MELISSA BLOCK: This is ALL THINGS CONSIDERED, from NPR News. I'm Melissa Block. 

ROBERT SIEGEL: And I'm Robert Siegel. There is a chronic shortage of organs for transplant, in this country. Over the years, doctors have tried to design equitable, transparent systems to decide who gets a new heart or lungs. But they keep running into one, very tricky obstacle - themselves. When it comes to organ transplants, a doctor's desire to do what's best for his patient can end up hurting someone else's patient. 

Chana Joffe-Walt, of our Planet Money team, explains. 

CHANA JOFFE-WALT, BYLINE: You have to understand the position doctors are in every day. You're a doctor, and you know there aren't enough organs to go around. But you also know your patients really, really well; patients who are sick, some of whom are dying. 

So you're a doctor, and every day you meet someone like Ashley Dias. Ashley's waiting for lungs. She's 26 years old; has cystic fibrosis. She's got a tracheostomy tube in her neck, so she can only mouth out words - words her mom then repeats for her. 

(SOUNDBITE OF ASHLEY SPEAKING) 

ASHLEY'S MOTHER: (Repeating) She just assumed ...with the machine...she would breathe normal. 

JOFFE-WALT: At some point, Ashley gives up on speaking; and types a text into her phone, and hands it to her mom. 

ASHLEY'S MOTHER: (Reading) As much as I text, I never seem to get my point across. And that's really frustrating. 

JOFFE-WALT: Ashley grabs the phone back from her mom, and shakes her head at that last part. She didn't type "that's really frustrating." Her mom added that part - which seems to be really frustrating to Ashley. 

UNIDENTIFIED DOCTOR: Hi. How are you? 

ASHLEY'S MOTHER: Hi. I'm well, thanks. Yourself? 

UNIDENTIFIED DOCTOR: I'm fine. Are you Ashley's mom? 

ASHLEY'S MOTHER: I am. 

UNIDENTIFIED DOCTOR: OK. 

JOFFE-WALT: When doctors do come to see Ashley, she only has one question. She pulls out a marker and writes in enormous, big caps, as if it is the only thing she has ever wanted a voice to say. ANY NEWS ON LUNGS? 

UNIDENTIFIED DOCTOR: No. You will be the first person to know. OK? OK? It'll happen. It'll happen. 

ASHLEY'S MOTHER: Thank you. 

UNIDENTIFIED DOCTOR: All right? Have a great day. Take care. Nice meeting you. 

ASHLEY'S MOTHER: You, too. 

(To Ashley) See? You can't be discouraged. They all feel as confident as they can. So you do, too. You have to, OK? It's going to happen. 

JOFFE-WALT: Ashley has no words for her mom at this point, mouthed or texted. She just sits back and continues waiting. And this - if you were a doctor - this is image you hold in your mind: Ashley waiting, when you're driving to work, falling asleep. 

DR, MARIE BUDEV: There's 124 patients right now, on my list. 

JOFFE-WALT: Ashley Dias' doctor is Dr. Marie Budev, at the Cleveland Clinic. She desperately wants Ashley to get lungs, and she also wants that for her 123 other patients. 

How many of those 124 will get lungs? 

BUDEV: It depends on who's dying out there; what organs are available. 

JOFFE-WALT: And what condition the lungs are in. Car accidents - Dr. Budev says - can be great for hearts and livers, but not so much for lungs. The very best thing for lungs... 

BUDEV: Either gunshot wounds to the head, that sort of thing; or strokes or bleeding. But we do take motor-vehicle accident patients, as long as their lungs aren't severely contused. 

JOFFE-WALT: When they do get good lungs, there are rules - strict rules, about who gets those lungs; just like there are with hearts, kidneys, livers. But here's where the fact that doctors always want to help their patients, can become a problem. Consider the story of what happened with liver transplants. 

JASON SNYDER: So before 2002, the waiting list was ordered in terms of the sickest person first. 

JOFFE-WALT: This is Jason Snyder, an economist at UCLA, who has studied a bizarre finding from the liver-allocation system. Before 2002, to determine which liver patients were the sickest, they would measure people's blood; and look at whether or not they were in the intensive care unit, the ICU. For years, that was what determined your place on the liver waiting list. 

SNYDER: Yes, up until March 1st, 2002. 

JOFFE-WALT: March 1st, 2002, they changed the rules. They said, forget the ICU; we will only measure your blood. And almost immediately, the ICU got a lot emptier - which seemed to indicate that doctors were putting their patients in the ICU not because they necessarily needed to be there, but to get them bumped up the waiting list. And it's not just that it seemed that way. Liver doctors will tell you now, yeah; that's what we were doing. Here's Dr. William Carey, a hepatologist at the Cleveland Clinic. 

WILLIAM CAREY: I mean, let's face it. I have patients. I want my patients to get transplanted. I care more about my patients than I care about patients in another city, in another part of the country. And it clearly is in the interest of my patient to get transplanted, however I can make that happen. 

JOFFE-WALT: Doing what is in the best interest of his patient - Dr. Carey reminds me, that's his job. But here's what's complicated. It is also a doctor's job to do no harm. And in this case, doctors acting in the best interest of their patient, causes harm. It means other people's patients will have to wait longer. Here's Jason Snyder again. 

SNYDER: It's not just an issue of waiting. Many, many people die on the waiting list. 

JOFFE-WALT: So we're actually talking about a doctor making a decision that helps their patients, and potentially kills other people's patients? 

SNYDER: Absolutely. I think it's a really tough problem. 

JOFFE-WALT: It was clear to everyone there was a problem, not just liver doctors. Dr. Budev, Ashley's doctor, told me lung doctors realized they were doing a similar thing. 

BUDEV: That patient is everything - and that's why I think we can't be trusted. 

JOFFE-WALT: What's interesting about what you're saying is, you're saying you need to be controlled. 

BUDEV: We do. 

JOFFE-WALT: In 2005, the lung doctors followed the liver doctors, and put in place a system that would, among other things, control them; a system that would score patients on objective medical data only - how much oxygen a patient is on, how far he or she can walk. 

BUDEV: There's no way for me to manipulate that score, to put that patient higher on the list. There is really no way to game the system. 

JOFFE-WALT: This is the ungameable system Ashley Dias finds herself in today. She's actually near the top of the list - although she's small and probably needs pediatric lungs, which don't become available often. I asked Dr. Budev, what if Ashley wasn't near the top? There's really nothing you could do, to help her? Dr. Budev says no matter how hard you try to design a system that is completely resistant to manipulation, there's always some room. 

BUDEV: I guess there is room for you to put everybody you have on 100 percent oxygen, and tell them to walk less - because that will increase the score. 

JOFFE-WALT: But you don't do that? 

BUDEV: We don't, and most people don't. The reason why is, we're audited very closely. 

JOFFE-WALT: Do you think you would, if you weren't audited? 

BUDEV: Um - I would be tempted to. I would be tempted to. 

JOFFE-WALT: For a system like this to work, you need people like Dr. Budev, who understand they are tempted; and you need a group of independent people - auditors - trying to keep those tempted people in check. 

Chana Joffe-Walt, NPR News.