Multiple issues/questions:
1) http://build.fhir.org/medicationrequest0316.xml.html shows a rateQuantity = 20 minutes, which seems incorrect since 20 minutes is more like it is the infuse over time period (i.e. timing.repeat.duration). The spec says "when rate doesn't imply duration (e.g. 250mL/hour), then the timing.repeat.duration is needed to convey the infuse over time period"
2) The same example has dosageInstructions.text = "1.8 mg/kg IV infusion over 30 minutes every 3 weeks for 16 cycles" – which seems inconsistent to say infuse over 30 minutes in the text, but then show 20 minutes in the structured data.
3) I'd like to see an example for weight-based dosing and/ confirmation of the right way to represent the rate and doseQuantity from the example in https://gforge.hl7.org/gf/project/fhir/tracker/?action=TrackerItemEdit&tracker_item_id=8345 MedicationRequest ordered for a patient with weight of 50 kg. Base solution is D5W with bag volume = 500mL, Rate = 7.5ml/hr, infuse over 33.3 hours. Additive is Dopamine, 400mg, to be given at a rate of 4 mcg/kg/min, which for this specific patient would be 200 mcg/min.
* The prior tracker suggested that rate = active ingredient rate (200 mcg/min), but it could also be the bag rate (7.5ml/hr) – is there guidance on which is correct or preferred?
* doseQuantity is more controversial with the suggested 4 mcg/kg/min (since this feels like an alternative way to represent rate). Shouldn't the doseQuantity be more like 400 mg (= 4mcg/kg/min * 50 kg * 33.3 hours * 60 min/hr)?