Seven-year-old Aishwarya Aswath went from sitting up in the resuscitation bay to collapsing and her heart stopping in just 15 minutes, an inquest into the little girl's death has heard.
Dr Michael Francis Hale took part in attempts to revive Aishwarya, which saw doctors perform CPR for 40 minutes in a bid to restart her heart.
Dr Hale said he suspected Aishwarya was in shock as she deteriorated quickly in the resuscitation bay.
"She's gone from a position to where she was sat up, to not being able to do so," Dr Hale said.
"I would say that's (15 minutes) particularly rapid."
The inquest has heard children compensate very well when they have sepsis, but their decline can be sudden.
Sepsis hard to detect
Aishwarya was somewhat responsive when she was triaged but became increasingly unwell as she waited almost two hours in Perth Children's Hospital for treatment.
The inquest is examining why medical staff didn't pick up on the severity of her illness sooner, and why her parents' concerns weren't listened to.
Experienced paediatric ICU practitioner Dr Jarrod Cross gave evidence that sepsis was a reasonably regular occurrence in children.
Dr Cross said children typically had better outcomes from sepsis, but it was "notoriously difficult to diagnose".
He said testing showed Aishwarya had severe acidosis – which reflected the severity of her illness.
The doctor said it would have taken at least several hours for it to build up to that level.
Dr Cross was asked by the family's lawyer Tim Hammond if a child presented with the constellation of symptoms Aishwarya did when assessed in the waiting room, it would trigger a potential sepsis diagnosis.
Dr Cross said it would, along with other potential diagnoses that fit with those symptoms.
Symptoms 'extremely rare'
Dr Hale was also asked what steps he took to be alert to the possibility of sepsis.
"I think we just have to do exactly that, keep it in the forefront of our minds," he told the court.
Dr Hale said he saw patients with sepsis once or twice a week, but never with such a severe case.
He said such symptoms presented "extremely rarely" and had only ever seen fatal cases in adults.
The inquest has heard Aishwarya was not continuously observed by the waiting room nurse who began her assessment but was called away to other duties, and the hospital was extremely busy.
Staff have told the inquest they thought the hospital was understaffed compared to patient demand.
Desperate resuscitation attempts
The two doctors were asked about the quality of the care provided to Aishwarya in the resuscitation area.
Dr Cross agreed with the proposition, put by the hospital's lawyer, that the resuscitation was of a very high standard and the team did everything it could to save Aishwarya's life.
Dr Hale gave evidence he managed to perform two difficult procedures – inserting a canula and intubation on the first go, something the hospital's lawyer pointed out was exemplary.
Dr Hale also told the court there had been objections from nursing staff about ceasing resuscitation efforts, but ultimately it was conceded there was nothing more that could be done.
"It's always hard when there are objections in a (resuscitation)," Dr Hale said, but added it was a valuable process to ask everyone in the room that night whether they thought any more could be done for her.
"I think it was good for them to have time to discuss this," he said.
"Everyone threw everything they had to try to save Aishwarya.
"From the time we entered resuscitation we did everything that we could.
"It was a very well-led, calm and coordinated approach."
