It has been revealed that 9,864 people aged 75 or older were on trolleys in emergency departments for longer than 24 hours in the first eight months of the year.
The figures have been released to Fianna Fáil's health spokesperson, Stephen Donnelly.
Deputy Donnelly has said the figures "represent a serious indictment of Fine Gael's management of the public hospital system in this country".
The numbers are an increase of more than 650 on last year - when 9,206 people aged over-75 had spent longer than 24 hours on a trolley.
Commenting on the figures, Mr Donnelly said: "2018 is already far worse than last year, and I really do fear for the coming winter.
"I fully expect the total number for this year to exceed 14,000 - a shocking statistic in itself but even worse when we consider that these are our parents, our aunts and uncles left lying, often in a very vulnerable state, on uncomfortable and unsuitable trolleys."
He added that best practice, based on a 2012 HIQA report, is that total patient time spent in an emergency department should be six hours or less.
"I am deeply worried and concerned for the public hospital system as we move towards winter proper.
"The winter crisis is now a 10 month of the year emergency."
He also criticised Health Minister Simon Harris Harris as "absolutely woeful and negligent" in preparations for dealing with this issue.
"High demand for unscheduled care"
In a response, Minister Harris acknowledged the distress overcrowded emergency departments cause to patients, their families and frontline staff working in very challenging working conditions.
The Health Service Executive (HSE) said this year has been characterised by "high demand for unscheduled care, particularly among the over-75 age group."
It said by the end of September, total attendances were up by 3.6% and admissions up by 2.0% - compared to the same period in 2017.
For those over 75, attendances were up by 5.7% and admissions up by 5.1%, compared to the same period in 2017.
It said this increased demand was "further exacerbated" by the severe weather associated with Storm Emma earlier this year.
It also said preparations and planning for winter have already begun at hospital and local level.
"The Department of Health is working with the HSE to ensure that these local and regional plans are consolidated and supported through policies and plans at national level to ensure the most effective response to the winter challenges to unscheduled care provision."
While an additional €10m in funding is being provided this year, as part of Budget 2019, to prepare for and manage the expected peak in demand for health services in the winter ahead.
