A number of departments are already under significant stress including the intensive care unit, surgical wards, mental health and coronary care wards.

Advocates say the hospital needs to do better at communicating how it plans to tackle capacity issues in the medium term.

SPIRE, short for surgical procedures, interventional radiology and emergency centre, is an expansion of Canberra Hospital due to be completed by 2024

In recent answers to questions on notice, the government acknowledged the intensive care unit would be at or near capacity before the completion of SPIRE.

But the government's publicly stated plans to increase bed capacity in the interim are well short of what was called for by the hospital's chief of clinical operations, Mark Dykgraaf, this time last year.

In internal documents written this time last year, Mr Dykgraaf - who is now general manager of Calvary Public Hospital Bruce - said the ICU needed an urgent and immediate increase in capacity because it was projected to be full by as early as 2020.

He last year suggested the available beds in the unit would need to grow from the current 31 to between 48 and 52 beds, in the next 12 to 18 months.

He said this could be achieved by building onto the roof of the emergency department, recommending work to begin this year, and would deal with capacity for the next 10 to 15 years.

"The current bed spaces do not meet Australian standards and storage is a significant issue for the unit," Mr Dykgraaf said in the correspondence.

"Bed areas are routinely used to store equipment and patients chairs are being held at the end of corridors."

A Canberra Health Services spokeswoman says it plans to increase the unit's capacity by six to eight beds when promised commonwealth funding is delivered.

It has also commissioned a report outlining intensive care unit expansion options to address short-medium term pressures on the unit's infrastructure.

Health did not elaborate on what the report's options were.

Australian Medical Association ACT president Antonio Di Dio said he trusted ACT Health knew the importance of managing capacity in the short to medium term, but wanted them to be more upfront about their plan.

"I don't doubt for one minute their intention but increasing capacity is not just something that you have a single plan for, you have a plan that is discussed with a whole range of stakeholders," he said.

"A lot of different groups in community that I've spoken to don't have a really clear idea of what the ACT Health capacity plan is as this point."

Dr Di Dio said workforce strategy also had to be central to a capacity plan, with several areas - including mental health, general practice and intensive care - facing staffing shortages.

A Canberra Health Services spokeswoman said the demand for intensive care services in the territory was increasing in volume and complexity.

The spokeswoman said the use of private facilities was one way of managing that demand.

But Dr Di Dio said some public hospital doctors were concerned that the private intensive care units may not meet the the minimum standard stipulated by the college of intensive care medicine.

He said they also contributed to a labor force problems in the territory, with a maldistribution of intensive carer doctors.

The spokeswoman said ACT Health Directorate planed to expand the Canberra Hospital ICU once the recently announced federal grants worth $13.5 million were released.

This will provide and additional six to eight ICU beds, supporting medical equipment and infrastructure.

"The ACT Health Directorate has commissioned an architectural report outlining ICU expansion options to address short-medium term pressures on ICU infrastructure," she said.

"The report offers the ACT Health Directorate two solutions, both of which can be completed within 18-24 months including detailed investigations, design, procurement, construction and commissioning.

"The ACT Health Directorate and Canberra Health Services are also working on expanding operational capacity."

Know more? Email daniella.white@canberratimes.com.au