The following data is obtained from a man with smoke inhalation injury who is breathing 100% oxygen:

1
Case Studies
W.R. Law/Respiration BMS 653 Human Physiology
PHYB 401 Graduate Physiology

• The following data is obtained from a man with
  smoke inhalation injury who is breathing 100
  oxygen
• PaO2 190 mmHg
• PaCO2 36 mmHg
• SaO2 59
• COHb 40
• pH 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?

2
Case Study

• 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 SaO2 75
• PaCO2 39 mmHg SmvO2 60
• Calculate shunt fraction
• On 50 oxygen, the data obtained are
• PaO2 65 mmHg SaO2 80
• PaCO2 35 mmHg SmvO2 60
• Calculate shunt fraction. Is the value the same
  as above? Explain.
• After performing these calculations, the
  attending physician decides to change the
  patients body position. What position change is
  appropriate and why?

3
Case Study

• 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 15 ml/dl
• aO2 content 19 ml/dl
• Assuming that oxygen content of blood leaving
  ideally ventilated regions of the dependent lung
  is 20 ml/dl, calculate the shunt fraction.
• Is this the value you would expect in this
  setting when approximately ½ of the lung mass is
  not being ventilated? Explain.

4

• 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
• Provide a rationale for either an increase or
  decrease in the patients pulmonary arterial
  blood pressure after being placed on PEEP.
• Why might you consider putting a flow-directed
  pulmonary arterial (Swan-Ganz) catheter under
  fluroscopic guidance in this patient?