- Barrel shape chest
- Avascular zones
- Extended upper lung fields
97
Causes of pleural effusion
- CHF
- Cancer Mets
- Pancreatitis
- PE
- Trauma
- Empyema
- Collagen vascular issues (lupus, scleroderma)
- Ovarian tumor (Meigs sx)
- Chylothorax
98
What is hamptom's hump/westermarks sign on CXR?
High density areas in the middle of the lung indicating PE and engorged pulm vasculature
99
Characteristics of CHF on CXR
Cardiac silhouette will be >55% of chest width
May have engorged pulm vasculature
100
Describe the discovery of xray
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…
101
What are four different types of radiation
```
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
```
102
What are the similarities and differences in xray and visible light rays?
Similarities
- Both are EM energy
- Both carried by particles called photons
Differences
-Energy level aka wavelength
103
Describe xray and radio waves wavelength vs energy level.
Are they visible or not?
Xray: (not visible)
wavelength = shorter
Energy = higher
Radio waves: (not visible)
wavelength = longer
Energy = lower
104
How is light emitted
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
105
Describe characteristics of xray photons
Have lots of energy
Pass through most things
Can knock e- away from atoms or send them flying through space
106
How does the size of an atom correlate to xray absorption
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
107
Example of small vs large atom tissues and how they are affected by xray photons
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
108
Describe the mechanics of how the xray machine works
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
109
Describe the electrode pair in relation to xray machine function
```
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
110
Describe how xray cameras record pictures
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
111
Describe the difference in darker and lighter areas of exposure on films
DARK areas = More light exposure
Less dense tissues = less photons absorbed
LIGHT areas = Less light exposure
More dense tissue = more photons absorbed
112
What are medical x-rays uses
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
What is ioinizing radiation and what can this lead to?
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
Describe the side effects of radiation therapy r/t location of irradiation.
How might this affect anesthetic plan
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
How is radiation dosing measured?
| What are recommended annual allowable doses?
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
What are various radiation exposure sources?
DIRECT source
- Primary x-ray beam
- leakage from equipment
INDIRECT source:
-Scattered radiation (reflected off tables, pt, surfaces etc)
117
```
Estimated mrem exposure for each:
CXR
Coronary angiogram
Angioplasty
CT
```
CXR: 5-10 mrem
Coronary angiogram: 1,500 mrem
Angioplasty: 5,700 mrem
CT: 5,00 mrem
118
Methods or protection against direct and indirect sources of radiation
- Lead
| - Distance
119
At what doses would s/sx of radiation be present. What may that include
200,000 mrem = transient erythema
120
At what mrem dose can lead to fetal effects
Fetal doses <10,000 mrem unlikely to cause effects AFTER 20 weeks
121
What are principles of radiation protective measures
Time
Distance
Shielding
122
How do time, distance and shielding affect radiation exposure.
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
Why is an angoi performed via femoral approach more desirable than via brachial approach
The provider is decreasing exposure time and increasing distance between themself and the xray
124
The provider moves from 2 ft to 4 ft away from the pt during an xray. What are the respective mrem exposure
moving from 2 ft to 4 ft might change exposure from 20mrem/min to 5 mrem/min
125
What is an protective measure device for radiation exposure.
| Related principles for use?
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
Describe the principles of MRI
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
How is contrast between tissue generated w/ MRI
Generated by amount of time to tissue relaxation when RF turned off
-time for atoms to realign in the N-S pole
128
What does contrast of tissues for MRI depend on?
- 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
What are the 2 types of MRI contrast and what are the characteristics of each
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
What is the common MRI contrast material and principles for use
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
When using gadolinium, what are common side effects or reactions.
How is it cleared?
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
How does the MRI static field affect ferro magnetic objects?
Attractive force:
-Objects are pulled toward center of magnet
Torque:
-Objects attempt to line up with the field
133
What equipment is not compatible w/ MRI static field?
* Oxygen/nitrous oxide tanks
* Anesthesia machine
* Monitors
* Infusion pumps
* Stretchers
* Crash carts
134
What are risks r/t MRI
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
Anesthesia considerations for MRI
- 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
AANA standards of care and considerations for providing anesthesia during MRI
- 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
Positioning considerations for anesthesia pts in MRI
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
What are provider and pt safety considerations when caring for MRI pts
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
What is the definition of laser
```
Light
Amplification by
Simulated
Emission of
Radiation
```
140
How do lasers and ordinary light compare
Ordinary light
- has MANY wavelengths
- Spreads out in MANY directions
Laser:
- Specific wavelength
- Focuses, narrow beam
- High-intensity
141
What are common uses of medical lasers
- 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
What are properties of Laser radiation
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
What are advantages of surgical use of laser
- Precision (r/t collimation)
- Good hemostasis
- Rapid healing
- Less scar formation
- Less post-op edema/pain
- Lower infectin rates
144
What are the 3 most common lasing mediums
Argon
CO2
Nd:YAG
145
Describe the benefits and uses of Argon, CO2 and Nd:YAG lasing mediums
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
What are 5 hazards of Laser use
1. Atmospheric contamination
2. Perforation of vessel or structure
3. Embolism
4. Inappropriate energy transfer
5. Airway fire
147
What is atmospheric contamination r/t laser plume and potential consequences?
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
What is the fire triad.
Examples of each component
What are 2 major sources for OR fires
Triad:
Ignition
-laser, electrocautery
Fuel
-drapes, paper
Oxidizer
-O2, nitrous
Sources:
ESU
Laser
149
What are the most common ETT fire scenarios
- 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
What are airway fire safety techniques
- 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
What are fire safety techniques r/t FiO2 level
Use lowest FiO2 possible to maintain sats
May need to accept pt SpO2 in low 90s rather than having higher FiO2
152
What is the purpose of using wet pledgets to prevent in fire safety
Using wet pledgets around ETT prevents gas escaping and decreases risk of airway fire
Lowers temp at site of laser
153
What is the purpose of methylene blue in cuff rather than air
It is a visual cue for surgeon that cuff has ruptured and to cease lasering
154
When surgeon is incising through trachea w/ bovie, what is a fire safety measure that can be taken to reduce airway fire
-Encourage surgeon to switch from bovie to scissor/scalpel to incise through trachea to avoid damage to ETT and igniting a fire
155
Rational of ETT removal during laser procedures
Removal and reinsertion to maintain sats can decrease airway fire risk
156
What are anesthesia considerations when preparing and providing anesthesia for pts in laser surgeries
- 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
What are important anesthesia preop assessment considerations for airway management in the pt receiving laser
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
What type of anesthesia may be provided to the pt receiving airway lasering and why
TIVA
-b/c gas cannot be used w/ repeated intubations
159
What are considerations for gas use w/ the intermittent apnea technique vs jet ventilation
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
What can be used to help protect the face when performing laser procedures to face
Purpose of this technique
Saline gauze protection of airway/face
Purpose:
• ↓ heat to surrounding laser site
• ↓ fire changes
161
What laser technique can the surgeon use to help decrease inadvertant laser related damage
Short, repeated pulses rather than long continuous mode
162
What is ventilation
Spontaneous movement of air in/out of lungs
-inspired gas = IN
Expired gas = OUT
163
Goal of ventilation
To generate flow and volume
| To provide adequate alveolar ventilation w/ minimal WOB
164
How is ventilation controlled/performed
Contraction of respiratory muscles = POWER
Phrenic nerve = Respiratory timing and intensity regulation
165
What are components of dynamic respiratory mechanic
Resistance
Elastance
Compliance
Intertial properties
166
Describe why resistance occurs in the lungs
- Arises from viscous and turbulent losses associated w/:
- -Airway tree
- -Deformation of parenchymal and chest wall tissues
167
Why does elastance exist in the lungs
Arises from the recoil of the lungs and chest wall (which are opposing forces)
168
What is compliance
Ability of lung tissue to expand
Amount of pressure need to add volume
169
What is the significance of inertial properties in the lungs
They are associated w/ acceleration of the gas column in the central lairways and motion of respiratory tissues
170
How do inertial properties in the lungs affect breathing
Little effect on respirations except when there are sudden changes to air flow like HFJV
171
How is pulmonary resistance calculated
R = (Ppeak - Pplat) / Vi
Vi is immediately before inspiratory pause
172
What can resistance reflect about pulmonary status
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
what percent of pulmonary resistance dose lung tissue comprise
Approx 60% of total subglottal resistance at normal RR
174
How can ETT affect resistance
Inc resistance esp w/ obstruction
175
What can lead to ETT obstructions. How does surgery length affect this
- mucous, too much humidification, surgical debris, ETT kinking
- longer the procedure the more likely there could be an obstruction
176
What is the compliance equation
(change vol)/(change P)
177
How is compliance measured and what affects this
Measured in mls
Affected by lung and chest wall
178
At rest, what are alv P and Pl P
Alv P = 0
Pl P = NEGATIVE
179
What does compliance depend on and what disease inc/dec compliance
Depends on lung volume
Lung dx:
DEC-ARDS, pulm fibrosis, edema
INC- emphysema
180
What effect does extremes in FRC have on compliance and why
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
What is the effect on insp/exp pressure by increased resistance
More pressure for volume
- -Ppeak is much higher
- -Greater change btwn Ppeak and Pplat
182
What effect does increased resistance have on air flow in the lungs
Inspiratory air flow is the same
Expiratory air flow is lower rate and takes longer
183
What effect does increased resistance have on lung volume during respiration
W/ an increased pressure, volume inspired is the same.
| To expire full amount of volume takes much longer
184
What effect does increased elastance have on insp/exp pressures
Much greater Ppeak for same volume
Same difference between Ppeak and Pplat (Pr) as normal lungs.
Pplat is much higher
185
What effect does increased elastance have on insp/exp air flow
Air flow in is the same
Air flow out is rapid and rate is fast d/t rapid recoil
186
What effect does increased elastance have on insp/exp volumes
Volumes are the same, but expiring same volume is much quicker
187
What is work of breathing
Energy required to inflate/deflate lungs, chest wall, or both by a specified volume
W = PV
188
What is mechanical ventilation
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
Historical use of ventilators date back to when?
1400s
1530- first bellows used
1838 - first neg pressure vent
190
Describe how negative pressure ventilators worked
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
Why is negative pressure ventilation no longer used
- Volume target ventilators invented
| - Jet ventilation developed leading to compact intermittent pos press devices
192
What were the disadvantages of negative pressure ventilation
Leaks
Huge and heavy
Can't sustain high airway pressures
Pt access limited
193
Describe early PP vents including problems
- 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
What were 3 advantages as ventilators developed synchrony w/ pt respiration
Synchrony allowed for:
- Assuming WOB
- Improved gas exchange
- Resp muscle relaxation
195
How do OR vents differ from ICU vents
- 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
Hod do ICU vents differ from OR vents
- Not a reservoir
- Open circuit
- Vents gas to atm
- Uses high flow
- Humidification system
197
What are benefits of the circle system
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
What is fresh gas compensation
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
What is fresh gas decoupling
Prevention of FGF affecting Vt by isolating FGF from system during inspiration
----To prevent over-pressurization of lungs
200
What is tidal volume
Volume of gas entering/leaving the pt during both inspiration and expiration
Vt = (min vent) / RR
201
What is minute ventilation
Sum of Vt per minute
Vt x RR = min Vent
202
What are factors that affect Vt
- FGF
- Compliance/compression volumes
- Leaks
203
How does FGF affect Vt
Anesthetic gas flows continuous from CGO into circuit
| Fills bellows and provides the working pressure
204
What must be done to ensure compliance and compression volumes don't affect Vt
- Morning machine check
- Check machine pressures etc when changes are made to the circuit
-prevents volume loss or pressure issues
205
How do leaks affect Vt
- Leaks can occur around ETT or supraglottic device(LMA)
- Vt will decrease
- May flatten bellows
206
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
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
Drawbacks and advantage to I:E of 1:1
advantage:
Allows more time for oxygenation to atelectatic regions
Disadvantage:
DEC exp time in pts that need longer exp phase
208
What is the I:E ratio and how does it affect oxygenation and CO2
Ratio of insp phase time to exp phase time
INC I = INC O2
INC E = INC CO2 OUT
209
How should the I:E ratio be adjusted to improve oxygenation and CO2 level
Inc inspiratory phase to improve oxygenation
Inc exp phase to blow off CO2
210
What is peak pressure? When is it considered elevated?
- Max pressure during the inspiratory phase time
| - Elevated when >5 mmHg over Pplat
211
What are causes of INC Ppeak? What does Ppeak represent?
Causes:
bronchospasm, asthma, secretions, ETT obstruction
Represents:
P in airways
212
What is plateau pressure? What does it represent?
- Pressure when there's NO airflow at end inspiration
| - Represents lung compliance and alveolar pressure
213
Primary source of resistance when there is air flow vs no air flow
Which pressure do these correlate with
Air flow = most resistance from airways (Ppeak)
NO air flow = resistance come from alveoli (Pplat)
214
What is inspiratory pause time
Length of time the lungs are inflated
| --at a fixed pressure or volume
215
What is total ventilator-controlled ventilatory support
Pt breathing pattern is totally replaced by ventilator
Respiratory muscles are stopped by MR/sedation
216
What are the inspiratory and expiratory flow times
Inspiratory flow time :
time btwn beginning and end of inspiratory flow
Expiratory flow time:
Time btwn beginning and end of expiratory flow
217
Describe how high vs low pressure sources control Inspiratory waveform
High P source:
Flow generates P >5x airway P to move air
Low P source:
Flow generates P slightly above airway P
218
Purpose of flow generators for inspiratory flow
Constant flow generator creates reliable Vt for insp breath
- -Regardless of pt airway P
- -Accomplished by bellows having weight or spring inside
219
What is PEEP
The difference between end-occlusion and pre-occlusion pressures
Occluding airway at end-expo to see rise in airway P
220
What are some advantages and disadvantages to PEEP
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
What is auto PEEP. What can cause this
- 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
Describe how auto-peep occur
- 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
What pts can suffer from auto-peep and what are the implications
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
What is the ventilator driving gas supply and considerations depending on OR setting?
The gas that drive the bellows
--O2, air or mix
Very high flow
--Can exhaust e-cylinders if no pipeline gases
225
What are ventilator controls and alarms
Controls:
-Regulate flow, volume, timing and piston movement
Alarms:
Grouped by priorities based on response promptness
226
What is ventilator standard 6
Mandates an alarm indicate when pressure and breathing system has exceeded a set limit
227
What is the ventilator pressure limiting mechanism and the suggested setting
- Setting designed to limit inspiratory pressure
- To achieve desired Vt and prevent trauma
Suggested = 10 cmH2O higher than Ppeak
228
What is the purpose of the pressure limiting mechanism and what can happen if set too low or high
Limit pressure while maintaining Vt and preventing trauma
Too low = ineffective ventilation and hypoxia
Too high = risk for bars/volutrauma
229
What are the bellows assembly and bellows housing
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
What is the ventilator exhaust valve and how does it work? Which type has an exhaust valve?
- 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
What is the ventilator spill valve.
| How does it work
aka adjustable pressure limiting valve
Valve that is isolated from the breathing sys during vent mode
```
INSP = closed
EXP = open to vent
```
232
Recommendation for APL valve setting during vent mode and why
Set to 0/open
| -to prevent in adverting delivery of large volumes of gas when vent turned back to manual mode
233
Ventilator standard 6 requirement for ventilator hose connection
• requires that the fitting on the tubing connecting the ventilator to the breathing system be a standard 22mm male conical fitting.
234
What is the ventilator PEEP valve
In modern vents, it's an electrically operated valve to give peep to spontaneous or mechanically vented pts
235
How are modern ventilators classified
Type of reservoir
- bellows
- piston-
- volume reflector
Driving mechanism of the reservoir
- pneumatic
- mechanical
236
What is the ventilator reservoir
The area that receives and delivers gas to the pt
237
What is the volume reflector reservoir
How does it differ from bellows/piston
Possible advantages
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
How does the bellows function on inspiration vs expiration
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
What does the bellows interface with
Breathing system and driving gas
240
How are bellows reservoirs defined
By the direction of bellow movement on expiration
ascending vs descending
241
Describe how the ascending bellows functions and safety features
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 >> FGF
242
Describe the descending bellows function and disadvantages?
| What are the essential safety features?
-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
What is a very important consideration about the source of drive gas?
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
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
7 hours
1.8 hrs
245
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?
less than 1.5 hrs
246
How does the piston reservoir differ from bellows on inhalation and exhalation
Exhalation = reservoir bag NOT isolate
Inspiration = piston forces gases into breathing system
247
What is and is not isolated in the piston reservoir system
Isolated:
the lung which collects the FGF
NOT isolated:
Reservoir bag during expiratory phase
248
What type of circuit ventilators are piston vs bellow driven?
Piston = single circuit
Bellow = double circuit
249
Why is the bellows system considered double circuit
b/c there is need for a drive gas circuit
250
Which reservoir systems will not visual show a pt disconnect from the vent
Descending/hanging bellows
| Piston driven
251
Advantages of piston driven vent
- Consumes less gas(b/c no driving gas needed)
- Can be used w/o pipeline gas
- Very accurate Vt delivery
252
Why do piston driven vents have more accurate Vt
B/c piston vents don't rely on pressure for Vt delivery like bellows do
253
What are disadvantages of the piston vent
- 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
Describe the assist control ventilation mode
Trigger = pt INSP effort
- -vent senses negative intrathoracic pressure
- --Vt delivered
Vent provides back-up rate to prevent hypoventilation
PEEP w/ back-up
255
What will the the vent pressure waveform look like in ACV mode for a pt triggered breath vs vent triggered breath
Pt triggered:
NEGATIVE deflection in pressure waveform
Vent triggered:
NO negative deflection
256
How would decreased compliance affect setting for ACV mode
Higher Vt will be required
BUT airway pressures may be TOO HIGH
257
How does proportional assisted ventilation differ from ACV
It rewards greater negative pt triggered deflections w/ large Vt
258
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
Increase Vt?
| Increase RR?
259
What is set by the vent in the PSV mode
What does pt control during PSV
Vent control:
I time
Ppeak delivered
Trigger
Pt control:
Initiation of each breath
260
What is the greatest use of PSV?
When weaning from vent to overcome ETT resistance
Low-pressure PSV
- matches ETT resistance
- Allows pt to compensate for resistance
261
What safety measures are used w/ PSV and why
How does inc PSV affect breaths
Safety measures:
apnea and back-up mode
b/c PSV relies 100% on pt breath initiation
INC PSV = larger breaths
262
What does the vent control when in IMV mode
Vent:
RR
Mandatory P OR V
Insp time
263
What are advantages of IMV mode
Pt can still produce spontaneous breaths while gettin event assistance for those breaths
Allows pt to work resp muscles while waking up
264
What is a disadvantage to IMV mode and how can this occur
Breath stacking
--Can lead to barotrauma
Cause:
Mandatory breaths can be delivered on-top of pt initiated breaths causing over pressure in lungs
265
What is set w/ SIMV mode
Vent sets:
- Mandatory P or V
- RR
- INSP time
266
What is the big difference between SIMV and IMV
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
How does SIMV mode coordinate breath delivery w/ spontaneous breaths at beginning and end of breaths
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
When are controlled breathing modes used and why
When pts are given MRs and cannot contribute to breathing effort at all
269
What are the fixed, set and variable parameters for pressure control ventilation
FIXED:
Pressure
SET:
Ppeak, RR, I:E time
Variable:
Flow to match Ppeak
270
How can compliance and resistance be inferred w/ Vt in PCV mode
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
What are the fixed and set values for VCV mode
FIXED:
Volume
SET:
Vt, RR, I:E ratio
272
Why is the calculated inspiratory time significant w/ VCV
- 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
What precautions should be considered with pts on VCV
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
What pts may VCV be contraindicated and why
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
Describe the VG-PVC setting and when it's use is advantageous
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
What is CPAP and when is it useful
| Normal setting
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
What are advantages and disadvantages of CPAP
Advantages
• To recruit alveoli
• Facilitate oxygenation
• Lung compliance characteristics evident
Disadvantages
• Does intrathoracic P
• May create air-trapping in COPD pt
278
MRI vents 1:19:15
slide 51 pg 23
