Canberra Hospital is at capacity with an occupancy rate "well above" 90 per cent, according to its emergency department specialist, despite ACT Health's attempts to hose down the extent at which it operates beyond the safe level for care.
The Australian Medical Association recommends a safe bed occupancy level of 85 per cent.
An ACT Health spokeswoman said Canberra's public hospitals were at 83 per cent occupancy in October and neither had reached levels of 110 to 120 per cent, in response to questions from The Canberra Times on Friday about reports it was operating over capacity.
"Canberra Hospital does aim to run at around 90 per cent occupancy," she said.
But Canberra Hospital's emergency department staff specialist associate professor Dr Drew Richardson said the hospital was "very full" with occupancy as high as 120 per cent depending on how it was calculated.
"The hospital is definitely getting more emergency admissions and so the longer they stay the greater the occupancy and the pressure on beds throughout the hospital," he said.
"That's why running a hospital is a difficult business ... we have to manage things the best we can to do the greatest good with the resources we've got."
On Friday, the ACT Health spokeswoman said October was typically a quieter month for the emergency department, but on Sunday it had its busiest day ever with a record number of 254 presentations – two more than the 2003 bushfires.
Opposition leader Jeremy Hanson was concerned at the "inconsistencies" in the occupancy rates reported, saying the health system was verging on crisis.
"My understanding is that the hospital has been close to 100 per cent for quite some time so I'm very surprised to hear they are now saying its 83 per cent," he said.
Data at the emergency department had previously been "deliberately fabricated to make results look better than they were," he said. "I'm always very sceptical now of any figures out of the Canberra Hospital."
Mr Hanson said the health system needed to be operated more efficiently and its capacity increased, but there was no "singular answer" to fix its problems.
"It's clear we've got a very dedicated and hardworking nursing staff ... my concern is the number of patients waiting to get into hospital beds," he said.
"We know there are problems with the numbers of beds; we know there have been significant delays in health infrastructure being delivered."
Dr Richardson said the emergency department was expected to peak in November while summer was typically quieter as people left Canberra.
"We are always bracing for tough times … but the emergency department is prepared for this and its workload does vary," he said.
Sunday's spike was blamed on a jump in asthma-related illness caused by thunderstorms and wind, but Dr Richardson acknowledged it was part of an upward trend.
"There were very few thunderstorms over the weekend but there was enough to give us 15 presentations in 27 hours. Normally, we only get about four asthmatic cases a day," he said.
Dr Richardson said the emergency department coped well under the extra pressure, but he admitted he was concerned the department had failed to meet its target of seeing 80 per cent of patients with an immediately life-threatening condition (category two) on time.
Of the 36 category two patients, 78 per cent were seen on time.
But the two more serious category one patients were seen on time and overall 62 per cent of patients were seen, treated and discharged within four hours.
"Obviously things took a bit longer than we wanted them to for some patients," Dr Richardson sad.
"We're very grateful to staff for the hard work they've put in."
Dr Richardson said the ED remained "crowded" on Monday.
He urged people seeking non-urgent care to consider alternatives such as the walk-in centres, or after-hours GP services, including CALMS and the National Home Doctor Service.