Alarmingly, alcohol, anaesthesia, some illnesses (such as hypothermia) and many drugs (including Valium) can shut down brain activity, conning doctors into thinking their patient is dead. In 2009, Colleen Burns was found in a drug-induced coma and doctors at a hospital in New York thought she was dead. She woke up in the operating room the day before doctors were due to remove her organs (NB: it’s unlikely this would have gone ahead, because her doctors had planned additional tests before the surgery).

Several decades earlier in 1968, a group of esteemed Harvard doctors called an emergency meeting to discuss exactly this. Over the course of several months, they devised a set of foolproof criteria which would allow doctors to avoid such blunders and establish that beating heart cadavers were definitely dead.

The tests remain the global standard today, though some of them look uncannily like those from the 19th Century. For a start, a patient should be “unresponsive to verbal stimuli”, such as yelling their name. And though leeches and nipple pincers are out, they should remain unresponsive despite numerous uncomfortable procedures, including injecting ice-cold water into one of their ears – a technique which aims to trigger an automatic reflex and make the eyes move. This particular test is so valuable it won its discoverer a Nobel Prize.

Finally, the patient shouldn’t be able to breathe on their own, since this is a sure sign that their primitive brain is still going. In the case of Burns, the horrifying incident was only possible because her doctors ignored tell-tale signs that she was alive; she curled her toes when they were touched, moved her mouth and tongue and was breathing independently, though she was hooked up to a respirator. Had they followed the Harvard criteria correctly, they would never have declared her dead.

Cadaver donor management

You might expect all medical treatment to stop after someone is considered dead – even if they are a beating heart cadaver – but that’s not quite true. Today beating heart cadavers have spawned a strange new medical specialty, “cadaver donor management”, which aims to improve the success of transplants by tending to the health of the dead. The aim of the game is to fool the body into thinking everything is fine until recipients are lined up and their surgeons are ready.

In all, nearly twice as many viable organs – around 3.9 per cadaver– are retrieved from these donors compared to those without a pulse and they’re currently the only reliable source of hearts for transplant.