Conditions at all three acute hospitals in the region have worsened.
Mullingar Regional Hospital has recorded its busiest conditions in 10 years.
The annual Trolley Watch Report from the Irish Nurses' and Midwives' Organisation shows 2,598 people were left waiting on trolleys in the hospital in 2021 - a figure not seen since 2011.
Tullamore and Portlaoise Hospitals also recorded a rise, after a fall in numbers waiting in 2020.
A total of 2,323 patients were left waiting on trolleys in Tullamore in 2021 - up over a thousand on the previous year - while Portlaoise rose by almost 70 to 549.
Assistant Director of Industrial Relations with the INMO, Albert Murphy says the problem creates significant pressure points for staff: