Typically every 5 years you would see updated info on CPR and first aid released by ILCOR which is an international group that includes American Heart Association and American Red Cross plus many top level healthcare professional as well as other related organizations.
More recently, ILCOR has been puting out yearly updates to the protocols but this time around they really put out a lot of information on the research and best practices as well as dispelling the myths that still many lay rescuers think work – which I normally have to address in my classes.
Here’s the link to the most current first aid information available – they are not guideline changes just information of what they reviewed. https://eccguidelines.heart.org/circulation/aha-red-cross-first-aid-guidelines/part-15-first-aid/
To make sense of all this for you is the instructors job, hopefully they do it in a way that makes it easy to undertand and remember. I hear stories from many students saying “my last instructor didn’t talk about that” or something along those lines so make sure you know what will be covered before you take the class – AND BE READY TO ASK A LOT OF QUESTIONS!