Contingency arrangements have been put in place as Middlemore Hospital is hit with a record demand for care across the hospital's services.
Dr Vanessa Thornton, acting chief medical officer for Counties Manukau Health, said the DHB had taken steps, including providing extra staff and additional beds in wards, but could not anticipate the sudden spike in demand.
"Last week we saw record numbers of patients coming into our emergency department, many with underlying medical conditions, including respiratory related illnesses which we often see in winter," Thornton said.
"Last Monday was a record number of patients for our emergency department and it did require us to call on extra staff to make themselves available to work across the hospital."
The department cared for over 350 patients on most days last week, with a record 393 seen on Monday, June 26.
"This is the highest and fastest rate of increase in demand for our services we have ever experienced," Thornton added.
People are being urged to see their family doctor in the first instance, and encouraged to ring the free Healthline on 0800 611116 for advice before heading to hospital.
"We are asking everyone to help keep our emergency department free for people with life threatening illnesses and injuries," said Thornton.
These include those experiencing chest pain, head injuries, severe blood loss or major accident.
Middlemore Hospital is the busiest of all hospital emergency departments in New Zealand, but Thornton said she was aware that other hospitals were also facing similar pressure with the onset of winter.
In the past four weeks, the hospital had seen 802 more patients compared to the same time last year. More than half were children.