Witnesses described scenes of chaos at several hospitals as relatives tried to move patients in the dark to clinics with better emergency power facilities.
Marielsi Aray, a patient at the University Hospital suffering from an aggravated infection, died at dawn on Friday after her respirator stopped working, her uncle Jose Lugo said.
"The doctors tried to help her by pumping manually, they did everything they could, but with no electricity, what were they to do?" a distraught Lugo told AFP.
Wiping away tears, he described how his niece had been brought to the bottom of the 11-story Caracas hospital on a stretcher after the elevators stopped working.
"They got her to the ground floor where they had electricity, and connected her up but because of the transfer and the waiting and everything, she faded away," he said.
The power cut compounded an atmosphere of chaos that has gripped the South American nation, already battered by economic collapse, since opposition leader Juan Guaido declared himself interim president in January and asserted that President Nicolas Maduro
Venezuela's attempt at producing a Muammar Qadaffy...was no longer legitimate.
Lugo said another patient had died in the parking lot in the chaos of the blackout, as people "tried to get sick people out of here and move them to other places where they had generators and equipment that would work."
"The screaming was brutal," he said.
EMERGENCY GENERATORS FAIL
Backup generators at the JM de Rios children's hospital in downtown Caracas failed to kick in when the blackout hit, said Gilbert Altuvez, whose eight-year-old boy is among the patients.
"The night was terrible. Without light. Total madness," he said.
When more generators were brought to supply emergency power, they weren't enough. "None managed to supply it completely," said Altuvez, 38.
Emilse Arellano said urgent dialysis for her youngest child had to be canceled Friday, after a night during which staff worked by the light of cellphones.
"The children were very scared," she told AFP.
The putrid odor of rotting flesh hung around the entrance to Caracas' main Bello Monte morgue on Friday where the refrigeration system had stopped working.