Respiratory Failure - Exam 2 Flashcards
(99 cards)
1
Q
Describe the modified Allen test. When do you need to perform it?
A
need to perform before doing an ABG, if the pt fails the test you cannot perform ABG
1
Q
Name 5 things that an arterial blood gas test will tell you. Which value is the same as pulse ox?
A
Oxygen tension (PaO2)
Oxyhemoglobin saturation (SaO2)- same as pulse ox
Carbon dioxide tension (PaCO2)
Acidity (pH)
Bicarbonate concentration (HCO3)
2
Q
arterial oxygen saturation is O2 that diffuses from the _____ to the _______ and bind to _______
A
alveolus
pulmonary capillary
binds to hemoglobin
3
Q
What is SaO2 a proportion of?
A
proportion of RBCs with hemoglobin that are bound to O2
4
Q
**What is the best marker of oxygenation? What is it? What is considered abnormal?
A
Arterial oxygen tension (PaO2)
unbound oxygen that is dissolved in plasma
Considered abnormal if less then 80mmHg but needs to be 55mmHg or less to qualify for home oxygen per Medicare guidelines
5
Q
**What is the best marker of how well a patient is ventilating? What is considered normal? Abnormal?
A
Carbon dioxide tension (PaCO2)
normal is 40mmHg
Considered abnormal if above 45mmHg or below 35mmHg
6
Q
_____ is the most important and strongest buffer in the body. How is it regulated? What are the normal levels?
A
bicarb
regulated by changing the amount generated or excreted by the kidneys
Normal level between 22 – 26 mEq/L
7
Q
What is the normal range for pH?
A
7.35 – 7.45
8
Q
How is hydrogen ion concentration determined?
A
determined by the balance of carbon dioxide (PaCO2) and bicarbonate (HCO3) levels
9
Q
_____ are the product of normal metabolism. What happens next?
A
Hydrogen ions
the body must continually dispose of acid to keep pH within narrow range
10
Q
_______ links the respiratory and metabolic (kidneys) system.
A
Carbonic acid (H2CO3)
11
Q
Carbon dioxide – > carbonic acid conversion is catalyzed by an enzyme called______.
Carbonic acid – bicarbonate conversion requires ________
A
carbonic anhydrase
no catalyst
12
Q
T/F: Compensatory responses help normalize the pH but usually do not return the pH fully to normal
A
True
13
Q
Appropriate compensatory response requires normal functioning _____ and _____. Failure to develop a compensatory response defines the ?????
A
lungs and kidney
presence of a secondary primary disorder
14
Q
What should normal A-a gradient be? What is the formula to calculate a quick A-a gradient?
A
less than 10mmHg
(age +10)/4
15
Q
How does A-a gradient change with time? Is a larger or smaller gap better?
A
A-a gradient increases with age
smaller gap is better
16
Q
What does a normal A-a gradient tell you about the cause of hypoxemia? elevated?
A
normal:
Hypoventilation
Low inspired O2
elevated:
V/Q mismatch
Shunt
Impaired diffusion
17
Q
Draw the Dr. Sheppard chart on how to define acidosis vs alkalosis
A
18
Q
What is complete compensation defined as? Will the body ever over compensate? How long does it take?
A
if it brings the pH back into normal range
NO! the body will not ever over compensate
hours to days
19
Q
What are the normal ranges for pH, PaCO2 and HCO3? What numbers are ideal for each?
A
pH = 7.35 to 7.45 (7.4 is ideal)
PaCO2 = 35 to 45 (40 is ideal)
HCO3 = 22 to 26 (24 is ideal)
20
Q
pH = 7.32
PaCO2 = 52
HCO3 = 19
What type?
A
respiratory and metabolic acidosis
21
Q
pH = 7.34
PaCO2 = 50
HCO3 = 31
What type?
A
respiratory acid with incomplete compensation
22
Q
pH = 7.38
PaCO2 = 24
HCO3 = 19
What type?
A
metabolic acidosis with complete compensation
23
Q
pH = 7.46
PaCO2 = 42
HCO3 = 31
What type?
A
metabolic alkalosis w/o compensation
24
pH = 7.39
PaCO2 = 41
HCO3 = 25
What type?
normal!!
25
pH = 7.42
PaCO2 = 51
HCO3 = 33
What type?
metabolic alkalosis with compensation
26
Name some causes of respiratory acidosis
Airway obstruction
Lung disease
Chest wall disease
Neuromuscular disease
Primary brain injury (ex. CVA, trauma), sleep apnea, drugs causing sedation like opioids.
aka anything that causes decreased ventilation
27
Name some causes of respiratory alkalosis
Voluntary hyperventilation
Involuntary hyperventilation (anxiety states, asthma exacerbation, CNS disease)
Lung disease causing hyperventilation (remember back to PE lecture)
28
**Asthma pt with resp alk now having resp acidosis with accessory muscle weakness. What do you do?
ventilation
29
What are some causes of metabolic acidosis?
bicarb loss: think GI
increased acid load: lactic acidosis, DKA, acid ingestion
impaired acid excretion: think renal failure
30
When do you need to calculate the anion gap?
when primary disorder is metabolic acidosis
31
What does the anion gap measure? What is the formula? What is a normal anion gap?
Measures the difference between cations (positively charged ions) and anions (negatively charged ions) using the formula below
= (Na) + (K) – (Cl) + (HCO3)
less than 12, greater suggests the presents of anions that cannot be measured
32
What are the 4 MC causes of anion gap metabolic acidosis?
lactic acidosis, ketoacidosis, acute renal failure and toxic acids
33
What is the mnemonic for causes of anion gap metabolic acidosis? Which 2 were highlighted in lecture?
M – Methanol (ex. Windshield washer 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)
34
What is the cause of non-anion gap acidosis?
Caused by loss of bicarbonate or decreased acid (H+) excretion
think diarrhea and renal tubular acidosis
35
What are some causes of metabolic alkalosis?
volume contraction: dehydration, over diuresis
loss of hydrochloride: vomiting, gastric suction, taking excessive antacids
hypokalemia
36
What is an acute lung injury?
A term that encompasses a continuum of clinical and radiographic changes that affect the lungs causing respiratory failure in the critically ill patient
37
What is acute lung injury characterized by? What is the most severe form of the illness?
acute severe hypoxia that is not due to the heart (non cardiogenic pulmonary edema). Acute hypoxemic respiratory failure following a systemic or pulmonary insult without evidence of heart failure
ARDS (acute respiratory distress syndrome)
38
______ is most common form of non cardiogenic pulmonary edema and most severe form of acute lung injury. What does it cause?
ARDS
causes hypoxemic respiratory failure
39
What is the MC cause of ARDS?
sepsis- most common cause in 1/3rd of causes
40
What are some examples of causes of ARDS?
sepsis
shock
lung contusion
toxic inhalation
near-drowning
41
_______ cause of ARDS is usually immune mediated
multiple transfusions
42
What is the pathogenesis behinds ARDs? Where does damage mainly occur? What is the pathological hallmark?
Pro-inflammatory cytokines cause lung injury
Damage occurs mainly at the capillary and alveolar cells
Pathological hallmark is diffuse alveolar damage (DAD on imaging report)
43
What pulmonary disorder causes excess fluid to accumulate in both the interstitium and alveoli which causes ______, _______ and ________. Also, the cell damage leads to ????
ARDS
impaired gas exchange,
decreased compliance
Increased pulmonary arterial pressure
decreased production of surfactant
44
What is the dx criteria for ARDS?
Acute onset within 1 week of known clinical insult (usually sooner)
Bilateral pulmonary infiltrates
Respiratory failure not fully explained by heart failure or volume overload
PaO2/FIO2 ratio < 300mmHg
45
What is FIO2?
fraction of inspired oxygen
46
What is the severity of ARDS based on? What are the categories?
Based off of level of impaired oxygenation
Mild - PaO2/FIO2 ratio between 200-300mmHg
Moderate-PaO2/FIO2 ratio between 100-200mmHg
Severe - PaO2/FIO2 ratio less than 100mmHg
47
Rapid onset of profound dyspnea usually within 12-48 hours after the initiating event
SOB, tachypnea, intercostal retractions and crackles on physical exam
What am I?
**What is a highlighted additional s/s?
What is an additional common finding?
ARDS
Marked hypoxemia occurs that does not respond to standard supplemental O2
multiple organ failure-> kidneys, liver, cardiovascular, CNS
48
What will the CXR show on a pt with ARDS?
CXR shows diffuse or patchy bilateral infiltrates that rapidly progress and characteristically spare the costophrenic angles
Heart size likely normal and small or no pleural effusions
Air bronchograms are seen in 80% of patients
49
Are IV steroids effective for ARDS?
NO! and nothing is effective for preventing ARDS
50
What is the tx for ARDS? What position?
treat the underlying condition
tx secondary conditions (sepsis)
supportive care: think oxygen and ventilator (if neccessary) Low Tidal Volume Ventilation (LTVV) is preferred
prone positioning
strategies to decrease O2 consumption (sedatives, analgesics and antipyretics)
51
How do you treat hypoxemia related to ARDS? What do you need to keep the PaO2 above?
Requires tracheal intubation mechanical ventilation
Supplemental O2 required to maintain the PaO2 above 55mmHg
52
What do you need to keep the FIO2 at? Why?
Efforts to keep FIO2 less than 60% as soon as possible in order to avoid O2 toxicity
53
What is PEEP? When is it used? What does it put the pt at risk for? What does it improve?
Positive end-expiratory pressure
used to prevent alveolar collapse
aka in the pause before next breath, airway collapses during pause in between breathes
increases pt risk for barotrauma
Has been shown to improve hemodynamic outcomes but NOT shown to improve mortality
54
What is the outcome associated with ARDS?
Mortality ranges 30-40% and increases to 90% when associated with sepsis
Median survival is 2 weeks
Most survivors are left with chronic pulmonary symptoms that may improve with time (cough, dyspnea, lung fibrosis)
55
Define respiratory failure. Is it a dz or condition?
Inability of the lungs to meet the metabolic demands of the body. This can be from failure of tissue oxygenation and/or CO2 elimination
condition! that occurs as a result of one or more diseases involving the lungs or other body system
56
What are some potential causes of respiratory failure?
carotid body ressection
CN IX compression
obesity
kyphoscolosis
airway obstruction
medulla: infection, bleeding, trauma, syringomyelia, drugs
spinal cord transection, poliomyelitis
guillain barre syndrome
myasthenia gravis
myotonic dystrophy
57
What is type 1 respiratory failure? What is another name for it?
lungs fail to provide adequate oxygenation of the blood (PaO2 <60mmHg)
hypoxemic respiratory failure
58
What is the MC form of respiratory failure? What is it caused by?
type 1 respiratory failure
Caused by diseases that interfere with O2 exchange, but ventilation is maintained
Occurs when significant intrapulmonary shunting or V/Q mismatch is present
aka PCO2 is normal but low PO2
59
What are some causes of hypoxemic respiratory failure? What type?
Decreased inspired O2 tension (↓PIO2) like in high altitude
V/Q mismatch (COPD)
Diffusion limitation (fibrosis)
Intrapulmonary shunt: Pneumonia, Atelectasis, CHF, ARDS
60
If your patient has type 1 respiratory failure with a normal CXR, What does that makes you think?
COPD
intracardiac shunt (right to left)
pulmonary embolism
61
If your patient has type 1 respiratory failure with a focal infiltrates on CXR, what does that make you think?
Atelectasis
Pneumonia
62
If your patient has type 1 respiratory failure with a diffuse infiltrates on CXR, what does that make you think?
Cardiogenic pulmonary edema
Noncardiogenic pulmonary edema (ARDS)
Interstitial pneumonitis or fibrosis
Infectious (bilateral pneumonia)
63
define type 2 respiratory failure. What will O2 and PaCO2 levels look like?
Type 2 – Defect in ventilation (CO2 elimination)
low O2 and PaCO2 will be elevated. PaCO2 > 50mmHg
64
In type 2 respiratory failure, what does the pH depend on?
pH depends on the level of bicarb buffering
Level of bicarbonate depends on the duration of hypercapnia since renal response occurs over days (2-5 days)
65
What are some causes of type 2 respiratory failure?
Respiratory center dysfunction (medulla)
Drug overdose, CVA, tumor
Central Hypoventilation= Odiene's curse: varing degrees of involuntary ven
Neuromuscular disease: Polio, myasthenia gravis, spinal injuries, guillain- barre
chest wall/pleural dz
upper airway obstruction
peripheral airway disorder
66
What are some causes of type 2 respiratory failure? What is the arterial pH?
Sedative drug over dose
Acute muscle weakness, ex. Myasthenia Gravis
Severe lung disease
Acute on chronic respiratory failure
arterial pH will be low
67
COPD pt with pnue would be what type of respiratory failure?
type 2 and would need to be ventilated
68
What are the the main s/s of hypoxemia?
dyspnea, cyanosis, confusion, anxiety, delirium
69
What are the main s/s of hypercapnia?
dyspnea and HA, papilledema, asterixis, tachycardia
70
What is asterixis?
dorsiflex hand movements that rhythmically flaps
71
What is the main goal in hypoxemic respiratory failure? What else do you need to keep in mind?
Keeping O2 sat ≥ 90% or PaO2 ≥ 60mmHg
not to OVER oxygen the pt for the fear of causing progressive respiratory acidosis
72
What is the generic rule for supplemental oxygen?
For every liter increase in O2, FiO2 increases about 4%
73
What is a SE that you need to be mindful of when a pt is using a nasal cannula? What is considered low flow? high flow?
Higher flow rates can dry out the nasal mucosa fast
low: 1-6 L/min (FiO2 of 24% to 44%)
high:up to 10 L/min
74
How often does the nasal catheter need to be changed?
changed nostrils, every 8 hours
75
the simple face masks delivers FIO2 of ______ at flow rates of ______ respectively. Why would you NOT want to use below the min level?
40 to 60%
5 L/min to 8 L/min
Never use less then 5 L/min as patient may rebreathe most of their own air and become hypoxemic/hypercapnic
76
Partial rebreather mask delivers FiO2 of ______ at a flow rate of ______ respectively. How does it increase FIO2?
35% to 60%
6 L/min to 10 L/min
by recycling expired O2
O2 reservoir bag allows the patient to rebreathe the first 1/3 of exhaled air (dead space air)
77
Non rebreather mask delivers the highest FiO2 ______ at a flow rate of _____. What do the two one-way valves prevent?
possible 95%
10-12 L/min
Entrance of room air during inspiration
Retention of exhaled gases during expiration
78
venturi mask delivers FiO2 varying from______ at flow rates of ______. This mask is a good choice for _____ pts
24% up to 60%
4 L/min to 10 L/min
COPD
79
______ is first line therapy in COPD patients with hypercapnic respiratory failure who can:
Protect their own airway, handle their own secretions, tolerate the BPAP mask. What is their goal?
Noninvasive positive pressure ventilation (NPPV)
to reduce intubation rates and the amount of ICU stay
80
What is important to note about Bilevel positive airway pressure (BPAP)? How does it work? When is it commonly used?
Patients must initiate each breath on most machines
Delivers preset inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP)
COPD, conditions causing respiratory muscle weakness and obesity hypoventilation
81
_____ is continuous level of positive airway pressure throughout respiratory cycle. When is it commonly used?
Continuous positive airway pressure (CPAP)
sleep apnea or cardiogenic pulmonary edema
82
What are some indications the patient needs to be intubated?
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
83
_____ intubation is preferred since easier, faster and less traumatic than _______. Position of the tip of the endotracheal tube should be positioned at the level of the _____ and verified by _____
Orotracheal
nasotracheal
aortic arch
CXR
84
What are 3 benefits of mechanical ventilation.
Improved gas exchange
Decreased work of breathing
More precise titration of oxygen needs
85
What are the 2 different types of breaths?
vent initiated breaths
patient initiated breaths
86
What are volume control breaths?
Breaths are ventilator-initiated with a set inspiratory flow rate
Inspiration is terminated once the set tidal volume was reached
87
What are volume assist breaths?
Breaths are initiated by the patient with a set inspiratory flow rate
Inspiration is stopped when the set tidal volume was delivered
88
What is continuous mandatory ventilation mode?
Minute ventilation is determined entirely by the set respiratory rate and tidal volume
Pt does NOT initiate additional breaths and does not require any patient effort
think heavy sedation, pharm paralysis or coma
89
What is Intermittent mandatory ventilation (IMV) Mode?
Clinician determines minimum minute ventilation by setting the respiratory rate and tidal volume
The patient can increase the minute ventilation by spontaneously breathing addition breaths
90
What is Synchronized IMV (SIMV) Mode? What is a benefit?
vent breaths are synchronized with pt effort
support can vary from full to no support depending on the pt
helps to prevent muscle function decline
91
What is Pressure support ventilation (PSV) mode? When is it commonly used?
pt must trigger breath, no set respiratory rate
work of breathing is inversely proportional to the pressure support level
when weaning a pt from mechanical ventilation
92
What is PEEP? When is it commonly used?
Positive end-expiratory pressure
added to ventilation to prevent alveolar collapse with end expiration
commonly used with ARDS
93
What is the usually PEEP pressure? What pressure is used in ARDS?
normal: 5cmH20
ARDS: 20cmH20
94
What are 3 potential complications of PEEP?
Decreased cardiac output
Increased risk for barotrauma
Possibility of impairing cerebral blood flow (d/t decreased cerebral venous outflow which causes increased intracranial pressure)
95
What are the potential complications of mechanical ventilation?
barotrauma
ventilator-associated pneu
trauma
96
What are the general guidelines for lung transplant?
Appropriate age (usually under age 65)
Severe lung disease that is progressive
Limited life expectancy because of their lung disease
Good nutritional status and BMI less than 30
Good support system and mentally intact
97
What are the contraindications for a lung transplant?
Active smoking (within the past 6 months)
Active malignancy in last 2 years
Drug or ETOH dependency
Significant disease of other organs including CAD and heart failure
Untreatable pulmonary or extrapulmonary infection
BMI >35
Hep B, C or HIV infection (they have become relative contraindications recently
98
