Domino kidney transplants mean fewer people are left on waiting lists, says Dr. Edward Cole. (CBC)

Four Canadians have new kidneys thanks to the country's first pay-it-forward exchange of organs from Toronto, Edmonton and Vancouver.

Living-donor kidney swaps are based on the idea of group co-operation: a donor whose kidney isn't compatible with a loved one who needs a new kidney agrees to donate to a stranger. In exchange, the partner receives a kidney from someone else.

Simultaneous kidney swaps have been done in Toronto before, but this multi-city swap had to be carefully co-ordinated across three time zones.

"It's been challenging," said Dr. Edward Cole, chair of the National Living Donor Kidney Exchange Program. "This is a real success story of people collaborating across the country, and with important input from Canadian Blood Services."

Timing is key, given ethical fears that once a patient receives a kidney, their partner could rescind an offer to donate. A donor or recipient might also have to back out after falling sick.

To avoid any last-minute problems, all donors were put under general anesthesia and none of the donor operations were started until all surgeons confirmed by telephone that they were ready to begin.

In this case, donors travelled to where the recipients were: two to Toronto General Hospital, one to Edmonton's University of Alberta Hospital, and another to St. Paul's Hospital in Vancouver. Each site had more than 50 medical personnel involved.

It's also possible to fly kidneys between cities, since the organs remain viable for 12 hours after donation.

For some patients with severe kidney failure, a donation from a live donor offers better and faster results than transplants from deceased donors, said Cole, who is also the head of the University Health Network's kidney transplant program in Toronto.

Good Samaritan

In kidney swaps, the living donors are medically acceptable but are incompatible with their loved one based on blood type and other traits. The intricate process was featured on an episode of Grey's Anatomy.

Previously it has not been possible to use donors in this way because there was no national database to co-ordinate the matches.

Three of the donors had offered to give loved ones a kidney before, but weren't the right match. The fourth donor was a Good Samaritan.

"The best untold story is that one of the donors is an anonymous donor," said Dr. Sandra Cockfield, medical director of the renal transplant program at the University of Alberta.

"So this is an individual who came forward to donate not to someone they actually know on the waiting list, but had heard about the long waiting lists and the difficulty of living on dialysis," and came forward to donate to a stranger.

In this surgical marathon, the Good Samaritan or "non-directed donor" came forward and was matched to a recipient, allowing the chain of paired exchanges or domino surgeries to take place. The Good Samaritan was thus able to facilitate four transplants, including the last to someone on the waiting list.

Since many pairs are needed to improve the odds of a match, a national program works much better than a local one, Cole said.

The transplant surgical marathon required months of planning by Canadian Blood Services, which set up the national registry. Paired exchanges have also been performed in the U.S., but no national registry exists there.

"We're offering a new of getting transplants, and then it puts less pressure for all those who are waiting on the wait list," said Dr. Peter Nickerson of Canadian Blood Services in Winnipeg.

Donors and recipients are all recovering well in different wards to maintain their anonymity.

The pilot project involving B.C., Alberta and Ontario is going national.

"The fact that it's a possibility for me now opens up so many more doors, and it's a very exciting prospect," said Didja Nawolsky of Calgary, who is on the waiting list for a kidney. While she waits, Nawolsky gets 10 hours of dialysis daily.

Doctors involved are already scouting their next cross-Canada, multi-kidney swap.