Repeated requests by Launceston General Hospital staff to instigate a code yellow - signalling an internal emergency - have been ignored by senior management, unions say.
On Saturday there were 35 admitted patients waiting for in-patient beds at the hospital, and more than 50 patients waiting in the emergency department.
One patient spent 16 hours in a ramped ambulance, in what's been described as one of the worst nights in the hospital's history.
Health and Community Services Union state secretary Tim Jacobson said calls from staff to initiate a code yellow on Saturday night were shut down, despite unprecedented demand.
Code yellows are declared when a hospital has either an infrastructure or other internal emergency affecting its service delivery.
Tasmania Health Service executive director of operations for the North and North-West Eric Daniels said disaster codes were designed for specific events largely outside a facilities' control, which required a "system-wide response and delineated management protocols".
"Managing patient flow is not one of those events, and I am not aware of any conditions within the LGH that would have required any of these codes to be activated," he said.
However Australian Nursing and Midwifery Federation Tasmania branch secretary Emily Shepherd said staff were resorting to desperate measures in response to the hospital's "new norm", including treating admitted patients in the ED due to a lack of beds.
"A code yellow is not something staff take lightly. But the situation in the ED at the moment isn't something they should be faced with," she said.
The unions have called for an urgent review of the hospital's escalation protocols, including the implementation of a level four.
The Royal Hobart Hospital revised its escalation protocol to include a fourth level in 2017, in response to unprecedented demand - including increased rates of code yellows.
Meanwhile the LGH spent 70 per cent of time between June 2018 and January 2019 at level three of its three-level escalation protocol.
Mr Jacobson said it was clear the demand warranted urgent action.
"What's the point of having these internal systems, if the people who make the assessments aren't able to use it," he said.
Mr Daniels said Saturday's demand pressure was "appropriately and effectively managed by staff".
"I pass on my thanks to those whose commitment and dedication to ensuring the public receives the emergency care they require was again on display," he said.