Your first port of call will the be Critical Care Unit, where there are four patients waiting to be treated, one of whom needs immediate surgery, two who need non-surgical treatment and one who needs elective surgery. And even after having played the game, I have no idea what elective surgery is - it's just one of those things the manual doesn't go into. You need to diagnose their conditions before you decide to operate - well, you're supposed to. You can in fact send them straight to surgery and operate on them, but then you get reprimanded for performing unnecessary surgery - some people are so intolerant. Plaster of Paris 'Open heart surgery - with some alfa beans and nice kiante.
Diagnosis involves performing a number of tests on each of the patients.
The first test involves tapping your patient's chest with your strangely flattened hands, and listening to their heartbeat and breathing. You can also order other tests including x-rays, Cardiograms, and Stress Tests, all of which should help you to determine your patient's ailments. Except they usually don't, because of the appallingly poor medical reference system used in the game. The manual is ridiculously sparse, and only lists the steps you need to complete an operation. It doesn't have any reference to the causes of the various illnesses you encounter in the game, nor does it explain any of the medical terminology within the game - in fact, there's very little medical information in the manual.