The doc has decided to give me propofol during my colon test. how do they no how much to give what if i stop breathing?

Propofol: They have protocols on how and how much Propofol to give. They also have protocols to address issues of breathing arrest. If you've had troubles with Propofol administration in the past or allergy to it, you will need to alert your doc prior to administration.

Monitoring: Some form of IV sedation is usually given for endoscopic procedures. Propofol is used by some physicians. Assuming you are having the procedure in an endoscopy center or hospital, you will be monitored closely with heart tracing, pulse oximetry, and direct observation by the nurse and physician. They are trained to respond to emergencies and have appropriate resuscitation equipment available.