Transcript
Chapter 33: Determinants and Assessment of Oxygen Delivery and Oxygen Consumption
Critical Thinking Checkpoint Case Studies
Mr. T. is a 75-year-old admitted to the high-acuity unit with right lower lobe pneumonia. He has a history of chronic renal failure, anemia, and myocardial infarction. He is currently receiving 4 liters O2 by nasal cannula and IV antibiotics. His vital signs are BP 90/60 mm Hg, HR 108/min., RR 34/min., temperature 38.5°C (101.5°F).
This activity contains 5 questions.
1. Identify conditions present in Mr. T. that impair pulmonary gas exchange.
Answers: Conditions present that impair pulmonary gas exchange include:
Ventilation impairment-inspiratory muscle weakness due to his age
Diffusion impairment-decrease in alveolar-capillary membrane surface area related to atelectasis and pneumonia
Perfusion impairment-decreased hemoglobin with anemia; decreased perfusion with decreased CO related to history of myocardial infarction
2. Identify conditions present in Mr. T. that impair oxygen delivery.
Answers: Conditions present that impair oxygen delivery include:
Decreased cardiac output related to history of myocardial infarction
Decreased oxygen transport related to anemia and decreased hemoglobin, decreased SaO2
3. Identify conditions present in Mr. T. that alter oxygen consumption.
Answers: Conditions present that alter oxygen consumption include:
He has many conditions that increase oxygen consumption: hyperventilation, hyperthermia, anxiety, stress, and increased muscle activity if he is shivering with the hyperthermia.
4. What parameters could the nurse use in the high-acuity unit to assess Mr. T.'s pulmonary gas exchange?
Answers: ABGs, PaO2, and SaO2 to assess diffusion, PaCO2 to assess ventilation
Auscultation-Assesses ventilation and can detect airflow changes. The nurse should listen for crackles or wheezes.
PaO2/FiO2 ratio-Can reflect the degree of shunt. Normal value is greater than 350, with a value of less than 200 suggesting a large intrapulmonary shunt.
5. What parameters could the nurse use in the high-acuity unit to assess Mr. T.'s oxygen delivery?
Answers: Parameters the nurse can use to assess oxygen delivery:
ABG—Assess SaO2, PaO2, Hb, RBCs (although PaO2 minimally contributes to oxygen delivery (less than 3%)).
Pulse oximetry—used for continuous noninvasive measurement of arterial oxygenation saturation. It is recommended for any patient at risk for hypoxemia, because desaturation is detected earlier by pulse oximetry than by clinical observation.
Physical assessment—Assess skin color, looking for signs of cyanosis, skin temperature, and capillary refill.
Cardiac output—Can be assessed either directly or indirectly. Since Mr. T. is not in an ICU, his CO cannot be measured directly. The nurse would assess for signs of hypoperfusion.
