Walsh: Neonatal and Pediatric Respiratory Care, 4th Edition
Chapter 10: Oxygen Administration
Answers to Case Studies
You are presented with providing oxygen therapy for a mildly hypoxic 12-year-old child with an
SpO2 of 86% to 88%. The child has been recently diagnosed with moderate persistent asthma.
She is admitted for a moderate exacerbation. The patient is in moderate distress, tachypneic, with
good air entry and prolonged expiratory wheezes. The last blood gas obtained from a referral
hospital is only remarkable for a mild respiratory alkalosis. The physician asks you to initiate
oxygen therapy with the device of your choice and to maintain the PaO2 above 60 torr. Which of
the following answers best describes the device you would choose, and what noninvasive oxygen
saturation range would you target?
a. A nasal cannula and an SpOO2 of 92% to 95%
b. A nasal cannula and an SpO2 of 89% to 92%
c. A Venturi mask set at 28% to achieve an SpO2 of 92% to 95%
d. Do nothing because the patient’s PaO2 is already above 60.
Answer: A, C
Since the child is mildly hypoxic, any variable or fixed performance device set to a fairly low
FiO2 would have worked. However, due to the mild respiratory alkalosis, the oxygen
disassociation curve will be shifted to the left. This means that a slightly higher SpO2 of 92% to
95% will be required to maintain a PaO2 of > 60. This eliminates choices b and d because with a
normal pH, an SpO2 of 90% is estimated to be a PaO2 of 60. An SpO2 of < 90 would be a PaO2 of
< than 60.
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