When the 999 call came through from Cromarty on th e Black Isle, it ended with the skipper of the local ferry saving his great-uncle's life.

But Ronald Young didn't have to pluck anyone from the waters of the Cromarty Firth. It was in the sheltered surroundings of Mr Young's parents' house - where he had been staying on a holiday from Glasgow - that his great-uncle John had suffered a cardiac arrest.

Mr Young had answered the call as a member of the local community first responder scheme run by the Scottish Ambulance Service. There are now around 60 such volunteer schemes from Gretna in the south to Ness in the north of Lewis, and many hundreds south of the border.

"Immediately I started giving him CPR (cardiopulmonary resuscitation) and my colleague Marigold put the pads of the automatic defibrillator on my uncle's chest," said Mr Young. "We gave him one shock and I gave him another two rounds of CPR, and then he began breathing again. Shortly afterwards his eyes opened and I knew he was OK."

The first responders were set up to do exactly what Mr Young did. This is because when a person suffers a cardiac arrest they can lose consciousness in a matter of seconds. Unless someone begins to resuscitate them quickly, they may suffer permanent damage to the brain and other organs. The idea is simple, to win the patient enough time until an ambulance arrives either through CPR or keeping an airway open. So volunteers undergo intensive training for five or six days to give them the resuscitation skills necessary to win that time.

However, the first responder schemes have become associated in the public mind with the local GPs opting out of being on call out of hours. Some see them as a cynical attempt by health boards to save money. There has been just such a controversy in Kinloch Rannoch in Perthshire in recent weeks. This is robustly denied by health boards. The providers of first responder teams say they are present in communities where the GPs still do out-of-hours work. But there is some concern that first responders are being used more often than originally intended.

David Alston, Black Isle councillor, said: "The Cromarty First Responders team have done a wonderful job and have already saved one life. There has been strong community support in raising funds to provide them with their own vehicle. However, I am concerned at the number of times they are called out each year. I think it was around 40 times in the last year. It seems that they are being used as a first line of response by the Scottish Ambulance Service for all emergency calls, rather than being called to those incidents for which the service was intended, such as cardiac arrests."

First responders schemes were piloted by the ambulance service in Essex in 1997, long before the new GP contract allowed them to opt out. The following year a new charity, First Response, was founded by Scott Bateman who at the time was an RAF pilot. His father had died of a heart attack in Auchterhouse near Dundee, as he waited for an ambulance to arrive. First Response now acts as partner to the ambulance service.

It is First Response which is preparing to go into Kinloch Rannoch. The charity has 22 schemes across the UK with five in Scotland. Some are associated with RAF bases, but others such as Comrie and Auchterhouse are community schemes. The charity is also seeking volunteers in Dunblane, Bridge of Allan and Doune.

According to local paper, the Allan Water News, First Response told a recent meeting of Dunblane community council that in the period between early June last year and the end of February this year, the ambulance service got 211 category-A calls from the Dunblane area. Of these, community first responders could have attended 63. It reported that it would cost around £10,000 to set up a scheme and around £4000 to run each year, with the schemes community funded.

First Response is growing in importance, but the vast majority of schemes are run by the Scottish Ambulance Service, which now has 52 First Responder schemes operating all over Scotland, with in total about 500 volunteers. They are largely funded by the service.

But the ambulance service has not always been so keen on volunteers treating those in distress. In 2001, researchers from Glasgow University published a paper in the British Medical Journal, exploring survival rates for patients who had suffered a cardiac arrest. Survival was linked to ambulance response times and to whether the patient received defibrillation (administering an electric shock to restore a normal heartbeat).

The researchers suggested that people other than paramedics, such as firefighters and the police, should be able to defibrillate patients. The Scottish Ambulance Service urged caution at the time. However, subsequently there was a growing acceptance that in a cardiac emergency it's not the attendance of paramedics that is needed, but simply someone who can administer basic life-support or defibrillation.

Now the ambulance service is enthusiastic and a spokesman stressed first responders are not used inappropriately.

The spokesman said: "They are deployed to appropriate calls by the ambulance service's emergency medical dispatch centre, but they are only deployed if they can make a difference. They are not used in the likes of maternity cases or serious road accidents and they do not administer drugs.

"Their skills are comparatively basic, but speed of intervention can often be critical when responding to 999 calls. The First Responder initiative creates an even faster response for patients and is co-ordinated with our existing ambulance resources. In a medical emergency it is often the simple first aid skills, like making sure an airway is clear, that save a life."