I don't see that we can have that data yet, nor can it be answered simply. In Wuhan, Italy and New York when ICUs were being overwhelmed with patients, and there was a ventilator shortage, then only the most sick were being invasively ventilated, and others were left to die. Or, ventilators were split so that each patient shared the same settings which is not ideal. Or, patients were not being ventilated early enough after a failure of (high flow nasal cannulae) HFNC and were switched to CPAP/BiPAP. And there is controversy whether HFNC should be used in an ideal situation as COVID-19 patient can crash easily requiring urgent intubation so it may be better to switch to IV early.
Then you have to look at the patient demographics. Italian patients tended to be older with more co-morbid conditions whereas younger patients needing ventilation were more likely to survive. In an elderly population needing invasive ventilation the mortality rate was higher than 90%
The most recent data is from New York and given the constraints above
Mortality rates for those who received mechanical ventilation in the 18-to-65 and older-than-65 age groups were 76.4% and 97.2%, respectively. Mortality rates for those in the 18-to-65 and older-than-65 age groups who did not receive mechanical ventilation were 19.8% and 26.6%, respectively.2
Settings are fairly standard and include standardized ventilator protocols and proning.
Update from New York study 27 April 2020
It found that, overall, about 20% of Covid-19 patients treated at Northwell Health died, and 25% of those placed on ventilators died. A ventilator is a device that forces air into the lungs of patients who cannot breathe on their own because of severe pneumonia or acute respiratory distress syndrome.3
- April 7, 2020: https://www.medscape.com/viewarticle/928259
- April 22, 2020: Presenting Characteristics, Comorbidities, and Outcomes Among 5700 Patients Hospitalized With COVID-19 in the New York City Area