Question

Explain diffusion of oxygen and its physio mechanism and how it can be used to measure the diffusing capacity of an ill patient with shortness of breath, fever, sputum with cough. Which conditions of the vital signs are probably affecting the impaired diffusion mechanism.

Physical Examination:  

Vital Signs. TA 110/70mmHg   HR 110bpm   RR 25rpm   Temp 39 C (102.2 F) Pulse Oximetry 83%

Lung auscultation crackles in right subscapularis and egophony. Dehydrated and disoriented.

Answer 1

The diffusion of gases depends on the difference of partial pressure of the individual gas across the alveolar capillary membrane.this is also called as the diffusion gradient for the gas.

• oxygen diffuse easily across the membrane because of a greater difference in PO2 between the alveoli and pulmonary capillaries(oxygen diffusion gradient)
• The diffusion gradient for oxygen is about 60mmHg,which is the difference between the PO2 of the alveolar air and the arterial blood.
• The diffusing capacity of an ill patient with certain lung related disease measure with Pulmonary Function Test.