SJS, that’s true. One way to make hacking much tougher would be to use biometric identification instead of usernames & passwords. While a hacker might be able to find a user id & password it would be tougher to copy a fingerprint.
The theoretical hacker would in any case need to have a good medical background. He would need to falsify the record in a way that would point to using a medication/ treatment that would be immediately fatal to the patient, so the medical staff could not correct the mistake. But the change would also have to be one that would not arouse suspicion, since usually when confronted with an anomalous result the doctor would order further testing.