The Southampton study: 63 cardiac arrest survivors and boards on the ceiling

Step 1

Before the study · The question

Hundreds of accounts, and no way of knowing when they happened

The authors had collected about 750 accounts from people who described an NDE or said they had left their body. All of them were told after the fact.

Those accounts had a problem that couldn’t be solved. It was never clear whether the experience had happened before the person lost consciousness, while they were unconscious, or as they were waking up.

No study had done two things at once. One is asking patients within a few days. The other is comparing what they describe with measured medical data, such as the oxygen in their blood.

So they decided to run a trial in a single hospital. This is called a pilot study.

Step 2

Over one year · According to the study

A year at Southampton General Hospital

The study was led by Sam Parnia, a doctor at Southampton General Hospital. He worked with D. G. Waller and R. Yeates from the same hospital, and with Peter Fenwick of the Institute of Psychiatry in London. Their own department paid for the study. The paper doesn’t say what year it was carried out.

The team spent one year looking for every person who survived a cardiac arrest on the medical wards, in the emergency department, or in the coronary care unit. To find them, they used the log kept by the hospital switchboard. Every cardiac arrest call is recorded in that log.

To be interviewed, each person had to meet five conditions:

• Have survived a cardiac arrest in one of those units.
• Be over 18.
• Score 10 out of 10 on a short mental test, to leave out anyone who was confused.
• Have the agreement of the doctors and nurses caring for them.
• Give their consent after the study had been explained to them.

Before the first interview, they set up one more thing.

Step 3

Before it began · According to the study

Boards with drawings that can only be seen from the ceiling

Some people who have had an NDE say they saw themselves from the ceiling while they were being resuscitated. They also say they saw things they couldn’t have seen from the bed. The authors note that doctors and nurses later confirmed some of those accounts.

To put this to the test, the authors hung boards from the ceilings of the wards before the study began. The boards had drawings on the top side, the one facing the ceiling. From the floor, the drawings couldn’t be seen.

If someone said they had left their body and been up near the ceiling, they should be able to say what drawing was there.

The authors explain it this way. If the mind creates those perceptions, no one will name the right drawing.

Step 5

Within the following week · According to the study

A single question, with no mention of NDEs

The team interviewed them in the hospital, within a week of the cardiac arrest. They were told the researchers wanted to find out what people remember after being in a coma following a cardiac arrest.

Then they were asked an open question. The team asked whether they remembered anything from the time they were unconscious.

They were not asked anything about NDEs or about leaving the body.

What they described was scored on the scale created by Bruce Greyson, an American psychiatrist. It has 16 questions, and each thing the person went through adds points, for example peace, a light, seeing a relative who had died or leaving the body. A score of 7 points or more counts as an NDE.

The team also took several kinds of data from each patient’s medical records. In the blood tests, they looked at oxygen, CO₂, sodium, and potassium. They also looked at the medications and the heart rhythm during the cardiac arrest. And they asked each person about their religion.

Step 6

At the interview · According to the study

Of 63 people, 56 remembered nothing and 4 described an NDE

That year, 63 people survived, and all of them were interviewed.

• 56 remembered nothing from the time they were unconscious.
• 7 remembered something. That is 11 out of 100.
• 4 of those 7 described an NDE, scoring 7 points or more. That is about 6 out of 100.

Each dot stands for one person out of 100. The 6 filled-in dots are the people who described an NDE. That was 4 of the 63 people.

The other 3 people who remembered something scored under 7 points. Two described a few things typical of an NDE, such as peace or seeing relatives who had died. The third had a confused memory of unknown people jumping off a mountain.

What did the 4 people with an NDE describe?

Step 8

At the end of the year · According to the study

No one described leaving their body, and no one got to look at the boards

The boards stayed up all year. But none of the 63 people said they had left their body.

So there was never a chance to check whether anyone could see the drawings.

For the authors, it is not clear whether people who say they watch their own resuscitation from above are really seeing it or are hallucinating. Some may know things they couldn’t have known while unconscious. But those things may also have reached them through their senses, in the ordinary way.

What the researchers could compare were the blood tests.

Step 9

Comparing the blood tests · According to the study

More oxygen in those who had an NDE, but in only 4 people

One idea put forward to explain NDEs is that the brain runs out of oxygen. The authors compared the 4 people who had an NDE with the other 59.

• The oxygen in the blood was twice as high in those who had an NDE as in the others. Those who had an NDE had 33.1 kPa on average. The others had 16.8 kPa. The kPa is the unit it is measured in.
• Sodium, potassium, and CO₂ were similar in both groups.
• Heart rhythm: 3 of the 4 people had a rhythm called ventricular fibrillation or ventricular tachycardia. The fourth had asystole. Asystole is when the heart is not beating at all.

The authors say 4 people were not enough for statistical testing. They give only the averages.

The authors offer two possible explanations. First, it may be “simply a skewed result due to the low patient numbers.” Second, the people who had an NDE may have had more oxygen in their blood. In that case, a lack of oxygen would not be what causes the experience. In the end, the authors conclude that “it would be unwise, with such small numbers, to draw any significant conclusion.”

There is one more detail. The paper says the blood samples were taken during the cardiac arrest. A footnote says the data were recorded from the time the patient was on the ward. That footnote may only mean from when the data were reviewed. But the paper doesn’t give the time of each sample.

Step 10

Discussing the data · According to the study

At what moment does the experience happen?

The authors think the NDE probably happened while the person was unconscious. And they call this “a surprising conclusion.” With the brain so impaired, no one should be able to experience something so complex, or to remember it afterward.

The authors also consider another possibility. The experience could happen as consciousness is lost or as it returns. But the authors think it unlikely:

• As consciousness is lost: in a cardiac arrest, consciousness goes within a few seconds. And no one said their experience began at that moment.
• As consciousness returns: memories are usually confused, and these were not.

The authors did not measure the timing. They themselves write that more data are needed to confirm it.

There is one more thing to keep in mind. To be in the study, people had to score 10 out of 10 on the mental test. That left out confused people. And they are the ones who might report confused memories.

Step 11

February 2001 and after · According to other researchers

The study is published, and its oxygen figure gets cited both ways

The paper was published in 2001 in Resuscitation. At the end of the paper, the authors call for a study in many hospitals at once. They wanted enough people to look in detail at both body and mind. They also wanted to study out-of-body experiences.

In 2003, the psychiatrist Bruce Greyson relied on the Southampton study in his own, with 1,595 heart patients. He wrote that “those models that have been studied empirically, such as the influence of blood gases, have been disconfirmed.” But that study ran no statistical tests, and its authors warned against drawing conclusions.

In 2010, another study, in Slovenia, measured the same thing in 52 people resuscitated outside the hospital. There, the 11 people who had an NDE had less oxygen than the others. But that difference wasn’t conclusive either. They also had more CO₂ than the others, and that difference was conclusive. We cover this in the Klemenc-Ketis study.

The multi-hospital study the authors had called for came in 2014. It was called AWARE. Now let’s look at what is known from the Southampton study.