NSW Bureau of Health Information data released on Wednesday shows the median ambulance response time for emergency cases was 14.4 minutes in the September quarter, making it the slowest response time of any quarter since official records began in 2010.
The Australian Paramedics Association said while the result reflected the pressures of the COVID-19 Delta outbreak, it also showed a broader trend of worsening results.
APA NSW President Chris Kastelan says 1500 more paramedics are needed to bring NSW into line with ratios in other states.
"In the event of something like a cardiac arrest, we're failing to get to four out of six patients on time. And minutes really matter in these situations.
"For years, NSW Ambulance has chosen to prioritise tightening the purse strings, and we're left with a service running on staff fatigue instead of proper resourcing."
The highest priority cases, known as P1A, had a response time of 8.8 minutes, which was also its slowest average time since reports started, the BHI quarterly report found.
P1A cases attended by an ambulance within a 10-minute window clocked in at 60.4 per cent, marking its lowest level on record.
There were 314,281 ambulance responses in the quarter, down from the record high of 329,709 in the preceding quarter.
BHI chief executive Diane Watson said while overall demand in NSW fell, there was an unprecedented number of life-threatening call-outs.
Dr Watson said there were 9322 responses to such patients, which was about 30 per cent more than in the corresponding period in 2019.
"The report shows the impact of lockdown restrictions on health system activity, particularly in metropolitan areas where the outbreak was concentrated," she said in a statement.
The report found emergency department attendances fell to 719,143 in the three months to September, down from 807,124 in the previous quarter.
It found 75 per cent of ED patients were seen on time.
"Although EDs were generally less busy ... Imminently life-threatening presentations were the highest of any July to September quarter since BHI began reporting in 2010," Dr Watson said.
Meanwhile, there were 44,768 elective surgeries performed over the quarter, down from a record 64,599 in the June quarter.
At the same time, elective surgery waiting lists ballooned with 92,276 people listed at the end of September. That was up from 85,296 in the three months to June, but below the mid-2020 peak of 101,024 cases.
The wait time for elective surgery also surged, with 6611 people waiting longer than the clinically recommended time-frame, up from 2108 in the previous three months.
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