My Mother Is In The Hospital. She Developed A Bad

My mother Is In the hospital. She developed a bad sinus cold, and has not been able to get any good amount of sleep In almost 2 weeks. She drank a lot of water to counter her cough, but her legs swelled a lot. She was admitted to the hospital. She Is 85 years old, has congestive heart failure, with kidney Issues and a liver Issue as well. She Is very weak, and has coughed a good amount. Today, when I visited her In the hospital, she started coughing, and then reared her head back like she was trying to yawn. All of a sudden her mouth stood open, and her eyes stared straight up. and she became unresponsive. I called for the help, and the doctors were able to wake her up by speaking to her, and patting her face. They did a number of tests on her, and she did not appear to get hurt by this situation, but my question Is, why happen to her when she blanked out?