She has lost her sight and suffered severe brain damage, but her parents Chris Squire and Stephanie Allan have not given up.
There was only a 50/50 chance their baby girl would survive having her tube taken out, and even if she did her outlook was still bleak.
"If she does get through this, and they are monitoring her, she should be okay to live for another few months," Allan told the Herald earlier this week.
"We can go home with this machine and that machine, and they will monitor that.
"We can provide her with the most love she can get. We can give her a better farewell than she can get in hospital."
Doctors believe that Chrissa has a rare genetic condition called malignant hyperthermia, but there had been no previous indication of it because neither parent is aware of the condition in their families.
She was born on February 16 with Pierre Robin Syndrome, which gave her an unusually small chin and consequent obstruction of the airway caused by backwards displacement of the tongue.
About three weeks after she was born, doctors also discovered a large hole in her heart.
She was allowed to go home on May 6, but her parents had to feed her via a tube through her nose, and were told that they might have to keep doing that for two or three years until her chin grew enough for her to eat normally.
On September 16 she had to go back to hospital with bronchiolitis and, later, pneumonia. She was given an oxygen mask to increase the air flow through a nasal tube, and the crisis was caused by vomiting inside the mask.
Her paediatrician Dr Nicola Austin said Chrissa's reaction against the anaesthetic was "totally unpredictable".
