Rsp Failure Flashcards
1
Q
what testing evaluates oxygenation, ventilation and acid-base
disorders
one of the MC tests drawn in the ICU
A
ABG
2
Q
what does the ABG measure?
A
- Oxygen tension (PaO2)
- Oxyhemoglobin saturation (SaO2)
- Carbon dioxide tension (PaCO2)
- Acidity (pH)
- Bicarbonate concentration (HCO3)
- Can also request Methemoglobin, carboxyhemoglobin and hemoglobin levels if needed
3
Q
what test can be used to find out if blood flow to your hand is normal?
This test checks to see if both of these blood vessels are open and working correctly
A
modified allens test
4
Q
Most of O2 that diffuses from ___ to
the ____ binds to hemoglobin
A
alveolus
pulmonary capillary
5
Q
what is the proportion of RBCs with hemoglobin bound to O2?
Most commonly measured by pulse oximetry?
ABG
A
SaO2 - arterial oxygen saturation
6
Q
a SaO2 level below __ is considered abnormal and needs to be below ___ to qualify for home O2
A
95%
89%
7
Q
Best marker of oxygenation in an ABG?
A
PaO2 - arterial oxygen tension
8
Q
What part of the ABG is the Best marker of how well a patient is ventilating
A
PaCO2 - Carbon dioxide tension
9
Q
what are abnormal values of PaCO2? what is normal?
A
> 45mmHg or
< 35mmHg
normal = 40 mmHg
10
Q
Carbon dioxide is an ___ gas so rapid or
deep inspiration can “blow off CO2” and
cause rapid ____
A
acidic
respiratory alkalosis
11
Q
Most important and strongest buffer in our body
A
HCO3 - bicarbonate level
12
Q
HCO3 can be regulated by changing the amount generated/excreted by what organ?
A
kidneys
13
Q
normal values of HCO3?
A
22 – 26 mEq/L
14
Q
how fast is the buffering system? (HCO3)
A
Buffers blood acidity but slower and can take
a few days (3-5) to reach full effect
15
Q
normal value of pH?
what values are considered acidemia or alkalemia?
A
Normal pH range is 7.35 – 7.45 (7.4)
=< 7.35 is acidemia
=> 7.45 is alkalemia
16
Q
how are [H+] and pH related
A
inversely related
17
Q
[H+] is determined by the balance of what two levels?
A
carbon dioxide (PaCO2)
bicarb (HCO3)
18
Q
what is the main system that regulates body pH
A
carbonic acid/bicarbonate buffering system
Carbonic acid (H2CO3) links the respiratory and
metabolic (kidneys) system
19
Q
carbonic acid conversion is
catalyzed by an enzyme called ?
A
carbonic anhydrase
20
Q
bicarbonate conversion requires what to convert?
A
nothing! no catalyst
21
Q
equation Used to relate the pH of blood to the
buffering system
A
henderson hasselbalch
22
Q
Compensatory responses help normalize the pH but usually don’t do what?
A
do not return the pH fully to normal
23
Q
Appropriate compensatory response of acid-base disturbances requires what two things?
A
normal functioning lungs and kidneys
Failure to develop a compensatory response defines the presence of a secondary primary disorder
24
Q
equation of the simplified A-a gradient
A
PAO2 = [150] - [PaCO2/0.8]
Normal A-a gradient increases with age:
how to calculate: (age+10)/4
25
a normal A-a gradient means what?
hypoventilation
low inspired O2
26
an elevated A-a gradient means what?
1. V/Q mismatch
2. Shunt
3. Impaired diffusion
27
steps of interpreting an ABG
1. Is the ABG normal? Is acidemia or alkalemia present or all levels normal range
2. Is the cause respiratory? Look at PaCO2 (40 is ideal)
3. assess bicarbonate level (HCO3) (24 is ideal)
4. assess if compensation is present
28
when interpreting an ABG, this usually represents the primary disorder
1. Is acidemia or alkalemia present or all levels normal range
◦ pH < 7.35 is acidemia
◦ pH > 7.45 is alkalemia
29
PaCO2 >45 means what acid-base disorder?
rsp acidosis
30
PaCO2 < 35 is what acid-base disorder?
rsp alkalosis
31
HCO3 < 22 is what type of acid-base disorder?
metabolic acidosis
32
HCO3 >26 is what acid-base disorder?
metabolic alkalosis
33
Compensation is either considered ___ or ___ depending on if it brings pH back in normal range
complete
incomplete
34
causes of rsp acidosis
* Airway obstruction
* Lung disease
* Chest wall disease
* Neuromuscular disease
* Primary brain injury (ex. CVA, trauma), sleep apnea, drugs causing sedation like opioids.
35
causes of metabolic acidosis
1. Bicarbonate loss
- GI loss - diarrhea, biliary drainage
2. Increased acid load
- Lactic acidosis, DKA, ethylene
glycol intoxication, methanol intoxication, ASA intoxication
3. Impaired acid excretion
- Renal failure, Type 1 renal tubular acidosis, adrenal insufficiency
36
When the primary disorder is metabolic acidosis what is the next step?
calculate anion gap
Often calculated when trying to find out the cause of metabolic acidosis
Measures the difference between cations (positively charged ions) and anions (negatively charged ions)
37
what is the value of a normal anion gap
<12
If greater = presence of anion that cannot be measured
38
MCC of high anion gaps
lactic acidosis, ketoacidosis, acute renal failure , toxic acids
MUDPILES
M - Methanol (ex. Windshield fluid, bad moonshine)
U – Uremia (BUN >60)
D – Diabetic ketoacidosis
P – Paracetamol (acetaminophen)
I – Isoniazid, iron
L – Lactic acidosis
E – Ethylene glycol (ex. Antifreeze)
S – Salicylates (ASA)
39
causes of Non‑anion gap acidosis
Caused by loss of bicarb or decreased acid (H+) excretion
Common causes: Diarrhea, Renal tubular acidosis
40
Causes of metabolic alkalosis
1. Volume contraction
- Dehydration
- Over diuresis
2. Loss of hydrochloride
- Vomiting
- Gastric suction
- Taking excessive antacids
3. Hypokalemia
41
A term that encompasses a continuum of
clinical and radiographic changes that affect
the lungs causing respiratory failure in the
critically ill patient
acute lung injury (ALI)
42
ALI is Characterized by ___ (noncardiogenic pulmonary edema)
acute severe hypoxia that is not due to the heart
43
_most common_ form of non cardiogenic
pulmonary edema and _most severe_ form of
ALI
what does it cause?
acute respiratory distress syndrome (ARDS)
Causes hypoxemic respiratory failure
44
MC causative event to trigger ARDS
sepsis (1/3)
45
what is the pathogenesis that are pivotal in causing lung injury?
how does it work?
pro-inflammatory cytokines
Damage occurs mainly at the capillary and
alveolar cells
46
diffuse alveolar damage is the pathological hallmark for ?
pro-inflammatory cytokines causing lung injury
47
Lung injury causes _excess fluid to accumulate_ in both the _interstitium_ and _alveoli_ which causes the following: (4)
1. Impaired gas exchange
2. Decreased compliance
3. Increased pulmonary arterial pressure
4. decreased production of surfactant
48
diagnostic criteria for ARDS
1. Acute onset within 1 week of known clinical insult (usually sooner)
2. Bilateral pulmonary infiltrates
3. Rsp failure not explained by HF or volume overload
4. PaO2/FIO2 ratio < 300mmHg
49
ARDS severity
Based off of level of impaired oxygenation
(PaO2/FIO2 ratio)
Mild - 200-300mmHg
Moderate - 100-200mmHg
Severe - <100mmHg
50
Rapid onset of profound dyspnea
within 12-48 hours after the initiating event
SOB, tachypnea, intercostal retractions and
crackles on PE
Marked hypoxemia occurs that does not
respond to standard supplemental O2
multiple organ failure
this presentation is associated with what dx?
ARDS
51
Many patients with ARDS demonstrate
multiple organ failure, particularly where?
kidneys, liver, CV system, CNS
52
CXR shows diffuse / patchy _bilateral
infiltrates_ that rapidly progress and **spare the costophrenic angles**
_Heart size normal_ and small / no pleural effusions
**Air bronchograms** present
what are you suspicious of?
ARDS
_Air bronchograms_ are seen in 80% of
pts
53
with ARDS you must exclude which other ddx?
Cardiogenic pulmonary edema
Pneumonia
54
tx for ARDS
1. Treat the underlying condition
2. Treat secondary conditions (sepsis)
3. Supportive care to help prevent
complications
4. txing hypoemia
- tracheal intubation mech vent
- Supplemental O2 to maintain _PaO2 >55mmHg_
- Efforts to keep _FIO2 less than 60%_ ASAP - **avoid O2 toxicity**
5. PEEP
6. prone positioning
7. Volume controlled ventilation with Low Tidal
Volume Ventilation (LTVV)
8. decrease O2 consumption - sedatives,
analgesics, antipyretics
*_Nothing is effective at preventing ARDS_*
55
what tx is Used to prevent alveolar collapse
PEEP - Positive end-expiratory pressure
The lowest levels of PEEP that is effective
Has been shown to _improve hemodynamic
outcomes_ but not shown to improve mortality
56
Auto-PEEP can develop which can cause what?
decrease venous return, reduce CO, hypotension, at risk for barotrauma (pneumothorax)
57
what tx has resulted in 10% reduction in mortality over standard therapy
Volume controlled ventilation with Low Tidal
Volume Ventilation (LTVV)
58
outcomes of ARDS
1. Mortality 30-40%, 90% with sepsis
2. _Median survival is 2 wks_
3. Most survivors are left with chronic pulmonary sx that may improve with time (cough, dyspnea, lung fibrosis)
59
Inability of the lungs to meet the metabolic
demands of the body
can be from failure of tissue oxygenation and/or CO2 elimination
rsp failure
a condition that occurs as a result of +1 diseases involving the lungs or other body systems
60
parts of the rsp system includes:
CNS (Medulla)
Peripheral nervous system (phrenic nerve)
Respiratory muscles
Chest wall
Lung
Upper airway
Bronchial tree
Alveoli
Pulmonary vasculature
61
Types of respiratory failure, which is MC?
1. **hypoxemic respiratory failure (MC)** - lungs fail to provide adequate oxygenation of the blood (PaO2 <60mmHg)
2. Defect in ventilation (CO2 elimination) - Hypoxemia is always present but PaCO2 is elevated (PaCO2>50mmHg)
62
etiology of hypoxemic respiratory failure can be evaluated by what modality?
CXR
63
causes of hypoxemic rsp failure
interfere with O2 exchange, but ventilation is maintained
1. Decreased inspired O2 tension (↓PIO2)
2. V/Q mismatch (COPD)
3. Diffusion limitation (fibrosis)
4. Intrapulmonary shunt
- Pneumonia
- Atelectasis
- CHF
- ARDS
5. disorder of heart, lungs or blood
64
pt with Hypoxemic Respiratory Failure has a Normal CXR
what do you consider the causes to be?
COPD
Intracardiac shunt (right to left)
Pulmonary embolism
65
pt with Hypoxemic Respiratory Failure has Focal infiltrates on CXR
what do you consider the causes to be?
Atelectasis
Pneumonia
66
pt with Hypoxemic Respiratory Failure has Diffuse infiltrates on CXR
what do you consider the causes to be?
Cardiogenic pulmonary edema
Noncardiogenic pulmonary edema (ARDS)
Interstitial pneumonitis or fibrosis
Infectious (bilateral pneumonia)
67
why does the level of bicarbonate depends on the duration of hypercapnia?
renal response occurs over days (2-5 days)
68
Causes of Hypercapnic Respiratory Failure
1. Respiratory center dysfunction (medulla)
2. Drug overdose, CVA, tumor
3. Central Hypoventilation
4. Neuromuscular disease
- Polio, Myasthenia Gravis, spinal injuries, Guillain-Barre
5. Chest wall/Pleural diseases
- Kyphoscoliosis, pneumothorax, large pleural effusion
6. Upper airway obstruction
- Tumor, FB, laryngeal edema
7. Peripheral airway disorder
- COPD, pulmonary fibrosis
69
the arterial pH of Acute Hypercapnic Respiratory Failure is ?
causes?
low
1. Sedative drug OD
2. Acute muscle weakness, ex. Myasthenia Gravis
3. Severe lung disease
4. Acute on chronic respiratory failure
- Occurs with chronic CO2 retention who acutely worsen and have rising CO2 and low pH
- Caused by rsp muscle fatigue
70
s/s of hypoxemia
Sx: **dyspnea**
Signs:
- Cyanosis
- Restlessness, confusion, anxiety, delirium
- Tachypnea, tachycardia, hypertension, tremor
71
s/s of hypercapnia
1. Sx: **Dyspnea, HA**
2. Signs:
- Peripheral and conjunctival hyperemia
- Tachycardia, tachypnea, hypertension
- _Impaired consciousness_, papilledema, asterixis
72
tx for rsp failure
1. Specific therapy directed toward the
underlying disease
- Example: abx for pna, anticoagulants for PE, BD and corticosteroids for COPD exacerbation
2. Rsp supportive care to maintain
adequate gas exchange
3. General supportive care
73
The main tx goal in acute hypoxemic
respiratory failure?
how?
_ensuring adequate oxygenation_
1. Keeping O2 sat ≥ 90% or PaO2 ≥ 60mmHg
2. *Rarely*, restoring oxygenation can cause hypoventilation in pts w/ chronic hypercapnia. However, _oxygen therapy should never be withheld for fear of causing progressive rsp acidosis_
74
7 methods of oxygen delivery methods from least/low FiO2 to most invasive/high FiO2
1. Nasal cannula
2. Nasal catheter
3. Simple mask
4. Partial rebreather mask
5. Non rebreather mask
6. Venturi mask
7. Oxygen tent
75
For every liter increase in O2, FiO2 increases about what %?
4%
76
Common and inexpensive
Does not interfere with eating or talking, well
tolerated
Higher flow rates can dry out the nasal mucosa fast
Dependent on how much patient inhales
through the nose
what oxygen method is this
cannula
77
low and high flow for nasal cannula
Low flow: 1-6 L/min (FiO2 of 24% to 44%)
High flow: up to 10 L/min
78
Not used often since so uncomfortable
Inserted through the nostril with the end of the catheter resting in the oropharynx.
Needs changed to other nostril every 8 hours
what oxygen method is this
catheter
79
Has vents on both sides to allow room air to
enter and exhaled CO2 to escape
Used when increased O2 delivery is needed
for short periods (<12 h)
what oxygen method is this
simple face mask
80
flow rate of simple face mask
Delivers FIO2 of 40 to 60% at flow rates of 5 L/min to 8 L/min respectively
81
why must you never use <5 L/min with simple face masks?
patient may rebreathe most of their own air and become hypoxemic/hypercapnic
82
O2 reservoir bag allows pt to rebreathe the first 1/3 of exhaled air (dead space air)
increases FIO2 by recycling expired O2
what oxygen method is this?
flow rate?
partial rebreather mask
Delivers FiO2 of 35-60% at a flow rate of 6-10 L/min
83
what do the Two one-way valves do on a non-rebreather mask?
prevents:
Entrance of room air during inspiration
Retention of exhaled gases during expiration
84
flow rate of a non rebreather mask
Delivers the highest FiO2 possible 95% at a
flow rate of 10-12 L/min
85
this oxygen method is used by mixing room air with precise amount of oxygen you can dial in the FiO2.
The size of the port and oxygen flow rate determine the FiO2
what is this method?
flow rate?
venturi mask
Delivers FiO2 varying from 24-60% x flow rates 4-10 L/min
86
Designed for patients who cannot wear a
mask or nasal cannula (examples: facial
surgery or trauma)
what is this oxygen method?
face tent
87
Rigid plastic dome encloses the infant’s head
what is this oxygen method
oxygen hood (infants)
88
Plastic canopy that supplies humidified O2
what is this oxygen method?
oxygen tent
89
first line therapy for COPD
Noninvasive positive airway ventilation (NPPV)
Reduces intubation rates and amount of ICU
stay
90
COPD pts with hypercapnic rsp failure may use NPPV only if they have these factors:
Protect their own airway
Handle their own secretions
Tolerate the BPAP mask
(must be neurologically competent)
91
MC used for COPD conditions causing respiratory muscle weakness and obesity hypoventilation
Bilevel positive airway pressure (BPAP)
92
MOA of Bilevel positive airway pressure (BPAP)
Delivers preset inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP)
93
pts must do what with BPAP machines?
must initiate each breath on most
machines
94
Continuous level of positive airway pressure
throughout respiratory cycle
Patients must initiate all breaths
MC used in patients with sleep
apnea or cardiogenic pulmonary edema
what is this machine?
Continuous positive airway pressure (CPAP)
No additional pressure above the CPAP level
is provided
95
when do you intubate?
Hypoxemia despite supplemental O2
Upper airway obstruction
Unable to protect airway or clear secretions
Acute hypercapnia that does not quickly
respond to noninvasive ventilation (CPAP or BiPAP)
Progressive fatigue, mental status changes, tachypnea, or use of accessory muscles
Apneas
96
which type of intubation is preferred since
easier, faster and less traumatic than
nasotracheal
orotracheal intubation
97
how can you verify both lungs are
being ventilated with intubation?
auscultating the lungs
98
Position of the tip of the ET tube
should be positioned where?
at the level of the aortic arch and verified by CXR
99
the cuff pressure during intubation should not exceed what level? why?
20mmHg
minimize tracheal injury
100
Can fully or partially replace spontaneous
breathing
Used for acute or chronic respiratory failure
when there is insufficient oxygenation or
ventilation, or both
what type of intervention is this?
mech vent
101
benefits of mech vent
Improved gas exchange
Decreased work of breathing
More precise titration of oxygen needs
102
types of breaths
1. Trigger
- Ventilator-initiated breaths – preset RR triggered by a timer on ventilator
- Patient-initiated breaths- patient effort causes flow change which initiates the breath
2. Volume assist
- initiated by the patient with a set inspiratory flow rate
- Inspiration is stopped when the set tidal
volume was delivered
3. Volume control breaths (VC)
- Breaths are ventilator-initiated with a set
inspiratory flow rate
- Inspiration is terminated once the set tidal
volume was reached
103
types of ventilation
1. Continuous mandatory Ventilation (CMV) Mode
2. Intermittent mandatory ventilation (IMV) Mode
3. Synchronized IMV (SIMV) Mode
4. Pressure support ventilation (PSV) mode
5. Positive end-expiratory pressure (PEEP)
104
- Minute ventilation is determined by set RR and tidal volume
- No pt initiation or effort
- Pt may be on heavy sedation, pharmacologic paralysis, or coma
- _deepest form of ventilation_
what type of ventilation?
Continuous mandatory Ventilation
CMV
105
Clinician determines minimum minute
ventilation by setting the respiratory rate and tidal volume
pt can increase the minute
ventilation by spontaneously breathing
addition breaths
what type of ventilation?
IMV
106
Variation of IMV
Ventilator breaths are synchronized _with_ patient effort
Support can range from full support to no support at all
Better patient-ventilatory synchrony, preserves respiratory muscle function, greater control over level of support
what type of ventilation
SIMV
107
_Pt triggers each breath_, no set RR
The work of breathing is inversely proportional to the pressure support level
Useful when weaning a patient from mechanical ventilation
- More comfortable mode
- pt has greater control
what type of ventilation?
Pressure support ventilation
PSV
108
Potential Complications of Mechanical Ventilation
1. Barotrauma (excessive tidal volumes, PEEP)
- Pneumothorax
- Subcutaneous emphysema
- Pneumomediastinum
2. Ventilator-associated pneumonia
3. Trauma - tracheal stenosis, vocal cord
dysfunction
109
Most common diseases that lead to
lung transplant
COPD
Idiopathic pulmonary fibrosis
Cystic fibrosis
Alpha-1 antitrypsin deficiency
Idiopathic pulmonary hypertension
Coal Worker’s Pneumoconiosis
bronchiectasis
110
what determines what pt gets a lung transplant and when?
Lung Allocation Score (LAS)
Unet computer system tracks pts and
when a lung becomes available the system
runs a donor/recipient match based on blood type, size of organ and distance from donor and recipient
111
general guidelines/criteria for a lung transplant
1. <65
2. Severe lung disease that is progressive
3. Limited life expectancy bc of their lung disease
4. Good nutritional status and BMI <30
5. Good support system and mentally intact
112
contraindications for a lung transplant
1. Active smoking (within past 6 months)
2. Active malignancy in last 2 years
3. Drug or ETOH dependency
4. Significant disease of other organs including CAD and HF
5. Untreatable pulmonary or extrapulmonary infection
6. BMI >35
7. Hep B, C or HIV infection
