Aishwarya Aswath's body was so ravaged by infection she stood little chance of survival without immediate treatment from Perth hospital staff, an inquest has heard.
Seven-year-old Aishwarya died of sepsis on Easter Saturday last year after being left in a waiting room at Perth Children's Hospital for more than 90 minutes.
An inquest is examining why the severity of her condition was not recognised after she presented with a fever, vomiting and diarrhoea.
Deputy state coroner Sarah Linton has been told there was intense demand on emergency department staff, including a junior waiting room nurse who was unable to monitor the girl because she was repeatedly called away on other duties.
That nurse did not consider sepsis, despite observing Aishwarya to have an elevated heart rate, respiratory rate and temperature, and to be floppy and grunting in pain.
Infectious diseases expert David Speers on Wednesday said those symptoms were collectively "pointers that would usually initiate a sepsis response".
He agreed Aishwarya's chances of survival would have increased if she had received antibiotics and fluids immediately upon presentation.
But the girl had faced the "perfect storm" of an extremely high bacterial load and the onset of streptococcal toxic shock syndrome which was evident when resuscitation efforts commenced.
Even with earlier intervention, "those two factors would have both made it less likely for Aishwarya to survive".
"I can't say that Aishwarya would have definitely survived if things were done earlier," Dr Speers told the inquest.
"This is a rare but terrible disease that progresses in this way."
Aishwarya was pronounced dead around 9pm, having succumbed to an infection related to group A streptococcus.
Nurses who saw Aishwarya earlier in the night believed she had gastro and Dr Speers agreed her symptoms were consistent with the viral illness.
He said identifying more sepsis cases would require screening more children with viral symptoms, most of whom would not have the condition.
"This involves resourcing, it requires a more thorough assessment more often for more children in the emergency department and that comes down to the number of doctors and nurses you have available," he said.
Staff shortages meant clinicians may not have appreciated how concerned Aishwarya's parents were.
"If the same concerns are expressed to three different people and those three different people don't know that it's been expressed to the other two, then it will appear less critical to them," Dr Speers said.
Aishwarya was given a triage score of four - the second-least serious category - by a nurse who observed her solely through a screen.
Expert pediatrician Sathiaseelan Nair told the inquest the triage layout at Perth Children's Hospital had not been fit for purpose and a more thorough assessment may have led to a better outcome.
Dr Nair said Aishwarya's symptoms upon presentation were "not typical of acute gastro" and questioned whether the views of her parents had been given sufficient weight.
"I am certain Aishwarya's parents knew something was wrong with her in terms of her behaviour. I am convinced of that," he said.
The inquest continues.
