What Is The Cause For Feet Turning Blue With Kidney Failure?

Hi I have a 42 year old son we just took to springfield mo. his wife saw him yesterday morning in a chair at 8:00 am and thought he was asleep took her daughter to school and came back home around 10:30 and could not wake him up and his feet were turning blue called an ambulance and got him to hospital after the dropped him started an air way and have got no response from poking and prodding him told us he had phonommia andcould not give us any idea why his kidneys was shutting down