Question

The patient is a 24 year-old truck driver who recently drove across the country, was admitted to the hospital because of shortness of breath (dyspnea) and chest pain. Her dyspnea began suddenly three hours before admission. It was associated with chest pain that the patient described as feeling "like a knife stabbing me in the chest when I breathe in." She also had right leg pain in her popliteal fossa (the slight depression on the back side of the knee). Physical Examination revealed an anxious-appearing female in obvious 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 right base
Legs: Tenderness and erythema (redness) over the right popliteal fossa; 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 pulmonary embolus.

The patient was placed on intravenous heparin and then began oral Coumadin during her weeklong hospital stay. Both drugs are anticoagulants which prevent enlargements of blood clots and allow the body's normal clot-dissolving pathways to work. The patient was sent home with a prescription for Coumadin, and advised to avoid factors that promote blood clotting, such as smoking, oral contraceptives, and prolonged inactivity (such as driving for long periods without breaks). The patient was able to stop taking Coumadin after six months.

Answer the following questions:

1. How are ventilation and perfusion affected in a pulmonary embolus?    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 right popliteal vein. List 3 major blood vessels that an embolus from here 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, causing the patient’s symptoms? [Hint: a blood vessel from question 2 above, based on patient’s symptoms].

4. Interpret the patient’s arterial blood gas results: pH of 7.48, pO2 of 70, pCO2 of 30 mmHg (see normal blood arterial gas results). 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 substances that act as buffers.

Answer 1

Solution:

1. Alveolar ventilation is the same inadequate perfusion {option B}

    Reason: Alveolar is in lung works as airsac its functionality will not reduce, if it fails the functionaing of lungs will collapse leads to death

2. limb - Leonardos vein, abdomen - abdominal aorta, thorax - vertebral artery

3. The first step of initiation starts from limb as it's the source place of oxygenated and deoxygenated blood supply from the entire body, once the flow in leg is blocked then the PE symptoms starts gradually, the first symptoms of continuous tingling of nerves in the limb.

4. based on reference source acidity of the blood is increased than above normal due to imbalanced circulation of oxygenated and deoxygenated blood flow.

5. Buffers are important in neutralizing the acidic condition, for eg:- in human body oxygen acts as buffer in normal maintainance of acidity in blood, another example is bile which acts as buffer in digestion process.