Coma (1978) on Netflix

Dr Susan Wheeler is devastated when her best friend is pronounced brain dead after minor surgery at her hospital. Looking at the records, Susan finds that over the previous year a number of other fit young people have ended up the same way. She comes across two similarities to the cases - they all took place in the same operating theatre, and all the comatose bodies were moved to somewhere called the Jefferson Institute. She continues to investigate increasingly alone, starting to wonder if she can trust even her own boyfriend.