This story is part of a series: Inside Ireland's Covid Battle
Staff in intensive care units deal with life and death situations every day of their lives.
The Intensive Care Unit in St James's Hospital is no different.
"When you come into ICU, you never know what you're going to be faced with. ICU nurses go towards the fire, rather than away from it," one ICU nurse told RTÉ.
But the onset of Covid-19 has added another layer of complexity.
In May, during filming in St James's non-Covid ICU, it suddenly emerges a patient who had previously tested negative for Covid-19 on three occasions has now shown up as positive.
"This patient had three prior swabs which were negative, and by swabs, I mean tests for Covid which were negative, and he deteriorated and ended up going on a ventilator. The first set of tests after that confirmed that he is now positive - he's acquired that while been in hospital," Intensive Care Consultant and ICU Director Dr Enda O'Connor explains.
Instances of hospital acquired Covid-19 is a reality management have had to accept.
"I have no doubt patients did contract Covid-19 in the hospital," says Ann Dalton, Deputy CEO.
"I think our focus because it was a new virus was to mitigate against that, but we were dealing with a virus that had no treatment, it had no vaccine and still hasn't so all that has to be taken into account."
In this case, the fact the patient was in a non-Covid ward for a number of days before being confirmed with the virus has serious ramifications.
"The implications are really quite significant for the Intensive Care Unit because it means that the staff who were looking after that patient for the last day or two potentially would have been exposed to a patient who is Covid positive, but also the patients around him are at risk and they're known as what we call contacts," Dr O'Connor adds.
At a crisis management meeting, it's decided to swab all nurses and doctors working in the unit to try to prevent the virus from spreading, meaning up to 170 nursing staff and approximately 50 medical staff will be tested.
Patients who were in the ward with the confirmed case must be relocated immediately.
"We'll get everybody out and get the room changed," ICU Consultant Dr Elizabeth Connolly explains.
"Then we're going to start taking some of the patients we know are swabbed negative into the main unit but it means you're moving a lot of patients all around the place. Now we have a cohort of patients who are very stable and who in fact would have gone to the ward but now they're all Covid contacts, so we can't get enough single rooms on the ward for them, so what we do is we cohort them in a group of four and we'll manage them here."
It's worrying news for non-Covid ICU patients like Sean Connaughton and Frankie Quinn.
Both men have had tracheotomies and cannot speak so they communicate with nurses via written messages.
On hearing that he's been in contact with a positive Covid-19 patient, Sean Connaughton writes that he feels deflated, like he has taken one step forward and two steps back.
The men are swabbed and wait nervously for their test results.
This time it's good news and both have tested negative.
Visibly emotional, Frankie Quinn communicates that he is "happy". While for Sean Connaughton his negative swab means he can progress forward and continue with his recuperation.
Stories from the series
Inside Ireland's Covid Battle
Behind the Mask
Inside One Dublin Hospital's Covid Battle
The last line of defence: Inside St James's ICU
A mirror to society: The ED during Covid
'The burden of death': Covid Inpatients
Mortuary witnessed 'major increase' in bodies
The 'terrifying' reality of ICU
RTÉ Investigates: Inside Ireland's Covid Battle
This story accompanies new documentaries from RTÉ Investigates going behind the scenes at St James's Hospital as it fights against Covid-19.
'Inside Ireland's Covid Battle' watch now on the RTÉ Player