It has just gone 6pm in Auckland Hospital's emergency department and Laura, a fresh-faced young nurse, seems ready to tear her hair out in frustration.
Amidst the busy chatter, beeping, and bleeping of the department's many monitors, she is raising her voice above the voice of a loud patient who insists he wants to go home, despite a gaping wound on his forearm that needs surgery.
"Everyone has told you what's happening three times already," she says firmly, as the 20-something man, who has learning disabilities after a head injury as a toddler, wanders the corridor partly dressed, shouting that he intends to leave. Now.
In a room next door, a man with mental health problems, a near-fatal blood alcohol level and a gash in the back of his head is threatening to harm himself and others.
He has already threatened one doctor that he will stab him in the neck. A burly security guard is stationed outside his room to keep an eye on him.
Laura returns to the staff base area, clipboard in hand, and rolls her eyes as the yelling continues.
She's drawn the short straw tonight.
This side of the department includes two rooms allocated to mental health patients, a side-room for terminal cases, and the infection control area, in which patients who are vomiting and have diarrhoea are kept separate from others "with their own toilet".
It's been a tough 12 hours. "But there you go," she says with a tired smile. "All part of the job."
It is a fairly typical Tuesday night in the city ED. Here, more than 55,000 patients are seen every year, in a hospital which increasingly reaches red and purple alert, signalling an urgent lack of bedspace.
Strangely, Tuesday is one of the busiest days for the department.
It is the day when the hospital absorbs a new intake of patients for the coming week, but hasn't quite discharged the patients left over from the weekend.
It means patients who need admitting to hospital for further treatment are often left waiting in ED for a bed in a ward, sometimes for more than 24 hours.
The backlog means when the emergency department is full, newly arrived patients can be left stranded in the ambulance bay or waiting room while the doctors try to make space and keep beds free for the most urgent of cases.
It has been a particularly busy day for ED clinical director Dr Tim Parke, 45, who has run this section of the hospital for the past three years.
A gregarious Irishman, Parke has practised emergency medicine for the past 20 years after graduating in Edinburgh in 1986.
His job is a mixture of clinical and administrative work.
Tonight, his role is clinical and he has two registrars, a house surgeon, and various specialist registrars reporting to him.
He also has a medical student to guide through her first taste of practical work.
His role includes taking on his own patients to treat (a total of 126 will pass through the department in this one 12-hour shift), consulting on the other doctors' patients, checking that staff have had meal breaks, and keeping an eye on the waiting times of those who arrive looking for help.
No two shifts in ED are the same and it's that variety that Parke likes. "Emergency medicine people are famously impatient and like to move quickly on to the next thing," Parke says of his own personality. "I just like the buzz of the front door, really."
An alarm sounds for one of the resuscitation beds where an elderly man is struggling to breathe, despite having an oxygen mask.
The staff work quickly but calmly around him as his lungs rasp and arms flail slightly by his sides. The monitors and machines seem panicked in their flurry of noise, but the team convey merely a sense of urgent purpose.
Parke quickly absorbs the notes on the patient, making suggestions for treatment and offering advice, completely engrossed in the current situation. Slowly, the man's breathing evens, his muscles relax and he leans back, exhausted.
Emergency department staff don't run as much as in the choreographed world of ER, and there is a notable lack of George Clooney-esque medics kissing nurses in the storage closets. However, when the reception desk's panic alarm suddenly roars through the main area, half the team race into the waiting room to check their frontline staff are safe. It is a false alarm tonight, although about once a month it's the real thing. Parke says:
"They get a lot of verbal abuse that we wouldn't set the alarm off for but we have had recent incidents of someone trying to strangle one of our doctors with his ID badge [chain], one of our nurses had her thumb broken, hot drinks were thrown through the grille at the triage nurses, and one of the security guards was stabbed [in the hand] with a pen-knife."
Parke hasn't been assaulted in the past few years although he has been punched in the past and was once picked up and held by his throat.
This is a place of raw emotions and the job can be dangerous. Parke says it is a kind of line between civilisation and "things going really badly.
"You're at that sort of frontier - buffering the chaos of the health needs of the community from the relative organisation within the hospital."
Many of those who turn up look like those oft-neglected by society. "The most disadvantaged people - the homeless, drug addicts, alcoholics, people with mental health issues - everyone deserves a fair crack at the whip and a decent level of healthcare," Parke says.
"A lot of people who work in emergency medicine feel passionately about that, that this is the backstop where people who are sick and ill come to for help, and that it should be free at the point of care.
"It should be accessible, be human in privacy and dignity, and also be of a very high standard."
It's finally time for Parke to take a break. He's worked seven-and-a-half hours straight. He says the best analogy to describe his role is that of a performer spinning plates - he has several in the air and has to shake the sticks every now and then to keep them all turning.
So what happens when one of the plates crashes to the ground? "I've made bad decisions," Parke says, solemnly. "To a certain extent, if a doctor makes no mistakes they are probably not seeing enough patients.
" Because it is impossible to work within the framework of risk we work in and not have any degree of error."
Aside from keeping the error level as low as possible, the most important thing is to never make the same mistake twice, he says.
Already tonight he has asked both registrars to conduct further scans or examinations of at least three people who may fall into the category of seven or eight particularly common ED mistakes.
According to Parke, these include misdiagnosis of chest pains as indigestion rather than a heart problem; thinking someone has a kidney stone when they have a burst aorta; or assuming that symptoms as vague as fever and body-aches are simply flu when they could be signs of meningitis.
Most worrying tonight, though, is the difficulty of diagnosing head trauma in someone who has been drinking. Parke is careful about this and asks a registrar to get a brain scan of a woman who has fallen over after drinking at a family party, but who doesn't seem injured after an examination.
On receiving the results, his concern was justified.
The woman has a brain haemorrhage and is immediately sent to the neurology ward for treatment. The balance always falls in favour of safety because Parke is the one who must ultimately live with the decision.
"I do go home at the end of certain shifts and worry about the decisions I've made. Occasionally, that worry will extend to me calling a patient up a couple of days later and ask how they're getting on, just to make sure."
Still, the focus for much of the evening appears to be getting patients out of the emergency department as quickly as possible. It's not as callous as it sounds - Parke knows no patient will be happy simply sitting unwell for hours and no doctor would want that.
So he is unhappy to learn that one patient has waited for 23 minutes in the ambulance bay, and the time in the waiting room has risen to more than an hour for many of the walking wounded.
Within half an hour the department is almost at the level of a purple alert, a patient-overload warning that indicates that almost all of the 55 clinical beds are taken, and extra measures may have to be taken, such as calling in extra staff.
Parke tries his best to clear space by booking patients into other wards, or discharging those who are safe to leave, but for the next 15 minutes the situation is critical.
Then, suddenly, a wave of patients leaves for other wards, the staff breathe a collective sigh of relief, and the beds start to fill all over again.
A 70-year-old woman with a fractured wrist has been waiting patiently for Parke in the plaster room for more than an hour.
X-rays have shown the bones will need to be reset to give her maximum flexibility in the wrist joint.
After injecting a local anaesthetic into the limb, Parke watches as registrar George pulls the arm straight with a very small, but slightly sickening, crunch.
The woman feels some pain but refuses to complain to Parke, whom she thanks profusely for his efforts.
"I trust you," she says, beaming at him as the nurse puts on a plaster cast. "You're the doctor, I should support you because you help me."
Parke doesn't finish his shift until 2.30am the following morning after seeing another six or seven patients, and continuing to shift people around the hospital to ensure extra bed space.
He says the worst stress comes from the sheer numbers of patients competing for a bed. "It's gridlock," he sighs. "The stress of making decisions quickly and correctly is what we signed up for, in a way.
"But the stress of having to deal with a completely gridlocked and overloaded department is not what we signed up for, and because that increases our stress and our error rate, that is something that needs to change."
Parke thinks there is a need for a nationally agreed policy on how hospitals deal with an overloaded emergency department.
He would also like to see a countrywide agreement on the target length of stay in an ED, which he believes should be six hours in total.
Currently, people spend an average of seven-and-a-half hours in Auckland Hospital's ED.
The situation is getting worse, particularly during the busy winter months, and should be given as much priority as reducing waiting lists for elective surgery, he claims.
But in the meantime, he is concerned that the public may think his department is unable to care for them. He and his team are dedicated to ensuring those frontiers are always open for those most in need.
"It's important to get across that we do take this seriously," he explains. "People [medical staff] don't just sit about, we really do try... and if we don't mop up a lot of this stuff, then nobody does, really."