Health Service Executive CEO Bernard Gloster has said delays in hospitals, particularly in Limerick, were unacceptable.
He said however that in the first nine weeks of this year attendances at emergency departments across the country had risen by just under 13% and in Limerick by 16%.
Speaking on RTÉ's Morning Ireland, Mr Gloster said: "Those kinds of numbers do not mean anything to people when they are waiting, but we have seen certainly post Christmas a very significant change in attendances at hospital.
"That pushes us to look exactly what we are doing in our hospitals but also outside in primary care and in the community, but certainly those types of numbers are not acceptable."
His comments come as elective surgery is to resume at all hospitals in the University of Limerick group after two days of cancellations.
It follows a meeting of the UL hospital management team to review planned surgery lists and decide on scheduled surgery cutbacks and deferrals to help manage high numbers of seriously ill patients attending at the region's only emergency department at UHL in recent days.
Around 450 patients who were due to attend at hospitals across the UHL group for elective procedures have had their surgery cancelled since the beginning of the year.
But the hospital group said that 1,499 scheduled procedures did go ahead over the same period and that it met all its targets for scheduled care under the National Waiting List Action Plan last year.
Emergency and time-critical surgeries continued at UHL and were not deferred.
The hospital group said it regrets that any patient has their scheduled procedure deferred and these patients are being rescheduled as soon as possible.
Fianna Fáil TD for Limerick Willie O'Dea said the UHL currently does not have the capacity to deal with the size of the population it services, and that a "recent configuration report indicated that we need at least another 100 beds, that might become outdated by this time next year because of an increasing and increasingly ageing population."
