Medical errors

On 09/21/16 mom 78 had Lung Biopsy and Surgery,Diagnostics not Cancer Hospital stay about 1 week Nurses errors:Drainage hose not draining for 3hrs (per Doctor it could have cause mom to go into cardiac arrest-he sculled the nurse in front of everyone) and kidney problems.Foot machine battery dead, nurse takes It upon herself to say it’s not necessary it never replaces it with another one, mom starts to get pains in legs, other nurse says machine should have been replaced 5 hrs. later. Oxygen level went down to 87% per doctor’s instruction wasn’t supposed to go down below 92% (mom called me on my cell phone to tell me she couldn’t Breathe-I had to call the hospital) My email to a friend-These people are incompetent, doc said no lower than 92! I asked aren't they watching in the nurse station? She said yes, so I stated why did it go so low? There is no answer Mom had to do exercise breathing, and was doing it wrong, nurses not even aware. Back in Hospital 11/6, mercer died 11/19