Transcript respiratory lectures

Case Studies
W.R. Law/Respiration
BMS 653 – Human Physiology
PHYB 401 – Graduate Physiology
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The following data is obtained from a man with smoke
inhalation injury who is breathing 100% oxygen:
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PaO2
PaCO2
SaO2
COHb
pH
190 mmHg
36 mmHg
59%
40%
7.47
-What might you expect the PaO2 to be? (Hint: what
should ideal alveolar PO2 be?)
-Can shunt fraction be calculated?
-Despite the high arterial PO2, the man is experiencing
problems related to tissue hypoxia. Why?
Case Study
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A patient presents with pneumonia which involves the
entire left lung, sparing the right. The following data is
obtained on ambient air:
PaO2: 52 mmHg
PaCO2: 39 mmHg
SaO2: 75%
SmvO2: 60%
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Calculate shunt fraction
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On 50% oxygen, the data obtained are:
PaO2: 65 mmHg
PaCO2: 35 mmHg
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SaO2: 80%
SmvO2: 60%
Calculate shunt fraction. Is the value the same as above? Explain.
After performing these calculations, the attending physician
decides to change the patient’s body position. What position
change is appropriate and why?
Case Study
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In one lung anesthesia, only one lung (referred
to as the dependent lung) is ventilated, while
the non-dependent lung is not ventilated. Blood
flow to the non-ventilated lung becomes shunt
flow. This is in addition to any shunt flow
through the dependent lung. During such a
procedure the following data were obtained:
mvO2 content
aO2 content
15 ml/dl
19 ml/dl
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Assuming that oxygen content of blood leaving
ideally ventilated regions of the dependent lung is 20
ml/dl, calculate the shunt fraction.
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Is this the value you would expect in this setting when
approximately ½ of the lung mass is not being
ventilated? Explain.
A patient sitting upright in bed is on positive
pressure ventilation that maintains a positive
end-expiratory pressure of 8 cm H20 (~2
inches). You should be able to discuss the
following questions concerning this patient
based on this information alone:
1.
2.
Provide a rationale for either an increase or
decrease in the patient’s pulmonary arterial
blood pressure after being placed on PEEP.
Why might you consider putting a flowdirected pulmonary arterial (Swan-Ganz)
catheter under fluroscopic guidance in this
patient?