The Irish Nurses and Midwives Organisation (INMO) has called for the management of the Mater Hospital in Dublin to urgently address condition's in its Emergency Department (ED).
The remarks come after the organisation said one patient was left waiting over 68 hours for a bed in the hospital.
Figures from the INMO found there were also 100 patients in the Mater's ED on Monday night.
"INMO members in the emergency department in the Mater are sounding the alarm on outrageous conditions they are currently working in," the organisation's assistant director of industrial relations Maeve Brehony said.
"These conditions have been allowed to fester in the emergency department leading to extreme burnout amongst nurses working in the Mater."
Ms Brehony highlighted the impact excess waiting times for hospital beds has on mortality is "widely proven", stressing that "management in the hospital cannot allow these conditions to continue".
"An immediate plan needs to be put in place to alleviate the pressure nurses and other healthcare workers are under in the Mater, including the use of capacity in the private hospital co-located on the Mater campus and the curtailment of non-urgent elective care.
"Bed availability should be prioritised for those who have been admitted and are being cared for on trolleys," she added.
Describing current trolley figures as "not normal or acceptable" for this time of the year, the INMO said the HSE's Emergency Taskforce should be convened urgently to discuss the issue of overcrowding at the Mater and in hospitals around the country.
