Less than 24-hours after Caitlin Cruz arrived at Westmead Children's Hospital in October 2016 she died from flu complications.

Paramedic Julia Hickman on Monday told the inquest into her death how she had to repeatedly advocate for Caitlin's need for urgent medical attention.

"We thought her condition warranted immediate attention and she shouldn't go into a waiting room," Ms Hickman told the court.

After one nurse noticed Caitlin was receiving fluids through a cannula in her arm she agreed she "had to" have a bed, Ms Hickman said.

On Monday Caitlin's mother said many people had been fighting for answers and hoped the inquest would shed some light on what happened to her daughter.

"We are not doing this just for Caitlin, we're doing this for her little sister who will never know her," she told reporters outside Lidcombe Coroners Court.

Caitlin's father Mitch said he wanted due processes to be examined so no other child "falls through the cracks".

In her opening statement to the court counsel assisting the coroner, Maria Gerace, said if proper medical therapy had been implemented earlier it may have prevented the serious complications that arose and ultimately took her life.

A report prepared by the Health Care Complaints Commission found some medical staff who attended to Caitlin failed to recognise the seriousness of her condition.

Caitlin was three years and nine months when she and her younger sister returned from preschool to their Lidcombe home with fevers.

After regular doses of Ibuprofen failed to alleviate her systems, Caitlin was taken for a medical examination but continued to deteriorate.

On October 22 at Myhealth Rhodes Medical Centre, Caitlin collapsed in her father's arms before GP Sumeena Qidwai screamed at her assistant to call an ambulance.

"She was floppy and blue and her face and body looked pale," she told the court.

"I was extremely concerned she's probably the sickest child I have ever seen."

Caitlin was resuscitated and taken to hospital without a referral note as Dr Qidwai felt her life was in imminent danger, prioritising her ambulance expedition instead.

Dr Qidwai said Ms Hickman appeared dismissive and refused to take the business card of Caitlin's regular doctor.

But the paramedic said Dr Qidwai originally told her the patient had "come up well" and failed to relay certain details including the fact that oxygen had been administered.

She agreed there was no time for a referral letter to be written.

After Caitlin was conveyed to hospital she presented with seizure-like activity and an electrocardiogram was organised.

The ECG could not be performed until three-and-a-half hours later because the machine was out of battery, and the results were misinterpreted by a junior doctor with no oversight from a senior practitioner.

The HCCC found it unacceptable that this emergency investigation took so long.

The inquest continues before Deputy State Coroner Derek Lee.

Australian Associated Press