Jeff Fraser, operations director at Emergency Medical Care, said non-union employees who are trained paramedics will be the only workers available in the event of a paramedic strike.
Fraser, who is organizing a contingency plan, said management paramedics can initially meet about 28 per cent of regular service, but this would vary from day-to-day and decrease over time.
"It certainly won't come without any interruptions," he said. "It will not be business as usual."
Asked if the situation would risk lives, he said, "There is no doubt it will be very challenging to provide service to a province the size of Nova Scotia."
He said managers will only be able to respond to "time critical" emergencies and other services, such as transferring patients from one hospital to another, won't happen.
But there is no guarantee that all emergencies will receive an immediate response, he added.
"Without having the agreement from the union to have essential services, it's going to be difficult," he said.
Paramedics in Nova Scotia aren't covered by essential services legislation that require some staff to remain on duty.
A news release on the Health Department's website late Friday said the union's strike deadline had been pushed from Sunday to Tuesday while a mediator worked to find a solution to the contract dispute. The union could not be reached for comment.
In an earlier interview, Terry Chapman, business manager of the International Union of Operating Engineers Local 727, said he's doubtful the management paramedics will be able to respond to all emergencies.
"If there's only 28 per cent contingency, that means 72 per cent are absent," he said, adding that with 400 calls each day, that would likely mean some emergency calls won't receive a response.
Chapman said patients are often not able to provide enough information over the phone to determine if the situation is an emergency.
"There's no way to tell before the ambulance gets there if it's an emergency or not," he said.
In addition to having fewer ambulances on the road, a helicopter used for critical-care service for adults would be grounded if the paramedics go on strike. A plane would be used instead, staffed with people trained in advanced life support.
IWK Health Centre staff in Halifax aren't part of the paramedics' bargaining unit, so helicopter service for children should continue.
The union membership is looking for wage increases, a three-year deal and a defined benefit pension plan rather than its existing defined contribution plan.
Emergency Medical Care says it is committed to reaching an agreement and isn't discussing the union's demands while a mediator assists the two sides in the talks.