1. The following data is obtained from a man with smoke inhalation injury who is breathing 100% oxygen: PaO2 190 mmHg PaCO2 36 mmHg SaO259% COHb40% pH7.47 -What might you expect the PaO 2 to be? (Hint: what should ideal alveolar PO 2 be?) -Can shunt fraction be calculated? -Despite the high arterial PO 2, the man is experiencing problems related to tissue hypoxia. Why? Case Studies W.R. Law/Respiration BMS 653 – Human Physiology PHYB 401 – Graduate Physiology

2. A patient presents with pneumonia which involves the entire left lung, sparing the right. The following data is obtained on ambient air: PaO2: 52 mmHgSaO2: 75% PaCO2: 39 mmHgSmvO2: 60% Calculate shunt fraction On 50% oxygen, the data obtained are: PaO2: 65 mmHgSaO2: 80% PaCO2: 35 mmHgSmvO2: 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

3. 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 content15 ml/dl aO2 content19 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. Case Study

4. A patient sitting upright in bed is on positive pressure ventilation that maintains a positive end-expiratory pressure of 8 cm H 2 0 (~2 inches). You should be able to discuss the following questions concerning this patient based on this information alone: 1.Provide a rationale for either an increase or decrease in the patient’s pulmonary arterial blood pressure after being placed on PEEP. 2.Why might you consider putting a flow- directed pulmonary arterial (Swan-Ganz) catheter under fluroscopic guidance in this patient?