Salvation (1972)

A biology professor, Adam enters a hospital for observation. He is a loner and a serious-minded man, who dislikes any display of emotions. He spends three months in the hospital while being tested. After observing patients and hospital routines around him from a distance, he learns that he will need a kidney transplant. Meanwhile his personal and professional life is falling apart: he refuses his wife's offer to donate the kidney for him; the scientific problem he was working on has been solved elsewhere. In the end Adam cracks under the prolonged pressure, waiting for the sound of an ambulance bringing a moribund patient whose kidney may be used for the transplant.

Unfortunately the movie Salvation is not yet available on HBO Max.