Blue lips...no test

Hi. Alex ended up not getting her MRU test done yesterday. During the first round of sedation Alexandria cried and held her breath (which she often does at home). Her oxygen levels dropped and her lips turned blue. This happened twice. After the second time we were informed that they can not take a chance sedating Alex and that she will need to be under general anesthesia rather then sedation. The difference between the two is that during sedation the patient breaths on his or her own - it is a step below general anesthesia. During general anesthesia the patients system is so slowed down that breathing must be done for them through a machine. Apparently when a baby holds their breath during crying they are supposed to turn red, not blue. This may be common sense but we are so used to Alexandria's lips turning blue when she holds her breath while crying that we assumed that was normal. What we need to do now is to have Alexandria's cardiologist take a look at her to make sure this is not a heart issue; especially because Alex is an ex-cardiac baby. The attending sedation doctor sent the cardiologist and email and I made an appointment for him to see Alex on the 16th of this month. After that we will need to reschedule the test; this time with general anesthesia instead of sedation. Weather or not Alex will need cardiac anesthesia remains to be seen. She had regular anesthesia for her Mic-Key button surgery and did fine...We are not sure what is going on. Your prayers regarding Alexandria's heart, kidneys, all the appointments and tests are much appreciated. Thank you.