Concerns have been raised about the absence of paramedics on some ambulance emergency vehicles in Scotland.
On average, ambulances arrive within 8.4 minutes of a call
It has been claimed that some have been sent out with technicians on board who cannot give drugs by injection.
Last March, a heart attack victim died after technicians staffing the two ambulances sent out were allegedly unable to treat him.
Solidarity MSP Tommy Sheridan has raised concerns, but ambulance managers have defended the service.
The number of calls to the Scottish Ambulance Service currently stands at about 500,000 and is increasing every year.
The average caller will get an ambulance in 8.4 minutes but while in 2005 the ambulance service promised that if a call was urgent a paramedic would be sent, this is no longer the case.
Many staff have expressed concerns and held a meeting with Glasgow MSP Mr Sheridan.
"They are being told 'we have to meet targets' but they are telling me that some people are being sent out and they are technicians or they are probationary staff and therefore they are not skilled to be going out alone," he said.
"They can't administer life saving drugs. They have to wait for other units anyway.
"The staffing has to be addressed now before it gets critical."
The family of the man who collapsed at his son's wedding and died following a heart attack have complained to the Scottish Ambulance Service because no paramedic was sent to his assistance.
However Pauline Moore, chief operating officer of the service, said the service was not to blame.
"We have reviewed the case in some detail and the treatment administered by the technician would have been the same as that administered by a paramedic," she said.
Although ambulance technicians can be very experienced, they can begin work on probation after nine weeks' training, while paramedics - who were introduced in 1988 - undergo two years' training and develop additional skills.
However, Ms Moore claimed technicians could always contact the base to ask for the back-up of a paramedic if they thought it was necessary.
"We would much rather have the vehicles out staffed by a higher skilled and experienced member of staff - a technician - than have the vehicles sitting idle in the station," she said.
The Scottish Executive said that funding for the ambulance service had increased by 30% and it was up to the service to decide how to spend additional resources.