Surrey and Sussex Healthcare NHS Trust, Portsmouth Hospitals University NHS Trust, United Lincolnshire Hospitals NHS Trust and the East of England Ambulance Service have all now taken the decision to escalate their status to critical.
Each of the trusts have cited record numbers of people attending A&E, calling NHS 111, accessing GP services and calling 999 as reasons why they have moved to a critical incident. Declaring the status allows a trust to instigate additional measures to protect patient safety.
The announcements come as the chairman of the British Medical Association in Scotland has said the NHS is "broken" and cannot survive in its current state.
Dr Iain Kennedy said Scotland faces "crises across workload, workforce, working conditions, pay and pensions".
In his view there needs to be a national discussion about the future of the health service, adding that the Scottish government must address shortfalls in the number of doctors and GPs.
He said: "All the statistics tell us that it’s a desperate state of affairs. Things are as bad, or worse, than they have ever been. Winter is a meaningless term now - this entire year has been winter.
"But looking beyond the statistics, looking at the people behind the statistics, the picture being painted is even more grim and concerning."
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What is a critical incident?
When a critical incident is declared it allows a trust to put in place extra measures to safeguard the health and safety of patients.
Among these provisions is the option to seek mutual aid, cancel all training to allow for the redeployment of all clinical staff, no longer take bookings for urgent non-emergency transportation and increase third-party provider provision.
Surrey and Sussex Healthcare NHS Trust said it had declared a critical incident so it would be able to take "additional steps to maintain safe services for our patients and help us cope with the growing pressures".
Portsmouth Hospitals University NHS Trust explained it was left with no choice but to adjust its status as "demand for emergency and urgent care is far outstripping the capacity available in Portsmouth and South-East Hampshire".
Meanwhile, an internal memo from United Lincolnshire Hospitals NHS Trust revealed that a critical incident had been declared due to a "high number of attendances" and "low level of discharges" over the past few days.
According to the East of England Ambulance Service, it too had moved its alert level to critical to "ensure our resources are focused on patients with the greatest need, as well as allowing us to access wider support from our health and care partners".