> I need some help in understanding the concept 'point in time'. As far > as I understand it now the completion date/time of an event (f.i. a > blood pressure measurement) is registered as a point in time in the > event section of the archetype.
yes, that's my understanding as well. > Thing is that I expected to find an entry field where I can enter > that particular date and time. In the EHR_IM I found the Action > class (p.71) which purpose seems to be to capture/record those points > in time, is I figured that's the place to be. well, there is a 'time' field in Action which is where you would record the time of an action. But blood pressure is an observation, and unlike Action, all observations are modeled as a HISTORY of events. So in OBSERVATION, we find a HISTORY that has an 'origin' time and also contains a set of time EVENT's. Each EVENT also has a 'time' field (with some restrictions on how it relates to 'origin' in the containing HISTORY). However, you will rarely find any reference to one of these fields in an ADL document because these fields are generally unconstrained (i.e you wouldn't write an archetype that said the blood pressure had to be measured at 03-06-2007). You will find that the 'offset' field is often used - this is defined as the difference in time between the EVENT and the base time in the HISTORY. It can be used to model EVENT's that must occur at set times after the 'origin' of the HISTORY (apgar etc). INTERVAL_EVENT can be used to record fancy averages over time etc. (I don't write archetypes so take this with a grain of salt! It's my understanding from a technical background, not a clinical background) Andrew
