Question

HISTORY

After a week of scuba diving in the Bahamas, Mary Ann boards an airplane. During her flight home, she develops aching joints, nausea, and dyspnea, which resolve upon landing. During the flight, the cabin pressure was equivalent to an altitude of 8000 feet, which amounts to 564 mmHg air pressure.

QUESTIONS

. Define dyspnea. Type answer as 2 words using lowercase letters.

2. What is the percentage of oxygen in the atmosphere?

3. What is the percentage of oxygen in the airplane cabin?

4. What is the partial pressure of oxygen in the airplane cabin?

5. What is the partial pressure of fully oxygenated, arterial blood?

6. Comparing the normal partial pressure of oxygen in the air at sea level, the partial pressure of fully oxygenated, arterial blood, and the partial pressure of oxygen in the airplane cabin calculated for question 3, could the blood become fully oxygenated in the airplane cabin- yes or no?

7. Explain your answer to question 6.

8. Would this cabin pressure be- less than, the same as, or more than- the pressure she experienced during scuba diving?

Answer 1

Ans) 1) Dyspnea- difficulty in breathing

Dyspnea is defined as shortness of breath, a subjective difficulty or distress in breathing, usually associated with disease of the heart or lungs; occurs normally during intense physical exertion or at high altitude.

Ans2 ) By volume, in atmosphere, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.

- Atmospheric air also contains a variable amount of water vapor, around 1% at sea level, and 0.4% over the entire atmosphere.

Ans3) The percentage of oxygen in the air of an aircraft cabin is the same as on the ground, but the cabin pressurization will be equal to an altitude as high as 8,000 feet in flight (which means there will be less oxygen in your bloodstream) so they may require oxygen masks.

Ans4) The partial pressure of oxygen at ground level is about 150 Torr (20% of atmospheric pressure at 760 Torr).

- Inside a plane at cruising altitude it is reduced to about 125 Torr, i.e. a negligible change.

- The blood in most people will remain fully saturated with oxygen at this pressure.

Ans5) The partial pressure of fully oxygenated, arterial blood:

Partial pressure of oxygen (PaO2) - 75 - 100 mmHg.

Partial pressure of carbon dioxide (PaCO2) - 38 - 42 mmHg.

Arterial blood pH of 7.38 - 7.42.

Oxygen saturation (SaO2) - 94 - 100%