Visits to NSW hospital emergency departments in the months before this year's COVID-19 outbreak were the highest since records began and ambulance wait times the worst, new data shows.
It comes as the state's hospital system braces for the impact of the worsening coronavirus crisis predicted to peak in October, with health staff warning the system could be overloaded.
There were 806,728 emergency department visits in NSW between April and June, the highest since reporting began in 2010, the state's latest Bureau of Health Information report reveals.
The number of ED patients receiving treatment within the clinically recommended window plummeted well below pre-pandemic levels, with fewer than seven in 10 patients starting treatment on time and spending four hours or less in the ED.
A fall was also recorded in the number arriving by ambulance who had their care transferred to the hospital on time.
About 79 per cent of ambulance arrivals had their care transferred from paramedics to hospital staff within 30 minutes, down almost 9 per cent on the same quarter in 2019.
Similarly, the sickest of ambulance patients spent record times waiting for paramedics to arrive during the quarter.
NSW Health deputy secretary Wayne Jones said the figures were not unexpected, and showed the system bouncing back from the impacts of the first COVID-19 wave and national halt of elective surgery in 2020.
Ambulance activity was at record levels in April to June 2021, with 329,709 ambulance responses including 8367 to the highest priority patients with life-threatening conditions.
The highest priority cases were on average left waiting 8.3 minutes, the longest median response time since records began.
Less than two-thirds of those patients were seen within the 10-minute target, a record low.
Median response times for emergency and urgent cases were also the worst on record, at 13.4 and 24.9 minutes respectively.
Health Services Union NSW secretary Gerard Hayes said the data shows more staff are desperately needed, even without outbreaks.
"Yet now we confront the furious heat of the worst health crisis this state has faced," he said in a statement.
"Even after that passes, the pent-up demand of people returning to pubs, restaurants and sporting fixtures mean there will be no let up for our paramedics and hospital workers over the summer.
"It simply won't do to rely on the goodwill of permanently fatigued, overstretched workforce."
NSW Nurses and Midwives' Association secretary Brett Holmes said the data shows the quality of health care was already being compromised.
Opposition health spokesman Ryan Park backed their calls for more staff, saying the report showed health system was already "on its knees" before the outbreak.
Recruitment of extra paramedics in particular is gallingly slow.
"When you call triple-O and you ask for ambulance and it's an emergency, you cannot wait half an hour to access that," he told reporters on Wednesday.
"At the moment, that's what's happening in some parts of southwest and western Sydney."
It wasn't all bad news, with the data showing enormous elective surgery waitlists declined dramatically and a record 19,113 babies were born in NSW public hospitals.
The 64,599 elective surgeries performed was the highest of any April-to-June quarter, and record numbers were seen across all urgency categories.
Almost nine in 10 elective surgeries were performed on time, a substantial improvement, and 16,000 fewer people were on the waiting list at the end of the quarter compared to the same time last year.
Only 2108 had waited longer than the clinically recommended time frame, down from 10,563 in 2020.
Australian Associated Press