Union officials are warning that crews are being spread too thinly across parts of Scotland and one-man crews are being used frequently in some areas.
During the Olympics, there were times when staff were re-located from their usual stations to Hampden Park and not replaced or replaced by one-man crews, the GMB union said.
Paramedics have also described being alone with deteriorating patients, including a child with a head injury, and being unable to transport them to hospital because they are waiting for a back-up vehicle.
The previous health secretary, Nicola Sturgeon, promised to halt the practice of asking one paramedic to man a two-man ambulance in all but "exceptional circumstances" four years ago, and the Scottish Ambulance Service say they have delivered on this commitment and "local management teams make every effort to cover shifts" properly.
However, Mick Conroy, senior organiser for the GMB in Scotland, said: "Shop stewards have raised these concerns for months. We believe the service is deteriorating to such an extent that people are not getting a proper service and the Scottish Ambulance Service and the Scottish Government are not doing enough to solve it.
"There are a lot of dropped shifts and a lot of single crews go out on their own. Our fear is a patient will die and it will be seen as the paramedic's fault."
The issues are due to be raised in a debate in the Scottish Parliament today, and it is understood paramedics from around the country will be attending.
Concern about gaps in cover in Tayside, Fife, Aberdeen, the Highlands and the Vale of Leven, have been raised by staff.
The GMB. which represents 1100 ambulance staff in Scotland, is seeking a meeting with new Health Secretary Alex Neil to discuss the problems.
Jackie Baillie, health spokeswoman for Scottish Labour, said: "Our emergency services deserve to be properly supported by the Scottish Government and not to be compromised with staff left on their own and covering vast tracts of the country with no back-up. To abandon our most valuable workers who save lives day in, day out, is bad enough, but the consequence for patient safety is one of the most horrendous betrayals that this government could oversee."
Mr Conroy said they felt cash shortages were behind the problems, with one-man crews being used to save money.
Most regional health boards in Scotland are having to make efficiency savings as their budgets have not increased in line with inflation. However, the Scottish Ambulance Service is in the process of recruiting an additional 150 frontline staff as part of a £5 million investment from the Scottish Government.
A spokesman for the Scottish Ambulance Service said: "We are getting to more patients faster and saving more lives than ever. This is being achieved with more staff and new, innovative ways of working to deliver the best standards of clinical care for patients. Shift rosters are continuously reviewed to ensure that the appropriate level of cover is in place to maintain fast response times."
A Scottish Government spokesperson said: "We fully support the ongoing commitment of the Scottish Ambulance Service to ensure that the single crewing of traditional emergency ambulances only occurs in exceptional circumstances."
Contextual targeting label: