POCUS can be an extremely helpful tool in approaching the patient with undifferentiated shock. The RUSH exam (or more properly, the RUSH protocol, it’s actually a set of POCUS exams packed together for efficiency and ease of memory) was developed for use in the ED, but it is equally useful in the ICU. In the original protocol, the exams are done in a specific order based on the likelihood of the cause. However, in the ICU I often adapt it based on what I already know about my patient (in a patient who just had a big belly surgery I might start with the abdomen, for example). Additionally, this exam is a good starting point for novice sonographers as it incorporates lots of different exams and doesn’t require the use of advanced techniques (like M-mode, color, or measurements). Scott Weingart over at EM:CRIT does a nice overview here, including some recent updates from Jacob Avilla from 5-Minute Sono and some good resources.
Here is a card I made for my students to help use the findings from RUSH to differentiate shock states.