How much air can be infused into a patient before they become symptomatic ? Does it vary from patient to patient depending on what other problems they have ( like COPD or CHF) ?

What is the sensitivity of air detectors on today's dialysis machines ?

I have done a literature search but have not been able to find a definite answer.

I DOUBT YOU WOULD FIND MUCH ABOUT AIR EMBOLI. MODERN AIR DETECTORS ARE EXTEREMELY SENSITIVE AND THE EXACT SPECIFICATIONS OF EACH INDIVIDUAL DEVICE UTILIZED IN VARIOUS HEALTHCARE SETTINGS WOULD HAVE TO BE SUPPLIED BY THE DEVICE MANUFACTURER. WITH THE ADVENT OF SUCH DEVICES, AIR EMBOLI ARE RARE, IF AT ALL.
AS TO HOW MUCH AIR, THAT ALSO WOULD NOT NECESSARILY BE READILY AT HAND SINCE AIR EMBOLI ARE RARE. I WAS INSTRUCTED THROUGH BOTH MY HEMODIALYSIS AS WELL AS INTRAVENOUS BACKGROUND THAT AT LEAST 30-60CC OF AIR WOULD HAVE TO BE INFUSED INTO A PERSON TO CREATE SYMPTOMS OF EMBOLI (SEVERE HYPOTENSION, BRADYCARDIA, DIFFUSE PERSPIRATION, ETC) AND PLACING THE PERSON IN REVERSE TRENDELENBERG POSITION AND ACTIVATING EMS SYSTEM IS THE DIRECT COURSE OF ACTION.
HOPE THIS ANSWERS SOME OF YOUR QUESTIONS RELATED TO AIR EMBOLI.