The new valves were printed in 24 hours and provided to a hospital in Brescia that had run out of them.
The hospital reportedly had 250 coronavirus patients in intensive care and the valves are only designed to be used for eight hours at a time.
Ventilators are an essential part of the life support machines used in intensive care departments, mechanically moving air into and out of the lungs of people unable to breathe by themselves.
Covid-19 causes coughs, fever and in some cases breathing difficulties, making the availability of functioning ventilators a major priority.
The valves connect the breathing apparatus to the oxygen cylinders.
According to the BBC, the 3D-printed valves cost less than €1 (90p) each to produce and the prototype, made by company Isinnova, took three hours to design.
The 3D printed version was rapidly rolled out when the original supplier of the plastic valves said they were unable to produce the numbers of parts required in such a short time.
After learning the hospital in Brescia lacked these essential parts, local journalist Nunzia Vallini put the hospital in touch with Isinnova chief executive Cristian Fracassi.
Dr Fracassi and mechanical engineer Alessandro Romaioli reportedly raced to the hospital, examined the existing parts the hospital lacked, and returned three hours later with a working prototype.
“They tested it on a patient and they told us that it worked well and so we ran again back to our office and we started to print new valves,” Mr Romaioli told the BBC.
They have now teamed up with another company called Lonati to produce greater quantities of the valves.
A second hospital in Italy has reportedly been in touch requesting more valves.
“We haven’t slept for two days,” Dr Fracassi told the BBC.
“We’re trying to save lives.”
In China, thousands of pairs of protective goggles for those healthcare workers on the frontline fighting the disease have also been 3D printed to speed up supply from 600 pairs a day being produced to over 2,000 at peak production.