A 75 year-old man develops sudden onset of shortness of breath at the orthopedic department

A 75 year-old man develops sudden onset of shortness of breath at the orthopedic department. He was admitted for suspected pathological fracture of femur 3 days ago. On examination, his pulse is 122, blood pressure 90/60, respiratory rate 34/min and oxygen saturation is 92%. Lung sounds are clear bilaterally. Heart rhythm is regular with no murmurs or gallops.
What is the appropriate immediate step to improve this patient’s condition?

A-Intravenous injection of brad spectrum antibiotics
B-Intravenous injection of heparin
C-Subcutaneous injection of epinephrine
D-Electric cardioversion
E-Call the cardiology attendant