Sydney's lockout laws should be extended across the entire state to reduce alcohol-fuelled violence, according to the New South Wales Nurses and Midwives' Association (NSWNMA).

Key points: St Vincent's Hospital in Darlinghurst has saved $500,000 in medical costs since the lockout laws came into effect

St Vincent's Hospital in Darlinghurst has saved $500,000 in medical costs since the lockout laws came into effect The Nurses' Association wants the laws applied state-wide to ensure all bars and clubs are on even economic ground

The Nurses' Association wants the laws applied state-wide to ensure all bars and clubs are on even economic ground The inquiry will deliver its report on Sydney's nightlife economy to the Premier next month

A parliamentary inquiry into the city's night time economy, which started this week, heard half of Sydney's venues had closed since the changes in 2014, which prevent people entering a venue in an entertainment precinct after 1:30am and mandate last drinks at 3:00am.

Entertainers told a hearing on Monday that Sydney's international reputation has been badly damaged.

But in its submission, the NSWNMA said there have been important public health benefits, with not one alcohol-related assault death at St Vincent's Hospital in Darlinghurst since the laws rolled out.

In the first year of the lockouts there were also 25 per cent fewer presentations for serious alcohol-related facial injuries at St Vincent's Hospital, and over two years the number of facial trauma surgeries required because of assault more than halved.

One nurse wrote that the "severity" of aggression significantly decreased since 2014.

Another said: "Prior to the laws coming in I was very much considering leaving emergency nursing … I would 100 per cent be opposed to relaxing or removing the lockout laws".

The NSWNMA said the lockout laws have already saved $500,000 at St Vincent's Hospital alone, due to a reduction in ambulance and medical costs linked to fewer surgeries for fractures.

There was no evidence the problem has been moved elsewhere, in particular to the Royal Prince Alfred Hospital in Camperdown.

"This isn't a unique success story for Sydney", the submission said.

"Following the implementation of similar measures in Newcastle CBD, the city saw similar improvements."

NSWNMA acknowledged opposition from the alcohol industry in central Sydney which is financially disadvantaged by the lockout laws and said the rules should be rolled out across NSW so that no particular 'hot spots' are unfairly disadvantaged.

A 'conveyer belt of carnage' from the Cross

In a separate submission, Paul Preisz, the director of emergency at St Vincent's Hospital, put it simply — "the lockout laws have worked".

"When change happened, we saw it straight away and it's maintained change," he said.

"The idea of winding back to where we were in 2012 seems like a terrible idea."

The St Vincent's submission stated that pre-lockout laws, clinicians likened the constant flow of injured from Kings Cross to the Emergency Department as a "conveyor belt of carnage".

Their submission said Emergency Department nurses are already overworked and there was insufficient funding to cover paramedics, hospital staff and beds if the night time economy is expanded.

"Community safety must be the priority," it said.

"The true cost to the community of increased demand for public services must be factored into any economic argument about the expansion of the night time economy."

The parliamentary committee chaired by Liberal MLC Natalie Ward will conduct two more hearings and report back to the Premier next month.