Juan Manuel Correa, the driver seriously injured in a Formula Two crash which killed Anthoine Hubert in Belgium last weekend, has been placed in an induced coma.
Correa, 20, is in a critical but stable condition after being diagnosed with Acute Respiratory Distress Syndrome.
The American broke both his legs and sustained spinal cord damage after the 160mph accident last weekend in Spa-Francorchamps.
He was transferred from Liege to a hospital in London where he is now in intensive care.
A statement released by Correa's family, read: "As time has progressed, new complications have surfaced as a consequence of the massive impact he (Correa) suffered in Belgium.
"On his arrival to London, Juan Manuel was diagnosed with Acute Respiratory Distress Syndrome. This is an injury considered common in high-impact accidents such as this one. Unfortunately, this injury resulted in Juan Manuel falling into Acute Respiratory Failure.
"Juan Manuel is currently in an Intensive Care Unit that specialises in respiratory injuries. At this point of time he is an in induced state of unconsciousness and under ECMO (Extracorporeal membrane oxygenation) support. Juan Manuel is in critical but stable condition.
"We are confident that our son will surprise us like he always does with his tremendous fighting will and strength and will recover completely."
The Formula Two drivers returned to the track for the first time since Hubert's death here in Monza on Friday.
Lewis Hamilton posted a message to Instagram on Friday in memory of the French driver.
He wrote: "Still thinking of Anthoine. It feels like the world has just moved on already but you are very much still in my thoughts."
Hubert was killed when he hit the barriers at Eau Rouge and rebounded back on to the track before Correa collected his car at high speed.