Difficulty in recruiting doctors and nurses means staffing levels in Blackpool's hospitals are 440 people short of what is needed.
In a recent single 12-month period, 540 staff left the hospital trust which employs around 6,725 people in total.
A meeting of the Blackpool Teaching Hospitals Board heard the situation was putting pressure on finances with spending on agency staff amounting to £2m instead of an expected £1m.
This is the main reason for a current £1.5m overspend on the Trust's annual budget.
Meanwhile a report to members of the board warned: "The Trust is at a significant risk due to the inability to attract, recruit and retain a high calibre and skilled workforce in areas which are hard to recruit, eg nursing and midwifery, medical and dental and allied health professionals."
Now a new recruitment and retention strategy has been launched on the Fylde coast to try and address some of the issues.
Aims include offering staff more flexible working arrangements, intervening early if people are unhappy in their roles and more support of those who are under-performing.
Kevin Moynes, joint director of human resources at the Trust, said: "We ask a lot of people why they leave, and often they don't want to say while others have already left before we ask.
"Sometimes it's people having incompatible relationships with managers. So it's important we have mediation and that we get there early, and say 'how are you feeling?'"
Trust chairman Pearse Butler added: "We have to retain our existing staff. We have to treat them better and make them think this is a great place to work.
"We are looking fundamentally at changing the culture of this organisation."
The most recent figures show there are currently 440 vacancies across the hospital Trust, including 227 in nursing.
A total of 540 staff left in a single year between August 2018 and August this year. Reasons included childcare issues and incompatible working relationships.
The board also agreed to invest £520,000 in strengthening nurse leadership at Fylde coast hospitals which it is hoped will drive forward improvement in care and underpin long term recruitment and staff retainment programmes.
Recruitment within the NHS is a national problem with more than 100,000 clinical vacancies nationally.
In the North West there are around 7,260 clinical vacancies, 2,845 of which are in nursing and midwives.