An unpublished Health Service Executive workforce plan warns of an urgent need to recruit more staff into the National Ambulance Service (NAS).
The document, seen by RTÉ News, says that at present recruitment efforts are being surpassed by service demands.
It also warns that by 2027, less than 40% of life-threatening calls will be responded to within 19 minutes due to a lack of resources.
Recruitment is currently proving problematic for the NAS, with the workforce plan concluding that the pandemic has led to a "shift in priorities" and contributed to the "great resignation of healthcare workers".
In a statement, the Health Service Executive said the NAS currently employs approximately 2,000 staff of which 1,700 work as paramedics "and there has been a 14% increase in demand since 2019 with more people calling 112/999 than ever before".
It continued: "The Workforce Plan recommends 2,161 additional staff by 2027. In relation to current staff retention NAS can confirm that 70 employees departed the service in the first six months of 2022 when 58 new staff were recruited.
"The National Ambulance Service is actively recruiting new staff and launched an advertising campaign for Qualified Paramedics, Student Paramedics and Intermedicate Care Operatives in March 2022.
"This campaign was successful and NAS has been oversubscribed for the September 2022 intake of Student Paramedics into its NAS College campuses in Tallaght, Ballinasloe and Tullamore."
Meanwhile, Parliamentary Questions provided to Sinn Féin show a fall in average response times during the first six months of 2022, compared with the first six months of last year.
According to the data, more than 50% of so-called Delta calls, which are life-threatening but non-cardiac related emergencies, were responded to within 19 minutes last year.
However, this fell to 42% for the first six months of this year.
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While Echo calls, which are cardiac and respiratory related emergencies, were responded to within 19 minutes 79% of the time in the first six months of last year, that fell to 72% in the first half of 2022.
According to Health Information and Quality Authority (HIQA) guidelines, Echo calls should be responded to within 19 minutes 80% of the time, while Delta calls must be responded to in that timeframe 50% of the time.
Sinn Féin's Spokesperson on Health David Cullinane said that major efforts are required in relation to recruitment, with a doubling in training capacity needed over the next five years.