The patient is a 24 year-old truck driver who recently droveacross the country, was admitted to the hospital because ofshortness of breath (dyspnea) and chest pain. Her dyspnea begansuddenly three hours before admission. It was associated with chestpain that the patient described as feeling \"like a knife stabbingme in the chest when I breathe in.\" She also had right leg pain inher popliteal fossa (the slight depression on the back side of theknee). Physical Examination revealed an anxious-appearing female inobvious respiratory distress.

Temperature: 100 degrees F
Pulse: 90
Respirations: 28
Blood pressure: 100/60
Skin: No cyanosis
Lungs: Inspiratory rales (crackling sounds) heard over the rightbase
Legs: Tenderness and erythema (redness) over the right poplitealfossa; mild edema of the right leg from the knee down.
Arterial blood gases:

pH of 7.48,          (normal   7.35-7.45 )

pO2 of 70 mmHg. (normal pO2 90-100 mmHg)

pCO2 of 30 mmHg.          (normal pCO2 35-45 mmHg)

One possible diagnosis for the patient is a pulmonaryembolus.

The patient was placed on intravenous heparin and then beganoral Coumadin during her weeklong hospital stay. Both drugs areanticoagulants which prevent enlargements of blood clots and allowthe body's normal clot-dissolving pathways to work. The patient wassent home with a prescription for Coumadin, and advised to avoidfactors that promote blood clotting, such as smoking, oralcontraceptives, and prolonged inactivity (such as driving for longperiods without breaks). The patient was able to stop takingCoumadin after six months.

Answer the following questions:

1. How are ventilation and perfusion affected in a pulmonaryembolus?    Circle one:   A or B

A. Reduced pulmonary ventilation, excessive perfusion           B. Alveolar ventilation is the same, inadequate perfusion

2. The patient was found to have a blood clot in her rightpopliteal vein. List 3 major blood vessels that an embolus fromhere would pass through on the way to the right lung. (3 pt)

R. popliteal vein          à___________________________________________ (limb) à

_______________________________________________ (abdomen) à

_______________________________________________(thorax)     à right lung

3. Where would a pulmonary embolus most likely lodge, causingthe patient’s symptoms? [Hint: a blood vessel from question 2above, based on patient’s symptoms].

4. Interpret the patient’s arterial blood gas results: pH of7.48, pO2 of 70, pCO2 of 30 mmHg (see normal blood arterial gasresults). How would you classify this patient’s acid-base status?Discuss in terms of arterial pH, arterial blood pO2 and pCO2.[Hint: Textbook 23.6 Effect of O2 and CO2 pressure gradients]

5. Give the importance of buffers. Name at least two substancesthat act as buffers.