Final answer:
The elderly man is most likely experiencing pulmonary edema, which is excess fluid in the air sacs of the lungs. This condition can result from heart and/or kidney failure and compromises gas exchange in the lungs. Immediate medical attention is necessary.
Step-by-step explanation:
The elderly man with respiratory distress who is coughing up bloody sputum and has an oxygen saturation of 85% is most likely experiencing pulmonary edema.
Pulmonary edema is the excess fluid in the air sacs of the lungs, which can occur as a result of heart and/or kidney failure. This condition compromises gas exchange in the lungs and can lead to difficulty breathing and chest pain. It is a serious condition that requires immediate medical attention.
In this case, the presence of coarse crackles in all lung fields during auscultation further supports the diagnosis of pulmonary edema.