There have been 130 assaults on staff at the mental health inpatient unit at Rotorua Hospital in the past five years, with one involving a staff member being punched in the head and jaw.
A nurses' union is "very concerned" about assaults and their psychological effect on nurses, and says some assaults go unreported.
But the Lakes District Health Board says the safety of staff remained "paramount" and it had several safety measures in place to protect staff and patients.
Data obtained under the Official Information Act from Lakes District Health Board showed there were 130 recorded assaults on health staff at its Whare Whakaue acute inpatient unit between January 1, 2017 and December 31, 2021.
One of the most serious assaults which required police to attend happened in June 2017 when a staff member was punched in the head and jaw.
Another serious assault occurred in September 2020 when a staff member suffered a concussion and was "badly bruised" and had a "superficial cut".
Of the 130 assaults, 41 required "external agency input" such as the police, Accident Compensation Corporation, the district inspector, the director of area mental health services and next of kin.
Data obtained under the Official Information Act from the Bay of Plenty District Health Board showed there were 176 recorded assaults on health staff at its two mental health inpatient facilities in Tauranga and Whakatāne in the same five-year period.
The New Zealand Nurses Organisation mental health nurses section chairperson Helen Garrick said the committee had been "very concerned" for "quite a long time" about assaults and the psychological effect they had on nurses.
From what had been reported to the committee, Garrick said it could leave nurses feeling "undervalued" if they thought the fact they had been assaulted was not important.
Garrick said the organisation had done Official Information Act requests for all DHBs about assaults on staff and got data back from most of them. Their situations were "very similar".
Speaking generally, Garrick said many assaults on nurses go unreported.
"There seems to be a sense that reporting will get you nowhere.
"I do understand people just get sick of it ... and just get on with things.
"And then maybe later regret not reporting it because they realise that sometimes injuries or traumas may sneak up on you later on."
Garrick said there were several reasons behind assaults occurring, including that people in the mental health inpatient units were "very unwell".
"When people are distressed they become fearful and reactive to anything that happens around them because they're frightened ... and sometimes that comes in the form of an assault."
Staffing was another common issue, in that there was a lack of "experienced knowledgeable skillful staff".
"We have a mental health worker shortage."
The presence of alcohol and methamphetamine also contributed to the number of assaults, she said.
A Lakes District Health Board spokesperson said ensuring the unit had appropriate staffing levels was a "key focus" and it was "actively recruiting" more mental health staff, particularly nurses and support workers.
The spokesperson said many patients were "very unwell" when admitted to mental health units.
"Staff need to balance creating a therapeutic environment - one that helps people get well - with an environment that is safe for everyone involved: the patient, other patients and visitors, and staff."
Safety measures in place included providing security when deemed "necessary", using an escalation plan when a "high-risk situation" was identified and having an updated duress system, the spokesperson said.
Staff were also trained using simulation, which meant role-playing for simulated situations. An "immediate debriefing" would take place after incidents.
The spokesperson said mental health units used risk assessment tools linked to clinical pathways. This helped clinicians work more closely with a distressed person to ensure they had the support and tools to manage distress and agitation before it escalated into violence or aggression.
Interventions included education, supportive listening, talking therapies, medication, sensory modulation and other more culturally specific interventions.
When situations got out of hand, staff called for security, the hospital duty manager and other senior staff available to assist.
"Police are called if there is a serious threat of harm to others. Any assault is reported to police."
Mental health intervention was done according to Safe Practice Effective Communication training.
The training supported staff in observing and practising de-escalation techniques and tools before situations with aggression or violence arise. It included training in restraint minimisation, communication, de-escalation, collaborative ways of working and the teaching of personal restraint and breakaway techniques.
Staff were also trained in self-awareness of how they may present when in escalating situations, the spokesperson said.
Bay of Plenty Police district prevention manager inspector Stephen Bullock said police worked closely with DHB staff when responding to incidents at DHB premises.
Officers approached all incidents of physical assault on a case-by-case basis using best practice as per police training.
They used an operational threat assessment tool - threat, exposure, necessity, response - to assess and decide on appropriate action, Bullock said.
"We acknowledge that being arrested and placed in custody can be a stressful experience, and people's behaviour can become volatile and unpredictable. Procedures have been developed to minimise the risks to everyone concerned."
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