A critical incident has been declared at Nottingham University Hospitals trust due to an increase in patients with respiratory issues putting pressure on A&E capacity.
The trust said it has seen 'significant demand' on services over the last week, which saw patients face 'unacceptable and lengthy waits' in corridors.
A critical incident, which is usually declared when the level of disruption means that A&E departments are no long able to deliver critical services safely, is the highest alert level used by the NHS.
It is the second time this year the hospital has been force to declare a critical incident.
Andrew Hall, chief operating office at NUH, said: 'We have been working tirelessly all week to mitigate the pressures we are currently seeing, but this has not had the desired impact, and so declaring a critical incident is necessary to protect patient safety.'
He also apologised to patients who have experienced longer than usual waiting times.
The NUH boss added that patients who could safely go home were staying in hospital longer than they needed to - making it harder for staff to meet increasing demand.
They are now hoping to send 200 patients home by the end of the day.
Queen's Medical Centre University Hospital, part of the Nottingham University Hospitals NHS Trust is one of the many hospitals that has been affected
Hall urged families and carers to prioritise getting patients home safely. even if this meant having to leave work early.
It comes as the hospitals - including Queen's Medical Centre and Nottingham City Hospital - have reported a significant increase in patients with respiratory issues, following a surge in norovirus and flu cases at the beginning of the year.
More than half of adult beds are currently occupied by patients over 80-years-old, who are more vulnerable to infection at this time of year.
To help alleviate pressure and meet demands sooner, the trust has asked some of its 19,000 staff to work additional shifts and are creating more beds.
However, Halls message remained clear as he asked people to 'consider carefully whether or not they need to attend A&E.'
As such, the Nottingham-based trust will continue to 'see the sickest patients first.'
Nottingham University Hospital trust is one of the biggest NHS trusts in the UK, and the largest employer in Nottingham.
The trust previously declared a critical incident last month due to a rise in demand, norovirus cases and staff sickness.