Study Guide Chapter 41- Egan’s
What are the criteria for a diagnosis of respiratory
failure?
Inadequate alveolar ventilation
pH under 7.35, PaCO2 over 45mmHg
Inadequate lung expansion
VT under 5ml/kg, VC under 10ml/kg
RR over 20 or under 8
Inadequate muscle strength
MIV under -20cmH2O, VC under 10ml/kg
MVV less than 2x the VE
Hypoxemia
A-a gradient over 350mmHg
P/F ratio under 200
PaO2 under 60mmHg
PaCO2 over 45mmHg
350-450
10-25mmHg
Diffusion defect
V/Q mismatch
Shunt
Alveolar hypoventilation
Low FiO2
A shunt will NOT be affected by O2.
What is the normal P/F ratio?
What is the normal A-a gradient on room air?
What are the causes of hypoxemia?
How do you tell if the problem is a shunt or V/Q
mismatch via oxygen?
The most severe sign of hypoxemia is
Which disease is associated with perfusiondiffusion impairment?
What is the normal A-a gradient on 100% O2?
What happens to A-a gradient for a shunt and a
V/Q mismatch?
How do you treat a shunt?
CNS dysfunction; comatose
Cirrhosis of the liver
25-65mmHg
Shunt = increase
V/Q mismatch = increase
With positive pressure, either noninvasive or
invasive
Type I-Hypoxemic = PaO2 under 60mmHg
Type II-Hypercapnic = PaCO2 over 45mmHg
Increased exposure
Impaired respiratory control
Neurological disease
Increased WOB
The decrease capacity of a rested muscle to
generate force and decrease endurance
Disease = Neuromuscular, COPD
Conditions = Obesity, kyphoscoliosis
Condition in which there is loss of the capacity to
develop force or velocity of a muscle resulting
from muscle activity under load, which is
reversible by rest
Conditions = hypoxemia, increase WOB, increase
strength of muscle contraction, decrease muscle
Classification of ABG of the 2 different ventilatory
failures
What are the causes of hypercapnic ventilatory
failure?
What is muscle weakness? What diseases cause
this?
What is muscle fatigue? What diseases cause this?
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Study Guide Chapter 41- Egan’s
efficiency, decrease inspiratory muscle blood flow,
poor nutrition, and inability of a muscle to extract
energy from supplied substrates
Central = exertion-induced reversible decrease in
central resp. drive
Transmission = exertion-induced reversible
impairment of transmission of neural impulses
Contractile = reversible impairment in the
contractile response to a neural impulse in an
overload muscle
Diseases= obstruction lung disease
COPD
Asthma
Conditions= upper airway obstruction
Obesity-hypoventilation
Pneumothorax
Severe burns
Chest wall disorders
Kyphoscoliosis
Ankylosing spondylitis
HCO3
What are the 3 types of muscle fatigue?
What diseases cause increased WOB?
How do you determine if it is an acute or chronic
respiratory failure?
Why do the kidneys keep HCO3?
What is the cardinal sign of increased WOB?
If you have the FiO2 and the PaO2 of several
patients, how would you tell who was worse?
In acute hypercapnic failure how much does the
pH decrease?
In chronic hypercapnic failure how much does the
pH decrease?
What should the NIF/MIV value be?
If a patient’s NIF value is not large enough, what
does this mean?
What values can be tested at the bedside to
determine if a patient needs ventilatory support?
How is alveolar ventilation assessed?
How is oxygenation determined?
to increase pH
Increased PaCO2
P/F ratio
*Bigger is better*
pH decreases 0.08 for every 10mmHg increase in
PaCO2
pH decreases 0.03 for every 10mmHg increase in
PaCO2
at least -20cmH2O
Ventilatory muscles are not strong enough
VT, VC, RR, VE
pH and PaCO2
PAO2 equation
(PB-PH2O)xFiO2 - (PaCO2 x 1.25)
Respiratory center is not responding
Signal is not getting to muscles
Lungs and chest wall are incapable of providing
adequate ventilation
NIF/MIV, MVV, MEP, FRC
VE (minute ventilation)
VD/VT % (dead space vol/tidal vol %)
physiological = natural
imposed = artificial
CPAP for the pressure
What 3 things increase PaCO2?
How is muscle strength determined?
What is used to determine increased WOB?
The 2 types of WOB are
If a patient has CHF, what should be done?
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Study Guide Chapter 41- Egan’s
If a patient has ARDS, what should be done?
If a patient has increased ICP, what should be
done?
Who is at the greatest risk for auto-PEEP?
What is indicated by a white radiograph?
What are the indications for ventilation in Type I
failure?
What are the indications for ventilation in Type II
failure?
Intubate with low volume and high pressure
Hyperventilate
COPD patients
Shunt b/c of hypoxemia (ARDS)
P/F ratio
increased FiO2 and PEEP
increased PaCO2
decreased pH
increased HCO3 (due to compensation by kidneys)
NIF/MIP
MEP
What measures inspiratory muscle strength?
What measures cough strength and ability to
maintain patent airway?
What is dead space?
What is a shunt?
What is the normal anatomic shunt?
Ventilation without perfusion
Perfusion without ventilation
2-3%
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