Last month was the worst ever July for overcrowding in emergency departments (EDs), nurses have said.
The Irish Nurses and Midwives Organisation (INMO) said 9,439 patients were forced to wait without a bed this month, an increase of 33pc compared to July 2018.
When records began in 2006, there were 3,460 patients on trolleys in July, just over a third of this month's figure.
Among the 9,439 patients were 45 children.
University Hospital Limerick was the worst offender, with 1,293 patients waiting for a bed this month.
It was followed by Cork University Hospital, which had 1,079 people waiting on trolleys; University Hospital Galway with 707; University Hospital Waterford with 590, and Dublin's Mater University Hospital with 560 waiting for beds.
INMO director of industrial relations Tony Fitzpatrick said each day there were hundreds of patients "languishing" in corridors waiting for a hospital bed.
"Currently over 700 patients cannot be discharged from hospital," he said.
"In the meantime, hundreds of front-line nursing and midwifery posts are currently vacant due to the HSE's dysfunctional and bureaucratic employment control processes.
"Vital roles across all services, at all grades, in all hospitals are left unfilled. This has direct negative consequences.
"We expect increased demands on the health service in winter, but now even summer sees patients crammed into corridors on trolleys."
University Hospital Limerick apologised for the "distress and inconvenience" that the extended waiting times have caused.
Nursing Home Ireland (NHI) slammed the HSE as completely "failing to heed" its projections.
"We are now seeing manifestation in our acute hospitals of State failure to appropriately resource care in the community," said NHI chief executive Tadhg Daly.
"We warned at the start of the year the very marginal increase in numbers to be supported by Fair Deal over the course of 2019 would manifest in severe pressures being placed upon our acute hospitals."