Currently, there are over 100 vacant nursing positions. More than half are permanent vacancies which have been advertised but not filled.
The work-to-rule, which started on Monday, followed a breakdown in talks between the parties at the WRC last Friday.
INMO industrial relations officer in the northeast Tony Fitzpatrick said the work-to-rule will continue and could be escalated.
He said bed capacity remained an outstanding issue that needed to be resolved because nurses needed to be able to deliver safe care.
“We are willing to reconvene at the WRC, primarily to talk about bed capacity because, pending the recruitment and retention of staff, the hospital needs to curtail the service to reflect the staff that they have,” said Mr Fitzpatrick.
“We have said that our dispute remains in place and we willing to engage with the WRC in the morning [today] to see if we can get a resolution.”
He said there were no immediate plans to escalate the work-to-rule that would be reviewed if no progress was made in the talks.
It could be escalated further, if necessary.
Mr Fitzpatrick said Our Lady of Lourdes was not the only acute hospital in the country experiencing a significant staff shortage.
“The Government and the HSE needs to address the shortage of nurses or else there will be a significant curtailment of services throughout the country.”
Nurses at the Drogheda hospital are limiting themselves to core care duties.
They are not attending non-clinical meetings, inputting computer data or answering telephones.
Speaking on RTÉ radio yesterday, Mr Fitzpatrick said patients would have better care during the work-to-rule because nurses would be able to concentrate on taking care of them rather than doing other work.
A spokesperson for the RCSI Hospitals Group would only confirm yesterday that both the hospital and the INMO had been invited to engage with the WRC this morning.
The group confirmed on Monday the hospital would implement a contingency plan to minimise, in so far as possible, the impact of the industrial action on patient care.
It said the emergency departments would remain open over the course of the industrial action to continue to meet patients’ urgent medical needs.
However, under the contingency plan, all planned, non-urgent, elective procedures, were cancelled yesterday. An exception was made for cancer-related procedures.
It said the hospital continued to be an extremely busy one with 52,000 attendances per year, 13,000 emergency admissions, and more than 22,000 inpatient discharges.
The HSE confirmed yesterday that critical posts would be exempted from a recruitment “pause”.
It also said existing contractual agreements and agreed funded posts would be honoured.
It said hospital groups were asked to submit a funded workforce plan and, pending agreement and approval of the plans, each had been advised of the need to pause on any further payroll additions.
“While existing contractual commitments will be honoured, the groups have been advised that no further offers should be made without the signed agreement of the hospital group chief executive officer,” the HSE stated.