Extra staff are being recruited and beds reopened as the health service struggles to cope with a surge in emergency admissions that saw more than 400 patients on trolleys yesterday.
The winter vomiting bug and respiratory illnesses were being blamed for the increased numbers attending emergency departments. Yesterday's figure of 385 patients on trolleys was the highest since last spring and did not include data from two hospitals, in Louth and Monaghan.
The biggest number was recorded in Beaumont Hospital in Dublin, which had 38 patients on trolleys yesterday morning. The Mater recorded 29 trolley waits, Cork University Hospital 28 and the Mid-Western Regional Hospital in Limerick 27.
Portiuncula Hospital in Ballinasloe had no patients on trolleys while St James's in Dublin, the largest hospital in the State, had just six.
HSE director designate Tony O'Brien told health managers the levels of waiting in emergency departments was unacceptable and immediate action was required.
In a memo to managers and clinical directors, Mr O'Brien said a series of measures needed to be started immediately.
"It is imperative that we take all necessary steps today as we head towards the weekend and the weather outlook turns colder, possibly presenting new challenges in demand."
The memo proposes a series of measures to deal with the crisis, including increases in ward rounds, a review of plans to handle the next six-monthly rotation of junior doctors due to take place next week and a review of theatre capacity to ensure the system can cope with any increase in fractures arising from cold weather.